import { google } from 'googleapis';
import { promises as fs } from 'fs';
import { DownloadFileParams } from './types';
import { validateFileIdOrUrl, getAuthClient } from './utils';

export const downloadFileFromGoogleDrive = async ({ fileId, fileUrl, fileName, downloadPath, onProgress }: DownloadFileParams) => {
   const auth = await getAuthClient();
   const drive = google.drive({ version: 'v3', auth });

   let validatedFileId: string | undefined;

   if (fileId) {
      validatedFileId = fileId;
   } else if (fileUrl) {
      validatedFileId = validateFileIdOrUrl({ fileUrl });
   } else if (fileName) {
      const res = await drive.files.list({
         q: `name='${fileName}' and trashed=false`,
         fields: 'files(id)'
      });

      if (res.data.files && res.data.files.length > 0) {
         validatedFileId = res.data.files[0].id;
      } else {
         throw new Error('File not found on Google Drive.');
      }
   }

   if (!validatedFileId) {
      throw new Error('Valid file ID could not be determined.');
   }

   downloadPath = downloadPath || process.env.DEFAULT_DOWNLOAD_PATH;
   if (!downloadPath) {
      throw new Error('Download path must be provided or set in DEFAULT_DOWNLOAD_PATH environment variable');
   }

   let status = false;
   let message = '';

   try {
      // Check if the file already exists and delete it
      try {
         await fs.access(downloadPath);
         await fs.unlink(downloadPath);
      } catch (error) {
         // File does not exist, no action needed
      }

      const dest = await fs.open(downloadPath, 'w');
      const res = await drive.files.get({ fileId: validatedFileId, alt: 'media' }, { responseType: 'stream' });

      const totalSize = parseInt(res.headers['content-length'] || '0', 10);
      let downloadedSize = 0;

      res.data.on('data', (chunk) => {
         downloadedSize += chunk.length;
         if (onProgress) {
            onProgress((downloadedSize / totalSize) * 100);
         }
      });

      await new Promise<void>((resolve, reject) => {
         res.data
            .on('end', async () => {
               status = true;
               message = 'File downloaded successfully.';
               await dest.close();
               resolve();
            })
            .on('error', async (err: Error) => {
               message = `Error downloading file: ${err.message}`;
               await dest.close();
               reject(err);
            })
            .pipe(dest.createWriteStream());
      });
   } catch (error) {
      message = `Error during file download: ${(error as Error).message}`;
   }

   return { status, message, downloadPath };
};