/**
 * Blend modes for layer compositing
 */
export type BlendMode =
  | 'normal'
  | 'multiply'
  | 'screen'
  | 'overlay'
  | 'darken'
  | 'lighten'
  | 'color-dodge'
  | 'color-burn'
  | 'hard-light'
  | 'soft-light'
  | 'difference'
  | 'exclusion'
  | 'hue'
  | 'saturation'
  | 'color'
  | 'luminosity';

/**
 * Layer mask data
 */
export interface LayerMask {
  /** Canvas element containing the mask's grayscale data */
  canvas: HTMLCanvasElement | null;
  /** Whether the mask is currently enabled */
  enabled: boolean;
  /** Whether to invert the mask (white=hide, black=reveal) */
  inverted: boolean;
}

/**
 * Layer interface representing a single layer in the canvas
 */
export interface Layer {
  /** Unique identifier for the layer */
  id: string;
  /** Display name of the layer */
  name: string;
  /** Canvas element containing the layer's image data */
  canvas: HTMLCanvasElement | null;
  /** Visibility state */
  visible: boolean;
  /** Opacity (0-1) */
  opacity: number;
  /** Blend mode for compositing */
  blendMode: BlendMode;
  /** Z-index order (higher = on top) */
  order: number;
  /** Lock state (prevents editing) */
  locked: boolean;
  /** Layer dimensions */
  width: number;
  height: number;
  /** Position offset */
  x: number;
  y: number;
  /** Layer mask for non-destructive editing */
  mask: LayerMask | null;
  /** Parent group ID (null if not in a group) */
  groupId: string | null;
  /** Whether this layer is a group */
  isGroup: boolean;
  /** Whether group is collapsed (only relevant if isGroup=true) */
  collapsed: boolean;
  /** Timestamp of creation */
  createdAt: number;
  /** Timestamp of last modification */
  updatedAt: number;
}

/**
 * Partial layer data for updates
 */
export type LayerUpdate = Partial<Omit<Layer, 'id' | 'createdAt'>>;

/**
 * Layer creation parameters
 */
export interface CreateLayerParams {
  name?: string;
  width: number;
  height: number;
  x?: number;
  y?: number;
  opacity?: number;
  blendMode?: BlendMode;
  fillColor?: string;
}