// @ts-check

const assert = require("assert").strict
const DiscordTypes = require("discord-api-types/v10")
const reg = require("../../matrix/read-registration")

const passthrough = require("../../passthrough")
const {discord, sync, db, select} = passthrough
/** @type {import("../../matrix/file")} */
const file = sync.require("../../matrix/file")
/** @type {import("../../matrix/api")} */
const api = sync.require("../../matrix/api")
/** @type {import("../../matrix/kstate")} */
const ks = sync.require("../../matrix/kstate")
/** @type {import("./create-space")}) */
const createSpace = sync.require("./create-space") // watch out for the require loop

/**
 * There are 3 levels of room privacy:
 * 0: Room is invite-only.
 * 1: Anybody can use a link to join.
 * 2: Room is published in room directory.
 */
const PRIVACY_ENUMS = {
	PRESET: ["private_chat", "public_chat", "public_chat"],
	VISIBILITY: ["private", "private", "public"],
	SPACE_HISTORY_VISIBILITY: ["invited", "world_readable", "world_readable"], // copying from element client
	ROOM_HISTORY_VISIBILITY: ["shared", "shared", "world_readable"], // any events sent after <value> are visible, but for world_readable anybody can read without even joining
	GUEST_ACCESS: ["can_join", "forbidden", "forbidden"], // whether guests can join space if other conditions are met
	SPACE_JOIN_RULES: ["invite", "public", "public"],
	ROOM_JOIN_RULES: ["restricted", "public", "public"]
}

const DEFAULT_PRIVACY_LEVEL = 0

/** @type {Map<string, Promise<string>>} channel ID -> Promise<room ID> */
const inflightRoomCreate = new Map()

/**
 * Async because it gets all room state from the homeserver.
 * @param {string} roomID
 */
async function roomToKState(roomID) {
	const root = await api.getAllState(roomID)
	return ks.stateToKState(root)
}

/**
 * @param {string} roomID
 * @param {any} kstate
 */
function applyKStateDiffToRoom(roomID, kstate) {
	const events = ks.kstateToState(kstate)
	return Promise.all(events.map(({type, state_key, content}) =>
		api.sendState(roomID, type, state_key, content)
	))
}

/**
 * @param {{id: string, name: string, topic?: string?, type: number}} channel
 * @param {{id: string}} guild
 * @param {string | null | undefined} customName
 */
function convertNameAndTopic(channel, guild, customName) {
	let channelPrefix =
		( channel.type === DiscordTypes.ChannelType.PublicThread ? "[⛓️] "
		: channel.type === DiscordTypes.ChannelType.PrivateThread ? "[🔒⛓️] "
		: channel.type === DiscordTypes.ChannelType.GuildVoice ? "[🔊] "
		: "")
	const chosenName = customName || (channelPrefix + channel.name);
	const maybeTopicWithPipe = channel.topic ? ` | ${channel.topic}` : '';
	const maybeTopicWithNewlines = channel.topic ? `${channel.topic}\n\n` : '';
	const channelIDPart = `Channel ID: ${channel.id}`;
	const guildIDPart = `Guild ID: ${guild.id}`;

	const convertedTopic = customName
		 ? `#${channel.name}${maybeTopicWithPipe}\n\n${channelIDPart}\n${guildIDPart}`
		 : `${maybeTopicWithNewlines}${channelIDPart}\n${guildIDPart}`;

	return [chosenName, convertedTopic];
}

/**
 * Async because it may create the guild and/or upload the guild icon to mxc.
 * @param {DiscordTypes.APIGuildTextChannel | DiscordTypes.APIThreadChannel} channel
 * @param {DiscordTypes.APIGuild} guild
 */
async function channelToKState(channel, guild) {
	const spaceID = await createSpace.ensureSpace(guild)
	assert(typeof spaceID === "string")
	const privacyLevel = select("guild_space", "privacy_level", {space_id: spaceID}).pluck().get()
	assert(typeof privacyLevel === "number")

	const row = select("channel_room", ["nick", "custom_avatar"], {channel_id: channel.id}).get()
	const customName = row?.nick
	const customAvatar = row?.custom_avatar
	const [convertedName, convertedTopic] = convertNameAndTopic(channel, guild, customName)

	const avatarEventContent = {}
	if (customAvatar) {
		avatarEventContent.url = customAvatar
	} else if (guild.icon) {
		avatarEventContent.discord_path = file.guildIcon(guild)
		avatarEventContent.url = await file.uploadDiscordFileToMxc(avatarEventContent.discord_path) // TODO: somehow represent future values in kstate (callbacks?), while still allowing for diffing, so test cases don't need to touch the media API
	}

	let history_visibility = PRIVACY_ENUMS.ROOM_HISTORY_VISIBILITY[privacyLevel]
	if (channel["thread_metadata"]) history_visibility = "world_readable"

	/** @type {{join_rule: string, allow?: any}} */
	let join_rules = {
		join_rule: "restricted",
		allow: [{
			type: "m.room_membership",
			room_id: spaceID
		}]
	}
	if (PRIVACY_ENUMS.ROOM_JOIN_RULES[privacyLevel] !== "restricted") {
		join_rules = {join_rule: PRIVACY_ENUMS.ROOM_JOIN_RULES[privacyLevel]}
	}

	const channelKState = {
		"m.room.name/": {name: convertedName},
		"m.room.topic/": {topic: convertedTopic},
		"m.room.avatar/": avatarEventContent,
		"m.room.guest_access/": {guest_access: PRIVACY_ENUMS.GUEST_ACCESS[privacyLevel]},
		"m.room.history_visibility/": {history_visibility},
		[`m.space.parent/${spaceID}`]: {
			via: [reg.ooye.server_name],
			canonical: true
		},
		/** @type {{join_rule: string, [x: string]: any}} */
		"m.room.join_rules/": join_rules,
		"m.room.power_levels/": {
			events: {
				"m.room.avatar": 0
			},
			notifications: {
				room: 20 // TODO: Matrix users should have the same abilities as unprivileged Discord members. So make this automatically configured based on the guild or channel's default mention everyone permissions. That way if unprivileged Discord members can mention everyone, Matrix users can too.
			},
			users: reg.ooye.invite.reduce((a, c) => (a[c] = 100, a), {})
		},
		"chat.schildi.hide_ui/read_receipts": {
			hidden: true
		},
		[`uk.half-shot.bridge/moe.cadence.ooye://discord/${guild.id}/${channel.id}`]: {
			bridgebot: `@${reg.sender_localpart}:${reg.ooye.server_name}`,
			protocol: {
				id: "discord",
				displayname: "Discord"
			},
			network: {
				id: guild.id,
				displayname: guild.name,
				avatar_url: await file.uploadDiscordFileToMxc(file.guildIcon(guild))
			},
			channel: {
				id: channel.id,
				displayname: channel.name,
				external_url: `https://discord.com/channels/${guild.id}/${channel.id}`
			}
		}
	}

	return {spaceID, privacyLevel, channelKState}
}

/**
 * Create a bridge room, store the relationship in the database, and add it to the guild's space.
 * @param {DiscordTypes.APIGuildTextChannel} channel
 * @param guild
 * @param {string} spaceID
 * @param {any} kstate
 * @param {number} privacyLevel
 * @returns {Promise<string>} room ID
 */
async function createRoom(channel, guild, spaceID, kstate, privacyLevel) {
	let threadParent = null
	if (channel.type === DiscordTypes.ChannelType.PublicThread) threadParent = channel.parent_id

	// Name and topic can be done earlier in room creation rather than in initial_state
	// https://spec.matrix.org/latest/client-server-api/#creation
	const name = kstate["m.room.name/"].name
	delete kstate["m.room.name/"]
	assert(name)
	const topic = kstate["m.room.topic/"].topic
	delete kstate["m.room.topic/"]
	assert(topic)

	const roomID = await postApplyPowerLevels(kstate, async kstate => {
		const roomID = await api.createRoom({
			name,
			topic,
			preset: PRIVACY_ENUMS.PRESET[privacyLevel], // This is closest to what we want, but properties from kstate override it anyway
			visibility: PRIVACY_ENUMS.VISIBILITY[privacyLevel],
			invite: [],
			initial_state: ks.kstateToState(kstate)
		})

		db.prepare("INSERT INTO channel_room (channel_id, room_id, name, nick, thread_parent) VALUES (?, ?, ?, NULL, ?)").run(channel.id, roomID, channel.name, threadParent)

		return roomID
	})

	// Put the newly created child into the space, no need to await this
	_syncSpaceMember(channel, spaceID, roomID)

	return roomID
}

/**
 * Handling power levels separately. The spec doesn't specify what happens, Dendrite differs,
 * and Synapse does an absolutely insane *shallow merge* of what I provide on top of what it creates.
 * We don't want the `events` key to be overridden completely.
 * https://github.com/matrix-org/synapse/blob/develop/synapse/handlers/room.py#L1170-L1210
 * https://github.com/matrix-org/matrix-spec/issues/492
 * @param {any} kstate
 * @param {(_: any) => Promise<string>} callback must return room ID
 * @returns {Promise<string>} room ID
 */
async function postApplyPowerLevels(kstate, callback) {
	const powerLevelContent = kstate["m.room.power_levels/"]
	const kstateWithoutPowerLevels = {...kstate}
	delete kstateWithoutPowerLevels["m.room.power_levels/"]

	/** @type {string} */
	const roomID = await callback(kstateWithoutPowerLevels)

	// Now *really* apply the power level overrides on top of what Synapse *really* set
	if (powerLevelContent) {
		const newRoomKState = await roomToKState(roomID)
		const newRoomPowerLevelsDiff = ks.diffKState(newRoomKState, {"m.room.power_levels/": powerLevelContent})
		await applyKStateDiffToRoom(roomID, newRoomPowerLevelsDiff)
	}

	return roomID
}

/**
 * @param {DiscordTypes.APIGuildChannel} channel
 */
function channelToGuild(channel) {
	const guildID = channel.guild_id
	assert(guildID)
	const guild = discord.guilds.get(guildID)
	assert(guild)
	return guild
}

/*
	Ensure flow:
	1. Get IDs
	2. Does room exist? If so great!
	(it doesn't, so it needs to be created)
	3. Get kstate for channel
	4. Create room, return new ID

	Ensure + sync flow:
	1. Get IDs
	2. Does room exist?
	2.5: If room does exist AND wasn't asked to sync: return here
	3. Get kstate for channel
	4. Create room with kstate if room doesn't exist
	5. Get and update room state with kstate if room does exist
*/

/**
 * @param {string} channelID
 * @param {boolean} shouldActuallySync false if just need to ensure room exists (which is a quick database check), true if also want to sync room data when it does exist (slow)
 * @returns {Promise<string>} room ID
 */
async function _syncRoom(channelID, shouldActuallySync) {
	/** @ts-ignore @type {DiscordTypes.APIGuildChannel} */
	const channel = discord.channels.get(channelID)
	assert.ok(channel)
	const guild = channelToGuild(channel)

	if (inflightRoomCreate.has(channelID)) {
		await inflightRoomCreate.get(channelID) // just waiting, and then doing a new db query afterwards, is the simplest way of doing it
	}

	const existing = select("channel_room", ["room_id", "thread_parent"], {channel_id: channelID}).get()

	if (!existing) {
		const creation = (async () => {
			const {spaceID, privacyLevel, channelKState} = await channelToKState(channel, guild)
			const roomID = await createRoom(channel, guild, spaceID, channelKState, privacyLevel)
			inflightRoomCreate.delete(channelID) // OK to release inflight waiters now. they will read the correct `existing` row
			return roomID
		})()
		inflightRoomCreate.set(channelID, creation)
		return creation // Naturally, the newly created room is already up to date, so we can always skip syncing here.
	}

	const roomID = existing.room_id

	if (!shouldActuallySync) {
		return existing.room_id // only need to ensure room exists, and it does. return the room ID
	}

	console.log(`[room sync] to matrix: ${channel.name}`)

	const {spaceID, channelKState} = await channelToKState(channel, guild) // calling this in both branches because we don't want to calculate this if not syncing

	// sync channel state to room
	const roomKState = await roomToKState(roomID)
	if (+roomKState["m.room.create/"].room_version <= 8) {
		// join_rule `restricted` is not available in room version < 8 and not working properly in version == 8
		// read more: https://spec.matrix.org/v1.8/rooms/v9/
		// we have to use `public` instead, otherwise the room will be unjoinable.
		channelKState["m.room.join_rules/"] = {join_rule: "public"}
	}
	const roomDiff = ks.diffKState(roomKState, channelKState)
	const roomApply = applyKStateDiffToRoom(roomID, roomDiff)
	db.prepare("UPDATE channel_room SET name = ? WHERE room_id = ?").run(channel.name, roomID)

	// sync room as space member
	const spaceApply = _syncSpaceMember(channel, spaceID, roomID)
	await Promise.all([roomApply, spaceApply])

	return roomID
}

/** Ensures the room exists. If it doesn't, creates the room with an accurate initial state. */
function ensureRoom(channelID) {
	return _syncRoom(channelID, false)
}

/** Actually syncs. Gets all room state from the homeserver in order to diff, and uploads the icon to mxc if it has changed. */
function syncRoom(channelID) {
	return _syncRoom(channelID, true)
}

async function _unbridgeRoom(channelID) {
	/** @ts-ignore @type {DiscordTypes.APIGuildChannel} */
	const channel = discord.channels.get(channelID)
	assert.ok(channel)
	return unbridgeDeletedChannel(channel.id, channel.guild_id)
}

async function unbridgeDeletedChannel(channelID, guildID) {
	const roomID = select("channel_room", "room_id", {channel_id: channelID}).pluck().get()
	assert.ok(roomID)
	const spaceID = select("guild_space", "space_id", {guild_id: guildID}).pluck().get()
	assert.ok(spaceID)

	// remove room from being a space member
	await api.sendState(roomID, "m.space.parent", spaceID, {})
	await api.sendState(spaceID, "m.space.child", roomID, {})

	// remove declaration that the room is bridged
	await api.sendState(roomID, "uk.half-shot.bridge", `moe.cadence.ooye://discord/${guildID}/${channelID}`, {})

	// send a notification in the room
	await api.sendEvent(roomID, "m.room.message", {
		msgtype: "m.notice",
		body: "⚠️ This room was removed from the bridge."
	})

	// leave room
	await api.leaveRoom(roomID)

	// delete room from database
	const {changes} = db.prepare("DELETE FROM channel_room WHERE room_id = ? AND channel_id = ?").run(roomID, channelID)
	assert.equal(changes, 1)
}

/**
 * Async because it gets all space state from the homeserver, then if necessary sends one state event back.
 * @param {DiscordTypes.APIGuildTextChannel} channel
 * @param {string} spaceID
 * @param {string} roomID
 * @returns {Promise<string[]>}
 */
async function _syncSpaceMember(channel, spaceID, roomID) {
	const spaceKState = await roomToKState(spaceID)
	let spaceEventContent = {}
	if (
		channel.type !== DiscordTypes.ChannelType.PrivateThread // private threads do not belong in the space (don't offer people something they can't join)
		&& !channel["thread_metadata"]?.archived // archived threads do not belong in the space (don't offer people conversations that are no longer relevant)
	) {
		spaceEventContent = {
			via: [reg.ooye.server_name]
		}
	}
	const spaceDiff = ks.diffKState(spaceKState, {
		[`m.space.child/${roomID}`]: spaceEventContent
	})
	return applyKStateDiffToRoom(spaceID, spaceDiff)
}

async function createAllForGuild(guildID) {
	const channelIDs = discord.guildChannelMap.get(guildID)
	assert.ok(channelIDs)
	for (const channelID of channelIDs) {
		const allowedTypes = [DiscordTypes.ChannelType.GuildText, DiscordTypes.ChannelType.PublicThread]
		// @ts-ignore
		if (allowedTypes.includes(discord.channels.get(channelID)?.type)) {
			const roomID = await syncRoom(channelID)
			console.log(`synced ${channelID} <-> ${roomID}`)
		}
	}
}

module.exports.DEFAULT_PRIVACY_LEVEL = DEFAULT_PRIVACY_LEVEL
module.exports.PRIVACY_ENUMS = PRIVACY_ENUMS
module.exports.createRoom = createRoom
module.exports.ensureRoom = ensureRoom
module.exports.syncRoom = syncRoom
module.exports.createAllForGuild = createAllForGuild
module.exports.channelToKState = channelToKState
module.exports.roomToKState = roomToKState
module.exports.applyKStateDiffToRoom = applyKStateDiffToRoom
module.exports.postApplyPowerLevels = postApplyPowerLevels
module.exports._convertNameAndTopic = convertNameAndTopic
module.exports._unbridgeRoom = _unbridgeRoom
module.exports.unbridgeDeletedChannel = unbridgeDeletedChannel