/** Directed canvas edges are live inputs, not a cache of earlier request URLs. */
export type CanvasConnection = { id: string; source: string; target: string };
export type ConnectionNode = {
  id: string;
  title?: string;
  kind?: string;
  inputType?: string;
  draftValues?: Record<string, any>;
};

export function connectionError(nodes: ConnectionNode[], edges: CanvasConnection[], source: string, target: string) {
  if (source === target) return "不能连接到同一个节点";
  const from = nodes.find(node => node.id === source), to = nodes.find(node => node.id === target);
  if (!from || !to) return "连接的节点已不存在";
  if ([from, to].some(node => node.kind === "group" || node.draftValues?.action === "TOOLBOX_TEMPLATE_GROUP"))
    return "请连接分组内的具体节点，分组框不是素材输入";
  if (edges.some(edge => edge.source === source && edge.target === target)) return "这两个节点已经连接";
  const pending = [target], seen = new Set<string>();
  while (pending.length) {
    const id = pending.pop()!;
    if (id === source) return "这条连线会形成循环依赖，请调整连接方向";
    if (seen.has(id)) continue;
    seen.add(id);
    pending.push(...edges.filter(edge => edge.source === id).map(edge => edge.target));
  }
  return null;
}

export function connectedInputNodes<T extends ConnectionNode>(nodes: T[], edges: CanvasConnection[], target: string): T[] {
  const seen = new Set<string>();
  return edges.filter(edge => edge.target === target).flatMap(edge => {
    if (seen.has(edge.source)) return [];
    seen.add(edge.source);
    const node = nodes.find(item => item.id === edge.source);
    if (!node) throw new Error("上游节点已删除，请移除失效连线后重试");
    // Also reject cycles restored from an older saved canvas.
    const remaining = edges.filter(item => item.id !== edge.id);
    const error = connectionError(nodes, remaining, edge.source, target);
    if (error && !error.includes("已经连接")) throw new Error(error);
    return [node];
  });
}

export function connectedText(node: ConnectionNode) {
  if (node.inputType !== "text" && node.kind !== "script" && node.kind !== "text") return "";
  const content = node.draftValues?.content;
  if (typeof content === "string") return content.trim();
  if (Array.isArray(content)) return content.filter(value => typeof value === "string").join("\n").trim();
  const rows = node.draftValues?.rows;
  return Array.isArray(rows) ? rows.map(row => [row.shot, row.sceneDescription, row.dialogue, row.imagePrompt, row.motionPrompt].filter(Boolean).join(" · ")).join("\n").trim() : "";
}

export function assertConnectedInputsReady(nodes: ConnectionNode[]) {
  for (const node of nodes) {
    const draft = node.draftValues || {};
    if (draft.uploadStatus === "uploading")
      throw new Error(`上游「${node.title || node.id}」仍在上传，请等待上传完成`);
    if (draft.uploadStatus === "failed")
      throw new Error(`上游「${node.title || node.id}」上传失败，请重新选择素材`);
    if (["pending", "running", "queued", "failed", "cancelled", "canceled", "interrupted"].includes(draft.generationStatus))
      throw new Error(`上游「${node.title || node.id}」尚未成功完成，请先完成该节点`);
    if (node.inputType === "text" || node.kind === "script" || node.kind === "text") {
      if (!connectedText(node)) throw new Error(`上游「${node.title || node.id}」没有文本内容`);
    } else if (["image", "video", "audio"].includes(node.inputType || "")) {
      // sourceUrl/poster is an input preview; it is never proof of a generated output.
      const output = draft.mediaUrl || draft.resultImage || draft.url?.[0] || draft.thumbnailUrl;
      if (!output) throw new Error(`上游「${node.title || node.id}」尚无可用素材，请先上传或生成`);
    }
  }
}

const inputStart = "\n\n<canvas-connected-text>\n";
const inputEnd = "\n</canvas-connected-text>";
export function withConnectedText(prompt: string, nodes: ConnectionNode[]) {
  // Remove only a section created by this resolver, so editing/disconnecting an
  // upstream text node replaces its previous content on a subsequent run.
  const start = prompt.indexOf(inputStart);
  const base = start >= 0 && prompt.endsWith(inputEnd) ? prompt.slice(0, start) : prompt;
  const text = nodes.map(connectedText).filter(Boolean).join("\n\n");
  return text ? `${base.trim()}${inputStart}${text}${inputEnd}` : base.trim();
}

export function connectedImageUrls(lists: string[][], extra: string[] = []) {
  // Keep edge order and identical URLs in separate slots (first/last frame).
  return [...lists.flat(), ...extra].map(url => url.trim()).filter(Boolean);
}


export function connectionTypeError(source: ConnectionNode, target: ConnectionNode) {
  const type = source.inputType || source.draftValues?.mediaType || (source.kind === "text" || source.kind === "script" ? "text" : "");
  const draft = target.draftValues || {};
  const key = draft.functionKey || draft.params?.functionKey || draft.targetPreset;
  const nodeType = draft.nodeType;
  if (source.kind === "material-effect" || source.kind === "material-role")
    return target.inputType === "video" && nodeType !== "smart-edit" ? null : "角色和视频特效素材只能连接到视频生成节点";
  const allowed = nodeType === "smart-edit" || nodeType === "video-clip" || nodeType === "frame-analysis" || draft.action === "VIDEO_HD_UPSCALE" ? ["video"]
    : target.inputType === "image" ? ["image", "text"]
    : target.inputType === "video" ? (key === "audio-to-video" ? ["image", "text", "audio"] : ["image", "text"])
    : target.inputType === "audio" ? ["text"]
    : target.inputType === "text" || target.kind === "script" || target.kind === "text" ? ["image", "video", "text"]
    : null;
  return allowed && !allowed.includes(type) ? "此节点不能消费该类型的输入，请连接匹配的素材或文本节点" : null;
}


export function videoInputLimitError(mode: string, count: number) {
  if (mode === "text-to-video" && count) return "已连接图片，请切换图生视频或全能参考模式后生成";
  if (mode === "first-frame" && count > 1) return "首帧模式只能使用 1 张图片，请移除多余连线或切换模式";
  if (mode === "first-last-frame" && count > 2) return "首尾帧模式只能使用 2 张图片，请移除多余连线或切换模式";
  if (mode === "reference-images" && count > 8) return "全能参考最多使用 8 张图片，请减少输入";
  return null;
}


export function requireResolvedReferenceImages(urls: string[], expectedCount: number) {
  const images = urls.map(url => url.trim());
  if (images.length !== expectedCount || images.some(url => !url))
    throw new Error("部分宫格参考图准备失败，尚未提交生成，请重试；不会使用整张原图代替");
  return images;
}