import type { AgentPsdTemplateImageContentBounds } from "@/lib/agents/psd-template-config";

type PsdImageLayerCandidate = {
  id: string;
  layerName: string;
  layerPath: string;
  x: number;
  y: number;
  width: number;
  height: number;
  contentBounds?: AgentPsdTemplateImageContentBounds;
};

const BACKGROUND_LAYER_PATTERN = /(背景|底图|bg|background)/i;
const ADJUSTMENT_LAYER_PATTERN =
  /(色相\s*\/?\s*饱和度|曲线|色阶|亮度\s*\/?\s*对比度|可选颜色|色彩平衡|自然饱和度|曝光|黑白|阈值|反相|海报化|通道混合器|渐变映射|纯色|渐变填充|图案填充|hue\s*\/?\s*saturation|curves?|levels?|brightness\s*\/?\s*contrast|selective color|color balance|vibrance|exposure|black\s*&?\s*white|threshold|invert|posterize|channel mixer|gradient map|solid color|gradient fill|pattern fill)/i;
const PRIMARY_IMAGE_HINT_PATTERN =
  /(主图|产品|商品|主体|sku|result|photo|image|product|subject|scene|素材)/i;

function getCanvasOverlapArea(params: {
  x: number;
  y: number;
  width: number;
  height: number;
  canvasWidth: number;
  canvasHeight: number;
}) {
  const left = Math.max(0, params.x);
  const top = Math.max(0, params.y);
  const right = Math.min(params.canvasWidth, params.x + params.width);
  const bottom = Math.min(params.canvasHeight, params.y + params.height);
  return Math.max(0, right - left) * Math.max(0, bottom - top);
}

export function isPsdAdjustmentLikeImageLayer(layer: {
  layerName: string;
  layerPath: string;
}) {
  return (
    ADJUSTMENT_LAYER_PATTERN.test(layer.layerName) ||
    ADJUSTMENT_LAYER_PATTERN.test(layer.layerPath)
  );
}

export function pickPrimaryPsdImageLayerId(params: {
  imageLayers: PsdImageLayerCandidate[];
  canvasWidth: number;
  canvasHeight: number;
}) {
  const { imageLayers, canvasWidth, canvasHeight } = params;
  if (imageLayers.length === 0) {
    return null;
  }

  const scored = imageLayers.map((layer) => {
    const overlapArea = getCanvasOverlapArea({
      x: layer.x,
      y: layer.y,
      width: layer.width,
      height: layer.height,
      canvasWidth,
      canvasHeight,
    });
    const layerArea = Math.max(1, layer.width * layer.height);
    const visibleArea =
      layer.contentBounds && layer.contentBounds.width > 0 && layer.contentBounds.height > 0
        ? layer.contentBounds.width * layer.contentBounds.height
        : overlapArea;
    const coversWholeCanvas =
      overlapArea >= canvasWidth * canvasHeight * 0.96 &&
      layer.x <= 0 &&
      layer.y <= 0 &&
      layer.width >= canvasWidth * 0.96 &&
      layer.height >= canvasHeight * 0.96;
    const isAdjustmentLike = isPsdAdjustmentLikeImageLayer(layer);
    const hasPrimaryImageHint =
      PRIMARY_IMAGE_HINT_PATTERN.test(layer.layerName) ||
      PRIMARY_IMAGE_HINT_PATTERN.test(layer.layerPath);
    const backgroundPenalty =
      BACKGROUND_LAYER_PATTERN.test(layer.layerName) ||
      BACKGROUND_LAYER_PATTERN.test(layer.layerPath) ||
      coversWholeCanvas
        ? 0.45
        : 1;
    const adjustmentPenalty = isAdjustmentLike ? 0.05 : 1;
    const oversizePenalty =
      layer.width > canvasWidth * 1.2 || layer.height > canvasHeight * 1.2 ? 0.9 : 1;
    const primaryHintBonus = hasPrimaryImageHint ? 1.2 : 1;

    return {
      layer,
      score:
        (visibleArea * 1.15 + overlapArea + layerArea * 0.2) *
        backgroundPenalty *
        adjustmentPenalty *
        oversizePenalty *
        primaryHintBonus,
      isAdjustmentLike,
    };
  });

  const preferredCandidates = scored.filter((entry) => !entry.isAdjustmentLike);
  const candidates = preferredCandidates.length > 0 ? preferredCandidates : scored;
  candidates.sort((left, right) => right.score - left.score);
  return candidates[0]?.layer.id || null;
}