63 lines
2.1 KiB
TypeScript
63 lines
2.1 KiB
TypeScript
/**
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* Decides which of a playlist's dumps a viewer may see. The playlist service
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* filters its listings with it, the WebSocket service filters each client's
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* `playlist_dumps_updated` message the same way, and the queries that list
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* playlists count their dumps by the same rule.
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*
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* @module
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*/
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import type { Playlist } from "../../shared/playlist.ts";
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/**
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* The fields of a playlist's dump that {@link isMemberVisibleTo} needs. A
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* `Dump` has them. For its broadcasts, the playlist service reads only these.
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*/
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export interface PlaylistMember {
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id: string;
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isPrivate: boolean;
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/** The dump's poster, not the playlist's owner. */
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userId: string;
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}
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/**
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* Checks whether `viewerId` may see `member` in `playlist`. A public dump is
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* visible to all. A private dump is visible only to the playlist's owner, and
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* only if they posted it: moderators don't see it, and neither does the owner
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* once someone else's dump in their playlist goes private. A null or undefined
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* `viewerId` is a signed-out viewer.
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*/
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export function isMemberVisibleTo(
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member: PlaylistMember,
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playlist: Pick<Playlist, "userId">,
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viewerId: string | null | undefined,
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): boolean {
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return !member.isPrivate ||
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(member.userId === viewerId && viewerId === playlist.userId);
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}
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/**
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* The `dump_count` column of a query on `playlists p`: how many of the
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* playlist's dumps the viewer may see, by {@link isMemberVisibleTo}'s rule.
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* Its `?` takes the viewer's id, or `""` for a signed-out one, and comes
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* before the query's other parameters, the column being in its select list.
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*/
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export const VISIBLE_DUMP_COUNT = `(SELECT COUNT(*) FROM playlist_dumps pd
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INNER JOIN dumps d ON d.id = pd.dump_id
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WHERE pd.playlist_id = p.id
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AND (d.is_private = 0 OR (d.user_id = p.user_id AND p.user_id = ?))
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) as dump_count`;
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/**
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* Returns how many of `members` the viewer may see in `playlist`, the
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* `dumpCount` the playlist has for them.
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*/
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export function countVisibleTo(
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members: PlaylistMember[],
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playlist: Pick<Playlist, "userId">,
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viewerId: string | null | undefined,
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): number {
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return members.filter((m) => isMemberVisibleTo(m, playlist, viewerId))
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.length;
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}
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