/*
	Spacebar: A FOSS re-implementation and extension of the Discord.com backend.
	Copyright (C) 2023 Spacebar and Spacebar Contributors
	
	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 { Router, Response, Request } from "express";
import {
	Attachment,
	Channel,
	ChannelType,
	Config,
	DmChannelDTO,
	emitEvent,
	FieldErrors,
	getPermission,
	Message,
	MessageCreateEvent,
	Snowflake,
	uploadFile,
	Member,
	MessageCreateSchema,
	ReadState,
	Rights,
	Reaction,
	User,
} from "@spacebar/util";
import { HTTPError } from "lambert-server";
import { handleMessage, postHandleMessage, route } from "@spacebar/api";
import multer from "multer";
import { FindManyOptions, FindOperator, LessThan, MoreThan } from "typeorm";
import { URL } from "url";

const router: Router = Router();

export default router;

export function isTextChannel(type: ChannelType): boolean {
	switch (type) {
		case ChannelType.GUILD_STORE:
		case ChannelType.GUILD_VOICE:
		case ChannelType.GUILD_STAGE_VOICE:
		case ChannelType.GUILD_CATEGORY:
		case ChannelType.GUILD_FORUM:
		case ChannelType.DIRECTORY:
			throw new HTTPError("not a text channel", 400);
		case ChannelType.DM:
		case ChannelType.GROUP_DM:
		case ChannelType.GUILD_NEWS:
		case ChannelType.GUILD_NEWS_THREAD:
		case ChannelType.GUILD_PUBLIC_THREAD:
		case ChannelType.GUILD_PRIVATE_THREAD:
		case ChannelType.GUILD_TEXT:
		case ChannelType.ENCRYPTED:
		case ChannelType.ENCRYPTED_THREAD:
			return true;
		default:
			throw new HTTPError("unimplemented", 400);
	}
}

// https://discord.com/developers/docs/resources/channel#create-message
// get messages
router.get("/", async (req: Request, res: Response) => {
	const channel_id = req.params.channel_id;
	const channel = await Channel.findOneOrFail({ where: { id: channel_id } });
	if (!channel) throw new HTTPError("Channel not found", 404);

	isTextChannel(channel.type);
	const around = req.query.around ? `${req.query.around}` : undefined;
	const before = req.query.before ? `${req.query.before}` : undefined;
	const after = req.query.after ? `${req.query.after}` : undefined;
	const limit = Number(req.query.limit) || 50;
	if (limit < 1 || limit > 100)
		throw new HTTPError("limit must be between 1 and 100", 422);

	const halfLimit = Math.floor(limit / 2);

	const permissions = await getPermission(
		req.user_id,
		channel.guild_id,
		channel_id,
	);
	permissions.hasThrow("VIEW_CHANNEL");
	if (!permissions.has("READ_MESSAGE_HISTORY")) return res.json([]);

	const query: FindManyOptions<Message> & {
		where: { id?: FindOperator<string> | FindOperator<string>[] };
	} = {
		order: { timestamp: "DESC" },
		take: limit,
		where: { channel_id },
		relations: [
			"author",
			"webhook",
			"application",
			"mentions",
			"mention_roles",
			"mention_channels",
			"sticker_items",
			"attachments",
		],
	};

	if (after) {
		if (BigInt(after) > BigInt(Snowflake.generate()))
			return res.status(422);
		query.where.id = MoreThan(after);
	} else if (before) {
		if (BigInt(before) < BigInt(req.params.channel_id))
			return res.status(422);
		query.where.id = LessThan(before);
	} else if (around) {
		query.where.id = [
			MoreThan((BigInt(around) - BigInt(halfLimit)).toString()),
			LessThan((BigInt(around) + BigInt(halfLimit)).toString()),
		];

		return res.json([]); // TODO: fix around
	}

	const messages = await Message.find(query);
	const endpoint = Config.get().cdn.endpointPublic;

	return res.json(
		messages.map((x: Partial<Message>) => {
			(x.reactions || []).forEach((y: Partial<Reaction>) => {
				// eslint-disable-next-line @typescript-eslint/ban-ts-comment
				//@ts-ignore
				if ((y.user_ids || []).includes(req.user_id)) y.me = true;
				delete y.user_ids;
			});
			if (!x.author)
				x.author = User.create({
					id: "4",
					discriminator: "0000",
					username: "Spacebar Ghost",
					public_flags: 0,
				});
			x.attachments?.forEach((y: Attachment) => {
				// dynamically set attachment proxy_url in case the endpoint changed
				const uri = y.proxy_url.startsWith("http")
					? y.proxy_url
					: `https://example.org${y.proxy_url}`;
				y.proxy_url = `${endpoint == null ? "" : endpoint}${
					new URL(uri).pathname
				}`;
			});

			/**
			Some clients ( discord.js ) only check if a property exists within the response,
			which causes errors when, say, the `application` property is `null`.
			**/

			// for (var curr in x) {
			// 	if (x[curr] === null)
			// 		delete x[curr];
			// }

			return x;
		}),
	);
});

// TODO: config max upload size
const messageUpload = multer({
	limits: {
		fileSize: Config.get().limits.message.maxAttachmentSize,
		fields: 10,
		// files: 1
	},
	storage: multer.memoryStorage(),
}); // max upload 50 mb
/**
 TODO: dynamically change limit of MessageCreateSchema with config

 https://discord.com/developers/docs/resources/channel#create-message
 TODO: text channel slowdown (per-user and across-users)
 Q: trim and replace message content and every embed field A: NO, given this cannot be implemented in E2EE channels
 TODO: only dispatch notifications for mentions denoted in allowed_mentions
**/
// Send message
router.post(
	"/",
	messageUpload.any(),
	(req, res, next) => {
		if (req.body.payload_json) {
			req.body = JSON.parse(req.body.payload_json);
		}

		next();
	},
	route({
		body: "MessageCreateSchema",
		permission: "SEND_MESSAGES",
		right: "SEND_MESSAGES",
	}),
	async (req: Request, res: Response) => {
		const { channel_id } = req.params;
		const body = req.body as MessageCreateSchema;
		const attachments: Attachment[] = [];

		const channel = await Channel.findOneOrFail({
			where: { id: channel_id },
			relations: ["recipients", "recipients.user"],
		});
		if (!channel.isWritable()) {
			throw new HTTPError(
				`Cannot send messages to channel of type ${channel.type}`,
				400,
			);
		}

		if (body.nonce) {
			const existing = await Message.findOne({
				where: {
					nonce: body.nonce,
					channel_id: channel.id,
					author_id: req.user_id,
				},
			});
			if (existing) {
				return res.json(existing);
			}
		}

		if (!req.rights.has(Rights.FLAGS.BYPASS_RATE_LIMITS)) {
			const limits = Config.get().limits;
			if (limits.absoluteRate.register.enabled) {
				const count = await Message.count({
					where: {
						channel_id,
						timestamp: MoreThan(
							new Date(
								Date.now() -
									limits.absoluteRate.sendMessage.window,
							),
						),
					},
				});

				if (count >= limits.absoluteRate.sendMessage.limit)
					throw FieldErrors({
						channel_id: {
							code: "TOO_MANY_MESSAGES",
							message: req.t("common:toomany.MESSAGE"),
						},
					});
			}
		}

		const files = (req.files as Express.Multer.File[]) ?? [];
		for (const currFile of files) {
			try {
				const file = await uploadFile(
					`/attachments/${channel.id}`,
					currFile,
				);
				attachments.push(
					Attachment.create({ ...file, proxy_url: file.url }),
				);
			} catch (error) {
				return res.status(400).json({ message: error?.toString() });
			}
		}

		const embeds = body.embeds || [];
		if (body.embed) embeds.push(body.embed);
		const message = await handleMessage({
			...body,
			type: 0,
			pinned: false,
			author_id: req.user_id,
			embeds,
			channel_id,
			attachments,
			edited_timestamp: undefined,
			timestamp: new Date(),
		});

		channel.last_message_id = message.id;

		if (channel.isDm()) {
			const channel_dto = await DmChannelDTO.from(channel);

			// Only one recipients should be closed here, since in group DMs the recipient is deleted not closed
			await Promise.all(
				channel.recipients?.map((recipient) => {
					if (recipient.closed) {
						recipient.closed = false;
						return Promise.all([
							recipient.save(),
							emitEvent({
								event: "CHANNEL_CREATE",
								data: channel_dto.excludedRecipients([
									recipient.user_id,
								]),
								user_id: recipient.user_id,
							}),
						]);
					}
				}) || [],
			);
		}

		if (message.guild_id) {
			// handleMessage will fetch the Member, but only if they are not guild owner.
			// have to fetch ourselves otherwise.
			if (!message.member) {
				message.member = await Member.findOneOrFail({
					where: { id: req.user_id, guild_id: message.guild_id },
					relations: ["roles"],
				});
			}

			// eslint-disable-next-line @typescript-eslint/ban-ts-comment
			//@ts-ignore
			message.member.roles = message.member.roles
				.filter((x) => x.id != x.guild_id)
				.map((x) => x.id);
		}

		let read_state = await ReadState.findOne({
			where: { user_id: req.user_id, channel_id },
		});
		if (!read_state)
			read_state = ReadState.create({ user_id: req.user_id, channel_id });
		read_state.last_message_id = message.id;

		await Promise.all([
			read_state.save(),
			message.save(),
			emitEvent({
				event: "MESSAGE_CREATE",
				channel_id: channel_id,
				data: message,
			} as MessageCreateEvent),
			message.guild_id
				? Member.update(
						{ id: req.user_id, guild_id: message.guild_id },
						{ last_message_id: message.id },
				  )
				: null,
			channel.save(),
		]);

		// no await as it shouldnt block the message send function and silently catch error
		postHandleMessage(message).catch((e) =>
			console.error("[Message] post-message handler failed", e),
		);

		return res.json(message);
	},
);