feat: add realtime Discord leaderboards

lib/leaderboard/discord.ts

@@ -0,0 +1,76 @@
+export type DiscordVoiceChannel = {
+  id: string;
+  name: string;
+  type: 2 | 13;
+  position: number;
+};
+
+type DiscordChannelPayload = {
+  id?: unknown;
+  name?: unknown;
+  type?: unknown;
+  position?: unknown;
+};
+
+const CHANNEL_CACHE_TTL_MS = 5 * 60_000;
+const channelCache: {
+  data: DiscordVoiceChannel[] | null;
+  expiresAt: number;
+} = {
+  data: null,
+  expiresAt: 0,
+};
+
+export function parseCurrentVoiceChannels(payload: unknown): DiscordVoiceChannel[] {
+  if (!Array.isArray(payload)) {
+    throw new Error("Discord returned an invalid channel list.");
+  }
+
+  return payload
+    .filter((channel): channel is DiscordChannelPayload => {
+      if (!channel || typeof channel !== "object") return false;
+      const type = (channel as DiscordChannelPayload).type;
+      return type === 2 || type === 13;
+    })
+    .filter((channel) => (
+      typeof channel.id === "string"
+      && typeof channel.name === "string"
+    ))
+    .map((channel) => ({
+      id: channel.id as string,
+      name: channel.name as string,
+      type: channel.type as 2 | 13,
+      position: typeof channel.position === "number" ? channel.position : 0,
+    }))
+    .sort((a, b) => a.position - b.position || a.name.localeCompare(b.name, "th"));
+}
+
+export async function getCurrentDiscordVoiceChannels() {
+  if (channelCache.data && Date.now() < channelCache.expiresAt) {
+    return channelCache.data;
+  }
+
+  const token = process.env.DISCORD_BOT_TOKEN;
+  const guildId = process.env.DISCORD_GUILD_ID;
+  if (!token || !guildId) {
+    throw new Error("Discord channel access is not configured.");
+  }
+
+  const response = await fetch(
+    `https://discord.com/api/v10/guilds/${guildId}/channels`,
+    {
+      headers: { Authorization: `Bot ${token}` },
+      cache: "no-store",
+      signal: AbortSignal.timeout(5_000),
+    },
+  );
+
+  if (!response.ok) {
+    throw new Error(`Discord channel request failed with status ${response.status}.`);
+  }
+
+  const channels = parseCurrentVoiceChannels(await response.json());
+  channelCache.data = channels;
+  channelCache.expiresAt = Date.now() + CHANNEL_CACHE_TTL_MS;
+  return channels;
+}