/**
 * HTTP client for the third-party wechat-agent backend.
 *
 * Zero external deps — uses Node 20+ global fetch. Keeps tgz tiny.
 *
 * Backend contract (verified against the customer's production daemon
 * @../../../daemon/auto-reply-daemon.js on 2026-04-18):
 *   POST  /login/check-online          -> { data: true }  OR  { ret: 200, data: { online: true } }
 *   GET   /messages?direction=received -> { data: [RawMsg, ...] }  (ret optional)
 *   POST  /message/send-text           -> { ret: 200, msg?: string }
 *
 * Both response shapes for check-online are tolerated because older/newer
 * backend builds (wcf vs xbot vs custom Express wrapper) differ here.
 *
 * RawMsg fields we expect (best-effort, unknown fields tolerated):
 *   msgId | id, fromWxid | from, toWxid | to, fromName | senderName,
 *   type, content | text | body, timestamp | time, isGroup, chatroomId,
 *   chatroomMemberWxid
 */

import type { RawWechatMessage, SendTextResult } from "./types.js";

export interface WechatAgentClient {
  readonly apiBase: string;
  checkOnline(): Promise<boolean>;
  getSelfWxid(): Promise<string | null>;
  getMessages(opts?: GetMessagesOptions): Promise<RawWechatMessage[]>;
  sendText(opts: SendTextOptions): Promise<SendTextResult>;
}

export type GetMessagesOptions = {
  /** Max messages to return. Default 50. */
  limit?: number;
  /** "received" = inbound only (what we want for auto-reply). */
  direction?: "received" | "sent" | "all";
  /** Abort signal for graceful shutdown. */
  signal?: AbortSignal;
  /** Per-request timeout (ms). Default 15s. */
  timeoutMs?: number;
  /** Optional incremental cursor fields (backend may ignore unknown params). */
  sinceTimestampMs?: number;
  sinceMsgId?: string;
};

export type SendTextOptions = {
  toWxid: string;
  content: string;
  /** Optional @mentions wxid list, comma-separated (for group chats). */
  ats?: string;
  signal?: AbortSignal;
  timeoutMs?: number;
};

export function createClient(apiBase: string): WechatAgentClient {
  const base = apiBase.replace(/\/+$/, "");

  async function request(
    path: string,
    init: RequestInit & { timeoutMs?: number } = {}
  ): Promise<unknown> {
    const { timeoutMs = 15000, signal: userSignal, ...rest } = init;
    const controller = new AbortController();
    const timeout = setTimeout(() => controller.abort(new Error("timeout")), timeoutMs);

    // Chain user-provided signal so caller abort propagates.
    if (userSignal) {
      if (userSignal.aborted) {
        controller.abort(userSignal.reason);
      } else {
        userSignal.addEventListener("abort", () => controller.abort(userSignal.reason), {
          once: true,
        });
      }
    }

    try {
      const resp = await fetch(`${base}${path}`, {
        ...rest,
        signal: controller.signal,
      });
      const text = await resp.text();
      if (!resp.ok) {
        throw new Error(`wechat-agent ${path} HTTP ${resp.status}: ${text.slice(0, 200)}`);
      }
      if (!text) return null;
      try {
        return JSON.parse(text);
      } catch {
        throw new Error(
          `wechat-agent ${path} returned non-JSON: ${text.slice(0, 200)}`
        );
      }
    } finally {
      clearTimeout(timeout);
    }
  }

  return {
    apiBase: base,

    async checkOnline(): Promise<boolean> {
      try {
        const body = (await request("/login/check-online", {
          method: "POST",
          headers: { "content-type": "application/json" },
          body: "{}",
        })) as { ret?: number; data?: unknown } | null;
        if (!body) return false;
        if (body.ret !== undefined && body.ret !== 200) return false;
        // Shape A (production daemon): { data: true }
        if (body.data === true) return true;
        // Shape B (alt backends):     { data: { online: true } }
        if (body.data && typeof body.data === "object") {
          return Boolean((body.data as { online?: boolean }).online);
        }
        return false;
      } catch {
        return false;
      }
    },

    async getSelfWxid(): Promise<string | null> {
      try {
        const body = (await request("/login/check-online", {
          method: "POST",
          headers: { "content-type": "application/json" },
          body: "{}",
        })) as { ret?: number; data?: unknown } | null;
        const d = body?.data;
        if (d && typeof d === "object") {
          const dd = d as Record<string, unknown>;
          const wxid = dd.wxid ?? dd.self;
          if (typeof wxid === "string" && wxid) return wxid;
        }
        return null;
      } catch {
        return null;
      }
    },

    async getMessages(opts: GetMessagesOptions = {}): Promise<RawWechatMessage[]> {
      const limit = opts.limit ?? 50;
      const direction = opts.direction ?? "received";
      const qs = new URLSearchParams({ limit: String(limit), direction });
      if (typeof opts.sinceTimestampMs === "number" && Number.isFinite(opts.sinceTimestampMs)) {
        qs.set("sinceTimestampMs", String(Math.floor(opts.sinceTimestampMs)));
      }
      if (opts.sinceMsgId?.trim()) {
        qs.set("sinceMsgId", opts.sinceMsgId.trim());
      }
      const body = (await request(`/messages?${qs.toString()}`, {
        method: "GET",
        signal: opts.signal,
        timeoutMs: opts.timeoutMs,
      })) as { ret?: number; data?: unknown[] } | null;
      if (!body) return [];
      if (body.ret !== undefined && body.ret !== 200) return [];
      const items = Array.isArray(body.data) ? body.data : [];
      return items.map(normalizeMessage).filter((m): m is RawWechatMessage => m !== null);
    },

    async sendText(opts: SendTextOptions): Promise<SendTextResult> {
      const payload = {
        toWxid: opts.toWxid,
        content: opts.content,
        ats: opts.ats ?? "",
      };
      const syntheticMessageId = `wx-${Date.now()}-${Math.random().toString(36).slice(2, 8)}`;
      try {
        const body = (await request("/message/send-text", {
          method: "POST",
          headers: { "content-type": "application/json" },
          body: JSON.stringify(payload),
          signal: opts.signal,
          timeoutMs: opts.timeoutMs,
        })) as { ret?: number; msg?: string } | null;
        const ret = body?.ret;
        const ok = ret === 200 || ret === undefined;
        return {
          ok,
          ret,
          msg: body?.msg,
          syntheticMessageId,
        };
      } catch (err) {
        return {
          ok: false,
          msg: err instanceof Error ? err.message : String(err),
          syntheticMessageId,
        };
      }
    },
  };
}

/** Best-effort normalization of the backend's message payload. */
function normalizeMessage(item: unknown): RawWechatMessage | null {
  if (!item || typeof item !== "object") return null;
  const o = item as Record<string, unknown>;

  const msgId = pickString(o, ["msgId", "id", "messageId", "msg_id"]);
  if (!msgId) return null;

  const fromWxid = pickString(o, ["fromWxid", "from", "fromId", "sender", "from_wxid"]);
  if (!fromWxid) return null;

  const toWxid =
    pickString(o, ["toWxid", "to", "toId", "receiver", "to_wxid"]) ?? "";
  const fromName = pickString(o, ["fromName", "senderName", "nickName", "fromNick"]);
  const type = pickString(o, ["type", "msgType"]) ?? "text";
  const content =
    pickString(o, ["content", "text", "body", "message"]) ?? "";
  const timestamp = (o.timestamp ?? o.time ?? o.createTime ?? Date.now()) as
    | string
    | number;

  const chatroomId = pickString(o, ["chatroomId", "roomId", "groupId"]);
  const isGroup = Boolean(chatroomId) || Boolean(o.isGroup);
  const chatroomMemberWxid = isGroup
    ? pickString(o, ["chatroomMemberWxid", "memberWxid", "groupMember"])
    : undefined;

  return {
    msgId,
    fromWxid,
    toWxid,
    fromName,
    type: String(type),
    content: String(content),
    timestamp,
    isGroup,
    chatroomId,
    chatroomMemberWxid,
    raw: o,
  };
}

function pickString(o: Record<string, unknown>, keys: string[]): string | undefined {
  for (const k of keys) {
    const v = o[k];
    if (typeof v === "string" && v.length > 0) return v;
    if (typeof v === "number") return String(v);
  }
  return undefined;
}