// entry/src/main/ets/common/DavClient.ets
// CalDAV HTTP 客户端：REPORT / PUT / DELETE
import { http } from '@kit.NetworkKit';
import { buffer } from '@kit.ArkTS';
import { BusinessError } from '@kit.BasicServicesKit';
import { LogUtil } from './LogUtil';

/** REPORT 返回的单个远端资源 */
export class RemoteItem {
  href: string = '';   // 资源完整 URL
  etag: string = '';
  ics: string = '';    // VCALENDAR 文本
}

/** PROPFIND 返回的集合颜色与写权限 */
export class DavColorEntry {
  href: string = '';   // 集合路径（服务器返回的是路径，不带域名）
  color: string = '';  // 规范化后的 #RRGGBB，可能为空
  writable: boolean = true; // current-user-privilege 是否含 write 权限（默认可写）
  privilegeKnown: boolean = false; // 服务器是否返回了 current-user-privilege-set（未返回时需要写探测）
}

/** 日历本集合条目（"添加/编辑账号"页列日历本用） */
export class DavCalendarEntry {
  href: string = '';        // 完整 URL（已补全域名）
  displayName: string = ''; // 显示名（服务器未给 displayname 时回退为路径末段）
  color: string = '';       // 规范化后的 #RRGGBB，可能为空
}

/**
 * 日历本发现结果。
 * 带 statusCode —— 调用方需要据此区分「401 凭据失效」与「非 207 异常」，故不能只返回列表。
 */
export class DavCalendarDiscovery {
  statusCode: number = 0;
  entries: DavCalendarEntry[] = [];
}

export class DavClient {
  /**
   * PROPFIND 拉取某路径下所有集合的 calendar-color
   * 返回「集合路径 → 颜色」列表（路径为服务器返回的原始 href）
   */
  static async propfindColors(serverUrl: string, auth: string): Promise<DavColorEntry[]> {
    const requestBody: string = '<?xml version="1.0" encoding="utf-8"?>' +
      '<d:propfind xmlns:d="DAV:" xmlns:cs="http://calendarserver.org/ns/" ' +
      'xmlns:ical="http://apple.com/ns/ical/"><d:prop>' +
      '<d:resourcetype/><cs:getcolor/><ical:calendar-color/>' +
      '<d:current-user-privilege-set/>' +
      '</d:prop></d:propfind>';
    const httpRequest = http.createHttp();
    try {
      const resp: http.HttpResponse = await httpRequest.request(serverUrl, {
        method: 'PROPFIND' as http.RequestMethod,
        header: {
          'Authorization': auth,
          'Content-Type': 'application/xml; charset=utf-8',
          'Depth': '1',
          'User-Agent': 'SyncCalendar/1.0'
        },
        extraData: requestBody,
        connectTimeout: 10000,
        readTimeout: 20000
      });
      console.info(`PROPFIND(颜色) 响应码: ${resp.responseCode}`);
      LogUtil.write(`HTTP PROPFIND(颜色) ${serverUrl} → ${resp.responseCode}`);
      if (resp.responseCode !== 207 && resp.responseCode !== 200) {
        return [];
      }
      const xml: string = resp.result as string;
      const result: DavColorEntry[] = [];
      const blocks: string[] = xml.split(/<\/[\w-]*:?response>/i);
      for (const block of blocks) {
        if (!/<[\w-]*:?response[\s>]/i.test(block)) {
          continue;
        }
        const href: string = DavClient.extractTag(block, 'href');
        if (href === '') {
          continue;
        }
        const resourcetype: string = DavClient.extractTag(block, 'resourcetype');
        if (!/calendar/i.test(resourcetype)) {
          continue;
        }
        const entry = new DavColorEntry();
        entry.href = href;
        // 两个命名空间都试：cs:getcolor（CalendarServer）/ ical:calendar-color（Apple）
        let color: string = DavClient.normalizeHex(DavClient.extractTag(block, 'getcolor'));
        if (color === '') {
          color = DavClient.normalizeHex(DavClient.extractTag(block, 'calendar-color'));
        }
        entry.color = color;
        // 写权限：current-user-privilege-set 存在且不含任何 write 权限 → 只读
        const privSet: string = DavClient.extractTag(block, 'current-user-privilege-set');
        if (privSet !== '') {
          entry.privilegeKnown = true;
          entry.writable = /write/i.test(privSet);
          LogUtil.write(`PROPFIND ${href} 权限声明：${privSet.replace(/\s+/g, '').substring(0, 150)}`);
        }
        result.push(entry);
      }
      if (result.length > 0 && result.every((e: DavColorEntry): boolean => e.color === '')) {
        // 全部没拿到颜色时打印原始响应片段，便于诊断命名空间
        console.info(`PROPFIND(颜色) 未取到颜色，响应片段: ${xml.substring(0, 600)}`);
      }
      return result;
    } finally {
      httpRequest.destroy();
    }
  }

  /**
   * PROPFIND 列出某账号下所有「日历集合」（resourcetype 含 calendar）。
   *
   * 供「添加账号 / 编辑账号」两页复用，取代它们各自维护的一份同逻辑拷贝 ——
   * 解析逻辑集中在此，避免多处正则各自漂移。
   * 解析用正则而非 XML 解析器（见 extractTag 的 XXE 说明）。
   * 网络/解析异常向上抛出由调用方决定提示文案；仅"HTTP 状态码非成功"经 statusCode 返回。
   */
  static async listCalendars(serverUrl: string, auth: string): Promise<DavCalendarDiscovery> {
    const requestBody: string = '<?xml version="1.0" encoding="utf-8"?>' +
      '<d:propfind xmlns:d="DAV:" xmlns:cs="http://calendarserver.org/ns/" ' +
      'xmlns:ical="http://apple.com/ns/ical/"><d:prop>' +
      '<d:displayname/><d:resourcetype/><cs:getcolor/><ical:calendar-color/>' +
      '</d:prop></d:propfind>';
    const httpRequest = http.createHttp();
    const out = new DavCalendarDiscovery();
    try {
      const resp: http.HttpResponse = await httpRequest.request(serverUrl, {
        method: 'PROPFIND' as http.RequestMethod,
        header: {
          'Authorization': auth,
          'Content-Type': 'application/xml; charset=utf-8',
          'Depth': '1',
          'User-Agent': 'SyncCalendar/1.0'
        },
        extraData: requestBody,
        connectTimeout: 10000,
        readTimeout: 15000
      });
      out.statusCode = resp.responseCode;
      LogUtil.write(`HTTP PROPFIND(日历本) ${serverUrl} → ${resp.responseCode}`);
      if (resp.responseCode !== 207 && resp.responseCode !== 200) {
        return out;
      }
      const xml: string = resp.result as string;
      const originMatch = /https?:\/\/[^/]+/i.exec(serverUrl);
      const origin: string = originMatch !== null ? originMatch[0] : '';
      const blocks: string[] = xml.split(/<\/[\w-]*:?response>/i);
      for (const block of blocks) {
        if (!/<[\w-]*:?response[\s>]/i.test(block)) {
          continue;
        }
        const href: string = DavClient.extractTag(block, 'href');
        if (href === '') {
          continue;
        }
        const resourcetype: string = DavClient.extractTag(block, 'resourcetype');
        if (!/calendar/i.test(resourcetype)) {
          continue;
        }
        let name: string = DavClient.extractTag(block, 'displayname');
        if (name === '') {
          // 服务器没给 displayname → 回退为 href 路径末段
          const segs: string[] = href.split('/').filter((s: string) => s !== '');
          if (segs.length > 0) {
            const last: string = segs[segs.length - 1];
            try {
              name = decodeURIComponent(last);
            } catch (err) {
              name = last;
            }
          } else {
            name = href;
          }
        }
        // 两个命名空间都试：cs:getcolor（CalendarServer）/ ical:calendar-color（Apple）
        let color: string = DavClient.normalizeHex(DavClient.extractTag(block, 'getcolor'));
        if (color === '') {
          color = DavClient.normalizeHex(DavClient.extractTag(block, 'calendar-color'));
        }
        const entry = new DavCalendarEntry();
        entry.href = href.startsWith('http') ? href : origin + href;
        entry.displayName = name;
        entry.color = color;
        out.entries.push(entry);
      }
      return out;
    } finally {
      httpRequest.destroy();
    }
  }

  /**
   * 规范化集合 href，用于「本地保存的 calendarHrefs」与「PROPFIND 返回的 href」比对。
   *
   * 为什么需要：同一集合在不同 PROPFIND 请求/不同服务器上的写法可能不同——
   *   ① 绝对 URL（https://nas/calendars/A/） vs 纯路径（/calendars/A/）
   *   ② URL 编码差异（/calendars/%E6%96%B0/ vs /calendars/新/）
   *   ③ 末尾斜杠有无、重复斜杠
   * 直接用字符串相等比对会匹配失败 → 服务器上的颜色取不回来，界面只能退回调色板色。
   * 这里统一成「解码后的路径、无尾斜杠」再比较（路径大小写保持敏感，不转小写）。
   */
  static normalizeHref(href: string): string {
    let s: string = href.trim();
    const m = /^[a-zA-Z]+:\/\/[^/]+/i.exec(s);
    if (m !== null) {
      s = s.substring(m[0].length);
    }
    try {
      s = decodeURIComponent(s);
    } catch (err) {
      // 解码失败（如含非法 % 序列）保持原样
    }
    s = s.replace(/\/{2,}/g, '/');
    if (s.length > 1 && s.endsWith('/')) {
      s = s.substring(0, s.length - 1);
    }
    return s;
  }

  /** 颜色规范化：#RRGGBBAA → #RRGGBB */
  static normalizeHex(raw: string): string {
    const v: string = raw.trim();
    if (/^#[0-9A-Fa-f]{8}$/.test(v)) {
      return '#' + v.substring(3, 9).toUpperCase();
    }
    if (/^#[0-9A-Fa-f]{6}$/.test(v)) {
      return v.toUpperCase();
    }
    return '';
  }

  /** Basic Auth 头 */
  static authHeader(username: string, password: string): string {
    return 'Basic ' + buffer.from(`${username}:${password}`).toString('base64');
  }

  /** GET 拉取单个资源的原始 ICS（调试诊断用） */
  static async getRaw(url: string, auth: string): Promise<string> {
    const httpRequest = http.createHttp();
    try {
      const resp: http.HttpResponse = await httpRequest.request(url, {
        method: http.RequestMethod.GET,
        header: {
          'Authorization': auth,
          'User-Agent': 'SyncCalendar/1.0'
        },
        connectTimeout: 10000,
        readTimeout: 15000
      });
      if (resp.responseCode >= 200 && resp.responseCode < 300) {
        return resp.result as string;
      }
      return `HTTP ${resp.responseCode}`;
    } finally {
      httpRequest.destroy();
    }
  }

  /**
   * 写权限探测：向日历本 PUT 一个探测资源——
   * 2xx → 可写（随后删除探测资源）；403/401 等 → 只读；网络异常 → 乐观按可写。
   * 用于服务器不返回 current-user-privilege-set 的情况（如部分 Synology 配置）。
   */
  static async probeWritable(href: string, auth: string): Promise<boolean> {
    const url: string = href.endsWith('/')
      ? `${href}synccalendar-probe.ics` : `${href}/synccalendar-probe.ics`;
    const ics: string = 'BEGIN:VCALENDAR\r\n' +
      'VERSION:2.0\r\n' +
      'PRODID:-//SyncCalendar//Probe//CN\r\n' +
      'BEGIN:VEVENT\r\n' +
      'UID:syncprobe\r\n' +
      'DTSTAMP:20000101T000000Z\r\n' +
      'DTSTART:20000101T000000Z\r\n' +
      'DTEND:20000101T010000Z\r\n' +
      'SUMMARY:probe\r\n' +
      'END:VEVENT\r\n' +
      'END:VCALENDAR\r\n';
    const httpRequest = http.createHttp();
    try {
      const resp: http.HttpResponse = await httpRequest.request(url, {
        method: http.RequestMethod.PUT,
        header: {
          'Authorization': auth,
          'Content-Type': 'text/calendar; charset=utf-8',
          'User-Agent': 'SyncCalendar/1.0'
        },
        extraData: ics,
        connectTimeout: 10000,
        readTimeout: 15000
      });
      LogUtil.write(`HTTP PUT(探测) ${url} → ${resp.responseCode}`);
      if (resp.responseCode >= 200 && resp.responseCode < 300) {
        // 写入成功：删除探测资源，避免污染日历本
        try {
          await DavClient.deleteRemote(url, auth);
        } catch (err) {
          // 删除失败不影响权限判定
        }
        return true;
      }
      if (resp.responseCode === 412 || resp.responseCode === 405 || resp.responseCode === 409) {
        // 资源已存在/方法冲突等：说明有写权限
        return true;
      }
      return false; // 403/401 等 → 只读
    } catch (err) {
      // 网络异常无法判定：乐观按可写，避免误标只读
      return true;
    } finally {
      httpRequest.destroy();
    }
  }

  /** REPORT calendar-query：全量拉取某日历本内所有 VEVENT（不加时间范围，保证数据完整） */
  static async reportCalendar(href: string, auth: string): Promise<RemoteItem[]> {
    return DavClient.reportComponents(href, auth, 'VEVENT', '');
  }

  /**
   * REPORT calendar-query：仅拉取 href + getetag（不含 calendar-data）。
   * 部分服务器（如群晖）的 REPORT calendar-data 会剥离 VALARM 导致提醒丢失，
   * 因此数据改为对变更资源逐个 GET 补拉（GET 返回完整 ICS）。
   */
  static async reportEtags(href: string, auth: string): Promise<RemoteItem[]> {
    const body: string = '<?xml version="1.0" encoding="utf-8"?>' +
      '<c:calendar-query xmlns:d="DAV:" xmlns:c="urn:ietf:params:xml:ns:caldav">' +
      '<d:prop><d:getetag/></d:prop>' +
      '<c:filter><c:comp-filter name="VCALENDAR">' +
      '<c:comp-filter name="VEVENT">' +
      '</c:comp-filter></c:comp-filter></c:filter></c:calendar-query>';
    const httpRequest = http.createHttp();
    try {
      const resp: http.HttpResponse = await httpRequest.request(href, {
        method: 'REPORT' as http.RequestMethod,
        header: {
          'Authorization': auth,
          'Content-Type': 'application/xml; charset=utf-8',
          'Depth': '1',
          'User-Agent': 'SyncCalendar/1.0'
        },
        extraData: body,
        connectTimeout: 10000,
        readTimeout: 30000
      });
      LogUtil.write(`HTTP REPORT(etag) ${href} → ${resp.responseCode}`);
      if (resp.responseCode < 200 || resp.responseCode >= 300) {
        throw new Error(`服务器返回状态码 ${resp.responseCode}`);
      }
      const xml: string = resp.result as string;
      const items: RemoteItem[] = [];
      const blocks: string[] = xml.split(/<\/[\w-]*:?response>/i);
      for (const block of blocks) {
        if (!/<[\w-]*:?response[\s>]/i.test(block)) {
          continue;
        }
        const resHref: string = DavClient.extractTag(block, 'href');
        if (resHref === '') {
          continue;
        }
        const item = new RemoteItem();
        item.href = resHref;
        item.etag = DavClient.extractTag(block, 'getetag').replace(/"/g, '');
        items.push(item);
      }
      return items;
    } finally {
      httpRequest.destroy();
    }
  }

  /** REPORT calendar-query：拉取某日历本内所有 VTODO 待办（不限时间范围，量小） */
  static async reportTodos(href: string, auth: string): Promise<RemoteItem[]> {
    return DavClient.reportComponents(href, auth, 'VTODO', '');
  }

  /** 通用 REPORT：按组件类型过滤拉取 calendar-data + getetag */
  private static async reportComponents(href: string, auth: string,
    compName: string, timeRange: string): Promise<RemoteItem[]> {
    const body: string = '<?xml version="1.0" encoding="utf-8"?>' +
      '<c:calendar-query xmlns:d="DAV:" xmlns:c="urn:ietf:params:xml:ns:caldav">' +
      '<d:prop><d:getetag/><c:calendar-data/></d:prop>' +
      '<c:filter><c:comp-filter name="VCALENDAR">' +
      `<c:comp-filter name="${compName}">` +
      timeRange +
      '</c:comp-filter></c:comp-filter></c:filter></c:calendar-query>';
    const httpRequest = http.createHttp();
    try {
      const resp: http.HttpResponse = await httpRequest.request(href, {
        method: 'REPORT' as http.RequestMethod,
        header: {
          'Authorization': auth,
          'Content-Type': 'application/xml; charset=utf-8',
          'Depth': '1',
          'User-Agent': 'SyncCalendar/1.0'
        },
        extraData: body,
        connectTimeout: 10000,
        readTimeout: 60000
      });
      console.info(`REPORT(${compName}) ${href} 响应码: ${resp.responseCode}`);
      LogUtil.write(`HTTP REPORT(${compName}) ${href} → ${resp.responseCode}`);
      if (resp.responseCode === 401) {
        LogUtil.write(`HTTP REPORT(${compName}) 401 拒绝凭据`);
        throw new Error('服务器拒绝凭据(401)');
      }
      if (resp.responseCode < 200 || resp.responseCode >= 300) {
        LogUtil.write(`HTTP REPORT(${compName}) 异常状态码 ${resp.responseCode}`);
        throw new Error(`服务器返回状态码 ${resp.responseCode}`);
      }
      const xml: string = resp.result as string;
      LogUtil.write(`HTTP REPORT(${compName}) 响应体 ${xml.length} 字符`);
      const originMatch = /https?:\/\/[^/]+/i.exec(href);
      const origin: string = originMatch !== null ? originMatch[0] : '';
      const items: RemoteItem[] = [];
      const blocks: string[] = xml.split(/<\/[\w-]*:?response>/i);
      for (const block of blocks) {
        if (!/<[\w-]*:?response[\s>]/i.test(block)) {
          continue;
        }
        const resHref: string = DavClient.extractTag(block, 'href');
        if (resHref === '') {
          continue;
        }
        const etag: string = DavClient.extractTag(block, 'getetag').replace(/"/g, '');
        const start: number = block.indexOf('BEGIN:VCALENDAR');
        const end: number = block.indexOf('END:VCALENDAR');
        if (start < 0 || end < 0) {
          continue;
        }
        const item = new RemoteItem();
        item.href = resHref.startsWith('http') ? resHref : origin + resHref;
        item.etag = etag;
        item.ics = block.substring(start, end + 'END:VCALENDAR'.length);
        items.push(item);
      }
      return items;
    } finally {
      httpRequest.destroy();
    }
  }

  /** PUT 新建/更新远端事件，返回响应 ETag（可能为空） */
  static async putEvent(url: string, auth: string, ics: string): Promise<string> {
    const httpRequest = http.createHttp();
    try {
      const resp: http.HttpResponse = await httpRequest.request(url, {
        method: http.RequestMethod.PUT,
        header: {
          'Authorization': auth,
          'Content-Type': 'text/calendar; charset=utf-8',
          'User-Agent': 'SyncCalendar/1.0'
        },
        extraData: ics,
        connectTimeout: 10000,
        readTimeout: 30000
      });
      console.info(`PUT ${url} 响应码: ${resp.responseCode}`);
      LogUtil.write(`HTTP PUT ${url} → ${resp.responseCode}`);
      if (resp.responseCode < 200 || resp.responseCode >= 300) {
        throw new Error(`推送失败，服务器返回 ${resp.responseCode}`);
      }
      const headers = resp.header as Record<string, string>;
      if (headers !== undefined && headers !== null) {
        const etag = headers['ETag'] ?? headers['etag'] ?? '';
        return typeof etag === 'string' ? etag.replace(/"/g, '') : '';
      }
      return '';
    } finally {
      httpRequest.destroy();
    }
  }

  /** DELETE 远端事件 */
  static async deleteRemote(url: string, auth: string): Promise<void> {
    const httpRequest = http.createHttp();
    try {
      const resp: http.HttpResponse = await httpRequest.request(url, {
        method: http.RequestMethod.DELETE,
        header: {
          'Authorization': auth,
          'User-Agent': 'SyncCalendar/1.0'
        },
        connectTimeout: 10000,
        readTimeout: 30000
      });
      console.info(`DELETE ${url} 响应码: ${resp.responseCode}`);
      LogUtil.write(`HTTP DELETE ${url} → ${resp.responseCode}`);
      // 404 视为已删除，成功
      if ((resp.responseCode < 200 || resp.responseCode >= 300) && resp.responseCode !== 404) {
        throw new Error(`删除失败，服务器返回 ${resp.responseCode}`);
      }
    } finally {
      httpRequest.destroy();
    }
  }

  /**
   * 提取任意命名空间前缀标签的文本内容（如 `<d:href>` / `<cs:getcolor>`）。
   *
   * 安全说明：此处**刻意用正则而不是 XML 解析器**——DAV 响应来自用户自填的远端服务器，
   * 属不可信输入；正则提取不构建 DOM、不解析实体，从根上规避了 XXE（外部实体扩展）
   * 与「十亿笑声」实体炸弹这类解析器层面的攻击面。
   * 另外 `tag` 只由本文件内的代码常量传入，不来自远端数据，故无需防注入。
   */
  static extractTag(xml: string, tag: string): string {
    const pattern: string = '<([\\w-]+:)?' + tag + '(?:\\s[^>]*)?>([\\s\\S]*?)<\\/([\\w-]+:)?' + tag + '>';
    const regex: RegExp = new RegExp(pattern, 'i');
    const match = regex.exec(xml);
    return match !== null ? match[2].trim() : '';
  }
}