server/src/util/entities/Channel.ts

/*
	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 { HTTPError } from "lambert-server";
import { Column, Entity, JoinColumn, ManyToOne, OneToMany, RelationId } from "typeorm";
import { DmChannelDTO } from "../dtos";
import { ChannelCreateEvent, ChannelRecipientRemoveEvent } from "../interfaces";
import { InvisibleCharacters, Snowflake, emitEvent, getPermission, trimSpecial, Permissions, BitField } from "../util";
import { BaseClass } from "./BaseClass";
import { Guild } from "./Guild";
import { Invite } from "./Invite";
import { Message } from "./Message";
import { ReadState } from "./ReadState";
import { Recipient } from "./Recipient";
import { User } from "./User";
import { VoiceState } from "./VoiceState";
import { Webhook } from "./Webhook";
import { Member } from "./Member";
import { ChannelPermissionOverwrite, ChannelPermissionOverwriteType, ChannelType, PublicUserProjection } from "@spacebar/schemas";

@Entity({
    name: "channels",
})
export class Channel extends BaseClass {
    @Column()
    created_at: Date;

    @Column({ nullable: true })
    name?: string;

    @Column({ type: "text", nullable: true })
    icon?: string | null;

    @Column({ type: "int" })
    type: ChannelType;

    @OneToMany(() => Recipient, (recipient: Recipient) => recipient.channel, {
        cascade: true,
        orphanedRowAction: "delete",
    })
    recipients?: Recipient[];

    @Column({ nullable: true })
    last_message_id?: string;

    @Column({ nullable: true })
    @RelationId((channel: Channel) => channel.guild)
    guild_id?: string;

    @JoinColumn({ name: "guild_id" })
    @ManyToOne(() => Guild, (guild) => guild.channels, {
        onDelete: "CASCADE",
        nullable: true,
    })
    guild?: Guild;

    @Column({ nullable: true })
    @RelationId((channel: Channel) => channel.parent)
    parent_id: string | null;

    @JoinColumn({ name: "parent_id" })
    @ManyToOne(() => Channel)
    parent?: Channel;

    // for group DMs and owned custom channel types
    @Column({ nullable: true })
    @RelationId((channel: Channel) => channel.owner)
    owner_id?: string;

    @JoinColumn({ name: "owner_id" })
    @ManyToOne(() => User)
    owner: User;

    @Column({ nullable: true })
    last_pin_timestamp?: number;

    @Column({ nullable: true })
    default_auto_archive_duration?: number;

    @Column({ type: "simple-json", nullable: true })
    permission_overwrites?: ChannelPermissionOverwrite[];

    @Column({ nullable: true })
    video_quality_mode?: number;

    @Column({ nullable: true })
    bitrate?: number;

    @Column({ nullable: true })
    user_limit?: number;

    @Column()
    nsfw: boolean = false;

    @Column({ nullable: true })
    rate_limit_per_user?: number;

    @Column({ nullable: true })
    topic?: string;

    @OneToMany(() => Invite, (invite: Invite) => invite.channel, {
        cascade: true,
        orphanedRowAction: "delete",
    })
    invites?: Invite[];

    @Column({ nullable: true })
    retention_policy_id?: string;

    @OneToMany(() => Message, (message: Message) => message.channel, {
        cascade: true,
        orphanedRowAction: "delete",
    })
    messages?: Message[];

    @OneToMany(() => VoiceState, (voice_state: VoiceState) => voice_state.channel, {
        cascade: true,
        orphanedRowAction: "delete",
    })
    voice_states?: VoiceState[];

    @OneToMany(() => ReadState, (read_state: ReadState) => read_state.channel, {
        cascade: true,
        orphanedRowAction: "delete",
    })
    read_states?: ReadState[];

    @OneToMany(() => Webhook, (webhook: Webhook) => webhook.channel, {
        cascade: true,
        orphanedRowAction: "delete",
    })
    webhooks?: Webhook[];

    @Column()
    flags: number = 0;

    @Column({ nullable: true })
    default_thread_rate_limit_per_user?: number = 0;

    /** Must be calculated Channel.calculatePosition */
    position: number;

    // TODO: DM channel
    static async createChannel(
        channel: Partial<Channel>,
        user_id: string = "0",
        opts?: {
            keepId?: boolean;
            skipExistsCheck?: boolean;
            skipPermissionCheck?: boolean;
            skipEventEmit?: boolean;
            skipNameChecks?: boolean;
        },
    ) {
        if (!opts?.skipPermissionCheck) {
            // Always check if user has permission first
            const permissions = await getPermission(user_id, channel.guild_id);
            permissions.hasThrow("MANAGE_CHANNELS");
        }

        const guild = await Guild.findOneOrFail({
            where: { id: channel.guild_id },
            select: {
                features: !opts?.skipNameChecks,
                channel_ordering: true,
                id: true,
            },
        });

        if (!opts?.skipNameChecks) {
            if (!guild.features.includes("ALLOW_INVALID_CHANNEL_NAMES") && channel.name) {
                for (const character of InvisibleCharacters) if (channel.name.includes(character)) throw new HTTPError("Channel name cannot include invalid characters", 403);

                // Categories skip these checks on discord.com
                if (channel.type !== ChannelType.GUILD_CATEGORY || guild.features.includes("IRC_LIKE_CATEGORY_NAMES")) {
                    if (channel.name.includes(" ")) throw new HTTPError("Channel name cannot include invalid characters", 403);

                    if (channel.name.match(/--+/g)) throw new HTTPError("Channel name cannot include multiple adjacent dashes.", 403);

                    if (channel.name.charAt(0) === "-" || channel.name.charAt(channel.name.length - 1) === "-")
                        throw new HTTPError("Channel name cannot start/end with dash.", 403);
                } else channel.name = channel.name.trim(); //category names are trimmed client side on discord.com
            }

            if (!guild.features.includes("ALLOW_UNNAMED_CHANNELS")) {
                if (!channel.name) throw new HTTPError("Channel name cannot be empty.", 403);
            }
        }

        switch (channel.type) {
            case ChannelType.GUILD_TEXT:
            case ChannelType.GUILD_NEWS:
            case ChannelType.GUILD_VOICE:
                if (channel.parent_id && !opts?.skipExistsCheck) {
                    const exists = await Channel.findOneOrFail({
                        where: { id: channel.parent_id },
                    });
                    if (!exists) throw new HTTPError("Parent id channel doesn't exist", 400);
                    if (exists.guild_id !== channel.guild_id) throw new HTTPError("The category channel needs to be in the guild");
                }
                break;
            case ChannelType.GUILD_CATEGORY:
            case ChannelType.UNHANDLED:
                break;
            case ChannelType.DM:
            case ChannelType.GROUP_DM:
                throw new HTTPError("You can't create a dm channel in a guild");
            case ChannelType.GUILD_STORE:
            default:
                throw new HTTPError("Not yet supported");
        }

        if (!channel.permission_overwrites) channel.permission_overwrites = [];
        // TODO: eagerly auto generate position of all guild channels

        const position = (channel.type === ChannelType.UNHANDLED ? 0 : channel.position) || 0;

        channel = {
            ...channel,
            ...(!opts?.keepId && { id: Snowflake.generate() }),
            created_at: new Date(),
            position,
        };

        const ret = Channel.create(channel);

        await Promise.all([
            ret.save(),
            !opts?.skipEventEmit
                ? emitEvent({
                      event: "CHANNEL_CREATE",
                      data: channel,
                      guild_id: channel.guild_id,
                  } as ChannelCreateEvent)
                : Promise.resolve(),
            Guild.insertChannelInOrder(guild.id, ret.id, position, guild),
        ]);

        return ret;
    }

    static async createDMChannel(recipients: string[], creator_user_id: string, name?: string) {
        recipients = [...new Set(recipients)].filter((x) => x !== creator_user_id);
        // TODO: check config for max number of recipients
        /** if you want to disallow note to self channels, uncomment the conditional below

		const otherRecipientsUsers = await User.find({ where: recipients.map((x) => ({ id: x })) });
		if (otherRecipientsUsers.length !== recipients.length) {
			throw new HTTPError("Recipient/s not found");
		}
		**/

        const type = recipients.length > 1 ? ChannelType.GROUP_DM : ChannelType.DM;

        let channel = null;

        const channelRecipients = [...recipients, creator_user_id];

        const userRecipients = await Recipient.find({
            where: { user_id: creator_user_id },
            relations: { channel: { recipients: true } },
        });

        for (const ur of userRecipients) {
            if (!ur.channel.recipients) continue;
            const re = ur.channel.recipients.map((r) => r.user_id);
            if (re.length === channelRecipients.length) {
                if (channelRecipients.every((_) => re.includes(_))) {
                    if (channel == null) {
                        channel = ur.channel;
                        await ur.assign({ closed: false }).save();
                    }
                }
            }
        }

        if (channel == null) {
            name = trimSpecial(name);

            channel = await Channel.create({
                name,
                type,
                owner_id: type === ChannelType.GROUP_DM ? creator_user_id : undefined,
                created_at: new Date(),
                last_message_id: undefined,
                recipients: channelRecipients.map((x) =>
                    Recipient.create({
                        user_id: x,
                        closed: !(type === ChannelType.GROUP_DM || x === creator_user_id),
                    }),
                ),
                nsfw: false,
            }).save();
        }

        const channel_dto = await DmChannelDTO.from(channel);

        if (type === ChannelType.GROUP_DM && channel.recipients) {
            for (const recipient of channel.recipients) {
                await emitEvent({
                    event: "CHANNEL_CREATE",
                    data: channel_dto.excludedRecipients([recipient.user_id]),
                    user_id: recipient.user_id,
                });
            }
        } else {
            await emitEvent({
                event: "CHANNEL_CREATE",
                data: channel_dto,
                user_id: creator_user_id,
            });
        }

        if (recipients.length === 1) return channel_dto;
        else return channel_dto.excludedRecipients([creator_user_id]);
    }

    static async removeRecipientFromChannel(channel: Channel, user_id: string) {
        await Recipient.delete({ channel_id: channel.id, user_id: user_id });
        channel.recipients = channel.recipients?.filter((r) => r.user_id !== user_id);

        if (channel.recipients?.length === 0) {
            await Channel.deleteChannel(channel);
            await emitEvent({
                event: "CHANNEL_DELETE",
                data: await DmChannelDTO.from(channel, [user_id]),
                user_id: user_id,
            });
            return;
        }

        await emitEvent({
            event: "CHANNEL_DELETE",
            data: await DmChannelDTO.from(channel, [user_id]),
            user_id: user_id,
        });

        //If the owner leave the server user is the new owner
        if (channel.owner_id === user_id) {
            channel.owner_id = "1"; // The channel is now owned by the server user
            await emitEvent({
                event: "CHANNEL_UPDATE",
                data: await DmChannelDTO.from(channel, [user_id]),
                channel_id: channel.id,
            });
        }

        await channel.save();

        await emitEvent({
            event: "CHANNEL_RECIPIENT_REMOVE",
            data: {
                channel_id: channel.id,
                user: await User.findOneOrFail({
                    where: { id: user_id },
                    select: PublicUserProjection,
                }),
            },
            channel_id: channel.id,
        } as ChannelRecipientRemoveEvent);
    }

    static async deleteChannel(channel: Channel) {
        // TODO Delete attachments from the CDN for messages in the channel
        await Channel.delete({ id: channel.id });

        if (channel.guild_id) {
            const guild = await Guild.findOneOrFail({
                where: { id: channel.guild_id },
                select: { channel_ordering: true },
            });

            const updatedOrdering = guild.channel_ordering.filter((id) => id != channel.id);
            await Guild.update({ id: channel.guild_id }, { channel_ordering: updatedOrdering });
        }
    }

    static async calculatePosition(channel_id: string, guild_id: string, guild?: Guild) {
        if (!guild)
            guild = await Guild.findOneOrFail({
                where: { id: guild_id },
                select: { channel_ordering: true },
            });

        return guild.channel_ordering.findIndex((id) => channel_id == id);
    }

    static async getOrderedChannels(guild_id: string, guild?: Guild) {
        if (!guild)
            guild = await Guild.findOneOrFail({
                where: { id: guild_id },
                select: { channel_ordering: true },
            });

        const channels = await Promise.all(guild.channel_ordering.map((id) => Channel.findOne({ where: { id } })));

        return channels
            .filter((channel) => channel !== null)
            .reduce((r, v) => {
                v = v as Channel;

                v.position = (guild as Guild).channel_ordering.indexOf(v.id);
                r[v.position] = v;
                return r;
            }, [] as Array<Channel>);
    }

    isDm() {
        return this.type === ChannelType.DM || this.type === ChannelType.GROUP_DM;
    }

    // Does the channel support sending messages ( eg categories do not )
    isWritable() {
        const disallowedChannelTypes = [ChannelType.GUILD_CATEGORY, ChannelType.GUILD_STAGE_VOICE, ChannelType.VOICELESS_WHITEBOARD];
        return disallowedChannelTypes.indexOf(this.type) == -1;
    }

    async getUserPermissions(opts: { user_id?: string; user?: User; member?: Member; guild?: Guild }): Promise<Permissions> {
        if (this.isDm()) return this.owner_id == (opts.user_id ?? opts.user?.id) ? Permissions.ALL : Permissions.DEFAULT_DM_PERMISSIONS;
        let guild = opts.guild;
        if (!guild) {
            if (this.guild) guild = this.guild;
            else if (this.guild_id) guild = await Guild.findOneOrFail({ where: { id: this.guild_id } });
            else {
                console.error("Channel.getUserPermissions: called without guild for non-DM channel.");
                return Permissions.NONE;
            }
        }

        // check if we can resolve here to short-circuit possibly calling the database unnecessarily
        // TODO: do we want to have an instance-wide opt out of this behavior? It would just be an extra if statement here
        const ownerId = guild?.owner?.id ?? guild?.owner_id;
        if (!!opts.user_id && ownerId === opts.user_id) return Permissions.ALL;
        if (!!opts.user?.id && ownerId === opts.user?.id) return Permissions.ALL;
        if (!!opts.member?.id && ownerId === opts.member?.id) return Permissions.ALL;

        let member = opts.member;
        if (!member) {
            if (opts.user) member = await Member.findOneOrFail({ where: { guild_id: guild.id, id: opts.user.id }, relations: { roles: true } });
            else if (opts.user_id) member = await Member.findOneOrFail({ where: { guild_id: guild.id, id: opts.user_id }, relations: { roles: true } });
            else {
                console.error("Channel.getUserPermissions: called without user or member for non-DM channel.");
                return Permissions.NONE;
            }
        }

        const roles = (
            member.roles ||
            (
                await Member.findOneOrFail({
                    where: { guild_id: guild.id, index: member.index },
                    relations: { roles: true },
                    select: {
                        roles: {
                            id: true,
                            permissions: true,
                            position: true,
                        },
                    },
                    loadEagerRelations: false,
                })
            ).roles
        ).sort((a, b) => a.position - b.position); // ascending by position

        return Permissions.finalPermission({
            user: {
                ...member,
                roles: roles.map((r) => r.id),
                flags: member.user?.flags ?? (await User.findOneOrFail({ where: { id: member.id }, select: { flags: true } })).flags,
            },
            guild: { id: guild.id, owner_id: guild.owner_id!, roles }, // We don't care about including *all* guild roles, as not all of them are relevant...
            channel: this,
        });
    }

    // TODO: should we throw for missing args?
    async canViewChannel(opts: { user_id?: string; user?: User; member?: Member; guild?: Guild }): Promise<boolean> {
        if (this.isDm()) return await this.canViewDmChannel(opts.user_id, opts.user);

        const userPerms = await this.getUserPermissions(opts);
        return userPerms.has("VIEW_CHANNEL");
    }

    private async canViewDmChannel(user_id?: string, user?: User): Promise<boolean> {
        const userId = user_id ?? user?.id;
        if (!userId) {
            console.error("Channel.canViewChannel: called without user for DM channel.");
            return false;
        }
        if (!user) return false;
        if (this.recipients) return this.recipients.some((r) => r.user_id === user.id && !r.closed);
        else {
            // we dont have recipients on hand
            const recipient = await Recipient.findOne({ where: { channel_id: this.id, user_id: user.id } });
            return recipient == null ? false : !recipient.closed;
        }
    }

    toJSON() {
        return {
            ...this,

            // these fields are not returned depending on the type of channel
            bitrate: this.bitrate || undefined,
            user_limit: this.user_limit || undefined,
            rate_limit_per_user: this.rate_limit_per_user || undefined,
            owner_id: this.owner_id || undefined,
        };
    }
}