//
//  AudioSessionManager.m
//  keyBoard
//
//  Created by Mac on 2026/1/15.
//

#import "AudioSessionManager.h"

@interface AudioSessionManager ()
@property(nonatomic, assign) BOOL isSessionActive;
@end

@implementation AudioSessionManager

#pragma mark - Singleton

+ (instancetype)sharedManager {
  static AudioSessionManager *instance = nil;
  static dispatch_once_t onceToken;
  dispatch_once(&onceToken, ^{
    instance = [[AudioSessionManager alloc] init];
  });
  return instance;
}

- (instancetype)init {
  self = [super init];
  if (self) {
    _isSessionActive = NO;
    [self setupNotifications];
  }
  return self;
}

- (void)dealloc {
  [[NSNotificationCenter defaultCenter] removeObserver:self];
}

#pragma mark - Notifications

- (void)setupNotifications {
  // 监听音频会话中断通知
  [[NSNotificationCenter defaultCenter]
      addObserver:self
         selector:@selector(handleInterruption:)
             name:AVAudioSessionInterruptionNotification
           object:nil];

  // 监听音频路由变化通知
  [[NSNotificationCenter defaultCenter]
      addObserver:self
         selector:@selector(handleRouteChange:)
             name:AVAudioSessionRouteChangeNotification
           object:nil];
}

- (void)handleInterruption:(NSNotification *)notification {
  NSDictionary *info = notification.userInfo;
  AVAudioSessionInterruptionType type =
      [info[AVAudioSessionInterruptionTypeKey] unsignedIntegerValue];

  if (type == AVAudioSessionInterruptionTypeBegan) {
    // 中断开始：来电、闹钟等
    dispatch_async(dispatch_get_main_queue(), ^{
      if ([self.delegate
              respondsToSelector:@selector(audioSessionManagerDidInterrupt:)]) {
        [self.delegate audioSessionManagerDidInterrupt:
                           KBAudioSessionInterruptionTypeBegan];
      }
    });
  } else if (type == AVAudioSessionInterruptionTypeEnded) {
    // 中断结束
    AVAudioSessionInterruptionOptions options =
        [info[AVAudioSessionInterruptionOptionKey] unsignedIntegerValue];
    if (options & AVAudioSessionInterruptionOptionShouldResume) {
      // 可以恢复播放
      [self activateSession:nil];
    }
    dispatch_async(dispatch_get_main_queue(), ^{
      if ([self.delegate
              respondsToSelector:@selector(audioSessionManagerDidInterrupt:)]) {
        [self.delegate audioSessionManagerDidInterrupt:
                           KBAudioSessionInterruptionTypeEnded];
      }
    });
  }
}

- (void)handleRouteChange:(NSNotification *)notification {
  NSDictionary *info = notification.userInfo;
  AVAudioSessionRouteChangeReason reason =
      [info[AVAudioSessionRouteChangeReasonKey] unsignedIntegerValue];

  switch (reason) {
  case AVAudioSessionRouteChangeReasonOldDeviceUnavailable:
  case AVAudioSessionRouteChangeReasonNewDeviceAvailable: {
    // 旧设备不可用（如耳机拔出）或新设备可用（如耳机插入）
    dispatch_async(dispatch_get_main_queue(), ^{
      if ([self.delegate respondsToSelector:@selector
                         (audioSessionManagerRouteDidChange)]) {
        [self.delegate audioSessionManagerRouteDidChange];
      }
    });
    break;
  }
  default:
    break;
  }
}

#pragma mark - Microphone Permission

- (void)requestMicrophonePermission:(void (^)(BOOL))completion {
  AVAudioSession *session = [AVAudioSession sharedInstance];

  [session requestRecordPermission:^(BOOL granted) {
    dispatch_async(dispatch_get_main_queue(), ^{
      if (!granted) {
        if ([self.delegate respondsToSelector:@selector
                           (audioSessionManagerMicrophonePermissionDenied)]) {
          [self.delegate audioSessionManagerMicrophonePermissionDenied];
        }
      }
      if (completion) {
        completion(granted);
      }
    });
  }];
}

- (BOOL)hasMicrophonePermission {
  AVAudioSession *session = [AVAudioSession sharedInstance];
  return session.recordPermission == AVAudioSessionRecordPermissionGranted;
}

#pragma mark - Session Configuration

- (BOOL)configureForConversation:(NSError **)error {
  AVAudioSession *session = [AVAudioSession sharedInstance];

  // 配置为录音+播放模式
  // Category: PlayAndRecord - 同时支持录音和播放
  // Mode: VoiceChat - 允许系统进行 AGC/降噪，提升输入音量
  // Options:
  //   - DefaultToSpeaker: 默认使用扬声器
  //   - AllowBluetooth: 允许蓝牙设备
  NSError *categoryError = nil;
  BOOL success =
      [session setCategory:AVAudioSessionCategoryPlayAndRecord
                      mode:AVAudioSessionModeVoiceChat
                   options:(AVAudioSessionCategoryOptionDefaultToSpeaker |
                            AVAudioSessionCategoryOptionAllowBluetooth)
                     error:&categoryError];

  if (!success) {
    if (error) {
      *error = categoryError;
    }
    NSLog(@"[AudioSessionManager] Failed to configure session: %@",
          categoryError.localizedDescription);
    return NO;
  }

  // 优先使用后端要求的采样率和缓冲时长，减少重采样误差
  NSError *sampleRateError = nil;
  [session setPreferredSampleRate:16000 error:&sampleRateError];
  if (sampleRateError) {
    NSLog(@"[AudioSessionManager] Failed to set sample rate: %@",
          sampleRateError.localizedDescription);
  }

  NSError *bufferError = nil;
  [session setPreferredIOBufferDuration:0.02 error:&bufferError];
  if (bufferError) {
    NSLog(@"[AudioSessionManager] Failed to set IO buffer: %@",
          bufferError.localizedDescription);
  }

  if ([session respondsToSelector:@selector(setPreferredInputNumberOfChannels:
                                                    error:)]) {
    NSError *channelsError = nil;
    [session setPreferredInputNumberOfChannels:1 error:&channelsError];
    if (channelsError) {
      NSLog(@"[AudioSessionManager] Failed to set input channels: %@",
            channelsError.localizedDescription);
    }
  }

  return YES;
}

- (BOOL)configureForPlayback:(NSError **)error {
  AVAudioSession *session = [AVAudioSession sharedInstance];

  // 仅播放模式
  NSError *categoryError = nil;
  BOOL success =
      [session setCategory:AVAudioSessionCategoryPlayback
                      mode:AVAudioSessionModeDefault
                   options:AVAudioSessionCategoryOptionDefaultToSpeaker
                     error:&categoryError];

  if (!success) {
    if (error) {
      *error = categoryError;
    }
    NSLog(@"[AudioSessionManager] Failed to configure playback: %@",
          categoryError.localizedDescription);
    return NO;
  }

  return YES;
}

- (BOOL)activateSession:(NSError **)error {
  if (self.isSessionActive) {
    return YES;
  }

  AVAudioSession *session = [AVAudioSession sharedInstance];
  NSError *activationError = nil;
  BOOL success = [session setActive:YES error:&activationError];

  if (!success) {
    if (error) {
      *error = activationError;
    }
    NSLog(@"[AudioSessionManager] Failed to activate session: %@",
          activationError.localizedDescription);
    return NO;
  }

  if (session.isInputGainSettable) {
    NSError *gainError = nil;
    [session setInputGain:1.0 error:&gainError];
    if (gainError) {
      NSLog(@"[AudioSessionManager] Failed to set input gain: %@",
            gainError.localizedDescription);
    }
  }

  self.isSessionActive = YES;
  return YES;
}

- (void)deactivateSession {
  if (!self.isSessionActive) {
    return;
  }

  AVAudioSession *session = [AVAudioSession sharedInstance];
  NSError *error = nil;

  // 使用 NotifyOthersOnDeactivation 通知其他应用可以恢复播放
  [session setActive:NO
         withOptions:AVAudioSessionSetActiveOptionNotifyOthersOnDeactivation
               error:&error];

  if (error) {
    NSLog(@"[AudioSessionManager] Failed to deactivate session: %@",
          error.localizedDescription);
  }

  self.isSessionActive = NO;
}

@end