import Foundation

/// PCM helpers (16-bit signed little-endian).
///
/// Mirrors Android `audio/PcmKit.kt` — stereo split / mono mix utilities used
/// by the stereo call-translation mode handler.
enum PcmKit {

  /// Split an interleaved 16-bit LE stereo buffer into two mono buffers
  /// (left, right). Each output has half the input byte length.
  static func splitStereo16(_ stereo: Data) -> (Data, Data) {
    var left = Data(); left.reserveCapacity(stereo.count / 2)
    var right = Data(); right.reserveCapacity(stereo.count / 2)
    let count = stereo.count - (stereo.count % 4)
    var i = 0
    stereo.withUnsafeBytes { (raw: UnsafeRawBufferPointer) in
      let p = raw.bindMemory(to: UInt8.self).baseAddress!
      while i < count {
        // L = bytes[i..i+1], R = bytes[i+2..i+3]
        left.append(p[i]);     left.append(p[i + 1])
        right.append(p[i + 2]); right.append(p[i + 3])
        i += 4
      }
    }
    return (left, right)
  }
}