LabWiseiOS/LabWise/ScanView.swift

import SwiftUI
import VisionKit
import Vision
import LabWiseKit
import FoundationModels

// MARK: - On-device AI label extraction

@Generable
struct LabelExtraction {
    @Guide(description: "The product or chemical name as it appears on the label, e.g. 'Neutralization/Binding Buffer (S3)' or 'Sodium Chloride'. Empty string if not found.")
    var chemicalName: String
    @Guide(description: "Physical state: 'Solid', 'Liquid', or 'Gas'. Infer from context clues like 'solution', 'buffer', 'powder', 'crystals'. Empty string if unknown.")
    var physicalState: String
    @Guide(description: "Vendor or manufacturer name, e.g. 'Sigma-Aldrich', 'Fisher Scientific'. Empty string if not found.")
    var vendor: String
    @Guide(description: "CAS registry number in the format XXXXXXX-XX-X, e.g. '7647-14-5'. Empty string if not found.")
    var casNumber: String
    @Guide(description: "Lot number or batch number, e.g. 'SLBH4570V', '123456'. Usually preceded by 'Lot', 'Lot#', or 'Batch'. Empty string if not found.")
    var lotNumber: String
    @Guide(description: "Expiration or use-by date found explicitly in the label text. Normalize to YYYY-MM-DD if possible, otherwise return as-is. Return empty string if no expiration keyword and date are present in the text — do not guess.")
    var expirationDate: String
    @Guide(description: "The amount or quantity of contents, as a number only, e.g. '5', '100', '2.5'. Empty string if not found.")
    var amount: String
    @Guide(description: "The unit for the amount, e.g. 'g', 'mL', 'kg', 'mg', 'L'. Empty string if not found.")
    var unit: String
    @Guide(description: "Catalog or product number, e.g. 'P0662-500G', 'S7653'. Empty string if not found.")
    var catalogNumber: String
    @Guide(description: "Your confidence in the chemical name extraction, from 0 to 100. Use 90+ only when the name is explicitly printed as a clear product/chemical name. Use 50-89 when inferred. Use below 50 if the text is ambiguous or noisy.", .range(0...100))
    var nameConfidence: Int
}

private let labelExtractionInstructions = Instructions {
    """
    You are a laboratory chemical label parser. Given raw OCR text lines from a reagent bottle label, \
    extract only the fields that are explicitly present in the text. \
    Do NOT invent, infer, or hallucinate values — if a field is not clearly visible in the provided text, return an empty string for it. \
    For expiration dates: look for keywords like EXP, EXPIRY, EXPIRATION, USE BY, BEST BEFORE followed by a date. \
    For amount and unit: look for a number directly followed by a unit like g, gm, mg, kg, mL, L, mol. \
    Set nameConfidence honestly: 90+ only when the product name is explicitly and clearly printed; 50-89 when inferred; below 50 when guessing.
    """
}

private let aiNameConfidenceThreshold = 60  // minimum confidence to apply AI-extracted name

// MARK: - Name arbitration

@Generable(description: "Result of comparing a chemical's IUPAC/systematic name against its label name")
struct NameArbitration {
    @Guide(description: "True if the labelName is a common name, abbreviation, or trade name that refers to the same compound as iupacName. False if they seem unrelated.")
    var isSameCompound: Bool
    @Guide(description: "True if labelName is a common/abbreviated name and iupacName is the corresponding systematic/IUPAC name for it. False if labelName is also a systematic or verbose name.")
    var labelIsCommonName: Bool
    @Guide(description: "The name to display: if labelIsCommonName is true use the labelName, otherwise use the iupacName.")
    var preferredName: String
}

private let nameArbitrationInstructions = Instructions {
    """
    You are a chemistry expert. You will be given two names for a chemical compound: \
    an IUPAC/systematic name from a database, and a name read from a product label. \
    Determine if they refer to the same compound, and whether the label name is a \
    common name or abbreviation (like 'CHAPS', 'HEPES', 'SDS', 'Ethanol') versus a \
    systematic/verbose name. Prefer the common name when it is clearly an established \
    abbreviation or trade name used in laboratory settings.
    """
}

@available(iOS 18.1, *)
private func arbitrateNames(iupacName: String, labelName: String) async -> NameArbitration? {
    let model = SystemLanguageModel.default
    guard case .available = model.availability else { return nil }
    let session = LanguageModelSession(instructions: nameArbitrationInstructions)
    let prompt = "IUPAC name: \(iupacName)\nLabel name: \(labelName)"
    return try? await session.respond(to: prompt, generating: NameArbitration.self).content
}

/// Strings the model emits when it has nothing real to return.
private let aiNullishValues: Set<String> = [
    "", "n/a", "na", "none", "null", "unknown", "not found", "not available",
    "not specified", "not present", "not visible", "not stated", "not given",
    "missing", "empty", "-", "—", "?", ".", "0", "00", "000"
]

/// Returns nil if the string is a model-generated placeholder rather than real data.
private func aiSanitize(_ value: String) -> String {
    let lowered = value.trimmingCharacters(in: .whitespaces).lowercased()
    if aiNullishValues.contains(lowered) { return "" }
    return value.trimmingCharacters(in: .whitespaces)
}

/// Validates and sanitizes a date string. Returns empty string if it doesn't
/// look like a real date (e.g. "0000-00-00", "1900-01-01", "9999-99-99").
private func aiSanitizeDate(_ value: String) -> String {
    let s = aiSanitize(value)
    guard !s.isEmpty else { return "" }
    // Reject zero/placeholder dates
    let stripped = s.replacingOccurrences(of: "-", with: "")
                    .replacingOccurrences(of: "/", with: "")
                    .replacingOccurrences(of: "0", with: "")
    if stripped.isEmpty { return "" }  // all zeros after stripping separators
    // Must contain a plausible 4-digit year (1900–2099)
    let yearRegex = try? NSRegularExpression(pattern: #"(19|20)\d{2}"#)
    let range = NSRange(s.startIndex..., in: s)
    guard yearRegex?.firstMatch(in: s, range: range) != nil else { return "" }
    return s
}

/// Validates a CAS number — must match the XXXXXXX-XX-X pattern.
private func aiSanitizeCAS(_ value: String) -> String {
    let s = aiSanitize(value)
    guard !s.isEmpty else { return "" }
    let range = NSRange(s.startIndex..., in: s)
    guard (try? NSRegularExpression(pattern: #"^\d{2,7}-\d{2}-\d$"#))?.firstMatch(in: s, range: range) != nil
    else { return "" }
    return s
}

/// Validates a numeric amount — must be a positive number.
private func aiSanitizeAmount(_ value: String) -> String {
    let s = aiSanitize(value)
    guard !s.isEmpty, let d = Double(s), d > 0 else { return "" }
    return s
}

/// Sanitizes a unit string — must be a known lab unit, not a filler word.
private let knownUnits: Set<String> = [
    "g", "gm", "mg", "kg", "ml", "ml", "l", "mmol", "mol", "ul", "µl", "oz", "lb"
]
private func aiSanitizeUnit(_ value: String) -> String {
    let s = aiSanitize(value)
    guard !s.isEmpty else { return "" }
    return knownUnits.contains(s.lowercased()) ? s : ""
}

// MARK: - Container type options

/// All container types available for the user to select.
let containerTypeOptions: [String] = [
    "Glass Bottle", "Plastic Bottle", "Vial", "Ampoule", "Flask",
    "Beaker", "Tube", "Jar", "Can", "Canister", "Drum", "Bag"
]



@available(iOS 18.1, *)
private func onDeviceLabelLookup(ocrLines: [String]) async -> LabelExtraction? {
    let model = SystemLanguageModel.default
    guard case .available = model.availability else { return nil }
    let session = LanguageModelSession(instructions: labelExtractionInstructions)
    let joined = ocrLines.joined(separator: "\n")
    let prompt = "Label text:\n\(joined)"
    guard var result = try? await session.respond(to: prompt, generating: LabelExtraction.self).content
    else { return nil }

    // Sanitize every field so callers never receive placeholders like "N/A", "0000-00-00", etc.
    result.chemicalName    = aiSanitize(result.chemicalName)
    result.physicalState   = aiSanitize(result.physicalState)
    result.vendor          = aiSanitize(result.vendor)
    result.casNumber       = aiSanitizeCAS(result.casNumber)
    result.lotNumber       = aiSanitize(result.lotNumber)
    result.expirationDate  = aiSanitizeDate(result.expirationDate)
    result.amount          = aiSanitizeAmount(result.amount)
    result.unit            = aiSanitizeUnit(result.unit)
    result.catalogNumber   = aiSanitize(result.catalogNumber)

    return result
}

// MARK: - Scanned item (one bottle's worth of data)

struct ScannedItem: Identifiable {
    let id = UUID()
    var chemicalName = ""
    var casNumber = ""
    var chemicalFormula = ""
    var molecularWeight = ""
    var vendor = ""
    var catalogNumber = ""
    var lotNumber = ""
    var concentration = ""
    var expirationDate = ""
    var physicalState = ""
    var storageDevice = "Glass Bottle"
    var amountPerContainer = ""
    var unitOfMeasure = ""
    var barcode: String?
    var percentageFull: Double = 50
    var thumbnail: UIImage?
}

// MARK: - Confidence accumulator

/// Tracks how many times a given value has been seen for a field.
/// A field "locks in" once the same value is seen `threshold` times.
private final class FieldAccumulator {
    private var votes: [String: Int] = [:]
    private let threshold: Int

    init(threshold: Int = 2) {
        self.threshold = threshold
    }

    /// Register a new observation. Returns the winning value if it
    /// has now reached the threshold, otherwise nil.
    func observe(_ value: String) -> String? {
        guard !value.trimmingCharacters(in: .whitespaces).isEmpty else { return nil }
        votes[value, default: 0] += 1
        if let (winner, count) = votes.max(by: { $0.value < $1.value }), count >= threshold {
            return winner
        }
        return nil
    }

    func reset() { votes = [:] }

    /// Best guess even before threshold (for live preview).
    var bestGuess: String? {
        votes.max(by: { $0.value < $1.value })?.key
    }
}

// MARK: - PubChem lookup

private struct PubChemResult {
    var iupacName: String?       // raw IUPAC/preferred name from props
    var commonName: String?      // best short synonym (e.g. "CHAPS", "HEPES")
    var chemicalFormula: String?
    var molecularWeight: String?
    var physicalState: String?

    /// The name to actually display: common name if one was found, otherwise IUPAC.
    var bestName: String? { commonName ?? iupacName }
}

/// Patterns that indicate a synonym is a database ID rather than a usable name.
private let synonymJunkPatterns: [NSRegularExpression] = [
    try! NSRegularExpression(pattern: #"^\d{2,7}-\d{2}-\d$"#),           // CAS number
    try! NSRegularExpression(pattern: #"^[A-Z]{2,}[:\-_]\d"#),           // DTXSID6…, CHEBI:…
    try! NSRegularExpression(pattern: #"^[A-Z0-9]{8,}$"#),               // InChIKey-style all-caps
    try! NSRegularExpression(pattern: #"(?i)InChI="#),                    // InChI strings
]

private func isJunkSynonym(_ s: String) -> Bool {
    let range = NSRange(s.startIndex..., in: s)
    return synonymJunkPatterns.contains { $0.firstMatch(in: s, range: range) != nil }
}

/// Returns the best human-readable synonym: shortest clean name that isn't the IUPAC name itself.
/// Prefers names ≤ 30 characters (abbreviations/common names) but will take up to 60 if nothing shorter exists.
private func bestSynonym(from synonyms: [String], iupacName: String?) -> String? {
    let iupacLower = iupacName?.lowercased() ?? ""
    let candidates = synonyms.filter { s in
        !isJunkSynonym(s) && s.lowercased() != iupacLower && s.count <= 60
    }
    // Prefer short names first (abbreviations like CHAPS, HEPES, SDS)
    if let short = candidates.filter({ $0.count <= 30 }).min(by: { $0.count < $1.count }) {
        return short
    }
    return candidates.min(by: { $0.count < $1.count })
}

private func pubChemLookup(cas: String) async -> PubChemResult? {
    guard !cas.isEmpty,
          let encoded = cas.addingPercentEncoding(withAllowedCharacters: .urlPathAllowed),
          let url = URL(string: "https://pubchem.ncbi.nlm.nih.gov/rest/pug/compound/name/\(encoded)/JSON")
    else { return nil }
    guard let (data, _) = try? await URLSession.shared.data(from: url),
          let json = try? JSONSerialization.jsonObject(with: data) as? [String: Any],
          let compounds = (json["PC_Compounds"] as? [[String: Any]])?.first
    else { return nil }

    var result = PubChemResult()

    // Extract CID for synonym lookup, plus formula/weight/state/IUPAC name
    var cid: Int?
    if let cidVal = compounds["id"] as? [String: Any],
       let cidCompound = cidVal["id"] as? [String: Any],
       let cidInt = cidCompound["cid"] as? Int {
        cid = cidInt
    }

    if let props = compounds["props"] as? [[String: Any]] {
        for prop in props {
            guard let urn = prop["urn"] as? [String: Any],
                  let value = prop["value"] as? [String: Any] else { continue }
            let label = urn["label"] as? String ?? ""
            let name  = urn["name"]  as? String ?? ""
            if label == "IUPAC Name", name == "Preferred" {
                result.iupacName = value["sval"] as? String
            }
            if label == "Molecular Formula" {
                result.chemicalFormula = value["sval"] as? String
            }
            if label == "Molecular Weight" {
                if let mw = value["fval"] { result.molecularWeight = "\(mw)" }
                else if let mw = value["sval"] as? String { result.molecularWeight = mw }
            }
            if label == "Physical Description" {
                let desc = (value["sval"] as? String ?? "").lowercased()
                if desc.contains("liquid") { result.physicalState = "Liquid" }
                else if desc.contains("solid") || desc.contains("powder") || desc.contains("crystal") {
                    result.physicalState = "Solid"
                } else if desc.contains("gas") { result.physicalState = "Gas" }
            }
        }
    }

    // Fetch synonyms to find common/trade name (e.g. "CHAPS" instead of the long IUPAC string)
    if let cid {
        if let synURL = URL(string: "https://pubchem.ncbi.nlm.nih.gov/rest/pug/compound/cid/\(cid)/synonyms/JSON"),
           let (synData, _) = try? await URLSession.shared.data(from: synURL),
           let synJSON = try? JSONSerialization.jsonObject(with: synData) as? [String: Any],
           let infoList = (synJSON["InformationList"] as? [String: Any])?["Information"] as? [[String: Any]],
           let synonyms = infoList.first?["Synonym"] as? [String] {
            result.commonName = bestSynonym(from: synonyms, iupacName: result.iupacName)
        }
    }

    return result
}

// MARK: - Regex extractors

private let casRegex = try! NSRegularExpression(pattern: #"\b(\d{2,7}-\d{2}-\d)\b"#)
private let lotRegex = try! NSRegularExpression(pattern: #"(?i)(?:lot|lot\s*#|lot\s*no\.?)\s*[:\s]?\s*([A-Z0-9]{4,})"#)
private let mwRegex  = try! NSRegularExpression(pattern: #"(?i)(?:M\.?W\.?|MW|Mol\.?\s*Wt\.?)\s*[:\s]?\s*([\d.,]+)"#)
private let sizeRegex = try! NSRegularExpression(pattern: #"\b(\d+(?:\.\d+)?)\s*(mL|ml|L|g|gm|kg|mg|oz|lb|gal|mol|mmol|µL|uL)\b"#, options: .caseInsensitive)
private let expRegex  = try! NSRegularExpression(pattern: #"(?i)(?:exp(?:iry|iration)?\.?\s*|use\s*by\s*|best\s*before\s*)(\d{1,2}[/\-]\d{4}|\d{4}[/\-]\d{2}(?:[/\-]\d{2})?|(?:jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)[a-z.]*\s+\d{4}|\d{4})"#)

private let knownVendors = ["Sigma-Aldrich", "Sigma Aldrich", "Aldrich", "Millipore Sigma",
                             "VWR", "Fisher", "Fisher Scientific", "Thermo Fisher",
                             "Acros", "Acros Organics", "BDH", "Amresco", "EMD",
                             "Alfa Aesar", "TCI", "Fluka", "J.T. Baker"]

private func extract(from lines: [String]) -> [String: String] {
    let full = lines.joined(separator: "\n")
    var fields: [String: String] = [:]

    func first(regex: NSRegularExpression, in text: String, group: Int = 1) -> String? {
        let range = NSRange(text.startIndex..., in: text)
        guard let m = regex.firstMatch(in: text, range: range),
              let r = Range(m.range(at: group), in: text) else { return nil }
        return String(text[r]).trimmingCharacters(in: .whitespaces)
    }

    if let cas = first(regex: casRegex, in: full) { fields["cas"] = cas }
    if let lot = first(regex: lotRegex, in: full) { fields["lot"] = lot }
    if let mw  = first(regex: mwRegex, in: full)  { fields["mw"]  = mw  }
    if let exp = first(regex: expRegex, in: full)  { fields["exp"] = normalizeDate(exp) }

    if let m = sizeRegex.firstMatch(in: full, range: NSRange(full.startIndex..., in: full)),
       let valRange = Range(m.range(at: 1), in: full),
       let unitRange = Range(m.range(at: 2), in: full) {
        fields["amount"] = String(full[valRange])
        fields["unit"]   = String(full[unitRange])
    }

    for vendor in knownVendors {
        if full.localizedCaseInsensitiveContains(vendor) {
            fields["vendor"] = vendor
            break
        }
    }

    // Catalog number: line matching vendor catalog patterns like "P0662-500G", "BDH9258-500G"
    for line in lines {
        let trimmed = line.trimmingCharacters(in: .whitespaces)
        if trimmed.range(of: #"^[A-Z]{1,4}\d{3,}-\d+[A-Z]*$"#, options: .regularExpression) != nil {
            fields["catalog"] = trimmed
            break
        }
    }

    return fields
}

private let monthNames: [String: Int] = [
    "jan": 1, "feb": 2, "mar": 3, "apr": 4, "may": 5, "jun": 6,
    "jul": 7, "aug": 8, "sep": 9, "oct": 10, "nov": 11, "dec": 12
]

private func normalizeDate(_ raw: String) -> String {
    let trimmed = raw.trimmingCharacters(in: .whitespaces)

    // Month-name formats: "Jun. 2018", "June 2018", "jun 2018"
    let monthNameRegex = try? NSRegularExpression(pattern: #"(?i)^([a-z]{3})[a-z.]*\s+(\d{4})$"#)
    if let m = monthNameRegex?.firstMatch(in: trimmed, range: NSRange(trimmed.startIndex..., in: trimmed)),
       let mRange = Range(m.range(at: 1), in: trimmed),
       let yRange = Range(m.range(at: 2), in: trimmed),
       let month = monthNames[String(trimmed[mRange]).lowercased()],
       let year = Int(trimmed[yRange]) {
        return String(format: "%04d-%02d-01", year, month)
    }

    // Numeric formats: MM/YYYY, MM-YYYY, YYYY/MM, YYYY-MM, YYYY-MM-DD
    let parts = trimmed.components(separatedBy: CharacterSet(charactersIn: "/-"))
    if parts.count == 2 {
        if parts[0].count <= 2, let month = Int(parts[0]), let year = Int(parts[1]), year > 2000 {
            return String(format: "%04d-%02d-01", year, month)
        }
        if parts[0].count == 4, let year = Int(parts[0]), let month = Int(parts[1]) {
            return String(format: "%04d-%02d-01", year, month)
        }
    }
    if parts.count == 3, parts[0].count == 4 {
        return "\(parts[0])-\(parts[1].padLeft(2))-\(parts[2].padLeft(2))"
    }
    return trimmed
}

private extension String {
    func padLeft(_ length: Int) -> String {
        count >= length ? self : String(repeating: "0", count: length - count) + self
    }
}

// MARK: - Scanner view model

@Observable
@MainActor
final class LabelScannerViewModel {
    // Session state
    var isScanning = false       // live scanning session active
    var scannedItems: [ScannedItem] = []
    var showReview = false

    // Current item being built
    var current = ScannedItem()
    var isLookingUpPubChem = false

    // Live preview fields (best-guess, updates every frame)
    var previewFields: [String: String] = [:]

    // Profile (pre-filled on location fields)
    var piFirstName = ""
    var bldgCode = ""
    var lab = ""
    var storageLocation = ""
    var contact = ""

    // Accumulators for current item.
    // CAS uses a higher threshold — a partial OCR read (e.g. missing last digit) looks valid
    // to the regex but is wrong. More votes = more confidence before committing.
    private var accumulators: [String: FieldAccumulator] = [
        "cas": FieldAccumulator(threshold: 3),
        "lot": FieldAccumulator(threshold: 2),
        "mw":  FieldAccumulator(threshold: 2),
        "exp": FieldAccumulator(threshold: 2),
        "amount": FieldAccumulator(threshold: 2),
        "unit":   FieldAccumulator(threshold: 2),
        "vendor": FieldAccumulator(threshold: 2),
        "catalog": FieldAccumulator(threshold: 2),
    ]

    // Tracks the last CAS number used to kick off a PubChem task.
    // If the accumulator later converges on a different CAS, we cancel and retry.
    private var lastPubChemCAS: String = ""
    // True if the last PubChem lookup returned no result (so AI should keep running)
    private var pubChemFailed = false

    // Tracks which fields have been confirmed by the regex accumulator (2+ OCR votes).
    // AI results never overwrite these — regex-confirmed data is more trustworthy for structured fields.
    private var lockedByRegex: Set<String> = []

    // Barcode: first hit wins (no need for accumulation)
    private var barcodeHandled = false
    private var pendingBarcode: String?   // barcode seen before scanning started
    private var pubChemTask: Task<Void, Never>?

    // On-device AI extraction
    var isRunningAI = false
    private var aiTask: Task<Void, Never>?
    private var allOCRLines: Set<String> = []   // accumulates unique lines seen across frames
    private var aiTriggered = false
    private var aiNameConfidence: Int = 0        // confidence of the currently applied AI name
    private var lastAITriggerTime: Date = .distantPast  // wall-clock time of last AI trigger
    private var aiSatisfied = false              // true once names have been reconciled — no more AI re-triggers
    // Incremented on every resetScanState(). Async tasks capture this value at launch;
    // if it differs when they complete, the result belongs to a previous scan and is discarded.
    private var scanGeneration: Int = 0
    // True once the user has picked a container type for this scan.
    var containerTypeSelected = false
    // True when the container type picker sheet should be shown.
    var showContainerTypePicker = false

    // Debug info shown in banner
    var debugBarcode: String = "—"
    var debugOCRLineCount: Int = 0
    var debugPubChemName: String = "—"     // raw name returned by PubChem
    var debugAIName: String = "—"          // name extracted by on-device AI (with confidence)
    var debugArbitration: String = "—"     // result of name arbitration

    var debugAIQueryCount: Int = 0         // how many times the AI extraction has been triggered
    var allOCRLinesCount: Int { allOCRLines.count }
    var showDebug: Bool = false

    private let profileClient = ProfileClient()

    func loadProfile() async {
        if let profile = try? await profileClient.get() {
            piFirstName = profile.piFirstName ?? ""
            bldgCode = profile.bldgCode ?? ""
            lab = profile.lab ?? ""
            contact = profile.contact ?? ""
        }
    }

    // Called from camera coordinator on every recognized-items update (~every 0.5s)
    func processFrame(texts: [String], barcode: String?, barcodeDebug: String?, thumbnail: UIImage?) {
        guard isScanning else {
            // Still buffer barcodes seen before play is tapped
            if let bc = barcode {
                pendingBarcode = bc
                debugBarcode = "buffered: \(barcodeDebug ?? bc)"
            }
            return
        }

        // Keep thumbnail fresh every frame (used by the fill slider preview)
        if let thumb = thumbnail {
            current.thumbnail = thumb
        }

        // Debug: track OCR line count every frame
        debugOCRLineCount = texts.count

        // Buffer barcode even before scanning starts so we don't miss a quick read
        if let bc = barcode {
            pendingBarcode = bc
            debugBarcode = barcodeDebug ?? bc
        }

        // Apply barcode on first hit once scanning is active
        if let bc = pendingBarcode, !barcodeHandled {
            barcodeHandled = true
            current.barcode = bc
            debugBarcode = "locked: \(debugBarcode)"
            if current.catalogNumber.isEmpty {
                current.catalogNumber = bc
                previewFields["catalog"] = bc
            }
        }

        // OCR extraction
        let extracted = extract(from: texts)

        for (key, value) in extracted {
            let acc = accumulators[key]
            if let locked = acc?.observe(value) {
                applyLocked(key: key, value: locked)
            }
            // Always update preview with best guess
            if let guess = acc?.bestGuess ?? value as String? {
                previewFields[key] = guess
            }
        }

        // Accumulate all OCR lines seen for AI extraction
        for line in texts {
            let trimmed = line.trimmingCharacters(in: .whitespacesAndNewlines)
            if !trimmed.isEmpty { allOCRLines.insert(trimmed) }
        }

        // Trigger on-device AI name extraction when:
        // - No CAS found yet, OR CAS was found but PubChem failed for it, AND
        // - Either not yet triggered, OR 5 seconds have passed and no AI query is running
        let enoughTimeSinceLastAI = Date().timeIntervalSince(lastAITriggerTime) >= 5
        let pubChemUnavailable = current.casNumber.isEmpty || pubChemFailed
        if !aiSatisfied, pubChemUnavailable, allOCRLines.count >= 6,
           (!aiTriggered || (enoughTimeSinceLastAI && !isRunningAI)) {
            triggerAIExtraction()
        }

        // Kick off PubChem lookup when CAS locks in, or retry if CAS has changed
        if !current.casNumber.isEmpty, current.casNumber != lastPubChemCAS {
            let cas = current.casNumber
            lastPubChemCAS = cas
            pubChemFailed = false
            pubChemTask?.cancel()
            pubChemTask = nil
            debugPubChemName = "querying…"
            debugArbitration = "—"
            pubChemTask = Task {
                isLookingUpPubChem = true
                if let result = await pubChemLookup(cas: cas) {
                    // Ignore result if CAS has changed again while we were waiting
                    guard cas == current.casNumber else {
                        isLookingUpPubChem = false
                        return
                    }
                    if current.chemicalFormula.isEmpty, let f = result.chemicalFormula {
                        current.chemicalFormula = f
                    }
                    if current.molecularWeight.isEmpty, let mw = result.molecularWeight {
                        current.molecularWeight = mw
                    }
                    if current.physicalState.isEmpty, let ps = result.physicalState {
                        current.physicalState = ps
                    }

                    // Build debug string showing both names
                    let iupac = result.iupacName ?? ""
                    let common = result.commonName ?? ""
                    debugPubChemName = common.isEmpty
                        ? (iupac.isEmpty ? "no name" : iupac)
                        : "\(common) [\(iupac.prefix(20))…]"

                    if let bestName = result.bestName {
                        current.chemicalName = bestName
                        previewFields["name"] = bestName
                        debugArbitration = result.commonName != nil ? "synonym▶︎\(bestName)" : "IUPAC▶︎\(bestName)"
                    } else {
                        debugArbitration = "no name from PubChem"
                    }
                    // PubChem result is definitive — stop AI from overriding
                    aiNameConfidence = 100
                    aiSatisfied = true
                } else {
                    debugPubChemName = "failed for \(cas)"
                    debugArbitration = "—"
                    pubChemFailed = true   // allow AI to keep running as fallback
                }
                isLookingUpPubChem = false
            }
        }
    }

    private func triggerAIExtraction() {
        aiTriggered = true
        aiTask?.cancel()
        aiTask = nil
        let lines = Array(allOCRLines)
        lastAITriggerTime = Date()
        debugAIQueryCount += 1
        debugAIName = "querying #\(debugAIQueryCount)…"
        let generation = scanGeneration
        aiTask = Task {
            isRunningAI = true
            if #available(iOS 18.1, *) {
                if let result = await onDeviceLabelLookup(ocrLines: lines),
                   generation == scanGeneration {
                    let conf = result.nameConfidence
                    let extracted = result.chemicalName.isEmpty ? "—" : result.chemicalName
                    debugAIName = "\(extracted) (\(conf)%)"
                    // Apply name if: confident enough AND (no name yet OR higher confidence than previous AI guess)
                    if !result.chemicalName.isEmpty, conf >= aiNameConfidenceThreshold,
                       (current.chemicalName.isEmpty || conf > aiNameConfidence) {
                        current.chemicalName = result.chemicalName
                        previewFields["name"] = result.chemicalName
                        aiNameConfidence = conf
                    }
                    // For secondary fields: AI can freely write or update values unless
                    // the regex accumulator has already confirmed them (2+ OCR votes = more reliable).
                    if !result.physicalState.isEmpty {
                        current.physicalState = result.physicalState
                    }
                    if !lockedByRegex.contains("vendor"), !result.vendor.isEmpty {
                        current.vendor = result.vendor
                        previewFields["vendor"] = result.vendor
                    }
                    // CAS: only fill from AI if regex hasn't seen it — regex is more reliable for structured numbers
                    if !lockedByRegex.contains("cas"), !result.casNumber.isEmpty {
                        current.casNumber = result.casNumber
                        previewFields["cas"] = result.casNumber
                    }
                    if !lockedByRegex.contains("lot"), !result.lotNumber.isEmpty {
                        current.lotNumber = result.lotNumber
                        previewFields["lot"] = result.lotNumber
                    }
                    if !lockedByRegex.contains("exp"), !result.expirationDate.isEmpty {
                        current.expirationDate = normalizeDate(result.expirationDate)
                        previewFields["exp"] = current.expirationDate
                    }
                    if !lockedByRegex.contains("amount"), !result.amount.isEmpty {
                        current.amountPerContainer = result.amount
                        previewFields["amount"] = result.amount
                    }
                    if !lockedByRegex.contains("unit"), !result.unit.isEmpty {
                        current.unitOfMeasure = result.unit
                        previewFields["unit"] = result.unit
                    }
                    if !lockedByRegex.contains("catalog"), !result.catalogNumber.isEmpty {
                        current.catalogNumber = result.catalogNumber
                        previewFields["catalog"] = result.catalogNumber
                    }
                } else {
                    debugAIName = "unavailable"
                }
            } else {
                debugAIName = "iOS 18.1+ req"
            }
            isRunningAI = false
        }
    }

    private func applyLocked(key: String, value: String) {
        // Mark field as regex-confirmed. AI will not overwrite these.
        lockedByRegex.insert(key)
        switch key {
        case "cas":
            current.casNumber = value
        case "lot":
            current.lotNumber = value
        case "mw":
            current.molecularWeight = value
        case "exp":
            current.expirationDate = value
        case "amount":
            current.amountPerContainer = value
        case "unit":
            current.unitOfMeasure = value
        case "vendor":
            current.vendor = value
        case "catalog":
            current.catalogNumber = value
        default: break
        }
    }

    private func resetScanState() {
        scanGeneration += 1
        resetAccumulators()
        current = ScannedItem()
        previewFields = [:]
        lockedByRegex = []
        barcodeHandled = false
        pendingBarcode = nil
        pubChemTask?.cancel()
        pubChemTask = nil
        lastPubChemCAS = ""
        pubChemFailed = false
        aiTask?.cancel()
        aiTask = nil
        isRunningAI = false
        containerTypeSelected = false
        showContainerTypePicker = false
        aiTriggered = false
        aiNameConfidence = 0
        lastAITriggerTime = .distantPast
        aiSatisfied = false
        allOCRLines = []
        debugBarcode = "—"
        debugOCRLineCount = 0
        debugPubChemName = "—"
        debugAIName = "—"
        debugArbitration = "—"
        debugAIQueryCount = 0
        isLookingUpPubChem = false
    }

    func startScanning() {
        resetScanState()
        isScanning = true
        showContainerTypePicker = true
    }

    func stopScanning() {
        isScanning = false

        let snapshot = current
        scannedItems.append(snapshot)
        let appendedIndex = scannedItems.count - 1

        // Cancel any in-flight tasks before starting the post-stop AI pass
        pubChemTask?.cancel()
        pubChemTask = nil

        // Final AI pass — update the already-appended item when it completes
        if snapshot.chemicalName.isEmpty, !allOCRLines.isEmpty {
            let lines = Array(allOCRLines)
            let lockedSnapshot = lockedByRegex   // capture by value — resetScanState clears the original
            let generation = scanGeneration
            debugAIQueryCount += 1
            debugAIName = "querying #\(debugAIQueryCount) (post-stop)…"
            aiTask?.cancel()
            aiTask = Task {
                isRunningAI = true
                if #available(iOS 18.1, *) {
                    if let result = await onDeviceLabelLookup(ocrLines: lines),
                       generation == scanGeneration,
                       appendedIndex < scannedItems.count {
                        let conf = result.nameConfidence
                        let extracted = result.chemicalName.isEmpty ? "—" : result.chemicalName
                        debugAIName = "\(extracted) (\(conf)%)"
                        if !result.chemicalName.isEmpty, conf >= aiNameConfidenceThreshold,
                           (scannedItems[appendedIndex].chemicalName.isEmpty || conf > aiNameConfidence) {
                            scannedItems[appendedIndex].chemicalName = result.chemicalName
                        }
                        if !result.physicalState.isEmpty {
                            scannedItems[appendedIndex].physicalState = result.physicalState
                        }
                        if !lockedSnapshot.contains("vendor"), !result.vendor.isEmpty {
                            scannedItems[appendedIndex].vendor = result.vendor
                        }
                        if !lockedSnapshot.contains("cas"), !result.casNumber.isEmpty {
                            scannedItems[appendedIndex].casNumber = result.casNumber
                        }
                        if !lockedSnapshot.contains("lot"), !result.lotNumber.isEmpty {
                            scannedItems[appendedIndex].lotNumber = result.lotNumber
                        }
                        if !lockedSnapshot.contains("exp"), !result.expirationDate.isEmpty {
                            scannedItems[appendedIndex].expirationDate = normalizeDate(result.expirationDate)
                        }
                        if !lockedSnapshot.contains("amount"), !result.amount.isEmpty {
                            scannedItems[appendedIndex].amountPerContainer = result.amount
                        }
                        if !lockedSnapshot.contains("unit"), !result.unit.isEmpty {
                            scannedItems[appendedIndex].unitOfMeasure = result.unit
                        }
                        if !lockedSnapshot.contains("catalog"), !result.catalogNumber.isEmpty {
                            scannedItems[appendedIndex].catalogNumber = result.catalogNumber
                        }
                    } else {
                        debugAIName = "unavailable"
                    }
                } else {
                    debugAIName = "iOS 18.1+ req"
                }
                isRunningAI = false
            }
        }
    }

    func finishSession() {
        isScanning = false
        showReview = true
    }

    private func resetAccumulators() {
        accumulators.values.forEach { $0.reset() }
    }
}

// MARK: - ScanView (main)

struct ScanView: View {
    @Environment(\.dismiss) private var dismiss
    @State private var viewModel = LabelScannerViewModel()

    var body: some View {
        NavigationStack {
            ZStack {
                // Camera feed (always live)
                if DataScannerViewController.isSupported && DataScannerViewController.isAvailable {
                    LiveScannerView(viewModel: viewModel)
                        .ignoresSafeArea()
                } else {
                    Color.black.ignoresSafeArea()
                    ContentUnavailableView(
                        "Scanner Unavailable",
                        systemImage: "camera.slash",
                        description: Text("This device does not support scanning.")
                    )
                }

                // Overlay
                VStack(spacing: 0) {
                    // Banner
                    if viewModel.isScanning {
                        ScanBanner(viewModel: viewModel)
                            .transition(.move(edge: .top).combined(with: .opacity))
                    }

                    Spacer()

                    // Bottom controls
                    ScanBottomBar(viewModel: viewModel)
                }
            }
            .navigationBarTitleDisplayMode(.inline)
            .toolbarBackground(.hidden, for: .navigationBar)
            .toolbar {
                ToolbarItem(placement: .topBarLeading) {
                    Button("Cancel") { dismiss() }
                        .foregroundStyle(.white)
                        .shadow(radius: 2)
                }
                ToolbarItem(placement: .topBarTrailing) {
                    if !viewModel.scannedItems.isEmpty && !viewModel.isScanning {
                        Button {
                            viewModel.finishSession()
                        } label: {
                            HStack(spacing: 4) {
                                Image(systemName: "checkmark")
                                Text("Done (\(viewModel.scannedItems.count))")
                            }
                            .fontWeight(.semibold)
                        }
                        .foregroundStyle(.white)
                        .shadow(radius: 2)
                    }
                }
            }
        }
        .task { await viewModel.loadProfile() }
        .sheet(isPresented: $viewModel.showReview) {
            ScanReviewView(viewModel: viewModel, onDone: { dismiss() })
        }
        .sheet(isPresented: $viewModel.showContainerTypePicker) {
            ContainerTypePickerSheet(viewModel: viewModel)
                .presentationDetents([.medium])
                .presentationDragIndicator(.visible)
        }
        .animation(.easeInOut(duration: 0.3), value: viewModel.isScanning)
    }
}

// MARK: - Live scanner UIViewControllerRepresentable

struct LiveScannerView: UIViewControllerRepresentable {
    let viewModel: LabelScannerViewModel

    func makeUIViewController(context: Context) -> DataScannerViewController {
        let scanner = DataScannerViewController(
            recognizedDataTypes: [.text(), .barcode()],
            qualityLevel: .accurate,
            recognizesMultipleItems: true,
            isHighFrameRateTrackingEnabled: false,
            isHighlightingEnabled: false   // we draw our own banner, no overlays needed
        )
        scanner.delegate = context.coordinator
        context.coordinator.viewModel = viewModel
        try? scanner.startScanning()
        return scanner
    }

    func updateUIViewController(_ uiViewController: DataScannerViewController, context: Context) {}

    func makeCoordinator() -> Coordinator { Coordinator() }

    @MainActor
    final class Coordinator: NSObject, DataScannerViewControllerDelegate, @unchecked Sendable {
        var viewModel: LabelScannerViewModel?
        private var lastProcessed = Date.distantPast

        func dataScanner(_ dataScanner: DataScannerViewController, didAdd addedItems: [RecognizedItem], allItems: [RecognizedItem]) {
            // Process immediately when new items are first recognized (catches barcodes that don't trigger didUpdate)
            processItems(allItems, in: dataScanner, forceBarcode: true)
        }

        func dataScanner(_ dataScanner: DataScannerViewController, didUpdate updatedItems: [RecognizedItem], allItems: [RecognizedItem]) {
            // Throttle to ~2 frames/sec to avoid hammering
            let now = Date()
            guard now.timeIntervalSince(lastProcessed) >= 0.5 else { return }
            lastProcessed = now
            processItems(allItems, in: dataScanner, forceBarcode: false)
        }

        private func processItems(_ allItems: [RecognizedItem], in dataScanner: DataScannerViewController, forceBarcode: Bool) {
            var texts: [String] = []
            var barcode: String?       // raw payload stored in the item
            var barcodeDebug: String?  // includes symbology, shown on screen only
            for item in allItems {
                switch item {
                case .text(let t): texts.append(t.transcript)
                case .barcode(let b):
                    if let p = b.payloadStringValue {
                        barcode = p
                        let sym = b.observation.symbology.rawValue.replacingOccurrences(of: "VNBarcodeSymbology", with: "")
                        barcodeDebug = "[\(sym)] \(p)"
                    }
                default: break
                }
            }

            // Skip if no barcode found and this was only called for barcode detection
            if forceBarcode && barcode == nil { return }

            // Capture thumbnail
            let thumb: UIImage? = {
                let renderer = UIGraphicsImageRenderer(bounds: dataScanner.view.bounds)
                return renderer.image { ctx in dataScanner.view.layer.render(in: ctx.cgContext) }
            }()

            Task { @MainActor in
                viewModel?.processFrame(texts: texts, barcode: barcode, barcodeDebug: barcodeDebug, thumbnail: thumb)
            }
        }
    }
}

// MARK: - Container type picker sheet

struct ContainerTypePickerSheet: View {
    @Bindable var viewModel: LabelScannerViewModel

    var body: some View {
        VStack(alignment: .leading, spacing: 0) {
            Text("Container Type")
                .font(.headline)
                .padding(.horizontal)
                .padding(.top, 20)
                .padding(.bottom, 12)

            ScrollView {
                LazyVGrid(columns: [GridItem(.flexible()), GridItem(.flexible())], spacing: 12) {
                    ForEach(containerTypeOptions, id: \.self) { option in
                        let isSelected = viewModel.current.storageDevice == option
                        Button {
                            viewModel.current.storageDevice = option
                            viewModel.previewFields["container"] = option
                            viewModel.containerTypeSelected = true
                            viewModel.showContainerTypePicker = false
                        } label: {
                            Text(option)
                                .font(.subheadline)
                                .frame(maxWidth: .infinity)
                                .padding(.vertical, 14)
                                .background(isSelected ? Color.accentColor : Color(.secondarySystemBackground))
                                .foregroundStyle(isSelected ? .white : .primary)
                                .clipShape(RoundedRectangle(cornerRadius: 10))
                        }
                    }
                }
                .padding(.horizontal)
                .padding(.bottom, 20)
            }
        }
    }
}

// MARK: - Scan banner

struct ScanBanner: View {
    @Bindable var viewModel: LabelScannerViewModel

    var body: some View {
        VStack(alignment: .leading, spacing: 0) {
            // Header
            HStack {
                if viewModel.isLookingUpPubChem || viewModel.isRunningAI {
                    ProgressView().scaleEffect(0.7).tint(.white)
                } else {
                    Image(systemName: "checkmark.circle.fill")
                        .foregroundStyle(Color(.brandPrimary))
                }
                Text("Scanning…")
                    .font(.subheadline.weight(.semibold))
                    .foregroundStyle(.white)
                Spacer()
                Button {
                    viewModel.showDebug.toggle()
                } label: {
                    Label("Debug", systemImage: viewModel.showDebug ? "chevron.up.circle.fill" : "chevron.down.circle")
                        .font(.caption2)
                        .foregroundStyle(.white.opacity(viewModel.showDebug ? 1 : 0.55))
                        .labelStyle(.iconOnly)
                }
                .buttonStyle(.plain)
            }
            .padding(.horizontal, 16)
            .padding(.top, 12)
            .padding(.bottom, 8)

            Divider().background(.white.opacity(0.3))

            // Fields grid
            let fields: [(String, String)] = [
                ("Chemical", viewModel.current.chemicalName.isEmpty
                    ? (viewModel.previewFields["name"] ?? "—") : viewModel.current.chemicalName),
                ("CAS",    viewModel.current.casNumber.isEmpty
                    ? (viewModel.previewFields["cas"] ?? "—") : viewModel.current.casNumber),
                ("Lot",    viewModel.current.lotNumber.isEmpty
                    ? (viewModel.previewFields["lot"] ?? "—") : viewModel.current.lotNumber),
                ("Vendor", viewModel.current.vendor.isEmpty
                    ? (viewModel.previewFields["vendor"] ?? "—") : viewModel.current.vendor),
                ("Amount", viewModel.current.amountPerContainer.isEmpty
                    ? amountPreview : "\(viewModel.current.amountPerContainer) \(viewModel.current.unitOfMeasure)"),
                ("Exp",    viewModel.current.expirationDate.isEmpty
                    ? (viewModel.previewFields["exp"] ?? "—") : viewModel.current.expirationDate),
                ("Container", viewModel.current.storageDevice.isEmpty
                    ? (viewModel.previewFields["container"] ?? "—") : viewModel.current.storageDevice),
            ]

            LazyVGrid(columns: [GridItem(.flexible()), GridItem(.flexible())], spacing: 6) {
                ForEach(fields, id: \.0) { label, value in
                    BannerField(label: label, value: value)
                }
            }
            .padding(.horizontal, 16)
            .padding(.vertical, 10)

            // Debug strip (collapsible)
            if viewModel.showDebug {
                Divider().background(.white.opacity(0.2))
                VStack(alignment: .leading, spacing: 2) {
                    HStack(spacing: 4) {
                        Text("BCR").font(.system(size: 9, design: .monospaced)).foregroundStyle(.yellow.opacity(0.7)).frame(width: 28, alignment: .leading)
                        Text(viewModel.debugBarcode).font(.system(size: 9, design: .monospaced)).foregroundStyle(.yellow).lineLimit(1).truncationMode(.middle)
                    }
                    HStack(spacing: 4) {
                        Text("OCR").font(.system(size: 9, design: .monospaced)).foregroundStyle(.cyan.opacity(0.7)).frame(width: 28, alignment: .leading)
                        Text("\(viewModel.debugOCRLineCount) lines · \(viewModel.allOCRLinesCount) unique accumulated").font(.system(size: 9, design: .monospaced)).foregroundStyle(.cyan).lineLimit(1)
                    }
                    HStack(spacing: 4) {
                        Text("AI×\(viewModel.debugAIQueryCount)").font(.system(size: 9, design: .monospaced)).foregroundStyle(.orange.opacity(0.7)).frame(width: 28, alignment: .leading)
                        Text(viewModel.debugAIName).font(.system(size: 9, design: .monospaced)).foregroundStyle(.orange).lineLimit(1).truncationMode(.tail)
                    }
                    HStack(spacing: 4) {
                        Text("PUB").font(.system(size: 9, design: .monospaced)).foregroundStyle(.green.opacity(0.7)).frame(width: 28, alignment: .leading)
                        Text(viewModel.debugPubChemName).font(.system(size: 9, design: .monospaced)).foregroundStyle(.green).lineLimit(1).truncationMode(.tail)
                    }
                    HStack(spacing: 4) {
                        Text("ARB").font(.system(size: 9, design: .monospaced)).foregroundStyle(.mint.opacity(0.7)).frame(width: 28, alignment: .leading)
                        Text(viewModel.debugArbitration).font(.system(size: 9, design: .monospaced)).foregroundStyle(.mint).lineLimit(1).truncationMode(.tail)
                    }

                }
                .padding(.horizontal, 16)
                .padding(.vertical, 6)
                .transition(.opacity.combined(with: .move(edge: .top)))
            }

            // Fill slider
            HStack(spacing: 12) {
                Text("Fill level")
                    .font(.caption)
                    .foregroundStyle(.white.opacity(0.8))
                Slider(value: $viewModel.current.percentageFull, in: 0...100, step: 5)
                    .tint(Color(.brandPrimary))
                Text("\(Int(viewModel.current.percentageFull))%")
                    .font(.caption.monospacedDigit())
                    .foregroundStyle(.white)
                    .frame(width: 36, alignment: .trailing)
            }
            .padding(.horizontal, 16)
            .padding(.bottom, 12)
        }
        .background(.ultraThinMaterial.opacity(0.92))
        .background(Color.black.opacity(0.55))
        .animation(.easeInOut(duration: 0.2), value: viewModel.showDebug)
    }

    private var amountPreview: String {
        let a = viewModel.previewFields["amount"] ?? ""
        let u = viewModel.previewFields["unit"] ?? ""
        return (a.isEmpty && u.isEmpty) ? "—" : "\(a) \(u)".trimmingCharacters(in: .whitespaces)
    }
}

private struct BannerField: View {
    let label: String
    let value: String
    var locked: Bool { value != "—" }

    var body: some View {
        HStack(spacing: 4) {
            Text(label)
                .font(.caption2)
                .foregroundStyle(.white.opacity(0.6))
                .frame(width: 46, alignment: .leading)
            Text(value)
                .font(.caption.weight(locked ? .semibold : .regular))
                .foregroundStyle(locked ? .white : .white.opacity(0.4))
                .lineLimit(1)
                .truncationMode(.tail)
        }
        .frame(maxWidth: .infinity, alignment: .leading)
    }
}

// MARK: - Bottom bar

struct ScanBottomBar: View {
    let viewModel: LabelScannerViewModel

    var body: some View {
        HStack(spacing: 24) {
            // Scanned count badge
            VStack(spacing: 2) {
                Text("\(viewModel.scannedItems.count)")
                    .font(.title2.bold())
                    .foregroundStyle(.white)
                Text("saved")
                    .font(.caption2)
                    .foregroundStyle(.white.opacity(0.7))
            }
            .frame(width: 52)

            // Start / Stop button
            Button {
                if viewModel.isScanning {
                    viewModel.stopScanning()
                } else {
                    viewModel.startScanning()
                }
            } label: {
                ZStack {
                    Circle()
                        .fill(viewModel.isScanning ? Color(.brandDestructive) : Color(.brandPrimary))
                        .frame(width: 72, height: 72)
                    Image(systemName: viewModel.isScanning ? "stop.fill" : "play.fill")
                        .font(.title2)
                        .foregroundStyle(.white)
                }
            }
            .shadow(radius: 4)

            // Hint
            VStack(spacing: 2) {
                Text(viewModel.isScanning ? "Tap stop\nwhen done" : "Tap play\nto start")
                    .font(.caption2)
                    .foregroundStyle(.white.opacity(0.7))
                    .multilineTextAlignment(.center)
            }
            .frame(width: 52)
        }
        .padding(.vertical, 20)
        .padding(.horizontal, 32)
        .background(.ultraThinMaterial.opacity(0.85))
        .background(Color.black.opacity(0.4))
    }
}

// MARK: - Review view

struct ScanReviewView: View {
    @Bindable var viewModel: LabelScannerViewModel
    let onDone: () -> Void

    @State private var isSavingAll = false
    @State private var saveError: String?
    @State private var editingItem: ScannedItem?
    @State private var savedCount = 0

    private let chemicalsClient = ChemicalsClient()

    var body: some View {
        NavigationStack {
            List {
                Section {
                    Text("Review \(viewModel.scannedItems.count) scanned item\(viewModel.scannedItems.count == 1 ? "" : "s"). Tap any item to edit before saving.")
                        .font(.subheadline)
                        .foregroundStyle(.secondary)
                }

                ForEach(viewModel.scannedItems) { item in
                    ScannedItemRow(item: item)
                        .contentShape(Rectangle())
                        .onTapGesture { editingItem = item }
                        .swipeActions(edge: .trailing) {
                            Button(role: .destructive) {
                                viewModel.scannedItems.removeAll { $0.id == item.id }
                            } label: {
                                Label("Delete", systemImage: "trash")
                            }
                        }
                }

                if let error = saveError {
                    Section {
                        Text(error).foregroundStyle(.red).font(.footnote)
                    }
                }

                Section {
                    Button {
                        Task { await saveAll() }
                    } label: {
                        if isSavingAll {
                            HStack {
                                ProgressView().scaleEffect(0.8)
                                Text("Saving \(savedCount)/\(viewModel.scannedItems.count)…")
                            }
                            .frame(maxWidth: .infinity)
                        } else {
                            Text("Save All to Inventory")
                                .fontWeight(.semibold)
                                .frame(maxWidth: .infinity)
                        }
                    }
                    .buttonStyle(.borderedProminent)
                    .tint(Color(.brandPrimary))
                    .disabled(viewModel.scannedItems.isEmpty || isSavingAll)
                }
            }
            .navigationTitle("Review Scans")
            .navigationBarTitleDisplayMode(.inline)
            .toolbar {
                ToolbarItem(placement: .topBarLeading) {
                    Button("Back") {
                        viewModel.showReview = false
                    }
                }
            }
        }
        .sheet(item: $editingItem) { item in
            ScannedItemEditView(
                item: item,
                piFirstName: viewModel.piFirstName,
                bldgCode: viewModel.bldgCode,
                lab: viewModel.lab,
                storageLocation: viewModel.storageLocation,
                contact: viewModel.contact
            ) { updated in
                if let idx = viewModel.scannedItems.firstIndex(where: { $0.id == updated.id }) {
                    viewModel.scannedItems[idx] = updated
                }
                editingItem = nil
            }
        }
    }

    private func saveAll() async {
        isSavingAll = true
        saveError = nil
        savedCount = 0
        var failed = 0

        for item in viewModel.scannedItems {
            let body = ChemicalCreateBody(
                piFirstName: viewModel.piFirstName.isEmpty ? "Unknown" : viewModel.piFirstName,
                physicalState: item.physicalState.isEmpty ? "Solid" : item.physicalState,
                chemicalName: item.chemicalName.isEmpty ? "Unknown Chemical" : item.chemicalName,
                bldgCode: viewModel.bldgCode.isEmpty ? "Unknown" : viewModel.bldgCode,
                lab: viewModel.lab.isEmpty ? "Unknown" : viewModel.lab,
                storageLocation: viewModel.storageLocation.isEmpty ? "Unknown" : viewModel.storageLocation,
                storageDevice: item.storageDevice,
                numberOfContainers: "1",
                amountPerContainer: item.amountPerContainer.isEmpty ? "Unknown" : item.amountPerContainer,
                unitOfMeasure: item.unitOfMeasure.isEmpty ? "Unknown" : item.unitOfMeasure,
                casNumber: item.casNumber.isEmpty ? "Unknown" : item.casNumber,
                chemicalFormula: item.chemicalFormula.isEmpty ? nil : item.chemicalFormula,
                molecularWeight: item.molecularWeight.isEmpty ? nil : item.molecularWeight,
                vendor: item.vendor.isEmpty ? nil : item.vendor,
                catalogNumber: item.catalogNumber.isEmpty ? nil : item.catalogNumber,
                lotNumber: item.lotNumber.isEmpty ? nil : item.lotNumber,
                expirationDate: item.expirationDate.isEmpty ? nil : item.expirationDate,
                concentration: item.concentration.isEmpty ? nil : item.concentration,
                percentageFull: item.percentageFull,
                barcode: item.barcode,
                contact: viewModel.contact.isEmpty ? nil : viewModel.contact
            )
            do {
                _ = try await chemicalsClient.create(body)
                savedCount += 1
            } catch {
                failed += 1
            }
        }

        isSavingAll = false
        if failed > 0 {
            saveError = "\(failed) item(s) failed to save. The rest were saved successfully."
        } else {
            onDone()
        }
    }
}

// MARK: - Scanned item row (review list)

private struct ScannedItemRow: View {
    let item: ScannedItem

    var body: some View {
        HStack(spacing: 12) {
            if let thumb = item.thumbnail {
                Image(uiImage: thumb)
                    .resizable()
                    .scaledToFill()
                    .frame(width: 52, height: 52)
                    .clipShape(RoundedRectangle(cornerRadius: 8))
            } else {
                RoundedRectangle(cornerRadius: 8)
                    .fill(Color.secondary.opacity(0.15))
                    .frame(width: 52, height: 52)
                    .overlay {
                        Image(systemName: "flask.fill")
                            .foregroundStyle(.secondary)
                    }
            }
            VStack(alignment: .leading, spacing: 3) {
                Text(item.chemicalName.isEmpty ? "Unnamed chemical" : item.chemicalName)
                    .font(.subheadline.weight(.semibold))
                    .lineLimit(1)
                HStack(spacing: 6) {
                    if !item.casNumber.isEmpty {
                        Text("CAS: \(item.casNumber)").font(.caption).foregroundStyle(.secondary)
                    }
                    if !item.vendor.isEmpty {
                        Text("· \(item.vendor)").font(.caption).foregroundStyle(.secondary)
                    }
                }
                HStack(spacing: 6) {
                    if !item.amountPerContainer.isEmpty {
                        Text("\(item.amountPerContainer) \(item.unitOfMeasure)").font(.caption2).foregroundStyle(.secondary)
                    }
                    Text("· \(Int(item.percentageFull))% full").font(.caption2).foregroundStyle(.secondary)
                }
            }
            Spacer()
            Image(systemName: "chevron.right")
                .font(.caption)
                .foregroundStyle(.tertiary)
        }
        .padding(.vertical, 4)
    }
}

// MARK: - Edit a single scanned item

struct ScannedItemEditView: View {
    @State private var item: ScannedItem
    @State private var piFirstName: String
    @State private var bldgCode: String
    @State private var lab: String
    @State private var storageLocation: String
    @State private var contact: String
    let onSave: (ScannedItem) -> Void

    init(item: ScannedItem, piFirstName: String, bldgCode: String, lab: String,
         storageLocation: String, contact: String, onSave: @escaping (ScannedItem) -> Void) {
        _item = State(initialValue: item)
        _piFirstName = State(initialValue: piFirstName)
        _bldgCode = State(initialValue: bldgCode)
        _lab = State(initialValue: lab)
        _storageLocation = State(initialValue: storageLocation)
        _contact = State(initialValue: contact)
        self.onSave = onSave
    }

    var body: some View {
        NavigationStack {
            Form {
                Section("Identity") {
                    LabeledTextField("Chemical Name", text: $item.chemicalName)
                    LabeledTextField("CAS #", text: $item.casNumber)
                    Picker("Physical State", selection: $item.physicalState) {
                        Text("Select…").tag("")
                        ForEach(["Solid","Liquid","Gas"], id: \.self) { Text($0).tag($0) }
                    }
                    Picker("Storage Device", selection: $item.storageDevice) {
                        ForEach(AddChemicalViewModel.storageDevices, id: \.self) { Text($0).tag($0) }
                    }
                }
                Section("Location") {
                    LabeledTextField("PI First Name", text: $piFirstName)
                    LabeledTextField("Building Code", text: $bldgCode)
                    LabeledTextField("Lab", text: $lab)
                    LabeledTextField("Storage Location", text: $storageLocation)
                }
                Section("Quantity") {
                    LabeledTextField("Amount / Container", text: $item.amountPerContainer)
                    LabeledTextField("Unit of Measure", text: $item.unitOfMeasure)
                    HStack {
                        Text("Fill Level")
                        Spacer()
                        Text("\(Int(item.percentageFull))%")
                            .foregroundStyle(.secondary)
                    }
                    Slider(value: $item.percentageFull, in: 0...100, step: 5)
                        .tint(Color(.brandPrimary))
                }
                Section("Details") {
                    LabeledTextField("Formula", text: $item.chemicalFormula)
                    LabeledTextField("MW", text: $item.molecularWeight)
                    LabeledTextField("Vendor", text: $item.vendor)
                    LabeledTextField("Catalog #", text: $item.catalogNumber)
                    LabeledTextField("Lot #", text: $item.lotNumber)
                    LabeledTextField("Expiration", text: $item.expirationDate)
                    LabeledTextField("Concentration", text: $item.concentration)
                }
            }
            .navigationTitle("Edit Item")
            .navigationBarTitleDisplayMode(.inline)
            .toolbar {
                ToolbarItem(placement: .topBarTrailing) {
                    Button("Save") {
                        var updated = item
                        updated.percentageFull = item.percentageFull
                        onSave(updated)
                    }
                    .fontWeight(.semibold)
                }
            }
        }
    }
}

private struct LabeledTextField: View {
    let label: String
    @Binding var text: String
    init(_ label: String, text: Binding<String>) {
        self.label = label
        self._text = text
    }
    var body: some View {
        HStack {
            Text(label).foregroundStyle(Color(UIColor.label))
            Spacer(minLength: 8)
            TextField(label, text: $text)
                .multilineTextAlignment(.trailing)
                .foregroundStyle(Color(UIColor.secondaryLabel))
        }
    }
}