import { WECHAT_APP_ID, WECHAT_APP_SECRET } from "./config";

// ---- Token 管理 ----

interface TokenCache {
  token: string;
  expiresAt: number;
}

let tokenCache: TokenCache | null = null;

async function getAccessToken(): Promise<string> {
  if (tokenCache && Date.now() < tokenCache.expiresAt) {
    return tokenCache.token;
  }

  if (!WECHAT_APP_ID || !WECHAT_APP_SECRET) {
    throw new Error("微信 AppID 或 AppSecret 未配置");
  }

  const url = `https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=${WECHAT_APP_ID}&secret=${WECHAT_APP_SECRET}`;
  const res = await fetch(url);
  const data = await res.json() as { access_token?: string; expires_in?: number; errcode?: number; errmsg?: string };

  if (data.errcode) {
    throw new Error(`获取 access_token 失败: ${data.errmsg} (${data.errcode})`);
  }

  if (!data.access_token) {
    throw new Error("获取 access_token 失败: 返回为空");
  }

  // 提前 5 分钟过期
  tokenCache = {
    token: data.access_token,
    expiresAt: Date.now() + (data.expires_in! - 300) * 1000,
  };

  return tokenCache.token;
}

// ---- 状态检查 ----

export async function getWechatStatus(): Promise<{ configured: boolean; appId?: string }> {
  return {
    configured: !!(WECHAT_APP_ID && WECHAT_APP_SECRET),
    appId: WECHAT_APP_ID ? WECHAT_APP_ID.slice(0, 6) + "****" : undefined,
  };
}

// ---- 上传封面图片 ----

export async function uploadImage(imageUrl: string): Promise<string> {
  const token = await getAccessToken();

  // 下载图片
  const imgRes = await fetch(imageUrl);
  if (!imgRes.ok) throw new Error(`下载图片失败: ${imgRes.status}`);
  const imgBuffer = await imgRes.arrayBuffer();

  // 从 URL 推断文件名
  const urlParts = imageUrl.split("/");
  const filename = urlParts[urlParts.length - 1] || "cover.jpg";

  // 构造 multipart/form-data
  const formData = new FormData();
  const blob = new Blob([imgBuffer], { type: "image/jpeg" });
  formData.append("media", blob, filename);

  const uploadUrl = `https://api.weixin.qq.com/cgi-bin/material/add_material?access_token=${token}&type=image`;
  const uploadRes = await fetch(uploadUrl, { method: "POST", body: formData });
  const uploadData = await uploadRes.json() as { media_id?: string; url?: string; errcode?: number; errmsg?: string };

  if (uploadData.errcode) {
    throw new Error(`上传图片失败: ${uploadData.errmsg} (${uploadData.errcode})`);
  }

  return uploadData.media_id!;
}

// ---- 上传文章内图片（用于正文中引用的图片） ----

export async function uploadContentImage(imageUrl: string): Promise<string> {
  const token = await getAccessToken();

  const imgRes = await fetch(imageUrl);
  if (!imgRes.ok) throw new Error(`下载图片失败: ${imgRes.status}`);
  const imgBuffer = await imgRes.arrayBuffer();

  const urlParts = imageUrl.split("/");
  const filename = urlParts[urlParts.length - 1] || "image.jpg";

  const formData = new FormData();
  const blob = new Blob([imgBuffer], { type: "image/jpeg" });
  formData.append("media", blob, filename);

  const uploadUrl = `https://api.weixin.qq.com/cgi-bin/media/uploadimg?access_token=${token}`;
  const uploadRes = await fetch(uploadUrl, { method: "POST", body: formData });
  const uploadData = await uploadRes.json() as { url?: string; errcode?: number; errmsg?: string };

  if (uploadData.errcode) {
    throw new Error(`上传内容图片失败: ${uploadData.errmsg} (${uploadData.errcode})`);
  }

  return uploadData.url!;
}

// ---- 替换文章中的图片为微信 URL ----

async function replaceContentImages(html: string, imageUrls: string[]): Promise<string> {
  let result = html;
  for (const url of imageUrls) {
    try {
      const wxUrl = await uploadContentImage(url);
      result = result.replaceAll(url, wxUrl);
    } catch (e) {
      console.warn(`[wechat] 跳过图片 ${url}:`, e instanceof Error ? e.message : String(e));
    }
  }
  return result;
}

// ---- 创建草稿 ----

interface Article {
  title: string;
  author?: string;
  content: string;
  content_source_url?: string;
  thumb_media_id?: string;
  thumb_media_url?: string;
  show_cover_pic?: number;
  need_open_comment?: number;
  content_image_urls?: { original_url: string }[];
}

interface DraftResult {
  ok: boolean;
  media_id?: string;
  message?: string;
}

export async function syncWechat(articles: Article[]): Promise<DraftResult> {
  const token = await getAccessToken();

  const processedArticles: Record<string, unknown>[] = [];

  for (const article of articles) {
    let content = article.content;

    // 替换内容中的图片为微信 URL
    if (article.content_image_urls && article.content_image_urls.length > 0) {
      const urls = article.content_image_urls.map(u => u.original_url);
      content = await replaceContentImages(content, urls);
    }

    const processed: Record<string, unknown> = {
      title: article.title,
      author: article.author || "",
      content: content,
      content_source_url: article.content_source_url || "",
      show_cover_pic: article.show_cover_pic ?? 1,
      need_open_comment: article.need_open_comment ?? 0,
    };

    // 上传封面图
    if (article.thumb_media_url) {
      try {
        const mediaId = await uploadImage(article.thumb_media_url);
        processed.thumb_media_id = mediaId;
      } catch (e) {
        console.warn("[wechat] 封面图上传失败:", e instanceof Error ? e.message : String(e));
      }
    } else if (article.thumb_media_id) {
      processed.thumb_media_id = article.thumb_media_id;
    }

    processedArticles.push(processed);
  }

  // 创建草稿
  const draftUrl = `https://api.weixin.qq.com/cgi-bin/draft/add?access_token=${token}`;
  const draftRes = await fetch(draftUrl, {
    method: "POST",
    headers: { "Content-Type": "application/json" },
    body: JSON.stringify({ articles: processedArticles }),
  });
  const draftData = await draftRes.json() as { media_id?: string; errcode?: number; errmsg?: string };

  if (draftData.errcode) {
    return { ok: false, message: `创建草稿失败: ${draftData.errmsg} (${draftData.errcode})` };
  }

  return { ok: true, media_id: draftData.media_id };
}

// ---- 发布草稿 ----

export async function publishDraft(mediaId: string): Promise<DraftResult> {
  const token = await getAccessToken();

  const url = `https://api.weixin.qq.com/cgi-bin/freepublish/submit?access_token=${token}`;
  const res = await fetch(url, {
    method: "POST",
    headers: { "Content-Type": "application/json" },
    body: JSON.stringify({ media_id: mediaId }),
  });
  const data = await res.json() as { publish_id?: string; errcode?: number; errmsg?: string };

  if (data.errcode) {
    return { ok: false, message: `发布失败: ${data.errmsg} (${data.errcode})` };
  }

  return { ok: true, media_id: data.publish_id };
}