type LayoutReplaceModelDescriptor = {
  capabilities?: unknown;
  displayName?: string | null;
  healthStatus?: string | null;
  id: string;
  imageGenConfig?: unknown;
  isDefault?: boolean | null;
  isSubModel?: boolean | null;
  modelId?: string | null;
  supportsImageGen?: boolean | null;
  supportsVision?: boolean | null;
};

type LayoutReplaceProviderDescriptor = {
  type?: string | null;
};

export type CanvasLayoutReplaceModelCandidate = {
  model: LayoutReplaceModelDescriptor;
  provider: LayoutReplaceProviderDescriptor;
};

const MODEL_PREFERENCE_PATTERNS: RegExp[] = [
  /^snapgen\/gpt-image-2$/i,
  /^openai\/gpt-image-2-developer\/edit$/i,
  /^openai\/gpt-image-2\/edit$/i,
  /^bytedance\/seedream-v5(?:\.0)?-pro\/edit$/i,
  /^qwen\/qwen-image-2(?:\.0)?-pro\/edit$/i,
  /gpt-image.*\/edit/i,
  /seedream.*\/edit/i,
  /qwen-image.*\/edit/i,
  /(?:^|[\s/_-])edit(?:$|[\s/_-])/i,
];

const PROVIDER_PREFERENCE = new Map([
  ["vip98k", 30],
  ["atlascloud", 25],
  ["openai-image", 20],
  ["volcano-vision", 15],
  ["snapgen-image", 10],
]);

function readPositiveNumber(source: unknown, keys: string[]) {
  if (!source || typeof source !== "object") return null;
  const record = source as Record<string, unknown>;
  for (const key of keys) {
    const parsed = Number(record[key]);
    if (Number.isFinite(parsed) && parsed > 0) return parsed;
  }
  return null;
}

function getConfiguredReferenceImageLimit(model: LayoutReplaceModelDescriptor) {
  return (
    readPositiveNumber(model.imageGenConfig, [
      "maxReferenceImages",
      "maxInputImages",
    ]) ||
    readPositiveNumber(model.capabilities, [
      "maxReferenceImages",
      "maxInputImages",
    ])
  );
}

function getModelDescriptor(candidate: CanvasLayoutReplaceModelCandidate) {
  return JSON.stringify([
    candidate.model.modelId,
    candidate.model.displayName,
    candidate.model.capabilities,
    candidate.model.imageGenConfig,
  ]).toLowerCase();
}

export function isCanvasLayoutReplaceModelEligible(
  candidate: CanvasLayoutReplaceModelCandidate,
) {
  if (String(candidate.provider.type || "").trim() === "fal-image") return false;
  if (!candidate.model.supportsImageGen || candidate.model.isSubModel) return false;
  if (candidate.model.supportsVision === false) return false;
  if (candidate.model.healthStatus === "auto_disabled") return false;

  const referenceImageLimit = getConfiguredReferenceImageLimit(candidate.model);
  return referenceImageLimit === null || referenceImageLimit >= 2;
}

function getCanvasLayoutReplaceModelScore(
  candidate: CanvasLayoutReplaceModelCandidate,
) {
  const modelId = String(candidate.model.modelId || "").trim();
  const descriptor = getModelDescriptor(candidate);
  const preferenceIndex = MODEL_PREFERENCE_PATTERNS.findIndex(
    (pattern) => pattern.test(modelId) || pattern.test(descriptor),
  );
  const modelScore =
    preferenceIndex >= 0 ? (MODEL_PREFERENCE_PATTERNS.length - preferenceIndex) * 100 : 0;
  const healthScore = candidate.model.healthStatus === "healthy" ? 50 : 0;
  const providerScore =
    PROVIDER_PREFERENCE.get(candidate.provider.type || "") || 0;
  const defaultScore = candidate.model.isDefault ? 5 : 0;
  return modelScore + healthScore + providerScore + defaultScore;
}

export function rankCanvasLayoutReplaceModels(
  models: CanvasLayoutReplaceModelCandidate[],
  requestedModel?: string | null,
) {
  const eligible = models.filter(isCanvasLayoutReplaceModelEligible);
  const requested = String(requestedModel || "").trim();

  return eligible.sort((left, right) => {
    if (requested && requested !== "auto") {
      const leftRequested =
        left.model.id === requested || left.model.modelId === requested;
      const rightRequested =
        right.model.id === requested || right.model.modelId === requested;
      if (leftRequested !== rightRequested) return leftRequested ? -1 : 1;
    }

    const scoreDifference =
      getCanvasLayoutReplaceModelScore(right) -
      getCanvasLayoutReplaceModelScore(left);
    if (scoreDifference !== 0) return scoreDifference;
    return left.model.id.localeCompare(right.model.id);
  });
}

export function buildCanvasLayoutReplacePrompt(params: {
  referenceHeight?: number;
  referenceWidth?: number;
  sourceProductAspectRatio?: number;
  supplementalPrompt?: string;
}) {
  const geometry =
    params.referenceWidth && params.referenceHeight
      ? `${params.referenceWidth}x${params.referenceHeight}`
      : "与图2完全相同";
  const supplement = String(params.supplementalPrompt || "").trim();
  const sourceProductAspectRatio =
    Number.isFinite(params.sourceProductAspectRatio) &&
    Number(params.sourceProductAspectRatio) > 0
      ? Number(params.sourceProductAspectRatio)
      : null;
  const sourceProductRatioConstraint = sourceProductAspectRatio
    ? `【商品外框比例硬约束】图1透明轮廓测得商品有效外框宽高比为 ${sourceProductAspectRatio.toFixed(3)}:1。结果中完整商品外框的宽高比必须保持在 ${(sourceProductAspectRatio * 0.96).toFixed(3)} 至 ${(sourceProductAspectRatio * 1.04).toFixed(3)} 之间。若与图2原商品占位冲突，应缩短商品整体高度或扩大整体宽度，绝对不能压窄商品宽度或纵向拉长。生成前必须测量外框复核。`
    : "";
  const targetCanvasAspectRatio =
    params.referenceWidth && params.referenceHeight
      ? params.referenceWidth / params.referenceHeight
      : null;
  const targetProductHeightCoverage = 0.76;
  const targetProductWidthCoverage =
    sourceProductAspectRatio && targetCanvasAspectRatio
      ? Math.max(
          0.52,
          Math.min(
            0.86,
            (sourceProductAspectRatio / targetCanvasAspectRatio) *
              targetProductHeightCoverage,
          ),
        )
      : null;
  const targetProductLeftEdge = targetProductWidthCoverage
    ? (1 - targetProductWidthCoverage) / 2
    : null;
  const targetProductRightEdge = targetProductLeftEdge
    ? 1 - targetProductLeftEdge
    : null;
  const targetProductCoverageConstraint = targetProductWidthCoverage
    ? `【商品画布占比硬约束】新商品完整外框应占最终画布宽度约 ${Math.round(targetProductWidthCoverage * 100)}%，允许范围 ${Math.round((targetProductWidthCoverage - 0.03) * 100)}% 至 ${Math.round((targetProductWidthCoverage + 0.03) * 100)}%；左外沿应到达画布 x≈${Math.round(Number(targetProductLeftEdge) * 100)}% 处，右外沿应到达 x≈${Math.round(Number(targetProductRightEdge) * 100)}% 处，两侧都不得向中间收窄；外框高度约占画布 ${Math.round(targetProductHeightCoverage * 100)}%。图2旧商品原本偏窄的占位不得继承，这是唯一允许突破图2原商品边界的地方。扩大新商品时，边柜、台灯、花瓶、摆件和椅子保持原位，并继自然遮挡在新商品前方。`
    : "";

  return [
    "执行单一商品换模版任务。图1是新商品身份图，图2是目标场景与构图模版，最终只输出一张完整成图。",
    "【两图职责】以图2为最终画面底图和唯一场景真值；识别并完整移除图2中的原商品，只在原商品占据的合理空间内放入图1的新商品。图1只定义新商品本身，不得把图1的纯色/透明背景带入结果。",
    "【商品刚性身份锁定，最高优先级】把图1商品视为已经抠好的真实商品像素层，优先完整复用，不要重新绘制或重新设计。只允许对整个商品做等比缩放和整体平移；禁止透视拉伸、视角重构、横向或纵向拉伸、压扁、加宽、缩短、局部缩放、局部重绘、拼接、融合旧商品、改款、简化或增删部件。宁可保留图1的原始轻微侧视角，也不得把它强行改成正视图。",
    "【结构逐项核对】结果必须保持图1商品的完整外轮廓和长宽高比例，以及每块板件、柜门、玻璃、滑轨、把手、层板、洞洞板、抽屉、圆形拉手、桌面、横梁和四条桌腿的数量、形状、位置、尺寸关系、颜色及材质。尤其必须保留桌面下左侧带圆形拉手的窄抽屉及其右侧抽屉分区，不得合并成两个大抽屉。商品完整出现一次，不得裁切、复制或被旧商品残影穿插。",
    sourceProductRatioConstraint,
    targetProductCoverageConstraint,
    "【场景与前景物件锁定】逐像素保留图2的相机机位、画幅、墙面、地面、边柜、台灯、花瓶、椅子、光影和空间关系，也必须保留兔子摆件、书、玩偶、相框、杯子及桌面小物的原样、数量和位置。先把这些独立前景物件与椅子视为不可编辑覆盖层，只移除其后方的旧商品，再让它们按原遮挡关系覆盖到新商品前方；不得把摆件当作旧商品的一部分清除。",
    `【尺寸与放置】输出画布为 ${geometry}。根据图2原商品的地面接触点和整体占位，对图1商品只做统一等比缩放与整体平移；不做局部透视变形。宁可让边缘占位略有差异，也要优先保持图1商品的真实比例和结构。`,
    "【融合要求】清除图2旧商品后补全被遮挡背景，再放入图1商品；添加与图2一致的自然接触阴影、环境反射、景深和色温，但这些融合不得改变商品结构、材质纹理或深浅配色。",
    supplement
      ? `【用户补充】${supplement}。补充要求只能约束替换细节，不得放宽上述商品刚性身份锁定与场景锁定。`
      : "",
    "【生成前自检】逐项比较图1与结果中的商品轮廓、比例、柜体分区、孔洞、门轨、抽屉和腿；任一结构发生拉伸、缺失、增生、错位或与旧商品融合，都必须先修正再输出。不要输出对比图、拼图、说明文字、边框、水印或多个方案。",
  ]
    .filter(Boolean)
    .join("\n\n");
}