import { useEffect, useState } from 'react';
import { Loader2, Check, AlertTriangle } from 'lucide-react';
import { Button } from './ui/button';
import { Card, CardContent, CardHeader, CardTitle } from './ui/card';
import { Input } from './ui/input';
import { Label } from './ui/label';
import { useSession, signOut, updateUser } from '../lib/auth-client';
import { validatePhoneOrEmail } from '../lib/validators';

export function ProfileSettings() {
  const { data: session } = useSession();
  const [userName, setUserName] = useState('');
  const [savingName, setSavingName] = useState(false);
  const [nameSaved, setNameSaved] = useState(false);
  const [nameError, setNameError] = useState('');
  const [piFirstName, setPiFirstName] = useState('');
  const [bldgCode, setBldgCode] = useState('');
  const [lab, setLab] = useState('');
  const [contact, setContact] = useState('');
  const [loading, setLoading] = useState(true);
  const [saving, setSaving] = useState(false);
  const [error, setError] = useState('');
  const [saved, setSaved] = useState(false);
  const [showDeleteConfirm, setShowDeleteConfirm] = useState(false);
  const [deleting, setDeleting] = useState(false);
  const [deleteError, setDeleteError] = useState('');

  useEffect(() => {
    if (session?.user.name) setUserName(session.user.name);
  }, [session?.user.name]);

  useEffect(() => {
    fetch('/api/profile', { credentials: 'include' })
      .then(r => (r.ok ? r.json() : null))
      .then(data => {
        if (data) {
          setPiFirstName(data.pi_first_name || '');
          setBldgCode(data.bldg_code || '');
          setLab(data.lab || '');
          setContact(data.contact || '');
        }
      })
      .finally(() => setLoading(false));
  }, []);

  async function handleSaveName() {
    setNameError('');
    setNameSaved(false);
    const trimmed = userName.trim();
    if (!trimmed) {
      setNameError('Name is required.');
      return;
    }
    setSavingName(true);
    const { error: err } = await updateUser({ name: trimmed });
    setSavingName(false);
    if (err) {
      setNameError(err.message || 'Failed to save name.');
    } else {
      setNameSaved(true);
      setTimeout(() => setNameSaved(false), 3000);
    }
  }

  async function handleSubmit(e: React.FormEvent) {
    e.preventDefault();
    setError('');
    setSaved(false);

    if (!piFirstName.trim() || !bldgCode.trim() || !lab.trim()) {
      setError('PI first name, building code, and lab are required.');
      return;
    }
    if (contact.trim() && !validatePhoneOrEmail(contact.trim())) {
      setError('Contact must be a valid phone number or email address.');
      return;
    }

    setSaving(true);
    const res = await fetch('/api/profile', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      credentials: 'include',
      body: JSON.stringify({
        pi_first_name: piFirstName.trim(),
        bldg_code: bldgCode.trim(),
        lab: lab.trim(),
        contact: contact.trim() || undefined,
      }),
    });
    setSaving(false);

    if (res.ok) {
      setSaved(true);
      setTimeout(() => setSaved(false), 3000);
    } else {
      const data = await res.json().catch(() => ({}));
      setError(data.error || 'Failed to save profile.');
    }
  }

  if (loading) {
    return (
      <div className="flex h-full items-center justify-center">
        <Loader2 className="w-6 h-6 animate-spin text-muted-foreground" />
      </div>
    );
  }

  return (
    <div className="p-8 max-w-2xl mx-auto">
      <div className="mb-6">
        <h1 className="text-2xl font-semibold">Profile settings</h1>
        <p className="text-sm text-muted-foreground mt-1">
          Update your account details and lab defaults.
        </p>
      </div>

      <Card>
        <CardHeader>
          <CardTitle className="text-base">Account</CardTitle>
        </CardHeader>
        <CardContent className="space-y-4 pb-6">
          <div className="space-y-1">
            <Label htmlFor="name">Name</Label>
            <Input
              id="name"
              value={userName}
              onChange={e => setUserName(e.target.value)}
              placeholder="Your name"
            />
          </div>
          <div>
            <Label className="text-xs text-muted-foreground">Email</Label>
            <p className="text-sm">{session?.user.email || '—'}</p>
          </div>
          {nameError && <p className="text-sm text-red-600">{nameError}</p>}
          {nameSaved && (
            <p className="text-sm text-green-600 flex items-center gap-1">
              <Check className="w-4 h-4" /> Name saved
            </p>
          )}
          <div className="pt-1">
            <Button type="button" onClick={handleSaveName} disabled={savingName}>
              {savingName ? 'Saving…' : 'Save name'}
            </Button>
          </div>
        </CardContent>
      </Card>

      <form onSubmit={handleSubmit}>
        <Card className="mt-4">
          <CardHeader>
            <CardTitle className="text-base">Lab defaults</CardTitle>
          </CardHeader>
          <CardContent className="space-y-4 pb-6">
            <div className="space-y-1">
              <Label htmlFor="pi">
                PI first name <span className="text-red-500">*</span>
              </Label>
              <Input
                id="pi"
                value={piFirstName}
                onChange={e => setPiFirstName(e.target.value)}
                required
                placeholder="e.g. Smith"
              />
            </div>
            <div className="space-y-1">
              <Label htmlFor="bldg">
                Building code <span className="text-red-500">*</span>
              </Label>
              <Input
                id="bldg"
                value={bldgCode}
                onChange={e => setBldgCode(e.target.value)}
                required
                placeholder="e.g. EER"
              />
            </div>
            <div className="space-y-1">
              <Label htmlFor="lab">
                Lab <span className="text-red-500">*</span>
              </Label>
              <Input
                id="lab"
                value={lab}
                onChange={e => setLab(e.target.value)}
                required
                placeholder="e.g. 3.822"
              />
            </div>
            <div className="space-y-1">
              <Label htmlFor="contact">
                Contact{' '}
                <span className="text-muted-foreground font-normal">(optional)</span>
              </Label>
              <Input
                id="contact"
                type="text"
                value={contact}
                onChange={e => setContact(e.target.value)}
                placeholder="Phone (e.g. 555-123-4567) or email"
              />
            </div>
            {error && <p className="text-sm text-red-600">{error}</p>}
            {saved && (
              <p className="text-sm text-green-600 flex items-center gap-1">
                <Check className="w-4 h-4" /> Saved
              </p>
            )}
            <div className="pt-1">
              <Button type="submit" disabled={saving}>
                {saving ? 'Saving…' : 'Save changes'}
              </Button>
            </div>
          </CardContent>
        </Card>
      </form>

      <Card className="mt-4 border-red-200">
        <CardHeader>
          <CardTitle className="text-base text-red-600 flex items-center gap-2">
            <AlertTriangle className="w-4 h-4" /> Delete account
          </CardTitle>
        </CardHeader>
        <CardContent className="pb-6">
          {!showDeleteConfirm ? (
            <>
              <p className="text-sm text-muted-foreground mb-3">
                Permanently delete your account and all associated data including
                chemicals and protocols. This action cannot be undone.
              </p>
              <Button
                variant="destructive"
                onClick={() => setShowDeleteConfirm(true)}
              >
                Delete account
              </Button>
            </>
          ) : (
            <>
              <p className="text-sm text-red-600 font-medium mb-3">
                Are you sure? All your data will be permanently deleted.
              </p>
              {deleteError && (
                <p className="text-sm text-red-600 mb-3">{deleteError}</p>
              )}
              <div className="flex gap-2">
                <Button
                  variant="destructive"
                  disabled={deleting}
                  onClick={async () => {
                    setDeleting(true);
                    setDeleteError('');
                    try {
                      const res = await fetch('/api/account/delete', {
                        method: 'POST',
                        credentials: 'include',
                      });
                      if (!res.ok) {
                        const data = await res.json().catch(() => ({}));
                        setDeleteError(data.error || 'Failed to delete account.');
                        setDeleting(false);
                        return;
                      }
                      await signOut();
                      window.location.href = '/';
                    } catch {
                      setDeleteError('Failed to delete account.');
                      setDeleting(false);
                    }
                  }}
                >
                  {deleting ? 'Deleting...' : 'Yes, delete my account'}
                </Button>
                <Button
                  variant="outline"
                  disabled={deleting}
                  onClick={() => {
                    setShowDeleteConfirm(false);
                    setDeleteError('');
                  }}
                >
                  Cancel
                </Button>
              </div>
            </>
          )}
        </CardContent>
      </Card>

      <p className="text-center mt-6">
        <a href="/privacy" className="text-xs text-muted-foreground hover:text-foreground transition-colors">
          Privacy Policy
        </a>
      </p>
    </div>
  );
}
