import 'package:flutter_riverpod/flutter_riverpod.dart';
import '../domain/label_document.dart';
import '../domain/dynamic_field_definition.dart';
import '../services/template_data_resolver.dart';
import '../services/zpl_compiler.dart';
import '../../inventory/domain/product.dart';
import '../../inventory/domain/inventory_item.dart';

class BarcodeDesignerState {
  final LabelDocument document;
  final String? selectedElementId;
  final Product? sampleProduct;
  final InventoryItem? sampleInventoryItem;
  final bool isPreviewMode;
  final double zoom;
  final bool showGrid;
  final bool snapToGrid;
  final double gridStepMm;
  final int? savedTemplateId;
  final List<LabelDocument> undoStack;
  final List<LabelDocument> redoStack;
  final String liveCommands;

  const BarcodeDesignerState({
    required this.document,
    this.selectedElementId,
    this.sampleProduct,
    this.sampleInventoryItem,
    this.isPreviewMode = false,
    this.zoom = 2.4, // Good default zoom for 50x25mm labels on desktop/mobile
    this.showGrid = true,
    this.snapToGrid = true,
    this.gridStepMm = 1.0,
    this.savedTemplateId,
    this.undoStack = const [],
    this.redoStack = const [],
    this.liveCommands = '',
  });

  LabelElement? get selectedElement {
    if (selectedElementId == null) return null;
    return document.elements.where((e) => e.id == selectedElementId).firstOrNull;
  }

  LabelDocument get resolvedDocument {
    if (sampleProduct == null && sampleInventoryItem == null) {
      return document;
    }
    return TemplateDataResolver.resolveDocument(
      document: document,
      product: sampleProduct,
      inventoryItem: sampleInventoryItem,
    );
  }

  BarcodeDesignerState copyWith({
    LabelDocument? document,
    String? selectedElementId,
    bool clearSelectedElement = false,
    Product? sampleProduct,
    bool clearSampleProduct = false,
    InventoryItem? sampleInventoryItem,
    bool clearSampleInventoryItem = false,
    bool? isPreviewMode,
    double? zoom,
    bool? showGrid,
    bool? snapToGrid,
    double? gridStepMm,
    int? savedTemplateId,
    List<LabelDocument>? undoStack,
    List<LabelDocument>? redoStack,
    String? liveCommands,
  }) {
    return BarcodeDesignerState(
      document: document ?? this.document,
      selectedElementId: clearSelectedElement
          ? null
          : (selectedElementId ?? this.selectedElementId),
      sampleProduct: clearSampleProduct ? null : (sampleProduct ?? this.sampleProduct),
      sampleInventoryItem: clearSampleInventoryItem
          ? null
          : (sampleInventoryItem ?? this.sampleInventoryItem),
      isPreviewMode: isPreviewMode ?? this.isPreviewMode,
      zoom: zoom ?? this.zoom,
      showGrid: showGrid ?? this.showGrid,
      snapToGrid: snapToGrid ?? this.snapToGrid,
      gridStepMm: gridStepMm ?? this.gridStepMm,
      savedTemplateId: savedTemplateId ?? this.savedTemplateId,
      undoStack: undoStack ?? this.undoStack,
      redoStack: redoStack ?? this.redoStack,
      liveCommands: liveCommands ?? this.liveCommands,
    );
  }
}

class BarcodeDesignerNotifier extends Notifier<BarcodeDesignerState> {
  @override
  BarcodeDesignerState build() {
    final defaultDoc = LabelDocument.createDefault();
    final cmds = PrintCompiler.compile(document: defaultDoc);
    return BarcodeDesignerState(
      document: defaultDoc,
      liveCommands: cmds,
    );
  }

  void _pushUndo(LabelDocument oldDoc) {
    final newUndo = List<LabelDocument>.from(state.undoStack);
    if (newUndo.length >= 30) newUndo.removeAt(0);
    newUndo.add(oldDoc);
    state = state.copyWith(undoStack: newUndo, redoStack: []);
  }

  void undo() {
    if (state.undoStack.isEmpty) return;
    final newUndo = List<LabelDocument>.from(state.undoStack);
    final previousDoc = newUndo.removeLast();
    final newRedo = List<LabelDocument>.from(state.redoStack)..add(state.document);

    state = state.copyWith(
      document: previousDoc,
      undoStack: newUndo,
      redoStack: newRedo,
    );
    _updateLiveCommands();
  }

  void redo() {
    if (state.redoStack.isEmpty) return;
    final newRedo = List<LabelDocument>.from(state.redoStack);
    final nextDoc = newRedo.removeLast();
    final newUndo = List<LabelDocument>.from(state.undoStack)..add(state.document);

    state = state.copyWith(
      document: nextDoc,
      undoStack: newUndo,
      redoStack: newRedo,
    );
    _updateLiveCommands();
  }

  void loadDocument(LabelDocument doc, [int? templateId]) {
    final cmds = PrintCompiler.compile(document: doc);
    state = BarcodeDesignerState(
      document: doc,
      savedTemplateId: templateId,
      sampleProduct: state.sampleProduct,
      sampleInventoryItem: state.sampleInventoryItem,
      isPreviewMode: state.isPreviewMode,
      zoom: state.zoom,
      showGrid: state.showGrid,
      snapToGrid: state.snapToGrid,
      liveCommands: cmds,
    );
  }

  void resetToNew([double widthMm = 50.0, double heightMm = 25.0]) {
    final newDoc = LabelDocument(
      id: 'template_${DateTime.now().millisecondsSinceEpoch}',
      name: '${widthMm.round()}x${heightMm.round()} Barcode Template',
      config: LabelConfiguration(
        widthMm: widthMm,
        heightMm: heightMm,
      ),
      elements: [],
    );
    loadDocument(newDoc, null);
  }

  void updateTemplateName(String name) {
    state = state.copyWith(
      document: state.document.copyWith(name: name),
    );
  }

  void updateTemplateDescription(String desc) {
    state = state.copyWith(
      document: state.document.copyWith(description: desc),
    );
  }

  void setZoom(double z) {
    state = state.copyWith(zoom: z.clamp(0.8, 6.0));
  }

  void toggleGrid() {
    state = state.copyWith(showGrid: !state.showGrid);
  }

  void toggleSnap() {
    state = state.copyWith(snapToGrid: !state.snapToGrid);
  }

  void togglePreviewMode([bool? force]) {
    final nextMode = force ?? !state.isPreviewMode;
    state = state.copyWith(isPreviewMode: nextMode);
    _updateLiveCommands();
  }

  void setSampleProduct(Product? product, [InventoryItem? item]) {
    state = state.copyWith(
      sampleProduct: product,
      clearSampleProduct: product == null,
      sampleInventoryItem: item,
      clearSampleInventoryItem: item == null,
    );
    _updateLiveCommands();
  }

  void selectElement(String? id) {
    state = state.copyWith(
      selectedElementId: id,
      clearSelectedElement: id == null,
    );
  }

  void updateLabelConfig(LabelConfiguration newConfig) {
    _pushUndo(state.document);
    state = state.copyWith(
      document: state.document.copyWith(config: newConfig),
    );
    _updateLiveCommands();
  }

  double _snap(double valueMm) {
    if (!state.snapToGrid) return valueMm;
    final step = state.gridStepMm;
    return (valueMm / step).round() * step;
  }

  void addElement(LabelElement element) {
    _pushUndo(state.document);
    final elements = List<LabelElement>.from(state.document.elements)..add(element);
    state = state.copyWith(
      document: state.document.copyWith(elements: elements),
      selectedElementId: element.id,
    );
    _updateLiveCommands();
  }

  void updateElement(LabelElement element) {
    _pushUndo(state.document);
    final elements = state.document.elements.map((e) {
      return e.id == element.id ? element : e;
    }).toList();

    state = state.copyWith(
      document: state.document.copyWith(elements: elements),
    );
    _updateLiveCommands();
  }

  void recordUndo() {
    _pushUndo(state.document);
  }

  void setElementPosition(String id, double xMm, double yMm) {
    final elem = state.document.elements.where((e) => e.id == id).firstOrNull;
    if (elem == null || elem.isLocked) return;

    double newX = xMm;
    double newY = yMm;

    if (state.snapToGrid) {
      newX = _snap(newX);
      newY = _snap(newY);
    }

    newX = newX.clamp(0.0, state.document.config.widthMm - 1.0);
    newY = newY.clamp(0.0, state.document.config.heightMm - 1.0);

    final updated = elem.copyWithPosition(xMm: newX, yMm: newY);
    final elements = state.document.elements.map((e) => e.id == id ? updated : e).toList();

    state = state.copyWith(
      document: state.document.copyWith(elements: elements),
    );
    _updateLiveCommands();
  }

  void setElementSize(String id, double widthMm, double heightMm) {
    final elem = state.document.elements.where((e) => e.id == id).firstOrNull;
    if (elem == null || elem.isLocked) return;

    double w = widthMm;
    double h = heightMm;
    if (state.snapToGrid) {
      w = _snap(w);
      h = _snap(h);
    }
    w = w.clamp(2.0, state.document.config.widthMm);
    h = h.clamp(1.0, state.document.config.heightMm);

    final updated = elem.copyWithPosition(widthMm: w, heightMm: h);
    final elements = state.document.elements.map((e) => e.id == id ? updated : e).toList();

    state = state.copyWith(
      document: state.document.copyWith(elements: elements),
    );
    _updateLiveCommands();
  }

  void moveElement(String id, double deltaXMm, double deltaYMm) {
    final elem = state.document.elements.where((e) => e.id == id).firstOrNull;
    if (elem == null || elem.isLocked) return;

    double newX = (elem.xMm + deltaXMm);
    double newY = (elem.yMm + deltaYMm);

    if (state.snapToGrid) {
      newX = _snap(newX);
      newY = _snap(newY);
    }

    newX = newX.clamp(0.0, state.document.config.widthMm - 1.0);
    newY = newY.clamp(0.0, state.document.config.heightMm - 1.0);

    final updated = elem.copyWithPosition(xMm: newX, yMm: newY);
    final elements = state.document.elements.map((e) => e.id == id ? updated : e).toList();

    state = state.copyWith(
      document: state.document.copyWith(elements: elements),
    );
    _updateLiveCommands();
  }

  void resizeElement(String id, double newWidthMm, double newHeightMm) {
    final elem = state.document.elements.where((e) => e.id == id).firstOrNull;
    if (elem == null || elem.isLocked) return;

    double w = newWidthMm;
    double h = newHeightMm;
    if (state.snapToGrid) {
      w = _snap(w);
      h = _snap(h);
    }
    w = w.clamp(2.0, state.document.config.widthMm);
    h = h.clamp(1.0, state.document.config.heightMm);

    final updated = elem.copyWithPosition(widthMm: w, heightMm: h);
    final elements = state.document.elements.map((e) => e.id == id ? updated : e).toList();

    state = state.copyWith(
      document: state.document.copyWith(elements: elements),
    );
    _updateLiveCommands();
  }

  void deleteElement(String id) {
    _pushUndo(state.document);
    final elements = state.document.elements.where((e) => e.id != id).toList();
    state = state.copyWith(
      document: state.document.copyWith(elements: elements),
      clearSelectedElement: state.selectedElementId == id,
    );
    _updateLiveCommands();
  }

  void duplicateElement(String id) {
    final elem = state.document.elements.where((e) => e.id == id).firstOrNull;
    if (elem == null) return;

    _pushUndo(state.document);
    final newId = 'elem_${DateTime.now().millisecondsSinceEpoch}';
    final duplicated = elem.copyWithPosition(
      xMm: (elem.xMm + 2.0).clamp(0.0, state.document.config.widthMm - 2.0),
      yMm: (elem.yMm + 2.0).clamp(0.0, state.document.config.heightMm - 2.0),
    );

    final json = duplicated.toJson();
    json['id'] = newId;
    final finalElem = LabelElement.fromJson(json);

    final elements = List<LabelElement>.from(state.document.elements)..add(finalElem);
    state = state.copyWith(
      document: state.document.copyWith(elements: elements),
      selectedElementId: newId,
    );
    _updateLiveCommands();
  }

  void bringToFront(String id) {
    final index = state.document.elements.indexWhere((e) => e.id == id);
    if (index == -1 || index == state.document.elements.length - 1) return;

    _pushUndo(state.document);
    final elements = List<LabelElement>.from(state.document.elements);
    final elem = elements.removeAt(index);
    elements.add(elem);
    state = state.copyWith(
      document: state.document.copyWith(elements: elements),
    );
    _updateLiveCommands();
  }

  void sendToBack(String id) {
    final index = state.document.elements.indexWhere((e) => e.id == id);
    if (index == -1 || index == 0) return;

    _pushUndo(state.document);
    final elements = List<LabelElement>.from(state.document.elements);
    final elem = elements.removeAt(index);
    elements.insert(0, elem);
    state = state.copyWith(
      document: state.document.copyWith(elements: elements),
    );
    _updateLiveCommands();
  }

  void bringForward(String id) {
    final index = state.document.elements.indexWhere((e) => e.id == id);
    if (index == -1 || index >= state.document.elements.length - 1) return;

    _pushUndo(state.document);
    final elements = List<LabelElement>.from(state.document.elements);
    final elem = elements.removeAt(index);
    elements.insert(index + 1, elem);
    state = state.copyWith(
      document: state.document.copyWith(elements: elements),
    );
    _updateLiveCommands();
  }

  void sendBackward(String id) {
    final index = state.document.elements.indexWhere((e) => e.id == id);
    if (index <= 0) return;

    _pushUndo(state.document);
    final elements = List<LabelElement>.from(state.document.elements);
    final elem = elements.removeAt(index);
    elements.insert(index - 1, elem);
    state = state.copyWith(
      document: state.document.copyWith(elements: elements),
    );
    _updateLiveCommands();
  }

  /// Binds a product field directly to an existing DynamicTextElement or BarcodeElement
  void bindFieldToElement(String elementId, String source, String fieldKey) {
    final elem = state.document.elements.where((e) => e.id == elementId).firstOrNull;
    if (elem == null) return;

    _pushUndo(state.document);
    final fieldDef = DynamicFieldDefinition.find(source, fieldKey);

    LabelElement updated;
    if (elem is DynamicTextElement) {
      updated = elem.copyWithPosition(
        source: source,
        fieldKey: fieldKey,
        prefix: fieldDef?.defaultPrefix ?? elem.prefix,
        suffix: fieldDef?.defaultSuffix ?? elem.suffix,
      );
    } else if (elem is BarcodeElement) {
      updated = elem.copyWithPosition(
        valueType: 'dynamic',
        source: source,
        fieldKey: fieldKey,
      );
    } else if (elem is QrCodeElement) {
      updated = elem.copyWithPosition(
        valueType: 'dynamic',
        source: source,
        fieldKey: fieldKey,
      );
    } else {
      return;
    }

    final elements = state.document.elements.map((e) => e.id == elementId ? updated : e).toList();
    state = state.copyWith(
      document: state.document.copyWith(elements: elements),
    );
    _updateLiveCommands();
  }

  /// Adds a new element directly bound from a dragged DynamicFieldDefinition
  void addBoundFieldElement({
    required DynamicFieldDefinition fieldDef,
    required double dropXMm,
    required double dropYMm,
  }) {
    _pushUndo(state.document);
    final id = 'elem_${DateTime.now().millisecondsSinceEpoch}';

    LabelElement newElem;
    if (fieldDef.fieldKey == 'barcode' || (fieldDef.isBarcodeCompatible && fieldDef.fieldKey == 'sku')) {
      newElem = BarcodeElement(
        id: id,
        xMm: dropXMm.clamp(0.0, state.document.config.widthMm - 30.0),
        yMm: dropYMm.clamp(0.0, state.document.config.heightMm - 8.0),
        widthMm: 38.0,
        heightMm: 8.0,
        valueType: 'dynamic',
        source: fieldDef.source,
        fieldKey: fieldDef.fieldKey,
        showText: true,
      );
    } else {
      newElem = DynamicTextElement(
        id: id,
        xMm: dropXMm.clamp(0.0, state.document.config.widthMm - 20.0),
        yMm: dropYMm.clamp(0.0, state.document.config.heightMm - 4.0),
        widthMm: 28.0,
        heightMm: 4.0,
        source: fieldDef.source,
        fieldKey: fieldDef.fieldKey,
        prefix: fieldDef.defaultPrefix,
        suffix: fieldDef.defaultSuffix,
        fontSizePt: 8.0,
      );
    }

    addElement(newElem);
  }

  void _updateLiveCommands() {
    try {
      final docToCompile = state.isPreviewMode ? state.resolvedDocument : state.document;
      final cmds = PrintCompiler.compile(document: docToCompile);
      state = state.copyWith(liveCommands: cmds);
    } catch (_) {
      // Ignore intermediate compilation errors while typing
    }
  }
}

final barcodeDesignerProvider =
    NotifierProvider<BarcodeDesignerNotifier, BarcodeDesignerState>(() {
  return BarcodeDesignerNotifier();
});