/*
	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 { Payload, WebSocket } from "@spacebar/gateway";
import { Config, emitEvent, Guild, Member, VoiceServerUpdateEvent, VoiceState, VoiceStateUpdateEvent } from "@spacebar/util";
import { genVoiceToken } from "@spacebar/gateway";
import { check } from "./instanceOf";
import { Region, VoiceStateUpdateSchema } from "@spacebar/schemas";
// TODO: check if a voice server is setup

// Notice: Bot users respect the voice channel's user limit, if set.
// When the voice channel is full, you will not receive the Voice State Update or Voice Server Update events in response to your own Voice State Update.
// Having MANAGE_CHANNELS permission bypasses this limit and allows you to join regardless of the channel being full or not.

export async function onVoiceStateUpdate(this: WebSocket, data: Payload) {
    const startTime = Date.now();
    check.call(this, VoiceStateUpdateSchema, data.d);
    const body = data.d as VoiceStateUpdateSchema;
    const isNew = body.channel_id === null && body.guild_id === null;
    let isChanged = false;

    let prevState;

    let voiceState: VoiceState;
    try {
        voiceState = await VoiceState.findOneOrFail({
            where: { user_id: this.user_id },
        });
        if (voiceState.session_id !== this.session_id && body.channel_id === null) {
            //Should we also check guild_id === null?
            //changing deaf or mute on a client that's not the one with the same session of the voicestate in the database should be ignored
            return;
        }

        if (voiceState.channel_id !== body.channel_id) isChanged = true;

        //If a user change voice channel between guild we should send a left event first
        if (voiceState.guild_id && voiceState.guild_id !== body.guild_id && voiceState.session_id === this.session_id) {
            await emitEvent({
                event: "VOICE_STATE_UPDATE",
                data: { ...voiceState.toPublicVoiceState(), channel_id: null },
                guild_id: voiceState.guild_id,
            });
        }

        //The event send by Discord's client on channel leave has both guild_id and channel_id as null
        //if (body.guild_id === null) body.guild_id = voiceState.guild_id;
        prevState = { ...voiceState };
        VoiceState.merge(voiceState, body);
    } catch (error) {
        voiceState = VoiceState.create({
            ...body,
            user_id: this.user_id,
            deaf: false,
            mute: false,
            suppress: false,
        });
        isChanged = true;
    }

    // if user left voice channel, send an update to previous channel/guild to let other people know that the user left
    if (voiceState.session_id === this.session_id && body.guild_id == null && body.channel_id == null && (prevState?.guild_id || prevState?.channel_id)) {
        await emitEvent({
            event: "VOICE_STATE_UPDATE",
            data: {
                ...voiceState.toPublicVoiceState(),
                channel_id: null,
                guild_id: null,
            },
            guild_id: prevState?.guild_id,
            channel_id: prevState?.channel_id,
        });
    }

    //TODO the member should only have these properties: hoisted_role, deaf, joined_at, mute, roles, user
    //TODO the member.user should only have these properties: avatar, discriminator, id, username
    //TODO this may fail
    if (body.guild_id) {
        const member = await Member.findOne({
            where: { id: voiceState.user_id, guild_id: voiceState.guild_id },
            relations: { user: true, roles: true },
        });

        if (member) {
            voiceState.member = member;
        }
    }

    //If the session changed we generate a new token
    if (voiceState.session_id !== this.session_id) voiceState.token = genVoiceToken();
    voiceState.session_id = this.session_id;

    const { member } = voiceState;

    await Promise.all([
        voiceState.save(),
        emitEvent({
            event: "VOICE_STATE_UPDATE",
            data: {
                ...voiceState.toPublicVoiceState(),
                member: member?.toPublicMember(),
            },
            guild_id: voiceState.guild_id,
            channel_id: voiceState.channel_id,
            user_id: voiceState.user_id,
        } as VoiceStateUpdateEvent),
    ]);

    //If it's null it means that we are leaving the channel and this event is not needed
    if ((isNew || isChanged) && voiceState.channel_id !== null) {
        const guild = await Guild.findOne({
            where: { id: voiceState.guild_id },
        });
        const regions = Config.get().regions;
        let guildRegion: Region | undefined;

        const defaultRegion = regions.available.find((r) => r.id === regions.default);

        if (guild && guild.region) {
            // in case the configured guild region does not exist (which can
            // happen when server regions config is updated after guild creation),
            // fallback to default region
            guildRegion = regions.available.find((r) => r.id === guild.region) ?? defaultRegion;
        } else {
            guildRegion = defaultRegion;
        }

        if (!guildRegion) {
            throw new Error("Unable to find suitable region due to misconfiguration of regions");
        }

        await emitEvent({
            event: "VOICE_SERVER_UPDATE",
            data: {
                token: voiceState.token,
                guild_id: voiceState.guild_id,
                endpoint: guildRegion.endpoint,
                channel_id: voiceState.guild_id ? undefined : voiceState.channel_id, // only DM voice calls have this set, and DM channel is one where guild_id is null
            },
            user_id: voiceState.user_id,
        } as VoiceServerUpdateEvent);
    }

    console.log(
        `[Gateway/${this.user_id}] VOICE_STATE_UPDATE for user ${this.user_id} in channel ${voiceState.channel_id} in guild ${voiceState.guild_id} in ${Date.now() - startTime}ms`,
    );
}