/***********************************************************************************************************************************************************************
 * File Name: media.controller.js  (client)
 * Type of Program: Controller
 * Description: Secure media delivery for S3/Garage assets only.
 *
 *   Chibisafe assets use their raw file_url directly — no token needed.
 *   The block content already has the URL saved at CMS time (handleSelect).
 *
 *   S3 Flow:
 *     1. POST /client/media/token  { asset_id }
 *        → validates tier access
 *        → signs JWT with user_id + IP binding
 *        → returns { token, provider: "s3", file_type }
 *
 *     2. Browser sets <video/audio src> = API_BASE + "/client/media/stream/" + token
 *        → Express verifies JWT
 *        → Checks IP matches the one that issued the token
 *        → Generates 60s pre-signed Garage URL, proxies bytes
 *        → Real S3 URL never reaches the browser
 *
 *   Protection layers:
 *     1. JWT signature     — token can't be forged
 *     2. 5-min TTL         — token expires quickly
 *     3. IP binding        — token is useless if shared with another machine
 *     4. Token tracking    — tokens are tracked; logged after first use
 *                            (range requests from the same token are allowed
 *                             since the browser reuses the token for seeking)
 *
 *   Supported file_type values: video, audio, document, image
 *
 * Author: Kenneth Obsequio (@lash0000)
 * Date Created: Jun. 12, 2026
 ***********************************************************************************************************************************************************************/
"use strict";

const https = require("https");
const http  = require("http");
const jwt   = require("jsonwebtoken");

const R          = require("../../utils/response.util");
const mdl_Assets = require("../../models/assets/assets.mdl");
const s3         = require("../../services/s3.service");

const MEDIA_SECRET  = process.env.MEDIA_JWT_SECRET ?? process.env.JWT_SECRET;
const TOKEN_TTL_SEC = 4 * 60 * 60; // 4 hours — token must outlive the longest video

const SUPPORTED_TYPES = ["video", "audio", "document", "image"];

// ─── In-memory token tracker ──────────────────────────────────────────────────
//
// Tracks tokens that have been used at least once.
// Allows reuse within TTL for range requests (browser seeking reuses the token).
// Auto-cleans after TTL to prevent unbounded memory growth.
// In production with multiple server instances, replace with Redis.
//
const activeTokens = new Map(); // token → { firstUsed, ip }

function trackToken(token, ip) {
  if (activeTokens.has(token)) return; // already tracked, allow reuse
  activeTokens.set(token, { firstUsed: Date.now(), ip });
  setTimeout(() => activeTokens.delete(token), TOKEN_TTL_SEC * 1000);
}

// ─── Helper: resolve client IP ───────────────────────────────────────────────

// Collapses IPv4-mapped IPv6 ("::ffff:127.0.0.1") and IPv6 loopback ("::1")
// down to a single canonical form. Without this, a token minted off one
// "localhost" connection (IPv4) fails IP-pin verification on a sibling
// request that happened to land on the other stack (IPv6) — browsers race
// both when resolving "localhost", so mint and stream requests can land on
// different stacks even from the same client.
function normalizeIp(ip) {
  if (ip === "::1") return "127.0.0.1";
  if (ip.startsWith("::ffff:")) return ip.slice(7);
  return ip;
}

function resolveIp(req) {
  // x-forwarded-for is set by reverse proxies (nginx, Caddy, Cloudflare)
  const forwarded = req.headers["x-forwarded-for"];
  const raw = forwarded ? forwarded.split(",")[0].trim() : (req.ip ?? req.socket?.remoteAddress ?? "unknown");
  return normalizeIp(raw);
}

// ─── Helper: pipe S3 pre-signed URL to response (Range-aware) ────────────────

function pipeRemoteStream(remoteUrl, req, res) {
  const parsed    = new URL(remoteUrl);
  const transport = parsed.protocol === "https:" ? https : http;

  const proxyHeaders = { "User-Agent": "StarrMediaProxy/1.0" };
  if (req.headers.range) proxyHeaders["Range"] = req.headers.range;

  // Tracks whether the client dropped the connection first.
  // proxyReq.destroy() itself fires an "error" event — we silence it when
  // we were the ones who triggered the teardown (client-closed case).
  let clientClosed = false;

  const proxyReq = transport.request(remoteUrl, { headers: proxyHeaders }, (proxyRes) => {
    const status = proxyRes.statusCode ?? 502;

    // Upstream (Garage/S3) returned something other than a successful
    // content response — surface the real failure instead of piping its
    // (often tiny XML/JSON) error body through as if it were the file.
    if (status !== 200 && status !== 206) {
      proxyRes.resume(); // drain so the socket can close cleanly
      console.error(`[CLIENT][MEDIA][PROXY] Upstream returned ${status} for ${remoteUrl}`);
      if (!res.headersSent) res.status(502).json({ message: "Stream unavailable." });
      return;
    }

    [
      "content-type",
      "content-length",
      "content-range",
      "accept-ranges",
      "last-modified",
      "etag",
      "content-disposition",
    ].forEach((h) => {
      if (proxyRes.headers[h]) res.setHeader(h, proxyRes.headers[h]);
    });

    res.setHeader("Cache-Control", "no-store");
    res.setHeader("X-Content-Type-Options", "nosniff");
    res.status(status);
    proxyRes.pipe(res);
  });

  proxyReq.on("error", (err) => {
    if (clientClosed) return; // browser navigated away / component unmounted — expected
    console.error("[CLIENT][MEDIA][PROXY] Stream error:", err.message);
    if (!res.headersSent) res.status(502).json({ message: "Stream unavailable." });
  });

  req.on("close", () => {
    clientClosed = true;
    proxyReq.destroy();
  });
  proxyReq.end();
}

// ─── POST /client/media/token ─────────────────────────────────────────────────
//
// S3 assets only — Chibisafe assets use their raw file_url directly.
// Returns: { token, provider: "s3", file_type }
//
// TOKEN HITS: If a consumer (e.g. ClientNav badge) re-fetches unexpectedly,
// the fix lives on the frontend — not here. Use a useRef cache key by
// asset_id on the consumer side so this endpoint is called exactly once per
// asset per session. The 4h token TTL makes ref-caching safe within a session.

exports.issueToken = async (req, res) => {
  try {
    const { asset_id } = req.body;
    if (!asset_id) return R.error(res, "asset_id is required.", 400);

    const asset = await mdl_Assets.findOne({
      where: { asset_id, deletedAt: null },
      attributes: ["asset_id", "file_type", "storage_provider", "storage_key", "mime_type", "thumbnail_storage_key"],
    });

    if (!asset) return R.error(res, "File not found.", 404);

    if (!SUPPORTED_TYPES.includes(asset.file_type)) {
      return R.error(res, `File type "${asset.file_type}" is not supported.`, 400);
    }

    if (asset.storage_provider !== "s3") {
      return R.error(res, "Token flow is for S3 files only. Use the raw file_url for other providers.", 400);
    }

    // ── Bind token to the requester's IP ──────────────────────────────────────
    const ip = resolveIp(req);

    const token = jwt.sign(
      {
        asset_id,
        user_id:     req.user.user_id,
        storage_key: asset.storage_key,
        file_type:   asset.file_type,
        mime_type:   asset.mime_type,
        ip,           // ← IP binding — verified on every stream request
      },
      MEDIA_SECRET,
      { expiresIn: TOKEN_TTL_SEC }
    );

    // ── Presign thumbnail URL so the browser can load it directly ─────────────
    let thumbnail_url = null;
    if (asset.thumbnail_storage_key) {
      try {
        thumbnail_url = await s3.getPublicUrl(asset.thumbnail_storage_key);
      } catch {
        // Non-fatal — thumbnail is cosmetic
      }
    }

    return R.success(res, "Token issued.", {
      token,
      provider:      "s3",
      file_type:     asset.file_type,
      thumbnail_url,
    });

  } catch (err) {
    console.error("[CLIENT][MEDIA][TOKEN]", err);
    return R.error(res, "Could not issue media token.", 500);
  }
};

// ─── GET /client/media/stream/:token ─────────────────────────────────────────
//
// Called ONLY by the browser's <video>/<audio>/document element.
// Never called via axios — that would consume the stream as JSON.
//
// Protection checks (in order):
//   1. JWT signature valid
//   2. Token not expired (TTL enforced by JWT)
//   3. Requester IP matches the IP that issued the token
//
// Range requests for the same token are allowed (browser seeking).
// pipeRemoteStream() above forwards the real upstream status instead of
// collapsing everything to 200 — see its non-200/206 branch. A similar
// swallowed-status issue may still exist in s3.service.js (~line 168-171),
// not addressed here.

exports.streamAsset = async (req, res) => {
  const { token } = req.params;

  // ── CORS ──────────────────────────────────────────────────────────────────
  // Mirrors server.js's global cors() origin check (reflect against
  // ALLOWED_ORIGINS) instead of a single hardcoded FRONTEND_URL — a static
  // origin here silently overwrote the correct header the global middleware
  // already set, breaking any CORS-checked read (e.g. pdf.js's Range-header
  // fetch) whenever FRONTEND_URL drifted from the deployed frontend domain.
  // <img>/<video> tags were unaffected since opaque loads skip CORS checks.
  const allowedOrigins = (process.env.ALLOWED_ORIGINS || process.env.APP_URL || "*").split(",");
  const requestOrigin = req.headers.origin;
  if (requestOrigin && allowedOrigins.includes(requestOrigin)) {
    res.setHeader("Access-Control-Allow-Origin", requestOrigin);
  }
  res.setHeader("Access-Control-Allow-Credentials", "true");
  res.setHeader("Access-Control-Allow-Methods",     "GET, OPTIONS");
  res.setHeader("Access-Control-Allow-Headers",     "Range, Authorization");
  res.setHeader("Access-Control-Expose-Headers",    "Content-Range, Content-Length, Accept-Ranges, Content-Disposition");
  if (req.method === "OPTIONS") return res.sendStatus(204);

  // ── Block direct browser navigation ──────────────────────────────────────
  // Sec-Fetch-Mode is "navigate" when a user pastes the URL into the address
  // bar or opens it in a new tab. Legitimate <video src> requests use "no-cors"
  // and fetch() calls use "cors" — both are allowed.
  const fetchMode = req.headers["sec-fetch-mode"];
  if (fetchMode === "navigate") {
    return res.status(401).json({ message: "Unauthorized." });
  }

  // ── Verify JWT ────────────────────────────────────────────────────────────
  let payload;
  try {
    payload = jwt.verify(token, MEDIA_SECRET);
  } catch {
    return res.status(401).json({ message: "Invalid or expired media token." });
  }

  const { storage_key, ip: tokenIp } = payload;
  if (!storage_key) return res.status(401).json({ message: "Unauthorized." });

  // ── IP binding check ──────────────────────────────────────────────────────
  const requestIp = resolveIp(req);
  if (tokenIp && requestIp !== tokenIp) {
    console.warn(`[CLIENT][MEDIA][STREAM] IP mismatch — token: ${tokenIp}, request: ${requestIp}`);
    return res.status(403).json({ message: "Token IP mismatch." });
  }

  // ── Track token (allow reuse for range requests) ──────────────────────────
  trackToken(token, requestIp);

  // ── Generate pre-signed URL and proxy bytes ───────────────────────────────
  let presignedUrl;
  try {
    presignedUrl = await s3.getSignedDownloadUrl(storage_key, 60);
  // ── Just comment out for debug if S3_ENDPOINT is undefined ────────────────
    // console.log("Presigned URL:", presignedUrl);
  } catch (err) {
    console.error("[CLIENT][MEDIA][STREAM] Pre-sign failed:", err.message);
    return res.status(500).json({ message: "Could not resolve media stream." });
  }

  return pipeRemoteStream(presignedUrl, req, res);
};