/**
 * @file chat.js (routes)
 * @description `/api/chat` — chat between users in server mode (the pet's
 * window, `client/src/components/Sagi/ChatHub.tsx`): people to chat with,
 * the caller's rooms, a direct chat or a group, messages (text + files, a
 * multipart `POST`), read marks and a room's files. Everything acts on the
 * CALLER's own rooms (`server/lib/chat.js`): a room they are not in is 404,
 * whatever their role. Local mode has one person and no chat (`400 ELOCALMODE`).
 * Each change is broadcast as `chat_message` / `chat_room` / `chat_deleted` to exactly the
 * users concerned (`to`, `scope.exactAudience`).
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */

"use strict";

const express = require("express");
const chat = require("../lib/chat");
const { isServerMode } = require("../lib/auth");
const { sameOriginGuard } = require("../lib/same-origin");

const router = express.Router();

function send(res, e) {
  const status = e.status || (e.code === "ENOUSER" || e.code === "EBADFIELD" ? 400 : 500);
  if (status === 500) console.error("[chat]", e);
  res.status(status).json({ error: { code: e.code || "EINTERNAL", message: e.message } });
}

/** Run `fn(userId)`; refuses local mode and an anonymous request. */
const handle = (fn) => (req, res) => {
  if (!isServerMode() || !req.user) {
    return res
      .status(400)
      .json({ error: { code: "ELOCALMODE", message: "chat is for a shared server" } });
  }
  try {
    fn(req.user.id, req, res);
  } catch (e) {
    send(res, e);
  }
};

function tell(type, data, to) {
  try {
    require("../websocket").broadcast(type, { ...data, to });
  } catch {
    // no socket server (tests): nothing to tell
  }
}

/** Multipart `files` + `body`, in memory, within the chat's limits. */
function upload(req, res, next) {
  if (!req.is("multipart/form-data")) return next();
  const multer = require("multer");
  multer({
    storage: multer.memoryStorage(),
    limits: { fileSize: chat.MAX_FILE_BYTES, files: chat.MAX_FILES },
  }).array("files")(req, res, (e) => {
    if (!e) return next();
    const big = e.code === "LIMIT_FILE_SIZE" || e.code === "LIMIT_FILE_COUNT";
    return res.status(big ? 413 : 400).json({
      error: { code: big ? "ETOOBIG" : "EBADUPLOAD", message: e.message },
    });
  });
}

router.get(
  "/people",
  handle((me, _req, res) => res.json({ people: chat.people(me) }))
);

router.get(
  "/rooms",
  handle((me, _req, res) => res.json({ rooms: chat.listRooms(me) }))
);

router.post(
  "/rooms",
  sameOriginGuard,
  handle((me, req, res) => {
    const b = req.body || {};
    if (b.kind === "dm") {
      const { room, created } = chat.openDm(me, b.userId);
      if (created) tell("chat_room", { roomId: room.id }, room.members);
      return res.status(created ? 201 : 200).json({ room });
    }
    if (b.kind === "group") {
      const room = chat.createGroup(me, { name: b.name, userIds: b.userIds });
      tell("chat_room", { roomId: room.id }, room.members);
      return res.status(201).json({ room });
    }
    throw Object.assign(new Error("kind: dm or group"), { code: "EBADFIELD" });
  })
);

router.patch(
  "/rooms/:id",
  sameOriginGuard,
  handle((me, req, res) => {
    const b = req.body || {};
    const { room, notify } = chat.updateGroup(me, req.params.id, {
      name: b.name,
      add: b.add,
      remove: b.remove,
    });
    tell("chat_room", { roomId: room.id }, notify);
    res.json({ room });
  })
);

router.post(
  "/rooms/:id/leave",
  sameOriginGuard,
  handle((me, req, res) => {
    const { notify } = chat.leaveGroup(me, req.params.id);
    tell("chat_room", { roomId: Number(req.params.id) }, notify);
    res.json({ ok: true });
  })
);

// Delete the chat for the caller only (their history; a direct chat leaves their list).
router.post(
  "/rooms/:id/clear",
  sameOriginGuard,
  handle((me, req, res) => res.json(chat.clearChat(me, req.params.id)))
);

// The group's creator deletes it for everyone.
router.delete(
  "/rooms/:id",
  sameOriginGuard,
  handle((me, req, res) => {
    const { notify } = chat.disbandGroup(me, req.params.id);
    tell("chat_room", { roomId: Number(req.params.id) }, notify);
    res.json({ ok: true });
  })
);

router.get(
  "/rooms/:id/messages",
  handle((me, req, res) =>
    res.json(chat.messages(me, req.params.id, { before: req.query.before, limit: req.query.limit }))
  )
);

router.post("/rooms/:id/messages", sameOriginGuard, upload, (req, res) =>
  handle((me) => {
    const files = (req.files || []).map((f) => ({
      // multer reads names as latin1; browsers send UTF-8.
      name: Buffer.from(f.originalname, "latin1").toString("utf8"),
      type: f.mimetype,
      buffer: f.buffer,
    }));
    const { message, notify } = chat.post(me, req.params.id, { body: req.body?.body, files });
    tell("chat_message", { roomId: message.roomId, message }, notify);
    res.status(201).json({ message });
  })(req, res)
);

router.delete(
  "/rooms/:id/messages/:messageId",
  sameOriginGuard,
  handle((me, req, res) => {
    const { notify } = chat.removeMessage(me, req.params.id, req.params.messageId);
    const roomId = Number(req.params.id);
    tell("chat_deleted", { roomId, messageId: Number(req.params.messageId) }, notify);
    res.json({ ok: true });
  })
);

router.post(
  "/rooms/:id/read",
  sameOriginGuard,
  handle((me, req, res) => {
    const { lastReadId, moved, notify } = chat.markRead(me, req.params.id, req.body?.upTo);
    // "Seen": the other members' views move their read marks.
    if (moved) tell("chat_read", { roomId: Number(req.params.id), userId: me, lastReadId }, notify);
    res.json({ lastReadId });
  })
);

router.get(
  "/rooms/:id/files/:fileId",
  handle((me, req, res) => {
    const f = chat.file(me, req.params.id, req.params.fileId);
    const ascii = f.name.replace(/[^\x20-\x7e]|["\\]/g, "_");
    res.set({
      "Content-Type": f.type,
      "X-Content-Type-Options": "nosniff",
      "Content-Security-Policy": "sandbox; default-src 'none'",
      "Cache-Control": "private, max-age=86400",
      "Content-Disposition": `${f.inline ? "inline" : "attachment"}; filename="${ascii}"; filename*=UTF-8''${encodeURIComponent(f.name)}`,
    });
    require("../lib/send-file").sendFile(res, f.path);
  })
);

module.exports = router;