import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:image_picker/image_picker.dart';

import '../models/produit.dart';
import '../services/photo_service.dart';
import '../services/produit_repository.dart';
import '../services/reglages.dart';
import '../theme.dart';
import '../widgets/produit_image.dart';

/// Écran d'ajout / modification d'un produit.
///
/// - [produit] fourni  → mode modification.
/// - sinon             → mode création (les champs *Initial servent au scan).
class ProduitEditScreen extends StatefulWidget {
  final Produit? produit;
  final String? codeBarresInitial;
  final String? nomInitial;
  final String? imageUrlInitial;
  final double? quantiteInitial;
  final String? uniteInitial;

  const ProduitEditScreen({
    super.key,
    this.produit,
    this.codeBarresInitial,
    this.nomInitial,
    this.imageUrlInitial,
    this.quantiteInitial,
    this.uniteInitial,
  });

  @override
  State<ProduitEditScreen> createState() => _ProduitEditScreenState();
}

class _ProduitEditScreenState extends State<ProduitEditScreen> {
  final _repo = ProduitRepository.instance;
  final _formKey = GlobalKey<FormState>();

  late final TextEditingController _nom;
  late final TextEditingController _prix;
  late final TextEditingController _prixAchat;
  late final TextEditingController _quantite;
  late final TextEditingController _nbContenants;
  late final TextEditingController _stock;

  String? _codeBarres;
  String? _imageUrl;
  late String _unite;
  bool _estPack = false;
  bool _enregistre = false;

  bool get _modification => widget.produit != null;

  /// Produit scanné mais absent d'OpenFoodFacts (nom à saisir à la main).
  bool get _scanNonTrouve =>
      widget.produit == null &&
      widget.codeBarresInitial != null &&
      (widget.nomInitial == null || widget.nomInitial!.trim().isEmpty);

  @override
  void initState() {
    super.initState();
    final p = widget.produit;
    _nom = TextEditingController(text: p?.nom ?? widget.nomInitial ?? '');
    _prix = TextEditingController(text: p != null ? _fmt(p.prix) : '');
    _prixAchat = TextEditingController(
        text: (p != null && p.prixAchat > 0) ? _fmt(p.prixAchat) : '');
    final q = p?.quantite ?? widget.quantiteInitial;
    _quantite = TextEditingController(
        text: (q != null && q > 0) ? _fmtQuantite(q) : '');
    _estPack = p?.estPack ?? false;
    _nbContenants = TextEditingController(
        text: (p != null && p.estPack) ? p.nbContenants.toString() : '');
    _stock = TextEditingController(text: (p?.stock ?? 0).toString());
    // Unité : celle du produit si valide, sinon celle du scan, sinon 'g' par défaut.
    _unite = Unites.estValide(p?.unite)
        ? p!.unite!
        : (Unites.estValide(widget.uniteInitial) ? widget.uniteInitial! : Unites.g);
    _codeBarres = p?.codeBarres ?? widget.codeBarresInitial;
    _imageUrl = p?.imageUrl ?? widget.imageUrlInitial;

    // Nouveau produit sans unité connue → on re-propose la dernière unité utilisée.
    if (p == null && !Unites.estValide(widget.uniteInitial)) {
      Reglages.instance.derniereUnite().then((u) {
        if (mounted && _quantite.text.isEmpty && Unites.estValide(u)) {
          setState(() => _unite = u);
        }
      });
    }
  }

  @override
  void dispose() {
    _nom.dispose();
    _prix.dispose();
    _prixAchat.dispose();
    _quantite.dispose();
    _nbContenants.dispose();
    _stock.dispose();
    super.dispose();
  }

  String _fmtQuantite(double v) =>
      v == v.roundToDouble() ? v.toInt().toString() : v.toString();

  String _fmt(double v) =>
      v.toStringAsFixed(2).replaceAll('.', ',');

  double _parse(String s) =>
      double.tryParse(s.trim().replaceAll(',', '.')) ?? 0;

  Future<void> _enregistrer() async {
    if (!_formKey.currentState!.validate()) return;
    setState(() => _enregistre = true);

    final base = widget.produit;
    final q = _parse(_quantite.text);
    final nb = _estPack ? (int.tryParse(_nbContenants.text.trim()) ?? 0) : 1;
    final produit = Produit(
      id: base?.id ?? 'temp',
      codeBarres: _codeBarres,
      nom: _nom.text.trim(),
      imageUrl: _imageUrl,
      prix: _parse(_prix.text),
      prixAchat: _parse(_prixAchat.text),
      quantite: q > 0 ? q : null,
      unite: _unite,
      nbContenants: (_estPack && nb > 1) ? nb : null,
      creeLe: base?.creeLe ?? 0,
      stock: int.tryParse(_stock.text.trim()) ?? 0,
    );

    try {
      if (_modification) {
        await _repo.modifier(produit);
      } else {
        await _repo.ajouter(produit);
      }
      // Mémorise l'unité pour accélérer la saisie du produit suivant.
      await Reglages.instance.memoriserUnite(produit.unite ?? Unites.piece);
      if (mounted) Navigator.of(context).pop(true);
    } catch (e) {
      setState(() => _enregistre = false);
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text('Erreur : $e')),
        );
      }
    }
  }

  Future<void> _changerPhoto() async {
    FocusScope.of(context).unfocus();
    final action = await showModalBottomSheet<String>(
      context: context,
      showDragHandle: true,
      builder: (ctx) => SafeArea(
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            ListTile(
              leading: const Icon(Icons.photo_camera, color: AppTheme.accent),
              title: const Text('Prendre une photo'),
              onTap: () => Navigator.pop(ctx, 'camera'),
            ),
            ListTile(
              leading: const Icon(Icons.photo_library, color: AppTheme.accent),
              title: const Text('Choisir dans la galerie'),
              onTap: () => Navigator.pop(ctx, 'gallery'),
            ),
            if (_imageUrl != null)
              ListTile(
                leading: const Icon(Icons.delete_outline, color: Colors.red),
                title: const Text('Supprimer la photo'),
                onTap: () => Navigator.pop(ctx, 'remove'),
              ),
          ],
        ),
      ),
    );
    if (action == null) return;
    if (action == 'remove') {
      setState(() => _imageUrl = null);
      return;
    }
    final source =
        action == 'camera' ? ImageSource.camera : ImageSource.gallery;
    try {
      final chemin = await PhotoService.choisir(source);
      if (chemin != null && mounted) setState(() => _imageUrl = chemin);
    } catch (e) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text('Photo impossible : $e')),
        );
      }
    }
  }

  Future<void> _supprimer() async {
    final ok = await showDialog<bool>(
      context: context,
      builder: (_) => AlertDialog(
        title: const Text('Supprimer ce produit ?'),
        content: Text('« ${widget.produit!.nom} » sera retiré de la liste.'),
        actions: [
          TextButton(
              onPressed: () => Navigator.pop(context, false),
              child: const Text('Annuler')),
          FilledButton(
            style: FilledButton.styleFrom(backgroundColor: Colors.red),
            onPressed: () => Navigator.pop(context, true),
            child: const Text('Supprimer'),
          ),
        ],
      ),
    );
    if (ok == true) {
      await _repo.supprimer(widget.produit!.id);
      if (mounted) Navigator.of(context).pop(true);
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(_modification ? 'Modifier' : 'Nouveau produit'),
        actions: [
          if (_modification)
            IconButton(
              icon: const Icon(Icons.delete_outline),
              color: Colors.red,
              onPressed: _supprimer,
            ),
        ],
      ),
      body: SafeArea(
        child: Form(
          key: _formKey,
          child: ListView(
            padding: const EdgeInsets.fromLTRB(16, 8, 16, 24),
            children: [
              Center(
                child: GestureDetector(
                  onTap: _changerPhoto,
                  child: Stack(
                    clipBehavior: Clip.none,
                    children: [
                      ProduitImage(url: _imageUrl, taille: 120, radius: 20),
                      Positioned(
                        right: -6,
                        bottom: -6,
                        child: Container(
                          padding: const EdgeInsets.all(8),
                          decoration: BoxDecoration(
                            color: AppTheme.accent,
                            shape: BoxShape.circle,
                            border: Border.all(color: Colors.white, width: 2),
                          ),
                          child: const Icon(Icons.photo_camera,
                              color: Colors.white, size: 18),
                        ),
                      ),
                    ],
                  ),
                ),
              ),
              const SizedBox(height: 8),
              Center(
                child: Text(
                  _imageUrl == null ? 'Ajouter une photo' : 'Changer la photo',
                  style: const TextStyle(
                      color: AppTheme.accent,
                      fontWeight: FontWeight.w600,
                      fontSize: 13),
                ),
              ),
              if (_codeBarres != null) ...[
                const SizedBox(height: 12),
                Center(
                  child: Row(
                    mainAxisSize: MainAxisSize.min,
                    children: [
                      const Icon(Icons.qr_code, size: 16,
                          color: AppTheme.grisTexte),
                      const SizedBox(width: 6),
                      Text(_codeBarres!,
                          style: const TextStyle(
                              color: AppTheme.grisTexte,
                              fontWeight: FontWeight.w600)),
                    ],
                  ),
                ),
              ],
              const SizedBox(height: 20),
              if (_scanNonTrouve) ...[
                _banniereNonTrouve(),
                const SizedBox(height: 16),
              ],
              _label('Nom du produit'),
              TextFormField(
                controller: _nom,
                autofocus: !_modification && _nom.text.isEmpty,
                textCapitalization: TextCapitalization.sentences,
                onChanged: (_) => setState(() {}),
                decoration: const InputDecoration(hintText: 'Ex : Nutella 400g'),
                validator: (v) =>
                    (v == null || v.trim().isEmpty) ? 'Nom obligatoire' : null,
              ),
              const SizedBox(height: 20),
              Row(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Expanded(
                    child: Column(
                      crossAxisAlignment: CrossAxisAlignment.start,
                      children: [
                        _label('Prix d\'achat'),
                        _champPrix(_prixAchat, obligatoire: false),
                      ],
                    ),
                  ),
                  const SizedBox(width: 14),
                  Expanded(
                    child: Column(
                      crossAxisAlignment: CrossAxisAlignment.start,
                      children: [
                        _label('Prix de vente'),
                        _champPrix(_prix,
                            autofocus: !_modification && _nom.text.isNotEmpty),
                      ],
                    ),
                  ),
                ],
              ),
              _apercuMarge(),
              const SizedBox(height: 20),
              _label('Conditionnement'),
              _toggleUnitePack(),
              const SizedBox(height: 20),
              if (!_estPack)
                Row(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    Expanded(
                      flex: 3,
                      child: Column(
                        crossAxisAlignment: CrossAxisAlignment.start,
                        children: [_label('Quantité'), _champQuantite()],
                      ),
                    ),
                    const SizedBox(width: 14),
                    Expanded(
                      flex: 2,
                      child: Column(
                        crossAxisAlignment: CrossAxisAlignment.start,
                        children: [_label('Unité'), _selecteurUnite()],
                      ),
                    ),
                  ],
                )
              else
                Row(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    Expanded(
                      child: Column(
                        crossAxisAlignment: CrossAxisAlignment.start,
                        children: [_label('Nombre'), _champNombre()],
                      ),
                    ),
                    const SizedBox(width: 10),
                    Expanded(
                      child: Column(
                        crossAxisAlignment: CrossAxisAlignment.start,
                        children: [_label('Contenance'), _champQuantite()],
                      ),
                    ),
                    const SizedBox(width: 10),
                    Expanded(
                      child: Column(
                        crossAxisAlignment: CrossAxisAlignment.start,
                        children: [_label('Unité'), _selecteurUnite()],
                      ),
                    ),
                  ],
                ),
              _apercuPrixMesure(),
              const SizedBox(height: 24),
              _label('Inventaire (stock)'),
              _sectionStock(),
              const SizedBox(height: 24),
              FilledButton.icon(
                onPressed: _enregistre ? null : _enregistrer,
                icon: _enregistre
                    ? const SizedBox(
                        width: 18,
                        height: 18,
                        child: CircularProgressIndicator(
                            strokeWidth: 2, color: Colors.white))
                    : const Icon(Icons.check),
                label: Text(_modification ? 'Enregistrer' : 'Ajouter à la liste'),
              ),
            ],
          ),
        ),
      ),
    );
  }

  Widget _label(String t) => Padding(
        padding: const EdgeInsets.only(bottom: 8, left: 4),
        child: Text(t,
            style: const TextStyle(
                fontWeight: FontWeight.w600, fontSize: 14)),
      );

  Widget _banniereNonTrouve() {
    return Container(
      padding: const EdgeInsets.all(12),
      decoration: BoxDecoration(
        color: AppTheme.accent.withValues(alpha: 0.08),
        borderRadius: BorderRadius.circular(12),
        border: Border.all(color: AppTheme.accent.withValues(alpha: 0.3)),
      ),
      child: const Row(
        children: [
          Icon(Icons.info_outline, color: AppTheme.accent, size: 20),
          SizedBox(width: 10),
          Expanded(
            child: Text(
              'Produit non trouvé en ligne. Saisis-le : il sera mémorisé et '
              'reconnu automatiquement aux prochains scans.',
              style: TextStyle(fontSize: 13, color: AppTheme.noir),
            ),
          ),
        ],
      ),
    );
  }

  Widget _champPrix(TextEditingController c,
      {bool autofocus = false, bool obligatoire = true}) {
    return TextFormField(
      controller: c,
      autofocus: autofocus,
      keyboardType: const TextInputType.numberWithOptions(decimal: true),
      inputFormatters: [
        FilteringTextInputFormatter.allow(RegExp(r'[0-9.,]')),
      ],
      onChanged: (_) => setState(() {}),
      decoration: const InputDecoration(hintText: '0,00', suffixText: '€'),
      validator: (v) {
        if (v == null || v.trim().isEmpty) return obligatoire ? 'Requis' : null;
        if (_parse(v) <= 0) return 'Invalide';
        return null;
      },
    );
  }

  Widget _apercuMarge() {
    final achat = _parse(_prixAchat.text);
    final vente = _parse(_prix.text);
    if (achat <= 0 || vente <= 0) return const SizedBox.shrink();

    final gain = vente - achat;
    final coef = vente / achat;
    final positif = coef >= 1;
    final couleur = positif ? const Color(0xFF1B873F) : Colors.red;
    final signe = gain >= 0 ? '+' : '';
    final gainTxt = '$signe${gain.toStringAsFixed(2).replaceAll('.', ',')} €';
    final apercu = Produit(id: '', nom: '', prix: vente, prixAchat: achat);

    return Padding(
      padding: const EdgeInsets.only(top: 10, left: 4),
      child: Row(
        children: [
          Icon(positif ? Icons.trending_up : Icons.trending_down,
              color: couleur, size: 18),
          const SizedBox(width: 8),
          Text('Marge ${apercu.margeLibelle}  ($gainTxt)',
              style: TextStyle(color: couleur, fontWeight: FontWeight.w700)),
        ],
      ),
    );
  }

  Widget _champQuantite() {
    return TextFormField(
      controller: _quantite,
      keyboardType: const TextInputType.numberWithOptions(decimal: true),
      inputFormatters: [
        FilteringTextInputFormatter.allow(RegExp(r'[0-9.,]')),
      ],
      onChanged: (_) => setState(() {}),
      decoration: const InputDecoration(hintText: '0'),
      validator: (v) {
        if (v == null || v.trim().isEmpty) return 'Requis';
        if (_parse(v) <= 0) return 'Invalide';
        return null;
      },
    );
  }

  Widget _selecteurUnite() {
    return DropdownButtonFormField<String>(
      initialValue: _unite,
      isExpanded: true,
      items: [
        for (final u in Unites.tout)
          DropdownMenuItem(value: u, child: Text(Unites.libelle(u))),
      ],
      onChanged: (v) => setState(() {
        final nouvelle = v ?? Unites.g;
        _convertirQuantite(_unite, nouvelle);
        _unite = nouvelle;
      }),
    );
  }

  /// Convertit la quantité saisie quand on change d'unité dans la même
  /// dimension (ex : 1500 ml → L = 1,5 ; 1500 g → kg = 1,5).
  /// Changement de dimension (poids ↔ volume) : on garde la valeur telle quelle.
  void _convertirQuantite(String from, String to) {
    if (from == to) return;
    final q = _parse(_quantite.text);
    if (q <= 0) return;

    const poids = {Unites.g: 1.0, Unites.kg: 1000.0}; // base : grammes
    const volume = {Unites.ml: 1.0, Unites.cl: 10.0, Unites.l: 1000.0}; // base : ml

    double? conv;
    if (poids.containsKey(from) && poids.containsKey(to)) {
      conv = q * poids[from]! / poids[to]!;
    } else if (volume.containsKey(from) && volume.containsKey(to)) {
      conv = q * volume[from]! / volume[to]!;
    }
    if (conv != null) {
      conv = (conv * 1000).round() / 1000; // évite le bruit de virgule flottante
      _quantite.text = _fmtQuantite(conv);
    }
  }

  Widget _toggleUnitePack() {
    return SizedBox(
      width: double.infinity,
      child: SegmentedButton<bool>(
        segments: const [
          ButtonSegment(
              value: false,
              label: Text('Unité'),
              icon: Icon(Icons.water_drop_outlined)),
          ButtonSegment(
              value: true,
              label: Text('Pack'),
              icon: Icon(Icons.inventory_2_outlined)),
        ],
        selected: {_estPack},
        showSelectedIcon: false,
        onSelectionChanged: (s) => setState(() {
          _estPack = s.first;
          // En passant en Pack, on pré-remplit le nombre de contenants à 6
          // (valeur courante, modifiable) pour que l'étiquette affiche direct « 6X… ».
          if (_estPack && _nbContenants.text.trim().isEmpty) {
            _nbContenants.text = '6';
          }
        }),
      ),
    );
  }

  Widget _champNombre() {
    return TextFormField(
      controller: _nbContenants,
      keyboardType: TextInputType.number,
      inputFormatters: [FilteringTextInputFormatter.digitsOnly],
      onChanged: (_) => setState(() {}),
      decoration: const InputDecoration(hintText: '6', suffixText: '×'),
      validator: (v) {
        if (!_estPack) return null;
        if ((int.tryParse((v ?? '').trim()) ?? 0) < 2) return '≥ 2';
        return null;
      },
    );
  }

  void _ajusterStock(int delta) {
    final cur = int.tryParse(_stock.text.trim()) ?? 0;
    final n = (cur + delta).clamp(0, 999999);
    _stock.text = n.toString();
    setState(() {});
  }

  Widget _sectionStock() {
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Row(
          children: [
            _btnStock(Icons.remove, () => _ajusterStock(-1)),
            const SizedBox(width: 12),
            Expanded(
              child: TextFormField(
                controller: _stock,
                textAlign: TextAlign.center,
                keyboardType: TextInputType.number,
                inputFormatters: [FilteringTextInputFormatter.digitsOnly],
                onChanged: (_) => setState(() {}),
                style: const TextStyle(fontSize: 22, fontWeight: FontWeight.w800),
                decoration: const InputDecoration(suffixText: 'en stock'),
              ),
            ),
            const SizedBox(width: 12),
            _btnStock(Icons.add, () => _ajusterStock(1)),
          ],
        ),
        const SizedBox(height: 12),
        Wrap(
          spacing: 8,
          runSpacing: 8,
          alignment: WrapAlignment.center,
          children: [for (final d in [1, 5, 10, 50]) _chipStock(d)],
        ),
      ],
    );
  }

  Widget _btnStock(IconData icon, VoidCallback onTap) {
    return Material(
      color: AppTheme.accent.withValues(alpha: 0.12),
      shape: const CircleBorder(),
      child: InkWell(
        customBorder: const CircleBorder(),
        onTap: onTap,
        child: Padding(
          padding: const EdgeInsets.all(12),
          child: Icon(icon, color: AppTheme.accent, size: 22),
        ),
      ),
    );
  }

  Widget _chipStock(int d) {
    return ActionChip(
      label: Text('+$d',
          style: const TextStyle(
              fontWeight: FontWeight.w700, color: AppTheme.accent)),
      onPressed: () => _ajusterStock(d),
      backgroundColor: AppTheme.accent.withValues(alpha: 0.08),
      side: BorderSide(color: AppTheme.accent.withValues(alpha: 0.3)),
    );
  }

  Widget _apercuPrixMesure() {
    final q = _parse(_quantite.text);
    final nb = _estPack ? (int.tryParse(_nbContenants.text.trim()) ?? 0) : 1;
    final apercu = Produit(
      id: '',
      nom: _nom.text.trim(),
      prix: _parse(_prix.text),
      quantite: q > 0 ? q : null,
      unite: _unite,
      nbContenants: (_estPack && nb > 1) ? nb : null,
    );
    final mesure = apercu.prixMesure;
    if (mesure == null || apercu.nom.isEmpty) return const SizedBox.shrink();

    final txt =
        '${mesure.valeur.toStringAsFixed(2).replaceAll('.', ',')} €${mesure.suffixe}';
    return Container(
      margin: const EdgeInsets.only(top: 14),
      padding: const EdgeInsets.all(12),
      decoration: BoxDecoration(
        color: AppTheme.accent.withValues(alpha: 0.08),
        borderRadius: BorderRadius.circular(12),
      ),
      child: Row(
        children: [
          const Icon(Icons.sell_outlined, size: 18, color: AppTheme.accent),
          const SizedBox(width: 8),
          Expanded(
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Text('Sur l’étiquette : ${apercu.titre}',
                    style: const TextStyle(
                        color: AppTheme.noir, fontWeight: FontWeight.w700)),
                const SizedBox(height: 2),
                Text('soit $txt',
                    style: const TextStyle(
                        color: AppTheme.accent, fontWeight: FontWeight.w600)),
              ],
            ),
          ),
        ],
      ),
    );
  }
}