import os
import time
import email
from email.policy import default
from bs4 import BeautifulSoup
from watchdog.observers import Observer
from watchdog.events import FileSystemEventHandler
from database import SessionLocal, Email, EMBEDDING_DIMENSIONS
from google import genai
from google.genai import types
from datetime import datetime
from sqlalchemy.exc import IntegrityError

MAILDIR_PATH = os.environ.get("MAILDIR_PATH", "/Maildir")

# Initialize Gemini client
gemini_client = None
api_key = os.environ.get("GEMINI_API_KEY")
if api_key:
    gemini_client = genai.Client(api_key=api_key)
    print("Gemini client initialized for indexer.")
else:
    print("WARNING: GEMINI_API_KEY not set. Indexer will skip embedding generation.")

def extract_text_from_email(msg):
    text_content = ""
    if msg.is_multipart():
        for part in msg.walk():
            content_type = part.get_content_type()
            if content_type == "text/plain":
                payload = part.get_payload(decode=True)
                if payload:
                    text_content += payload.decode('utf-8', errors='ignore') + "\n"
            elif content_type == "text/html":
                payload = part.get_payload(decode=True)
                if payload:
                    html_content = payload.decode('utf-8', errors='ignore')
                    soup = BeautifulSoup(html_content, 'html.parser')
                    text_content += soup.get_text(separator=' ') + "\n"
    else:
        content_type = msg.get_content_type()
        payload = msg.get_payload(decode=True)
        if payload:
            if content_type == "text/html":
                html_content = payload.decode('utf-8', errors='ignore')
                soup = BeautifulSoup(html_content, 'html.parser')
                text_content = soup.get_text(separator=' ')
            else:
                text_content = payload.decode('utf-8', errors='ignore')
    return text_content.strip()

def process_email_file(filepath):
    print(f"Processing new email file: {filepath}")
    if not gemini_client:
        print("Skipping embedding generation: Gemini API key is missing.")
        return

    try:
        with open(filepath, 'rb') as f:
            msg = email.message_from_binary_file(f, policy=default)

        message_id = msg.get('Message-ID', filepath)
        subject = msg.get('Subject', '')
        sender = msg.get('From', '')
        date_str = msg.get('Date')
        
        try:
            email_date = email.utils.parsedate_to_datetime(date_str) if date_str else datetime.utcnow()
        except:
            email_date = datetime.utcnow()

        content = extract_text_from_email(msg)

        if not content:
            print(f"No text content found in {filepath}. Skipping.")
            return

        # Combine subject and content for better embedding
        text_to_embed = f"Subject: {subject}\nSender: {sender}\n\n{content}"
        
        # Limit text to avoid token limits (very rough truncation)
        text_to_embed = text_to_embed[:8000]

        # Get embedding via Gemini — RETRIEVAL_DOCUMENT is the correct task type
        # for content being stored and later retrieved by a query
        response = gemini_client.models.embed_content(
            model="gemini-embedding-001",
            contents=text_to_embed,
            config=types.EmbedContentConfig(
                task_type="RETRIEVAL_DOCUMENT",
                output_dimensionality=EMBEDDING_DIMENSIONS,
            ),
        )
        embedding = response.embeddings[0].values

        # Save to DB
        db = SessionLocal()
        try:
            new_email = Email(
                message_id=message_id,
                subject=subject,
                sender=sender,
                date=email_date,
                content=content,
                embedding=embedding
            )
            db.add(new_email)
            db.commit()
            print(f"Successfully indexed email: {subject}")
        except IntegrityError:
            db.rollback()
            print(f"Email {message_id} already exists in database.")
        except Exception as e:
            db.rollback()
            print(f"Database error saving email: {e}")
        finally:
            db.close()

    except Exception as e:
        print(f"Error processing email {filepath}: {e}")

class NewEmailHandler(FileSystemEventHandler):
    def on_created(self, event):
        if not event.is_directory:
            # Simple check if it's likely an email file (mbsync creates files in cur/ or new/)
            if 'new/' in event.src_path or 'cur/' in event.src_path:
                process_email_file(event.src_path)

def start_watching():
    print(f"Starting to watch {MAILDIR_PATH} for new emails...")
    
    # Optional: Do a full initial sync of existing files here.
    # We will skip that for brevity and just watch for new ones.
    
    event_handler = NewEmailHandler()
    observer = Observer()
    observer.schedule(event_handler, MAILDIR_PATH, recursive=True)
    observer.start()
    try:
        while True:
            time.sleep(1)
    except KeyboardInterrupt:
        observer.stop()
    observer.join()

if __name__ == "__main__":
    # Wait for DB to be initialized by FastAPI
    time.sleep(5)
    start_watching()