function processJavaScriptFilePath()

in packages/flow-upgrade/src/findFlowFiles.js [118:160]
31 lines of code
7 McCabe index (conditional complexity)

    function processJavaScriptFilePath(filePath: string, fileByteSize: number) {
      // If `all` was configured then we don't need to check for the Flow
      // header pragma.
      if (options.all) {
        filePaths.push(filePath);
        return;
      }
      // If we were rejected then we should not continue.
      if (rejected === true) {
        return;
      }
      // We are now waiting on this asynchronous task.
      waiting++;
      // Open the file path.
      fs.open(filePath, 'r', (error, file) => {
        if (error) {
          return reject(error);
        }
        // Get the smaller of our pragma chars constant and the file byte size.
        const bytes = Math.min(PRAGMA_BYTES, fileByteSize);
        // Create the buffer we will read to.
        const buffer = new Buffer(bytes);
        // Read a set number of bytes from the file.
        fs.read(file, buffer, 0, bytes, 0, error => {
          if (error) {
            return reject(error);
          }
          // If the buffer has the @flow pragma then add the file path to our
          // final file paths array.
          if (buffer.includes('@flow')) {
            filePaths.push(filePath);
          }
          // Close the file.
          fs.close(file, error => {
            if (error) {
              return reject(error);
            }
            // We are done with this async task
            done();
          });
        });
      });
    }