import browser from "webextension-polyfill";
import type { Message } from "../shared/messages";
import type { DetailUpdate } from "../types/playlist";
import { CATEGORY_MAP } from "../shared/category-map";

const LOG = "[yt-playlist-features:bg]";
const DEFAULT_API_KEY = "AIzaSyDPyWG3ABnVV3en_KBhIxUH6O2_A0oP4Wk";
const BATCH_SIZE = 50;

async function getApiKey(): Promise<string> {
  const result = await browser.storage.sync.get("apiKey");
  return (result.apiKey as string) || DEFAULT_API_KEY;
}

const BATCH_DELAY = 500; // ms between batches
const RETRY_DELAY = 5000; // ms before retrying after rate limit
const MAX_RETRIES = 3;

async function fetchVideoDetails(
  videoIds: string[],
  tabId: number,
): Promise<void> {
  const apiKey = await getApiKey();
  if (!apiKey) {
    browser.tabs.sendMessage(tabId, {
      type: "VIDEO_DETAILS_ERROR",
      error: "no-api-key",
    } satisfies Message);
    return;
  }

  for (let i = 0; i < videoIds.length; i += BATCH_SIZE) {
    if (i > 0) await new Promise((r) => setTimeout(r, BATCH_DELAY));

    const batch = videoIds.slice(i, i + BATCH_SIZE);
    const ids = batch.join(",");
    const url = `https://www.googleapis.com/youtube/v3/videos?part=snippet,statistics&id=${ids}&key=${apiKey}`;

    let success = false;
    for (let attempt = 0; attempt < MAX_RETRIES; attempt++) {
      try {
        if (attempt > 0) {
          console.log(LOG, `Retry ${attempt} after rate limit, waiting ${RETRY_DELAY}ms...`);
          await new Promise((r) => setTimeout(r, RETRY_DELAY));
        }

        const res = await fetch(url);
        if (res.status === 403) {
          console.warn(LOG, `Rate limited (attempt ${attempt + 1}/${MAX_RETRIES})`);
          continue;
        }
        if (!res.ok) {
          const body = await res.text();
          console.error(LOG, `API error ${res.status}:`, body);
          browser.tabs.sendMessage(tabId, {
            type: "VIDEO_DETAILS_ERROR",
            error: `api-error-${res.status}`,
          } satisfies Message);
          return;
        }

        const data = await res.json();
        const updates: DetailUpdate[] = (data.items ?? []).map((item: any) => ({
          videoId: item.id,
          viewCountText: item.statistics?.viewCount
            ? parseInt(item.statistics.viewCount, 10).toLocaleString()
            : null,
          publishedAt: item.snippet?.publishedAt?.slice(0, 10) ?? null,
          category: CATEGORY_MAP[item.snippet?.categoryId] ?? null,
        }));

        browser.tabs.sendMessage(tabId, {
          type: "VIDEO_DETAILS_UPDATE",
          updates,
        } satisfies Message);
        success = true;
        break;
      } catch (e) {
        console.error(LOG, "Fetch failed:", e);
        browser.tabs.sendMessage(tabId, {
          type: "VIDEO_DETAILS_ERROR",
          error: "network-error",
        } satisfies Message);
        return;
      }
    }

    if (!success) {
      console.error(LOG, "Max retries exceeded for batch");
      browser.tabs.sendMessage(tabId, {
        type: "VIDEO_DETAILS_ERROR",
        error: "rate-limit-exceeded",
      } satisfies Message);
      return;
    }
  }
}

browser.runtime.onMessage.addListener(
  async (message: unknown, sender: browser.Runtime.MessageSender) => {
    const msg = message as Message;

    if (msg.type === "PLAYLIST_EXTRACTED") {
      console.log(
        LOG,
        `Playlist: "${msg.data.metadata.title}" (${msg.data.extractedCount} videos)`,
      );
    }

    if (msg.type === "FETCH_VIDEO_DETAILS") {
      const tabId = sender.tab?.id;
      if (!tabId) return;
      fetchVideoDetails(msg.videoIds, tabId);
    }
  },
);

console.log(LOG, "Service worker started.");