const functions = require("firebase-functions");
const admin = require("firebase-admin");
const {Storage} = require("@google-cloud/storage");
const ffmpeg = require("fluent-ffmpeg");
const ffmpegStatic = require("ffmpeg-static");
const fs = require("fs-extra");
const path = require("path");
const ytdl = require("ytdl-core");

admin.initializeApp();

const gcs = new Storage();
const bucketName = admin.storage().bucket().name;
ffmpeg.setFfmpegPath(ffmpegStatic);

exports.processVideo = functions.firestore
    .document("lessons/{lessonId}")
    .onUpdate(async (change, context) => {
      const {videoUrl, processedUrl, processing} = change.after.data();
      const {lessonId} = context.params;

      if (!videoUrl || processedUrl || processing) {
        return null;
      }

      await change.after.ref.update({
        processing: true,
        processedUrl: null,
      });

      try {
        const tempLocalPath = path.join("/tmp", `${lessonId}-original.mp4`);
        const convertedPath = path.join("/tmp", `${lessonId}-converted.mp4`);

        functions.logger.log(`Baixando vídeo de: ${videoUrl}`);
        const videoStream = ytdl(videoUrl, {quality: "highestvideo"});

        await new Promise((resolve, reject) => {
          videoStream.pipe(fs.createWriteStream(tempLocalPath));
          videoStream.on("end", resolve);
          videoStream.on("error", reject);
        });
        functions.logger.log("Vídeo baixado com sucesso.");

        functions.logger.log(
            "Iniciando a conversão para 720p...");
        await new Promise((resolve, reject) => {
          ffmpeg(tempLocalPath)
              .videoCodec("libx264")
              .audioCodec("aac")
              .size("1280x720")
              .on("end", resolve)
              .on("error", reject)
              .save(convertedPath);
        });
        functions.logger.log("Conversão concluída.");

        const storageFilePath = `videos/${lessonId}-converted.mp4`;
        await gcs.bucket(bucketName).upload(convertedPath, {
          destination: storageFilePath,
          metadata: {
            contentType: "video/mp4",
            metadata: {
              firebaseStorageDownloadTokens: lessonId,
            },
          },
        });
        functions.logger.log("Upload para o Storage concluído.");

        const [url] = await gcs.bucket(bucketName)
            .file(storageFilePath)
            .getSignedUrl({
              action: "read",
              expires: "03-09-2491",
            });

        await change.after.ref.update({
          processedUrl: url,
          processing: false,
        });
        functions.logger.log("Firestore atualizado com o novo URL.");

        fs.removeSync(tempLocalPath);
        fs.removeSync(convertedPath);

        return null;
      } catch (error) {
        functions.logger.error("Erro no processamento do vídeo:", error);
        await change.after.ref.update({
          processing: false,
          processingError: true,
        });
        return null;
      }
    });