// matrix-appservice-kakaotalk - A Matrix-KakaoTalk puppeting bridge.
// Copyright (C) 2022 Tulir Asokan, Andrew Ferrazzutti
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.
import { Long } from "bson"

import {
	AuthApiClient,
	OAuthApiClient,
	ServiceApiClient,
	TalkClient,
	KnownAuthStatusCode,
	util,
} from "node-kakao"
import { ReadStreamUtil } from "node-kakao/stream"
/** @typedef {import("node-kakao").OAuthCredential} OAuthCredential */
/** @typedef {import("node-kakao").ChannelType} ChannelType */
/** @typedef {import("node-kakao").ReplyAttachment} ReplyAttachment */
/** @typedef {import("node-kakao").MentionStruct} MentionStruct */
/** @typedef {import("node-kakao").TalkNormalChannel} TalkNormalChannel */
/** @typedef {import("node-kakao").TalkOpenChannel} TalkOpenChannel */
/** @typedef {import("node-kakao/dist/talk").TalkChannelList} TalkChannelList */
// TODO Remove once/if some helper type hints are upstreamed
/** @typedef {import("node-kakao").OpenChannelUserInfo} OpenChannelUserInfo */

import openlink from "node-kakao/openlink"
const { OpenChannelUserPerm } = openlink

import chat from "node-kakao/chat"
const { KnownChatType } = chat

import * as modutil from "./modutil.js"
import { emitLines, promisify } from "./util.js"

/**
 * @typedef {object} ChannelProps
 * @property {Long} id
 * @property {ChannelType} type
 */


ServiceApiClient.prototype.requestFriendList = async function() {
	const res = await this._client.requestData(
		"POST",
		`${this.getFriendsApiPath("update.json")}`,
		{
			phone_number_type: 1,
		}
	)

	return {
		status: res.status,
		success: res.status === 0,
		result: res,
	}
}


class ProtocolError extends Error {}

class PermError extends ProtocolError {
	/** @type {Map<OpenChannelUserPerm, string> */
	static #PERM_NAMES = new Map([
		[OpenChannelUserPerm.OWNER, "the channel owner"],
		[OpenChannelUserPerm.MANAGER, "channel admininstrators"],
		[OpenChannelUserPerm.BOT, "bots"],
		[OpenChannelUserPerm.NONE, "registered KakaoTalk users"],
	])

	/**
	 * @param {?OpenChannelUserPerm[]} permNeeded
	 * @param {?OpenChannelUserPerm} permActual
	 * @param {string} action
	 */
	constructor(permNeeded, permActual, action) {
		const who =
			!permActual
			? "In this channel, no one"
			: "Only " + permNeeded
				.map(v => PermError.#PERM_NAMES.get(v))
				.reduce((prev, curr) => prev += ` and ${curr}`)
		super(`${who} can ${action}`)
		this.name = this.constructor.name
	}
}


class UserClient {
	static #initializing = false

	#connected = false
	#talkClient = new TalkClient()
	get talkClient() { return this.#talkClient }

	/** @type {ServiceApiClient} */
	#serviceClient
	get serviceClient() { return this.#serviceClient }

	/** @type {OAuthCredential} */
	#credential
	get userId() { return this.#credential.userId }

	/**
	 * DO NOT CONSTRUCT DIRECTLY. Callers should use {@link UserClient#create} instead.
	 * @param {string} mxid
	 * @param {PeerClient} peerClient TODO Make RPC user-specific instead of needing this
	 */
	constructor(mxid, peerClient) {
		if (!UserClient.#initializing) {
			throw new Error("Private constructor")
		}
		UserClient.#initializing = false

		this.mxid = mxid
		this.peerClient = peerClient

		this.#talkClient.on("chat", (data, channel) => {
			this.log(`Chat ${data.chat.logId} received in channel ${channel.channelId}`)
			this.write("chat", {
				//is_sequential: true, // TODO Make sequential per user & channel (if it isn't already)
				chatlog: data.chat,
				channelId: channel.channelId,
				channelType: channel.info.type,
			})
		})

		this.#talkClient.on("chat_deleted", (feedChatlog, channel, feed) => {
			this.log(`Chat ${feed.logId} deleted in channel ${channel.channelId} by user ${feedChatlog.sender.userId}`)
			this.write("chat_deleted", {
				chatId: feed.logId,
				senderId: feedChatlog.sender.userId,
				timestamp: feedChatlog.sendAt,
				channelId: channel.channelId,
				channelType: channel.info.type,
			})
		})

		this.#talkClient.on("message_hidden", (hideLog, channel, feed) => {
			this.log(`Message ${feed.logId} hid from channel ${channel.channelId} by user ${hideLog.sender.userId}`)
			this.write("chat_deleted", {
				chatId: feed.logId,
				senderId: hideLog.sender.userId,
				timestamp: hideLog.sendAt,
				channelId: channel.channelId,
				channelType: channel.info.type,
			})
		})

		this.#talkClient.on("chat_read", (chat, channel, reader) => {
			let senderId
			if (reader) {
				senderId = reader.userId
			} else if (channel.info.type == "MemoChat") {
				senderId = channel.clientUser.userId
			} else {
				this.error(`Chat ${chat.logId} read in channel ${channel.channelId} by unknown reader (channel type: ${channel.info.type || "none"})`)
				return
			}
			this.log(`Chat ${chat.logId} read in channel ${channel.channelId} by ${senderId}`)
			this.write("chat_read", {
				chatId: chat.logId,
				senderId: senderId,
				channelId: channel.channelId,
				channelType: channel.info.type,
			})
		})

		this.#talkClient.on("chat_event", (channel, author, type, count, chat) => {
			// TODO Figure out if this is can ever be for anything other than hearts on Shouts
			this.log(`Event ${type} (count = ${count}) on chat ${chat.logId} in channel ${channel.channelId} sent by user ${author.userId}`)
		})

		this.#talkClient.on("profile_changed", (channel, lastInfo, user) => {
			this.log(`Profile of ${user.userId} changed (in channel ${channel ? channel.channelId : "None"})`)
			this.write("profile_changed", {
				info: user,
				/* TODO Is this ever a per-channel profile change?
				channelId: channel.channelId,
				channelType: channel.info.type,
				*/
			})
		})

		this.#talkClient.on("perm_changed",
		/**
		 * TODO Upstream these type hints
		 * @param {TalkOpenChannel} channel
		 * @param {OpenChannelUserInfo} lastInfo
		 * @param {OpenChannelUserInfo} user
		 */
		(channel, lastInfo, user) => {
			this.log(`Perms of user ${user.userId} in channel ${channel.channelId} changed from ${lastInfo.perm} to ${user.perm}`)
			this.write("perm_changed", {
				is_sequential: true,
				userId: user.userId,
				perm: user.perm,
				senderId: getChannelOwner().userId,
				channelId: channel.channelId,
				channelType: channel.info.type,
			})
		})

		this.#talkClient.on("host_handover", (channel, lastLink, link) => {
			// TODO Find how or if this relates to permissions
			this.log(`Host of channel ${channel.channelId} changed from ${lastLink.linkOwner.nickname} to ${link.linkOwner.nickname}`)
		})

		this.#talkClient.on("channel_added", channel => {
			this.log(`Added channel ${channel.channelId}`)
			this.write("channel_added", {
				channelInfo: channel.info,
			})
		})

		this.#talkClient.on("channel_join", channel => {
			this.log(`Joined channel ${channel.channelId}`)
			this.write("channel_join", {
				channelInfo: channel.info,
			})
		})

		this.#talkClient.on("channel_left", channel => {
			this.log(`Left channel ${channel.channelId}`)
			this.write("channel_left", {
				channelId: channel.channelId,
				channelType: channel.info.type,
			})
		})

		this.#talkClient.on("channel_kicked", (kickedLog, channel, feed) => {
			// TODO Confirm whether this can refer to any user that was kicked, or only to the current user
			this.log(`Kicked from channel ${channel.channelId}`)
			this.write("channel_kicked", {
				userId: feed.member.userId,
				senderId: kickedLog.sender.userId,
				channelId: channel.channelId,
				channelType: channel.info.type,
			})
		})

		this.#talkClient.on("channel_link_deleted", (feedChatLog, channel, feed) => {
			// TODO Figure out what this means
			this.log(`Channel link deleted in channel ${channel.channelId}: feed=${JSON.stringify(feed)}, feedChatLog=${JSON.stringify(feedChatLog)}`)
		})

		this.#talkClient.on("link_created", link => {
			// TODO Figure out what this means
			this.log(`Link created: ${JSON.stringify(link)}`)
		})

		this.#talkClient.on("link_deleted", link => {
			// TODO Figure out what this means
			this.log(`Link deleted: ${JSON.stringify(link)}`)
		})

		this.#talkClient.on("user_join", (joinLog, channel, user, feed) => {
			this.log(`User ${user.userId} joined channel ${channel.channelId}`)
			this.write("user_join", {
				userId: user.userId,
				channelId: channel.channelId,
				channelType: channel.info.type,
			})
		})

		this.#talkClient.on("user_left", (leftLog, channel, user, feed) => {
			this.log(`User ${user.userId} left channel ${channel.channelId}`)
			this.write("user_left", {
				userId: user.userId,
				channelId: channel.channelId,
				channelType: channel.info.type,
			})
		})

		this.#talkClient.on("meta_change", (channel, type, newMeta) => {
			// TODO Handle announcements as pinned messages
			this.log(`Channel ${channel.channelId} metadata changed`)
		})

		this.#talkClient.on("push_packet", (method, data) => {
			// TODO Find a better way to do this...but data doesn't have much.
			if (method == "SYNCLINKUP") {
				if (!data?.ol) return
				const linkURL = data.ol?.lu
				if (!linkURL) return
				for (const channel of this.#talkClient.channelList.open.all()) {
					if (channel.info.openLink?.linkURL == linkURL) {
						this.write("channel_meta_change", {
							info: {
								name: data.ol?.ln,
								description: data.ol?.desc || null,
								photoURL: data.ol?.liu || null,
							},
							channelId: channel.channelId,
							channelType: channel.info.type,
						})
						break
					}
				}
			}
		})

		this.#talkClient.on("disconnected", reason => {
			this.log(`Disconnected (reason=${reason})`)
			this.disconnect()
			this.write("disconnected", {
				reason: reason,
			})
		})

		this.#talkClient.on("switch_server", () => {
			this.log(`Server switch requested`)
			this.write("switch_server", {
				is_sequential: true,
			})
		})

		this.#talkClient.on("error", err => {
			this.log(`Client error: ${err}`)
			this.write("error", {
				error: err,
			})
		})
	}

	/**
	 * @param {string} mxid The ID of the associated Matrix user
	 * @param {OAuthCredential} credential The token to log in with, obtained from prior login
	 * @param {PeerClient} peerClient What handles RPC
	 */
	static async create(mxid, credential, peerClient) {
		this.#initializing = true
		const userClient = new UserClient(mxid, peerClient)

		await userClient.setCredential(credential)
		return userClient
	}


	log(...text) {
		console.log(`[API/${this.mxid}]`, ...text)
	}

	error(...text) {
		console.error(`[API/${this.mxid}]`, ...text)
	}

	/**
	 * @param {OAuthCredential} credential
	 */
	async setCredential(credential) {
		this.#serviceClient = await ServiceApiClient.create(credential)
		this.#credential = credential
	}

	/**
	 * @param {ChannelProps} channelProps
	 */
	async getChannel(channelProps) {
		const talkChannel = this.#talkClient.channelList.get(channelProps.id)
		if (talkChannel) {
			return talkChannel
		}

		const channelList = getChannelListForType(
			this.#talkClient.channelList,
			channelProps.type
		)
		const res = await channelList.addChannel({ channelId: channelProps.id })
		if (!res.success) {
			this.error(`Unable to add ${channelProps.type} channel ${channelProps.id}`)
			throw res
		}
		return res.result
	}

	/**
	 * @param {Long} channelId
	 */
	async getNormalChannel(channelId) {
		const channelList = this.#talkClient.channelList.normal
		const talkChannel = channelList.get(channelId)
		if (talkChannel) {
			return talkChannel
		}

		const res = await channelList.addChannel({ channelId: channelId })
		if (!res.success) {
			this.error(`Unable to add normal channel ${channelProps.id}`)
			throw res
		}
		return res.result
	}

	/**
	 * @param {?OAuthCredential} credential The token to log in with, obtained from prior login
	 */
	async connect(credential) {
		// TODO Don't re-login if possible. But must still return a LoginResult!
		this.disconnect()
		if (credential && this.#credential != credential) {
			await this.setCredential(credential)
		}
		const res = await this.#talkClient.login(this.#credential)
		this.#connected = res.success
		return res
	}

	disconnect() {
		if (this.isConnected()) {
			this.#talkClient.close()
		}
		this.#connected = false
	}

	isConnected() {
		return this.#talkClient?.logon || false
	}

	isUnexpectedlyDisconnected() {
		return this.#connected && !this.isConnected()
	}

	/**
	 * Send a user-specific command with (optional) data to the socket.
	 *
	 * @param {string} command - The data to write.
	 * @param {?object} data - The data to write.
	 */
	write(command, data) {
		return this.peerClient.write({
			id: --this.peerClient.notificationID,
			command: `${command}:${this.mxid}`,
			...data
		})
	}
}

export default class PeerClient {
	/**
	 * @param {import("./clientmanager.js").default} manager
	 * @param {import("net").Socket} socket
	 * @param {number} connID
	 */
	constructor(manager, socket, connID) {
		this.manager = manager
		this.registerTimeout = manager.registerTimeout
		this.loggingKeys = manager.loggingKeys

		this.socket = socket
		this.connID = connID

		this.stopped = false
		this.notificationID = 0
		this.maxCommandID = 0
		this.peerID = ""
		this.deviceName = "KakaoTalk Bridge"
		/** @type {Map<string, UserClient>} */
		this.userClients = new Map()
	}


	log(...text) {
		if (this.peerID) {
			console.log(`[API/${this.peerID}/${this.connID}]`, ...text)
		} else {
			console.log(`[API/${this.connID}]`, ...text)
		}
	}

	error(...text) {
		if (this.peerID) {
			console.error(`[API/${this.peerID}/${this.connID}]`, ...text)
		} else {
			console.error(`[API/${this.connID}]`, ...text)
		}
	}

	start() {
		this.log("Received connection", this.connID)
		emitLines(this.socket)
		this.socket.on("line", line => this.handleLine(line)
			.catch(err => this.log("Error handling line:", err)))
		this.socket.on("end", this.handleEnd)

		setTimeout(() => {
			if (!this.peerID && !this.stopped) {
				this.log(`Didn't receive register request within ${this.registerTimeout/1000} seconds, terminating`)
				this.stop("Register request timeout")
			}
		}, this.registerTimeout)
	}

	async stop(error = null) {
		if (this.stopped) {
			return
		}
		this.stopped = true
		this.#closeUsers()
		try {
			await this.write({ id: --this.notificationID, command: "quit", error })
			await promisify(cb => this.socket.end(cb))
		} catch (err) {
			this.error("Failed to end connection:", err)
			this.socket.destroy(err)
		}
	}

	handleEnd = () => {
		this.stopped = true
		this.#closeUsers()
		if (this.peerID && this.manager.clients.get(this.peerID) === this) {
			this.manager.clients.delete(this.peerID)
		}
		this.log(`Connection closed (peer: ${this.peerID || "unknown peer"})`)
	}

	#closeUsers() {
		this.log(`Closing all API clients for ${this.peerID || "unknown peer"}`)
		for (const userClient of this.userClients.values()) {
			userClient.disconnect()
		}
		this.userClients.clear()
	}

	/**
	 * Write JSON data to the socket.
	 *
	 * @param {object} data - The data to write.
	 * @returns {Promise<void>}
	 */
	write(data) {
		return promisify(cb => this.socket.write(JSON.stringify(data, this.#writeReplacer) + "\n", cb))
	}

	/**
	 * @param {object} req
	 * @param {string} req.passcode
	 * @param {string} req.uuid
	 * @param {object} req.form
	 */
	registerDevice = async (req) => {
		// TODO Look for a deregister API call
		const authClient = await this.#createAuthClient(req.uuid)
		return await authClient.registerDevice(req.form, req.passcode, true)
	}

	/**
	 * Obtain login tokens. If this fails due to not having a device, also request a device passcode.
	 * @param {object} req
	 * @param {string} req.uuid
	 * @param {object} req.form
	 * @param {boolean} req.forced
	 * @returns The response of the login attempt, including obtained
	 * credentials for subsequent token-based login. If a required device passcode
	 * request failed, its status is stored here.
	 */
	handleLogin = async (req) => {
		const authClient = await this.#createAuthClient(req.uuid)
		const loginRes = await authClient.login(req.form, req.forced)
		if (loginRes.status === KnownAuthStatusCode.DEVICE_NOT_REGISTERED) {
			const passcodeRes = await authClient.requestPasscode(req.form)
			if (!passcodeRes.success) {
				loginRes.status = passcodeRes.status
			}
		}
		return loginRes
	}

	/**
	 * TODO Consider caching per-user
	 * @param {string} uuid
	 */
	async #createAuthClient(uuid) {
		return await AuthApiClient.create(this.deviceName, uuid, {}, modutil.ModXVCProvider)
	}

	// TODO Wrapper for per-user commands

	/**
	 * Checked lookup of a UserClient for a given mxid.
	 * @param {string} mxid
	 * @returns {UserClient}
	 */
	#getUser(mxid) {
		const userClient = this.userClients.get(mxid)
		if (userClient === undefined) {
			throw new Error(`Could not find user ${mxid}`)
		}
		return userClient
	}

	/**
	 * Unchecked lookup of a UserClient for a given mxid.
	 * @param {string} mxid
	 * @returns {UserClient | undefined}
	 */
	#tryGetUser(mxid) {
		return this.userClients.get(mxid)
	}

	/**
	 * @param {string} mxid
	 * @param {ChannelProps} channelProps
	 * @param {?OpenChannelUserPerm[]} permNeeded If set, throw if the user's permission level matches none of the values in this list.
	 * @param {?string} action The action requiring permission, to be used in an error message if throwing.
	 * @throws {PermError} if the user does not have the specified permission level.
	 */
	async #getUserChannel(mxid, channelProps, permNeeded, action) {
		const userClient = this.#getUser(mxid)
		const talkChannel = await userClient.getChannel(channelProps)
		if (permNeeded) {
			await this.#requireChannelPerm(talkChannel, permNeeded, action)
		}
		return talkChannel
	}

	/**
	 * @param {TalkOpenChannel} talkChannel
	 * @param {OpenChannelUserPerm[]} permNeeded Throw if the user's permission level matches none of the values in this list.
	 * @param {string} action The action requiring permission
	 * @throws {PermError} if the user does not have the specified permission level.
	*/
	async #requireChannelPerm(talkChannel, permNeeded, action) {
		const permActual = talkChannel.getUserInfo({ userId: talkChannel.clientUser.userId }).perm
		if (permNeeded.indexOf(permActual) == -1) {
			throw new PermError(permNeeded, permActual, action)
		}
	}

	/**
	 * @param {string} mxid
	 * @param {Long} channelId
	 */
	async #getUserNormalChannel(mxid, channelId) {
		return await this.#getUser(mxid).getNormalChannel(channelId)
	}

	/**
	 * @param {object} req
	 * @param {string} req.mxid
	 * @param {OAuthCredential} req.oauth_credential
	 */
	handleRenew = async (req) => {
		const userClient = this.#tryGetUser(req.mxid)
		const oAuthClient = await OAuthApiClient.create()
		const res = await oAuthClient.renew(req.oauth_credential)
		if (res.success && userClient) {
			await userClient.setCredential(res.result.credential)
		}
		return res
	}

	/**
	 * @param {object} req
	 * @param {string} req.mxid
	 * @param {OAuthCredential} req.oauth_credential
	 */
	userStart = async (req) => {
		let userClient = this.#tryGetUser(req.mxid)
		if (!userClient) {
			userClient = await UserClient.create(req.mxid, req.oauth_credential, this)
		} else {
			await userClient.setCredential(req.oauth_credential)
		}
		const res = await this.#getSettings(userClient.serviceClient)
		if (res.success) {
			this.userClients.set(req.mxid, userClient)
		}
		return res
	}

	/**
	 * @param {object} req
	 * @param {string} req.mxid
	 */
	userStop = async (req) => {
		this.handleDisconnect(req)
		this.userClients.delete(req.mxid)
	}

	/**
	 * @param {object} req
	 * @param {string} req.mxid
	 * @param {?OAuthCredential} req.oauth_credential
	 */
	handleConnect = async (req) => {
		return await this.#getUser(req.mxid).connect(req.oauth_credential)
	}

	/**
	 * @param {object} req
	 * @param {string} req.mxid
	 */
	handleDisconnect = (req) => {
		this.#tryGetUser(req.mxid)?.disconnect()
	}

	/**
	 * @param {object} req
	 * @param {string} req.mxid
	 */
	isConnected = (req) => {
		return this.#tryGetUser(req.mxid)?.isConnected()
	}

	/**
	 * @param {object} req
	 * @param {string} req.mxid
	 */
	getSettings = async (req) => {
		return await this.#getSettings(this.#getUser(req.mxid).serviceClient)
	}

	/**
	 * @param {ServiceApiClient} serviceClient
	 */
	#getSettings = async (serviceClient) => {
		const moreRes = await serviceClient.requestMoreSettings()
		if (!moreRes.success) return moreRes

		const lessRes = await serviceClient.requestLessSettings()
		if (!lessRes.success) return lessRes

		return makeCommandResult({
			more: moreRes.result,
			less: lessRes.result,
		})
	}

	/**
	 * @param {object} req
	 * @param {string} req.mxid
	 */
	getOwnProfile = async (req) => {
		return await this.#getUser(req.mxid).serviceClient.requestMyProfile()
	}

	/**
	 * @param {object} req
	 * @param {string} req.mxid
	 * @param {Long} req.user_id
	 */
	getProfile = async (req) => {
		return await this.#getUser(req.mxid).serviceClient.requestProfile(req.user_id)
	}

	/**
	 * @param {object} req
	 * @param {string} req.mxid
	 * @param {ChannelProps} req.channel_props
	 */
	getPortalChannelInfo = async (req) => {
		const talkChannel = await this.#getUserChannel(req.mxid, req.channel_props)

		const res = await talkChannel.updateAll()
		if (!res.success) return res

		return makeCommandResult({
			name: talkChannel.getDisplayName(),
			description: talkChannel.info.openLink?.description,
			// TODO Find out why linkCoverURL is blank, despite having updated the channel!
			photoURL: talkChannel.info.openLink?.linkCoverURL || null,
			participantInfo: {
				// TODO Get members from chatON?
				participants: Array.from(talkChannel.getAllUserInfo()),
				kickedUserIds: await this.#getKickedUserIds(talkChannel),
			},
		})
	}

	/**
	 * @param {object} req
	 * @param {string} req.mxid
	 * @param {ChannelProps} req.channel_props
	 */
	getPortalChannelParticipantInfo = async (req) => {
		const talkChannel = await this.#getUserChannel(req.mxid, req.channel_props)

		// TODO Get members from chatON?
		const participantRes = await talkChannel.getAllLatestUserInfo()
		if (!participantRes.success) return participantRes

		return {
			participants: participantRes.result,
			kickedUserIds: await this.#getKickedUserIds(talkChannel),
		}
	}

	/**
	 * @param {TalkNormalChannel | TalkOpenChannel} talkChannel
	 */
	async #getKickedUserIds(talkChannel) {
		if (!isChannelTypeOpen(talkChannel.info.type)) {
			return []
		} else {
			const kickListRes = await talkChannel.getKickList()
			if (!kickListRes.success) {
				return []
			} else {
				return kickListRes.result.map(kickUser => kickUser.userId)
			}
		}
	}

	/**
	 * @param {object} req
	 * @param {string} req.mxid
	 * @param {ChannelProps} req.channel_props
	 */
	getParticipants = async (req) => {
		const talkChannel = await this.#getUserChannel(req.mxid, req.channel_props)
		return await talkChannel.getAllLatestUserInfo()
	}

	/**
	 * @param {object} req
	 * @param {string} req.mxid
	 * @param {ChannelProps} req.channel_props
	 * @param {?Long} req.sync_from
	 * @param {?number} req.limit
	 */
	getChats = async (req) => {
		const talkChannel = await this.#getUserChannel(req.mxid, req.channel_props)

		const res = await talkChannel.getChatListFrom(req.sync_from)
		if (!res.success || !res.length) return res

		while (true) {
			const nextRes = await talkChannel.getChatListFrom(
				res.result[res.result.length - 1].logId
			)
			if (!nextRes.success) return nextRes
			if (!nextRes.result.length) break
			res.result.push(...nextRes.result)
		}
		if (0 < req.limit && req.limit < res.result.length) {
			res.result.splice(0, res.result.length - req.limit)
		}
		return res
	}

	/**
	 * @param {object} req
	 * @param {string} req.mxid
	 * @param {ChannelProps} req.channel_props
	 * @param {[Long]} req.unread_chat_ids Must be in DECREASING order
	*/
	getReadReceipts = async (req) => {
		const talkChannel = await this.#getUserChannel(req.mxid, req.channel_props)
		// TODO Is any pre-syncing needed?
		const userCount = talkChannel.userCount
		if (userCount == 1) return makeCommandResult([])
		/** @type {Map<Long, Long> */
		const latestReceiptByUser = new Map()
		let fullyRead = false
		for (const chatId of req.unread_chat_ids) {
			const chatReaders = talkChannel.getReaders({ logId: chatId })
			for (const chatReader of chatReaders) {
				if (!latestReceiptByUser.has(chatReader.userId)) {
					latestReceiptByUser.set(chatReader.userId, chatId)
					if (latestReceiptByUser.size == userCount) {
						fullyRead = true
						break
					}
				}
			}
			if (fullyRead) {
				break
			}
		}

		/**
		 * @typedef {object} Receipt
		 * @property {Long} userId
		 * @property {Long} chatId
		 */
		/** @type {[Receipt]} */
		const receipts = []
		latestReceiptByUser.forEach((value, key) => receipts.push({ "userId": key, "chatId": value }))
		return makeCommandResult(receipts)
	}

	/**
	 * @param {object} req
	 * @param {string} req.mxid
	 * @param {string} req.uuid
	 */
	canChangeUUID = async (req) => {
		return await this.#getUser(req.mxid).serviceClient.canChangeUUID(req.uuid)
	}

	/**
	 * @param {object} req
	 * @param {string} req.mxid
	 * @param {string} req.uuid
	 */
	changeUUID = async (req) => {
		const serviceClient = this.#getUser(req.mxid).serviceClient

		const checkRes = await serviceClient.canChangeUUID(req.uuid)
		if (!checkRes.success) return checkRes

		return await serviceClient.changeUUID(req.uuid)
	}

	/**
	 * @param {object} req
	 * @param {string} req.mxid
	 * @param {boolean} req.searchable
	 */
	setUUIDSearchable = async (req) => {
		const serviceClient = this.#getUser(req.mxid).serviceClient
		const moreRes = await serviceClient.requestMoreSettings()
		if (!moreRes.success) {
			throw new ProtocolError("Error checking status of KakaoTalk ID")
		}
		if (!moreRes.result.uuid) {
			throw new ProtocolError("You do not yet have a KakaoTalk ID")
		}
		if (req.searchable == moreRes.result.uuidSearchable) {
			throw new ProtocolError(`Your KakaoTalk ID is already ${req.searchable ? "searchable" : "hidden"}`)
		}
		return await serviceClient.updateSettings({
			uuid_searchable: req.searchable,
		})
	}

	/**
	 * @param {object} req
	 * @param {string} req.mxid
	 */
	listFriends = async (req) => {
		return await this.#getUser(req.mxid).serviceClient.requestFriendList()
	}

	/**
	 * @param {object} req
	 * @param {string} req.mxid
	 * @param {Long} req.user_id
	 * @param {boolean} req.add
	 */
	editFriend = async (req) => {
		return await this.#editFriend(
			this.#getUser(req.mxid).serviceClient,
			req.user_id,
			req.add
		)
	}

	/**
	 * @param {object} req
	 * @param {string} req.mxid
	 * @param {string} req.uuid
	 * @param {boolean} req.add
	 */
	editFriendByUUID = async (req) => {
		const serviceClient = this.#getUser(req.mxid).serviceClient

		const res = await serviceClient.findFriendByUUID(req.uuid)
		if (!res.success) return res

		return await this.#editFriend(
			serviceClient,
			res.result.member.userId instanceof Long
				? res.result.member.userId
				: Long.fromNumber(res.result.member.userId),
			req.add
		)
	}

	/**
	 * @param {ServiceApiClient} serviceClient
	 * @param {Long} id
	 * @param {boolean} add
	 */
	async #editFriend(serviceClient, id, add) {
		const listRes = await serviceClient.requestFriendList()
		if (listRes.success) {
			const isFriend = -1 != listRes.result.friends.findIndex(friend => id.equals(friend.userId))
			if (isFriend == add) {
				throw new ProtocolError(`User is already ${add ? "in" : "absent from"} friends list`)
			}
		}
		return add ? await serviceClient.addFriend(id) : await serviceClient.removeFriend(id)
	}

	/**
	 * @param {object} req
	 * @param {string} req.mxid The user whose friend is being looked up.
	 * @param {string} req.friend_id The friend to search for.
	 * @param {string} propertyName The property to retrieve from the specified friend.
	 */
	getFriendProperty = async (req, propertyName) => {
		const res = await this.#getUser(req.mxid).serviceClient.findFriendById(req.friend_id)
		if (!res.success) return res

		return makeCommandResult(res.result.friend[propertyName])
	}

	/**
	 * @param {object} req
	 * @param {string} req.mxid
	 */
	getMemoIds = (req) => {
		/** @type Long[] */
		const channelIds = []
		const channelList = this.#getUser(req.mxid).talkClient.channelList
		// TODO channelList.all() doesn't really return *all* channels...
		for (const channel of channelList.all()) {
			if (channel.info.type == "MemoChat") {
				channelIds.push(channel.channelId)
			}
		}
		return channelIds
	}

	/**
	 * @param {object} req
	 * @param {string} req.mxid
	 * @param {ChannelProps} req.channel_props
	 * @param {string} req.key
	 */
	downloadFile = async (req) => {
		const talkChannel = await this.#getUserChannel(req.mxid, req.channel_props)
		const res = await talkChannel.downloadMedia({ key: req.key }, KnownChatType.FILE)
		if (!res.success) return res

		const data = await ReadStreamUtil.all(res.result)
		return makeCommandResult(Array.from(data))
	}

	/**
	 * @param {object} req
	 * @param {string} req.mxid
	 * @param {ChannelProps} req.channel_props
	 * @param {string} req.text
	 * @param {?ReplyAttachment} req.reply_to
	 * @param {?MentionStruct[]} req.mentions
	 */
	sendChat = async (req) => {
		const talkChannel = await this.#getUserChannel(req.mxid, req.channel_props)
		const res = await talkChannel.sendChat({
			text: req.text,
			type: !!req.reply_to ? KnownChatType.REPLY : KnownChatType.TEXT,
			attachment: !req.mentions ? req.reply_to : {...req.reply_to, mentions: req.mentions},
		})
		if (res.success) res.result = res.result.logId
		return res
	}

	/**
	 * @param {object} req
	 * @param {string} req.mxid
	 * @param {ChannelProps} req.channel_props
	 * @param {int} req.type
	 * @param {number[]} req.data
	 * @param {string} req.name
	 * @param {?int} req.width
	 * @param {?int} req.height
	 * @param {?string} req.ext
	 */
	sendMedia = async (req) => {
		const talkChannel = await this.#getUserChannel(req.mxid, req.channel_props)
		const res = await talkChannel.sendMedia(req.type, {
			data: Uint8Array.from(req.data),
			name: req.name,
			width: req.width,
			height: req.height,
			ext: req.ext,
		})
		if (res.success) res.result = res.result.logId
		return res
	}

	/**
	 * @param {object} req
	 * @param {string} req.mxid
	 * @param {ChannelProps} req.channel_props
	 * @param {Long} req.chat_id
	 */
	deleteChat = async (req) => {
		const talkChannel = await this.#getUserChannel(req.mxid, req.channel_props)

		return await talkChannel.deleteChat({
			logId: req.chat_id,
		})
	}

	/**
	 * @param {object} req
	 * @param {string} req.mxid
	 * @param {ChannelProps} req.channel_props
	 * @param {Long} req.read_until_chat_id
	 */
	markRead = async (req) => {
		const talkChannel = await this.#getUserChannel(req.mxid, req.channel_props)

		return await talkChannel.markRead({
			logId: req.read_until_chat_id,
		})
	}

	/**
	 * @param {object} req
	 * @param {string} req.mxid
	 * @param {ChannelProps} req.channel_props
	 * @param {Long} req.user_id
	 * @param {OpenChannelUserPerm} req.perm
	 */
	sendPerm = async (req) => {
		const talkChannel = await this.#getUserChannel(
			req.mxid,
			req.channel_props,
			[OpenChannelUserPerm.OWNER],
			"change user permissions"
		)
		const user = { userId: req.user_id }
		if (!talkChannel.getUserInfo(user)) {
			throw new ProtocolError("Cannot set permission level of a user that is not a channel participant")
		}
		if (req.user_id.equals(talkChannel.clientUser.userId)) {
			throw new ProtocolError("Cannot change own permission level")
		}
		return await talkChannel.setUserPerm(user, req.perm)
	}

	/**
	 * @param {object} req
	 * @param {string} req.mxid
	 * @param {ChannelProps} req.channel_props
	 * @param {string} req.name
	 */
	setChannelName = async (req) => {
		if (!isChannelTypeOpen(req.channel_props.type)) {
			const talkChannel = await this.#getUserNormalChannel(req.mxid, req.channel_props.id)
			return await talkChannel.setTitleMeta(req.name)
		} else {
			return await this.#setOpenChannelProperty(req.mxid, req.channel_props, "linkName", req.name)
		}
	}

	/**
	 * @param {object} req
	 * @param {string} req.mxid
	 * @param {ChannelProps} req.channel_props
	 * @param {string} req.description
	 */
	setChannelDescription = async (req) => {
		return await this.#setOpenChannelProperty(req.mxid, req.channel_props, "description", req.description)
	}

	/**
	 * @param {string} mxid
	 * @param {ChannelProps} channelProps
	 * @param {string} propertyName
	 * @param {any} propertyValue
	 */
	async #setOpenChannelProperty(mxid, channelProps, propertyName, propertyValue) {
		if (isChannelTypeOpen(channelProps)) {
			throw ProtocolError(`Cannot set ${propertyName} of non-open channel ${channelProps.id} (type = ${channelProps.type})`)
		}

		const userClient = this.#getUser(mxid)
		/** @type {TalkOpenChannel} */
		const talkChannel = await userClient.getChannel(channelProps)
		this.#requireChannelPerm(talkChannel, [OpenChannelUserPerm.OWNER], `change channel ${propertyName}`)

		const linkRes = await talkChannel.getLatestOpenLink()
		if (!linkRes.success) throw linkRes

		const link = linkRes.result
		link[propertyName] = propertyValue
		return await userClient.talkClient.channelList.open.updateOpenLink(
			{ linkId: link.linkId }, link
		)
	}

	/*
	 * TODO
	 * @param {object} req
	 * @param {string} req.mxid
	 * @param {ChannelProps} req.channel_props
	 * @param {string} req.photo_url
	setChannelPhoto = async (req) => {
		const talkChannel = await this.#getUserChannel(
			req.mxid,
			req.channel_props,
			[OpenChannelUserPerm.OWNER],
			"change channel photo"
		)
		return await talkChannel.setProfileMeta({
			imageUrl: req.photo_url,
			fullImageUrl: req.photo_url,
		})
	}
	*/

	/**
	 * @param {object} req
	 * @param {string} req.mxid
	 * @param {Long} req.user_id
	 */
	createDirectChat = async (req) => {
		const userClient = this.#getUser(req.mxid)
		await this.#requireInFriendsList(userClient.serviceClient, req.user_id)

		const channelList = userClient.talkClient.channelList.normal
		const createChannel =
			!req.user_id.equals(userClient.userId)
			? channelList.createChannel.bind(channelList, {
				userList: [{ userId: req.user_id }],
			})
			: channelList.createMemoChannel.bind(channelList)

		const retry_delay = 2000
		let retries_left = 1
		let res
		do {
			res = await createChannel()
			if (res.success) {
				return makeCommandResult(res.result.channelId)
			}
			this.error(`Failed to create direct chat, try again in ${retry_delay} ms (${retries_left - 1} tries remaining)`)
			await new Promise(resolve => setTimeout(resolve, retry_delay))
		} while (retries_left--)

		this.error(`Failed to create direct chat, not retrying`)
		return res
	}

	/**
	 * @param {ServiceApiClient} serviceClient
	 * @param {Long} id
	 */
	async #requireInFriendsList(serviceClient, id) {
		let listRes = await serviceClient.requestFriendList()
		if (!listRes.success) {
			this.error("Failed to check friends list")
			throw listRes
		}
		const isFriend = -1 != listRes.result.friends.findIndex(friend => id.equals(friend.userId))
		if (!isFriend) {
			throw new ProtocolError("This user is not in your friends list")
		}
	}

	/**
	 * @param {object} req
	 * @param {string} req.mxid
	 * @param {ChannelProps} req.channel_props
	 */
	leaveChannel = async (req) => {
		const userClient = this.#getUser(req.mxid)
		const channelList = getChannelListForType(
			userClient.talkClient.channelList,
			req.channel_props.type
		)
		return await channelList.leaveChannel({ channelId: req.channel_props.id })
	}

	handleUnknownCommand = () => {
		throw new Error("Unknown command")
	}

	/**
	 * @param {object} req
	 * @param {string} req.peer_id
	 * @param {object} req.register_config
	 * @param {string} req.register_config.device_name
	 */
	handleRegister = async (req) => {
		this.peerID = req.peer_id
		this.deviceName = req.register_config.device_name || this.deviceName
		this.log(`Registered socket ${this.connID} -> ${this.peerID}`)
		if (this.manager.clients.has(this.peerID)) {
			const oldClient = this.manager.clients.get(this.peerID)
			this.log(`Terminating previous socket ${oldClient.connID} for ${this.peerID}`)
			await oldClient.stop("Socket replaced by new connection")
		}
		this.manager.clients.set(this.peerID, this)
		return { client_exists: this.authClient !== null }
	}

	async handleLine(line) {
		if (this.stopped) {
			this.log("Ignoring line, client is stopped")
			return
		}
		let req
		try {
			req = JSON.parse(line, this.#readReviver)
		} catch (err) {
			this.log("Non-JSON request:", line)
			return
		}
		if (!req.command || !req.id) {
			this.log("Invalid request:", line)
			return
		}
		if (req.id <= this.maxCommandID) {
			this.log("Ignoring old request", req.id)
			return
		}
		this.log(`Request ${req.id}:`, this.#logObj(req, req.command, this.loggingKeys.request))
		this.maxCommandID = req.id
		let handler
		if (!this.peerID) {
			if (req.command !== "register") {
				this.log("First request wasn't a register request, terminating")
				await this.stop("Invalid first request")
				return
			} else if (!req.peer_id) {
				this.log("Register request didn't contain ID, terminating")
				await this.stop("Invalid register request")
				return
			}
			handler = this.handleRegister
		} else {
			handler = {
				// TODO Wrapper for per-user commands
				generate_uuid: util.randomAndroidSubDeviceUUID,
				register_device: this.registerDevice,
				login: this.handleLogin,
				renew: this.handleRenew,
				start: this.userStart,
				stop: this.userStop,
				connect: this.handleConnect,
				disconnect: this.handleDisconnect,
				is_connected: this.isConnected,
				get_settings: this.getSettings,
				get_own_profile: this.getOwnProfile,
				get_profile: this.getProfile,
				get_portal_channel_info: this.getPortalChannelInfo,
				get_portal_channel_participant_info: this.getPortalChannelParticipantInfo,
				get_participants: this.getParticipants,
				get_chats: this.getChats,
				get_read_receipts: this.getReadReceipts,
				can_change_uuid: this.canChangeUUID,
				change_uuid: this.changeUUID,
				set_uuid_searchable: this.setUUIDSearchable,
				list_friends: this.listFriends,
				edit_friend: this.editFriend,
				edit_friend_by_uuid: this.editFriendByUUID,
				get_friend_dm_id: req => this.getFriendProperty(req, "directChatId"),
				get_memo_ids: this.getMemoIds,
				download_file: this.downloadFile,
				send_chat: this.sendChat,
				send_media: this.sendMedia,
				delete_chat: this.deleteChat,
				mark_read: this.markRead,
				send_perm: this.sendPerm,
				set_channel_name: this.setChannelName,
				set_channel_description: this.setChannelDescription,
				//set_channel_photo: this.setChannelPhoto,
				create_direct_chat: this.createDirectChat,
				leave_channel: this.leaveChannel,
			}[req.command] || this.handleUnknownCommand
		}
		const resp = { id: req.id }
		delete req.id
		delete req.command
		resp.command = "response"
		try {
			resp.response = await handler(req)
		} catch (err) {
			if (err.isAxiosError) {
				resp.response = {
					success: false,
					status: err.response.status,
				}
			} else if ("status" in err) {
				resp.response = err
			} else {
				resp.command = "error"
				let errorDetails
				if (err instanceof ProtocolError) {
					resp.error = err.message
					errorDetails = err.message
				} else if (err instanceof Error) {
					resp.error = err.toString()
					errorDetails = err.stack
				} else {
					resp.error = JSON.stringify(err)
					errorDetails = `throwed ${resp.error}`
				}
				this.error(`Response ${resp.id}: ${errorDetails}`)
			}
		}
		if (resp.response) {
			const success = resp.response.success !== false
			const logger = (success ? this.log : this.error).bind(this)
			logger(
				`Response ${resp.id}:`,
				this.#logObj(
					resp.response instanceof Object ? resp.response : {value: resp.response},
					success ? "success" : "failure",
					this.loggingKeys.response
				)
			)
		}
		await this.write(resp)
		if ("mxid" in req) {
			const userClient = this.#tryGetUser(req.mxid)
			if (userClient && userClient.isUnexpectedlyDisconnected()) {
				this.error("Unexpected disconnect for user", req.mxid)
				this.userClients.delete(req.mxid)
				await userClient.write("unexpected_disconnect")
			}
		}
	}

	/**
	 * @param {object} obj
	 * @param {string} desc
	 * @param {[string]} keys
	 */
	#logObj(obj, desc, keys) {
		return [desc].concat(
			keys.filter(key => key in obj).map(key => `${key}: ${JSON.stringify(obj[key], this.#writeReplacer)}`)
		).join(', ')
	}

	#writeReplacer(key, value) {
		if (value instanceof Long) {
			return value.toString()
		} else {
			return value
		}
	}

	#readReviver(key, value) {
		if (value instanceof Object) {
			// TODO Use a type map if there will be many possible types
			if (value.__type__ == "Long") {
				return Long.fromString(value.str)
			}
		}
		return value
	}
}


/**
 * @param {object} result
 */
function makeCommandResult(result) {
	return {
		success: true,
		status: 0,
		result: result
	}
}

/**
 * @param {TalkChannelList} channelList
 * @param {ChannelType} channelType
 */
function getChannelListForType(channelList, channelType) {
	return isChannelTypeOpen(channelType) ? channelList.open : channelList.normal
}

/**
 * @param {ChannelType} channelType
 */
function isChannelTypeOpen(channelType) {
	switch (channelType) {
	case "OM":
	case "OD":
		return true
	default:
		return false
	}
}

/**
 * @param {TalkOpenChannel} channel
 */
function getChannelOwner(channel) {
	for (const userInfo of channel.getAllUserInfo()) {
		if (userInfo.perm == OpenChannelUserPerm.OWNER) {
			return userInfo
		}
	}
	return null
}