audiotee/Sources/AudioTeeCLI/BinaryOutputHandler.swift

import AudioTeeCore
import Foundation

/// CLI-specific output handler that writes raw PCM audio to a file descriptor
/// (stdout by default) and lifecycle messages to stderr via the logger.
///
/// `source` tags every stderr message so a consumer running two tracks at
/// once (e.g. system audio + microphone, each on its own fd) can tell which
/// track a given metadata/lifecycle message belongs to.
class BinaryAudioOutputHandler: AudioOutputHandler {
  private let fd: Int32
  private let source: String

  init(fd: Int32 = STDOUT_FILENO, source: String = "audio") {
    self.fd = fd
    self.source = source
  }

  func handleAudioData(_ pointer: UnsafeRawPointer, count: Int) {
    var written = 0
    while written < count {
      let result = write(fd, pointer.advanced(by: written), count - written)
      if result >= 0 {
        written += result
      } else if errno == EINTR {
        continue
      } else {
        break  // EPIPE, EIO, etc — consumer gone or real error
      }
    }
  }

  func handleMetadata(_ metadata: AudioStreamMetadata) {
    let taggedMetadata = AudioStreamMetadata(
      sampleRate: metadata.sampleRate,
      channelsPerFrame: metadata.channelsPerFrame,
      bitsPerChannel: metadata.bitsPerChannel,
      isFloat: metadata.isFloat,
      captureMode: source,
      deviceName: metadata.deviceName,
      deviceUID: metadata.deviceUID,
      encoding: metadata.encoding
    )
    AudioTeeLogging.logger.writeMessage(.metadata, data: taggedMetadata)
  }

  func handleStreamStart() {
    AudioTeeLogging.logger.writeMessage(.streamStart, data: source)
  }

  func handleStreamStop() {
    AudioTeeLogging.logger.writeMessage(.streamStop, data: source)
  }
}