/**
 * Gitea API Client — ChildHood 项目进度管理
 *
 * 封装所有 Gitea REST API 调用，处理 UTF-8 编码和错误重试。
 * 供 gitea.js CLI 使用。
 */

const http = require('http');

const DEFAULT_CONFIG = {
  host: 'micecola.top',
  port: 8418,
  apiBase: '/api/v1',
  repoPath: '/repos/starmen1265/ChildHood',
  timeout: 15000,
};

class GiteaAPI {
  /**
   * @param {string} token - Gitea API Token
   * @param {object} [config] - 覆盖默认配置
   */
  constructor(token, config = {}) {
    if (!token) throw new Error('GITEA_TOKEN 未设置。请设置环境变量 GITEA_TOKEN。');
    this.token = token;
    this.config = { ...DEFAULT_CONFIG, ...config };
  }

  // ====== 底层 HTTP 请求 ======

  /**
   * 发送 API 请求
   * @param {string} method - GET / POST / PATCH / PUT / DELETE
   * @param {string} path - API 路径（相对于 repo root），如 /issues、/milestones/2
   * @param {object|null} data - 请求体（自动 JSON 序列化）
   * @param {object} [params] - URL 查询参数
   * @returns {Promise<any>} 解析后的 JSON 响应
   */
  async request(method, path, data = null, params = {}) {
    const basePath = this.config.apiBase + this.config.repoPath + path;
    const url = new URL(`http://${this.config.host}:${this.config.port}${basePath}`);

    for (const [k, v] of Object.entries(params)) {
      if (v !== undefined && v !== null && v !== '') {
        url.searchParams.set(k, String(v));
      }
    }

    const body = data ? JSON.stringify(data) : null;

    const headers = {
      'Authorization': `token ${this.token}`,
      'Accept': 'application/json',
    };
    if (body) {
      headers['Content-Type'] = 'application/json; charset=utf-8';
      headers['Content-Length'] = Buffer.byteLength(body, 'utf-8');
    }

    return new Promise((resolve, reject) => {
      const options = {
        hostname: url.hostname,
        port: url.port || 80,
        path: url.pathname + url.search,
        method: method.toUpperCase(),
        headers,
      };

      const req = http.request(options, (res) => {
        const chunks = [];
        res.on('data', (chunk) => chunks.push(chunk));
        res.on('end', () => {
          const raw = Buffer.concat(chunks).toString('utf-8');
          if (res.statusCode >= 400) {
            const err = new Error(`HTTP ${res.statusCode}: ${raw.substring(0, 300)}`);
            err.statusCode = res.statusCode;
            err.body = raw;
            reject(err);
            return;
          }
          if (!raw.trim()) { resolve(null); return; }
          try { resolve(JSON.parse(raw)); }
          catch { resolve(raw); }
        });
      });

      req.on('error', reject);
      req.setTimeout(this.config.timeout, () => {
        req.destroy();
        reject(new Error(`请求超时 (${this.config.timeout}ms): ${method} ${path}`));
      });

      if (body) req.write(body, 'utf-8');
      req.end();
    });
  }

  // ====== Issues ======

  listIssues(params = {}) {
    return this.request('GET', '/issues', null, { state: 'open', limit: 50, ...params });
  }

  getIssue(number) {
    return this.request('GET', `/issues/${number}`);
  }

  createIssue(data) {
    return this.request('POST', '/issues', data);
  }

  updateIssue(number, data) {
    return this.request('PATCH', `/issues/${number}`, data);
  }

  closeIssue(number, comment) {
    const p = this.updateIssue(number, { state: 'closed' });
    if (comment) return p.then(() => this.createComment(number, comment));
    return p;
  }

  reopenIssue(number) {
    return this.updateIssue(number, { state: 'open' });
  }

  // ====== Comments ======

  listComments(number) {
    return this.request('GET', `/issues/${number}/comments`);
  }

  createComment(number, body) {
    return this.request('POST', `/issues/${number}/comments`, { body });
  }

  // ====== Labels ======

  listLabels(params = {}) {
    return this.request('GET', '/labels', null, { page: 1, limit: 100, ...params });
  }

  createLabel(data) {
    return this.request('POST', '/labels', data);
  }

  getLabel(id) {
    return this.request('GET', `/labels/${id}`);
  }

  deleteLabel(id) {
    return this.request('DELETE', `/labels/${id}`);
  }

  getIssueLabels(number) {
    return this.request('GET', `/issues/${number}/labels`);
  }

  /** 添加标签到 Issue（不清除已有标签） */
  addIssueLabels(number, labelIds) {
    return this.request('POST', `/issues/${number}/labels`, { labels: labelIds });
  }

  /** 替换 Issue 的全部标签 */
  replaceIssueLabels(number, labelIds) {
    return this.request('PUT', `/issues/${number}/labels`, { labels: labelIds });
  }

  /** 移除 Issue 的单个标签 */
  removeIssueLabel(number, labelId) {
    return this.request('DELETE', `/issues/${number}/labels/${labelId}`);
  }

  // ====== Milestones ======

  listMilestones(params = {}) {
    return this.request('GET', '/milestones', null, { limit: 50, ...params });
  }

  getMilestone(id) {
    return this.request('GET', `/milestones/${id}`);
  }

  createMilestone(data) {
    return this.request('POST', '/milestones', data);
  }

  updateMilestone(id, data) {
    return this.request('PATCH', `/milestones/${id}`, data);
  }

  closeMilestone(id) {
    return this.updateMilestone(id, { state: 'closed' });
  }

  // ====== Dependencies ======

  /** 获取阻塞当前 Issue 的前置任务列表 */
  listDependencies(number) {
    return this.request('GET', `/issues/${number}/dependencies`);
  }

  /** 获取当前 Issue 阻塞的任务列表 */
  listBlocks(number) {
    return this.request('GET', `/issues/${number}/blocks`);
  }

  /** 设置依赖：number 阻塞 blockedNumber */
  addBlock(number, blockedNumber) {
    // Gitea 要求 body 为 IssueMeta 格式（含 owner + repo）
    return this.request('POST', `/issues/${number}/blocks`, {
      index: blockedNumber,
      owner: this.config.repoPath.split('/')[2], // /repos/{owner}/{repo}
      repo: this.config.repoPath.split('/')[3],
    });
  }

  /** 移除依赖 */
  removeBlock(number, blockedNumber) {
    return this.request('DELETE', `/issues/${number}/blocks`, {
      index: blockedNumber,
      owner: this.config.repoPath.split('/')[2],
      repo: this.config.repoPath.split('/')[3],
    });
  }

  // ====== 辅助方法 ======

  /** 通过名称查找标签，返回 ID（不存在则返回 null） */
  async findLabelByName(name) {
    const labels = await this.listLabels();
    return labels.find(l => l.name === name) || null;
  }

  /** 通过名称查找标签，不存在则创建，返回标签对象 */
  async ensureLabel(name, color) {
    const existing = await this.findLabelByName(name);
    if (existing) return existing;
    return this.createLabel({ name, color });
  }

  /** 通过标题查找 Milestone，返回 ID */
  async findMilestoneByTitle(title) {
    const milestones = await this.listMilestones();
    return milestones.find(m => m.title === title) || null;
  }

  /** 通过标题查找 Issue（模糊匹配） */
  async findIssueByTitle(title) {
    const issues = await this.listIssues({ state: 'all' });
    return issues.find(i => i.title.includes(title)) || null;
  }
}

module.exports = { GiteaAPI, DEFAULT_CONFIG };