const { onObjectFinalized } = require("firebase-functions/v2/storage");
const logger = require("firebase-functions/logger");
const admin = require("firebase-admin");
const ffmpeg = require("fluent-ffmpeg");
const ffmpegInstaller = require("@ffmpeg-installer/ffmpeg");
const fs = require("node:fs/promises");
const os = require("node:os");
const path = require("node:path");
const crypto = require("node:crypto");
const { refList } = require("../index");

ffmpeg.setFfmpegPath(ffmpegInstaller.path);

exports.generateVideoThumbnail = onObjectFinalized(
  {
    region: "europe-west1",
    timeoutSeconds: 180,
    memory: "1GiB",
    cpu: 1,
  },
  async (event) => {
    const file = event.data || {};
    const bucketName = file.bucket;
    const objectName = file.name || "";
    const contentType = file.contentType || "";

    // Basic guards + helpful logs for debugging why events might be ignored
    if (!bucketName || !objectName) {
      logger.info("[Thumbnail] Ignored: missing bucket or object name", {
        bucketName,
        objectName,
        contentType,
      });
      return;
    }

    // Avoid processing our own generated thumbnails
    if (/_thumb9x16\.jpg$/i.test(objectName)) {
      logger.info("[Thumbnail] Ignored: already a thumbnail", { objectName });
      return;
    }

    // Accept if contentType says it's a video OR fallback to extension-based check
    const isVideoContentType =
      typeof contentType === "string" && contentType.startsWith("video/");
    const isVideoLikeName = /\.(mp4|mov|webm|m4v|avi|mkv)$/i.test(
      objectName.toLowerCase()
    );
    if (!isVideoContentType && !isVideoLikeName) {
      logger.info("[Thumbnail] Ignored: not a video", {
        objectName,
        contentType,
      });
      return;
    }

    logger.info("[Thumbnail] Event accepted", {
      bucketName,
      objectName,
      contentType,
    });

    const bucket = admin.storage().bucket(bucketName);
    const playbackMatch = objectName.match(
      /^users\/[^/]+\/projects\/([^/]+)\/playback\.mp4$/i
    );
    const projectId = playbackMatch ? playbackMatch[1] : null;

    // Use unique folder under /tmp to avoid name collisions
    const tmpDir = path.join(
      os.tmpdir(),
      `thumb-${Date.now()}-${Math.round(Math.random() * 1000)}`
    );
    const baseName = path.basename(objectName);
    const dirName = path.posix.dirname(objectName);
    const localVideoPath = path.join(tmpDir, baseName);

    const thumbBase = baseName.replace(/\.[^.]+$/, "") + "_thumb9x16.jpg";
    const localThumbPath = path.join(tmpDir, thumbBase);
    const remoteThumbPath =
      dirName && dirName !== "."
        ? path.posix.join(dirName, thumbBase)
        : thumbBase;

    try {
      await fs.mkdir(tmpDir, { recursive: true });

      // Télécharger la vidéo depuis le bucket
      await bucket.file(objectName).download({ destination: localVideoPath });

      // Extraire 1 frame en 9:16 (1080x1920) de manière robuste
      const vfCoverCrop =
        "scale=1080:1920:force_original_aspect_ratio=increase,crop=1080:1920";
      const vfPad =
        "scale=1080:1920:force_original_aspect_ratio=decrease,pad=1080:1920:(ow-iw)/2:(oh-ih)/2";

      const extractFrame = (ssSeconds, vf) =>
        new Promise((resolve, reject) => {
          ffmpeg(localVideoPath)
            .inputOptions([`-ss ${ssSeconds}`])
            .frames(1)
            .outputOptions(["-vf", vf, "-q:v", "2"])
            .output(localThumbPath)
            .on("end", resolve)
            .on("error", reject)
            .run();
        });

      try {
        // 1) Essai principal: 1s + cover/crop
        await extractFrame(1, vfCoverCrop);
      } catch (e1) {
        logger.warn("[Thumbnail] First attempt failed, retrying at 0s", {
          objectName,
          error: e1?.message || String(e1),
        });
        try {
          // 2) Deuxième essai: 0s + cover/crop (si vidéo très courte)
          await extractFrame(0, vfCoverCrop);
        } catch (e2) {
          logger.warn("[Thumbnail] Second attempt failed, fallback to pad", {
            objectName,
            error: e2?.message || String(e2),
          });
          // 3) Fallback: 0s + pad (aucun crop, bandes latérales si besoin)
          await extractFrame(0, vfPad);
        }
      }

      // Upload du thumbnail avec un token de téléchargement public Firebase
      const downloadToken = crypto.randomUUID();
      await bucket.upload(localThumbPath, {
        destination: remoteThumbPath,
        metadata: {
          contentType: "image/jpeg",
          cacheControl: "public, max-age=86400",
          metadata: {
            original: objectName,
            aspect: "9:16",
            t: "1s",
            firebaseStorageDownloadTokens: downloadToken,
          },
        },
      });

      const encodedPath = encodeURIComponent(remoteThumbPath);
      const thumbnailUrl = `https://firebasestorage.googleapis.com/v0/b/${bucketName}/o/${encodedPath}?alt=media&token=${downloadToken}`;

      if (projectId) {
        await refList.projects.doc(projectId).set(
          {
            thumbnailUrl,
            updatedAt: admin.firestore.FieldValue.serverTimestamp(),
          },
          { merge: true }
        );
      }

      logger.info("✅ [Thumbnail] Uploaded", {
        objectName,
        remoteThumbPath,
        projectId,
        thumbnailUrl,
      });
    } catch (error) {
      logger.error("❌ [Thumbnail] Failed", {
        objectName,
        error: error?.message || String(error),
      });
      throw error;
    } finally {
      await fs.rm(tmpDir, { recursive: true, force: true });
    }
  }
);