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

#import "AudioStreamPlayer.h"
#import <AVFoundation/AVFoundation.h>

@interface AudioStreamPlayer ()

@property(nonatomic, strong) AVAudioEngine *audioEngine;
@property(nonatomic, strong) AVAudioPlayerNode *playerNode;
@property(nonatomic, strong) AVAudioFormat *playbackFormat;

// 片段跟踪
@property(nonatomic, copy) NSString *currentSegmentId;
@property(nonatomic, strong)
    NSMutableDictionary<NSString *, NSNumber *> *segmentDurations;
@property(nonatomic, strong)
    NSMutableDictionary<NSString *, NSNumber *> *segmentStartTimes;
@property(nonatomic, assign) NSUInteger scheduledSamples;
@property(nonatomic, assign) NSUInteger playedSamples;

// 状态
@property(nonatomic, assign) BOOL playing;
@property(nonatomic, strong) dispatch_queue_t playerQueue;
@property(nonatomic, strong) NSTimer *progressTimer;

@end

@implementation AudioStreamPlayer

- (instancetype)init {
  self = [super init];
  if (self) {
    _audioEngine = [[AVAudioEngine alloc] init];
    _playerNode = [[AVAudioPlayerNode alloc] init];
    _segmentDurations = [[NSMutableDictionary alloc] init];
    _segmentStartTimes = [[NSMutableDictionary alloc] init];
    _playerQueue = dispatch_queue_create("com.keyboard.aitalk.streamplayer",
                                         DISPATCH_QUEUE_SERIAL);

    // 默认播放格式：16kHz, Mono, Float32
    _playbackFormat =
        [[AVAudioFormat alloc] initWithCommonFormat:AVAudioPCMFormatFloat32
                                         sampleRate:16000
                                           channels:1
                                        interleaved:NO];
  }
  return self;
}

- (void)dealloc {
  [self stop];
}

#pragma mark - Public Methods

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

  // 连接节点
  [self.audioEngine attachNode:self.playerNode];
  [self.audioEngine connect:self.playerNode
                         to:self.audioEngine.mainMixerNode
                     format:self.playbackFormat];

  // 启动引擎
  NSError *startError = nil;
  [self.audioEngine prepare];

  if (![self.audioEngine startAndReturnError:&startError]) {
    if (error) {
      *error = startError;
    }
    NSLog(@"[AudioStreamPlayer] Failed to start engine: %@",
          startError.localizedDescription);
    return NO;
  }

  [self.playerNode play];
  self.playing = YES;

  // 启动进度更新定时器
  [self startProgressTimer];

  NSLog(@"[AudioStreamPlayer] Started");
  return YES;
}

- (void)stop {
  dispatch_async(self.playerQueue, ^{
    [self stopProgressTimer];

    [self.playerNode stop];
    [self.audioEngine stop];

    self.playing = NO;
    self.currentSegmentId = nil;
    self.scheduledSamples = 0;
    self.playedSamples = 0;

    [self.segmentDurations removeAllObjects];
    [self.segmentStartTimes removeAllObjects];

    NSLog(@"[AudioStreamPlayer] Stopped");
  });
}

- (void)enqueuePCMChunk:(NSData *)pcmData
             sampleRate:(double)sampleRate
               channels:(int)channels
              segmentId:(NSString *)segmentId {

  if (!pcmData || pcmData.length == 0)
    return;

  dispatch_async(self.playerQueue, ^{
    // 检查是否是新片段
    BOOL isNewSegment = ![segmentId isEqualToString:self.currentSegmentId];
    if (isNewSegment) {
      self.currentSegmentId = segmentId;
      self.scheduledSamples = 0;
      self.segmentStartTimes[segmentId] = @(CACurrentMediaTime());

      dispatch_async(dispatch_get_main_queue(), ^{
        if ([self.delegate respondsToSelector:@selector
                           (audioStreamPlayerDidStartSegment:)]) {
          [self.delegate audioStreamPlayerDidStartSegment:segmentId];
        }
      });
    }

    // 转换 Int16 -> Float32
    NSUInteger sampleCount = pcmData.length / sizeof(int16_t);
    const int16_t *int16Samples = (const int16_t *)pcmData.bytes;

    // 创建播放格式的 buffer
    AVAudioFormat *format =
        [[AVAudioFormat alloc] initWithCommonFormat:AVAudioPCMFormatFloat32
                                         sampleRate:sampleRate
                                           channels:channels
                                        interleaved:NO];

    AVAudioPCMBuffer *buffer = [[AVAudioPCMBuffer alloc]
        initWithPCMFormat:format
            frameCapacity:(AVAudioFrameCount)sampleCount];
    buffer.frameLength = (AVAudioFrameCount)sampleCount;

    float *floatChannel = buffer.floatChannelData[0];
    for (NSUInteger i = 0; i < sampleCount; i++) {
      floatChannel[i] = (float)int16Samples[i] / 32768.0f;
    }

    // 调度播放
    __weak typeof(self) weakSelf = self;
    [self.playerNode scheduleBuffer:buffer
                  completionHandler:^{
                    __strong typeof(weakSelf) strongSelf = weakSelf;
                    if (!strongSelf)
                      return;

                    dispatch_async(strongSelf.playerQueue, ^{
                      strongSelf.playedSamples += sampleCount;
                    });
                  }];

    self.scheduledSamples += sampleCount;

    // 更新时长
    NSTimeInterval chunkDuration = (double)sampleCount / sampleRate;
    NSNumber *currentDuration = self.segmentDurations[segmentId];
    self.segmentDurations[segmentId] =
        @(currentDuration.doubleValue + chunkDuration);
  });
}

- (NSTimeInterval)playbackTimeForSegment:(NSString *)segmentId {
  if (![segmentId isEqualToString:self.currentSegmentId]) {
    return 0;
  }

  // 基于已播放的采样数估算时间
  return (double)self.playedSamples / self.playbackFormat.sampleRate;
}

- (NSTimeInterval)durationForSegment:(NSString *)segmentId {
  NSNumber *duration = self.segmentDurations[segmentId];
  return duration ? duration.doubleValue : 0;
}

#pragma mark - Progress Timer

- (void)startProgressTimer {
  dispatch_async(dispatch_get_main_queue(), ^{
    self.progressTimer =
        [NSTimer scheduledTimerWithTimeInterval:1.0 / 30.0
                                         target:self
                                       selector:@selector(updateProgress)
                                       userInfo:nil
                                        repeats:YES];
  });
}

- (void)stopProgressTimer {
  dispatch_async(dispatch_get_main_queue(), ^{
    [self.progressTimer invalidate];
    self.progressTimer = nil;
  });
}

- (void)updateProgress {
  if (!self.playing || !self.currentSegmentId) {
    return;
  }

  NSTimeInterval currentTime =
      [self playbackTimeForSegment:self.currentSegmentId];
  NSString *segmentId = self.currentSegmentId;

  if ([self.delegate respondsToSelector:@selector
                     (audioStreamPlayerDidUpdateTime:segmentId:)]) {
    [self.delegate audioStreamPlayerDidUpdateTime:currentTime
                                        segmentId:segmentId];
  }

  // 检查是否播放完成
  NSTimeInterval duration = [self durationForSegment:segmentId];
  if (duration > 0 && currentTime >= duration - 0.1) {
    // 播放完成
    dispatch_async(self.playerQueue, ^{
      if ([self.delegate respondsToSelector:@selector
                         (audioStreamPlayerDidFinishSegment:)]) {
        dispatch_async(dispatch_get_main_queue(), ^{
          [self.delegate audioStreamPlayerDidFinishSegment:segmentId];
        });
      }
    });
  }
}

@end