import "server-only";
import { getDiscordServerConfig } from "@/lib/config/server";

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, guildId } = getDiscordServerConfig();

  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;
}