/*
 * ======= • ======= • ======= • ======= • =======• =======
 * MiruroAPI — pipe.js
 * Repository: https://github.com/Shineii86/MiruroAPI
 *
 * @description
 *   Miruro streaming pipe integration. Handles encoding/decoding
 *   of the secure/pipe tunnel that Miruro uses for episode lists
 *   and streaming sources. Decodes base64+gzip responses and
 *   injects simplified slug-based episode IDs.
 *
 * @exports
 *   getEpisodes, getSources, getWatchSources
 *
 * @author  Shinei Nouzen
 * @license MIT
 * ======= • ======= • ======= • ======= • =======• =======
 */

const axios = require("axios");
const { Buffer } = require("buffer");
const zlib = require("zlib");

// ══════════════════════════════════════════════════════════════
// MIRURO PIPE CONFIGURATION
// ══════════════════════════════════════════════════════════════

/**
 * Miruro's secure pipe endpoint URL.
 * All streaming requests go through this base64+gzip encoded tunnel.
 *
 * @type {string}
 */
const MIRURO_PIPE_URL = "https://www.miruro.tv/api/secure/pipe";

/**
 * Request headers mimicking a browser.
 * Referer is required for the pipe endpoint to accept requests.
 *
 * @type {object}
 */
const HEADERS = {
  "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/137.0.0.0 Safari/537.36",
  Referer: "https://www.miruro.tv/",
};

// ══════════════════════════════════════════════════════════════
// ENCODING / DECODING UTILITIES
// ══════════════════════════════════════════════════════════════

// ---- FEATURE: Base64url encode pipe request payload ----
/**
 * Encodes a JSON payload into the base64url format expected by the pipe endpoint.
 * Used for all pipe API requests (episodes, sources).
 *
 * @param {object} payload - The request payload to encode
 * @returns {string} Base64url-encoded string (no padding)
 *
 * @example
 *   const encoded = encodePipeRequest({ path: "episodes", method: "GET", query: { anilistId: 20 } });
 */
const encodePipeRequest = (payload) => {
  const json = JSON.stringify(payload);
  return Buffer.from(json).toString("base64url");
};

// ---- FEATURE: Decode base64+gzip pipe response ----
/**
 * Decodes a pipe response from base64url + gzip format into a plain object.
 * The Miruro pipe returns all responses in this compressed format.
 *
 * @param {string} encodedStr - The base64url-encoded gzipped response
 * @returns {object} Decoded JSON object
 * @throws {Error} If decoding or decompression fails
 *
 * @example
 *   const data = decodePipeResponse(res.text);
 *   console.log(data.providers); // { kiwi: {...}, bee: {...} }
 */
const decodePipeResponse = (encodedStr) => {
  try {
    // NOTE: Add padding if necessary (base64url may omit trailing =)
    const padded = encodedStr + "=".repeat((4 - (encodedStr.length % 4)) % 4);
    const compressed = Buffer.from(padded, "base64url");
    const decompressed = zlib.gunzipSync(compressed);
    return JSON.parse(decompressed.toString("utf-8"));
  } catch (e) {
    throw new Error("Failed to decode pipe response: " + e.message);
  }
};

// ---- FEATURE: Decode base64 episode ID to plain text ----
/**
 * Decodes a base64-encoded episode ID back to plain text.
 * Episode IDs from the pipe are base64-encoded with ":" separators.
 *
 * @param {string} encodedId - The base64url-encoded episode ID
 * @returns {string} Decoded plain text ID, or original if decoding fails
 *
 * @example
 *   const decoded = translateId("YW5pbWVwaGU6MjA6c3ViOjE=");
 *   // returns "animepahe:20:sub:1"
 */
const translateId = (encodedId) => {
  try {
    const padded = encodedId + "=".repeat((4 - (encodedId.length % 4)) % 4);
    const decoded = Buffer.from(padded, "base64url").toString("utf-8");
    // NOTE: Only return decoded value if it looks like a valid ID (contains ":")
    if (decoded.includes(":")) return decoded;
    return encodedId;
  } catch {
    return encodedId;
  }
};

// ---- FEATURE: Recursively decode all base64 IDs in a nested object ----
/**
 * Walks a JSON structure and decodes any base64 "id" fields.
 * Handles nested objects and arrays of objects.
 *
 * @param {object|Array} obj - The object or array to process
 * @returns {object|Array} The same object with decoded IDs (mutated in place)
 */
const deepTranslate = (obj) => {
  if (obj && typeof obj === "object") {
    for (const key of Object.keys(obj)) {
      if (key === "id" && typeof obj[key] === "string") {
        obj[key] = translateId(obj[key]);
      } else if (typeof obj[key] === "object") {
        deepTranslate(obj[key]);
      }
    }
  }
  return obj;
};

// ══════════════════════════════════════════════════════════════
// EPISODE ID INJECTION
// ══════════════════════════════════════════════════════════════

// ---- FEATURE: Transform episode IDs into simplified path-based slugs ----
/**
 * Converts raw pipe episode IDs into clean slug format:
 *   watch/{provider}/{anilistId}/{category}/{prefix}-{number}
 *
 * This makes episode IDs human-readable and URL-safe for the /watch endpoint.
 *
 * @param {object} data - Raw pipe response with providers
 * @param {number} anilistId - The AniList anime ID
 * @returns {object} Modified data with slug-based episode IDs
 *
 * @example
 *   // Before: "animepahe:20:sub:1"
 *   // After:  "watch/kiwi/20/sub/animepahe-1"
 */
const injectSourceSlugs = (data, anilistId) => {
  const providers = data.providers || {};

  for (const [provName, provData] of Object.entries(providers)) {
    if (!provData || typeof provData !== "object") continue;

    let episodes = provData.episodes;
    if (!episodes) continue;

    // NOTE: Some providers return a flat array — wrap it in { sub: [...] }
    if (Array.isArray(episodes)) {
      provData.episodes = { sub: episodes };
      episodes = provData.episodes;
    }

    for (const [category, epList] of Object.entries(episodes)) {
      if (!Array.isArray(epList)) continue;

      for (const ep of epList) {
        if (ep.id && ep.number) {
          const origId = ep.id;
          // NOTE: Take only the prefix before ":" for the slug
          const prefix = origId.includes(":") ? origId.split(":")[0] : origId;
          ep.id = `watch/${provName}/${anilistId}/${category}/${prefix}-${ep.number}`;
        }
      }
    }
  }

  return data;
};

// ══════════════════════════════════════════════════════════════
// PIPE API FUNCTIONS
// ══════════════════════════════════════════════════════════════

// ---- FEATURE: Fetch raw decoded episode data from Miruro pipe ----
/**
 * Internal helper to fetch and decode raw episode data from the pipe.
 * Sends a base64-encoded request and decodes the gzipped response.
 *
 * @param {number} anilistId - The AniList anime ID
 * @returns {Promise<object>} Decoded episode data with providers
 * @throws {Error} If the pipe request fails
 */
const fetchRawEpisodes = async (anilistId) => {
  const payload = {
    path: "episodes",
    method: "GET",
    query: { anilistId },
    body: null,
    version: "0.1.0",
  };

  const encodedReq = encodePipeRequest(payload);
  const res = await axios.get(`${MIRURO_PIPE_URL}?e=${encodedReq}`, {
    headers: HEADERS,
    timeout: 15000,
  });

  if (res.status !== 200) throw new Error(`Pipe request failed: ${res.status}`);
  const data = decodePipeResponse(res.text || res.data);
  return deepTranslate(data);
};

// ---- FEATURE: Get episodes with slug-based IDs ----
/**
 * Fetches the full episode list for an anime from all providers.
 * Returns episodes with simplified slug-based IDs for the /watch endpoint.
 *
 * @param {number} anilistId - The AniList anime ID
 * @returns {Promise<object>} Episode data with providers and mappings
 *
 * @example
 *   const episodes = await getEpisodes(20); // Naruto
 *   console.log(Object.keys(episodes.providers)); // ["kiwi", "bee", "bonk", ...]
 */
const getEpisodes = async (anilistId) => {
  const data = await fetchRawEpisodes(anilistId);
  const result = injectSourceSlugs(data, anilistId);

  // NOTE: Ensure mappings field is present (like Walter's API)
  if (!result.mappings) {
    result.mappings = { anilistId };
    if (result.malId) result.mappings.malId = result.malId;
    if (result.kitsuId) result.mappings.kitsuId = result.kitsuId;
  }

  return result;
};

// ---- FEATURE: Get streaming sources (detailed endpoint) ----
/**
 * Fetches M3U8 streaming sources for a specific episode.
 * This is the detailed/manual endpoint — use /watch for simpler access.
 *
 * @param {string} episodeId - The raw episode ID from the pipe
 * @param {string} provider - Provider name (e.g., "kiwi", "bee", "bonk")
 * @param {number} anilistId - The AniList anime ID
 * @param {string} [category="sub"] - Audio category ("sub" or "dub")
 * @returns {Promise<object>} Streaming sources with M3U8 URLs, subtitles, timestamps
 *
 * @example
 *   const sources = await getSources("animepahe:20:sub:1", "kiwi", 20, "sub");
 *   console.log(sources.streams[0].url); // "https://.../master.m3u8"
 */
const getSources = async (episodeId, provider, anilistId, category = "sub") => {
  const encId = Buffer.from(episodeId).toString("base64url");
  const payload = {
    path: "sources",
    method: "GET",
    query: { episodeId: encId, provider, category, anilistId },
    body: null,
    version: "0.1.0",
  };

  const encodedReq = encodePipeRequest(payload);
  const res = await axios.get(`${MIRURO_PIPE_URL}?e=${encodedReq}`, {
    headers: HEADERS,
    timeout: 15000,
  });

  if (res.status !== 200) throw new Error(`Pipe sources request failed: ${res.status}`);
  return deepTranslate(decodePipeResponse(res.text || res.data));
};

// ---- FEATURE: Get streaming sources (simple slug-based endpoint) ----
/**
 * Resolves a slug-based episode ID and fetches its streaming sources.
 * This is the recommended endpoint — just pass the slug from /episodes.
 *
 * @param {string} provider - Provider name (e.g., "kiwi", "bee")
 * @param {number} anilistId - The AniList anime ID
 * @param {string} category - Audio category ("sub" or "dub")
 * @param {string} slug - Episode slug (e.g., "animepahe-1")
 * @returns {Promise<object>} Streaming sources with M3U8 URLs, subtitles, timestamps
 * @throws {Error} If provider or episode slug is not found
 *
 * @example
 *   const sources = await getWatchSources("kiwi", 20, "sub", "animepahe-1");
 *   console.log(sources.streams[0].url); // "https://.../master.m3u8"
 */
const getWatchSources = async (provider, anilistId, category, slug) => {
  const data = await fetchRawEpisodes(anilistId);
  const provData = (data.providers || {})[provider];

  if (!provData) throw new Error(`Provider ${provider} not found`);

  const episodes = provData.episodes?.[category] || [];
  let targetId = null;

  // NOTE: Resolve slug back to the original pipe episode ID
  for (const ep of episodes) {
    const origId = ep.id || "";
    const prefix = origId.includes(":") ? origId.split(":")[0] : origId;
    const generated = `${prefix}-${ep.number}`;

    if (generated === slug) {
      targetId = origId;
      break;
    }
  }

  if (!targetId) throw new Error(`Episode slug '${slug}' not found for provider ${provider}`);
  return getSources(targetId, provider, anilistId, category);
};

module.exports = {
  getEpisodes,
  getSources,
  getWatchSources,
  encodePipeRequest,
  decodePipeResponse,
  translateId,
  deepTranslate,
  injectSourceSlugs,
};

// ══════════════════════════════════════════════════════════════ END: pipe.js