import AVFoundation
import CallsKit
import XCTest

/// The Bluetooth rule, which only exists on iOS and so can only be tested
/// here — CallsKitTests builds for macOS, where AVAudioSession does not
/// exist at all.
final class AudioRouteTests: XCTestCase {
  func testBluetoothIsAllowedOnlyWhenItIsTheChosenMicrophone() {
    // .allowBluetoothHFP is what lets a Bluetooth microphone be used, and
    // it is also what drags the whole call to the 8 kHz hands-free
    // profile the moment any headset connects. Left on unconditionally —
    // as it was until this change — every pair of AirPods silently cost
    // the call its audio quality in both directions, and nothing said so.
    let ordinary = AudioRoutes.options(bluetoothInput: false)
    XCTAssertFalse(
      ordinary.contains(.allowBluetoothHFP),
      "a call with no Bluetooth microphone chosen must not offer the hands-free profile")
    XCTAssertTrue(
      ordinary.contains(.allowBluetoothA2DP),
      "output should still reach a headset, at A2DP quality")
    XCTAssertTrue(ordinary.contains(.defaultToSpeaker))

    // Picking the headset microphone is an informed trade, and then HFP
    // is exactly what has to be allowed for it to work at all.
    let headset = AudioRoutes.options(bluetoothInput: true)
    XCTAssertTrue(headset.contains(.allowBluetoothHFP))
    XCTAssertTrue(headset.contains(.defaultToSpeaker))
  }

  func testOnlyTheHandsFreePortCountsAsABluetoothMicrophone() {
    // A2DP is output-only, so a Bluetooth device being used as a
    // microphone is always on the hands-free port. Treating A2DP as a
    // microphone would turn HFP back on for a headset nobody is
    // recording from, which is the bug this rule exists to avoid.
    XCTAssertEqual(AVAudioSession.Port.bluetoothHFP.rawValue, "BluetoothHFP")
    XCTAssertNotEqual(AVAudioSession.Port.bluetoothA2DP, AVAudioSession.Port.bluetoothHFP)
  }
}