// @ts-check

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

const passthrough = require("../../passthrough")
const { discord, sync, db } = 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 {Map<string, Promise<string>>} channel ID -> Promise<room ID> */
const inflightRoomCreate = new Map()

/**
 * @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?}} channel
 * @param {{id: string}} guild
 * @param {string?} customName
 */
function convertNameAndTopic(channel, guild, customName) {
	const convertedName = customName || 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 [convertedName, convertedTopic];
}

/**
 * @param {DiscordTypes.APIGuildTextChannel | DiscordTypes.APIThreadChannel} channel
 * @param {DiscordTypes.APIGuild} guild
 */
async function channelToKState(channel, guild) {
	const spaceID = db.prepare("SELECT space_id FROM guild_space WHERE guild_id = ?").pluck().get(guild.id)
	assert.ok(typeof spaceID === "string")

	const customName = db.prepare("SELECT nick FROM channel_room WHERE channel_id = ?").pluck().get(channel.id)
	const [convertedName, convertedTopic] = convertNameAndTopic(channel, guild, customName)

	const avatarEventContent = {}
	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
	}

	const channelKState = {
		"m.room.name/": {name: convertedName},
		"m.room.topic/": {topic: convertedTopic},
		"m.room.avatar/": avatarEventContent,
		"m.room.guest_access/": {guest_access: "can_join"},
		"m.room.history_visibility/": {history_visibility: "invited"},
		[`m.space.parent/${spaceID}`]: {
			via: ["cadence.moe"], // TODO: put the proper server here
			canonical: true
		},
		"m.room.join_rules/": {
			join_rule: "restricted",
			allow: [{
				type: "m.room_membership",
				room_id: spaceID
			}]
		}
	}

	return {spaceID, 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
 * @returns {Promise<string>} room ID
 */
async function createRoom(channel, guild, spaceID, kstate) {
	let threadParent = null
	if (channel.type === DiscordTypes.ChannelType.PublicThread) threadParent = channel.parent_id
	const invite = threadParent ? [] : ["@cadence:cadence.moe"] // TODO

	const [convertedName, convertedTopic] = convertNameAndTopic(channel, guild, null)
	const roomID = await api.createRoom({
		name: convertedName,
		topic: convertedTopic,
		preset: "private_chat",
		visibility: "private",
		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)

	// Put the newly created child into the space
	_syncSpaceMember(channel, spaceID, roomID)

	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

	New combined flow with ensure / sync:
	1. Get IDs
	2. Does room exist?
	2.5: If room does exist AND don't need 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
	}

	/** @type {{room_id: string, thread_parent: string?}} */
	const existing = db.prepare("SELECT room_id, thread_parent from channel_room WHERE channel_id = ?").get(channelID)

	if (!existing) {
		const creation = (async () => {
			const {spaceID, channelKState} = await channelToKState(channel, guild)
			const roomID = await createRoom(channel, guild, spaceID, channelKState)
			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.
	}

	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)

	// sync channel state to room
	const roomKState = await roomToKState(existing.room_id)
	const roomDiff = ks.diffKState(roomKState, channelKState)
	const roomApply = applyKStateDiffToRoom(existing.room_id, roomDiff)

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

	return existing.room_id
}

async function _unbridgeRoom(channelID) {
	/** @ts-ignore @type {DiscordTypes.APIGuildChannel} */
	const channel = discord.channels.get(channelID)
	assert.ok(channel)
	const roomID = db.prepare("SELECT room_id from channel_room WHERE channel_id = ?").pluck().get(channelID)
	assert.ok(roomID)
	const spaceID = db.prepare("SELECT space_id FROM guild_space WHERE guild_id = ?").pluck().get(channel.guild_id)
	assert.ok(spaceID)

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

	// 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)
}


/**
 * @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: ["cadence.moe"] // TODO: use the proper server
		}
	}
	const spaceDiff = ks.diffKState(spaceKState, {
		[`m.space.child/${roomID}`]: spaceEventContent
	})
	return applyKStateDiffToRoom(spaceID, spaceDiff)
}

function ensureRoom(channelID) {
	return _syncRoom(channelID, false)
}

function syncRoom(channelID) {
	return _syncRoom(channelID, true)
}

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.createRoom = createRoom
module.exports.ensureRoom = ensureRoom
module.exports.syncRoom = syncRoom
module.exports.createAllForGuild = createAllForGuild
module.exports.channelToKState = channelToKState
module.exports._convertNameAndTopic = convertNameAndTopic
module.exports._unbridgeRoom = _unbridgeRoom