#import "LFHardwareVideoEncoder.h"
#import <VideoToolbox/VideoToolbox.h>

@interface LFHardwareVideoEncoder (){
    VTCompressionSessionRef compressionSession; // 編碼器
    NSInteger frameCount; // 幀數（用於設置關鍵幀）
    NSData *sps;
    NSData *pps;
    FILE *fp;
    BOOL enabledWriteVideoFile;
}

@property (nonatomic, strong) LFLiveVideoConfiguration 
 
*configuration;
@property (nonatomic, weak) id<LFVideoEncodingDelegate> h264Delegate;
@property (nonatomic) NSInteger currentVideoBitRate;
@property (nonatomic) BOOL isBackGround;

@end

@implementation LFHardwareVideoEncoder

#pragma mark -- LifeCycle
- (instancetype)initWithVideoStreamConfiguration:(LFLiveVideoConfiguration *)configuration {
    
 
if (self = [super init]) {
        NSLog(@"USE LFHardwareVideoEncoder");
        _configuration = configuration;
        [self resetCompressionSession];
        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(willEnterBackground:) name:UIApplicationWillResignActiveNotification 
 
object:nil];
        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(willEnterForeground:) name:UIApplicationDidBecomeActiveNotification object:nil];
#ifdef DEBUG
        enabledWriteVideoFile = NO;
        [self initForFilePath];
#endif
        
    }
    return self;
}

- (void)resetCompressionSession {
   
    if (compressionSession) {
        /*
         1.強制完成一些或全部未處理的視頻幀數據
         2.編碼器失效（類似於讓Timer失效）
         3.釋放內存（VTCompressionSession是一套C函數，需要開發者手動管理內存）
         4.編碼器置空
         */
        VTCompressionSessionCompleteFrames(compressionSession, kCMTimeInvalid);
        VTCompressionSessionInvalidate(compressionSession);
        CFRelease(compressionSession);
        compressionSession = NULL;
    }

    /*
     創建編碼器
     1.分配器，NULL標識使用默認的
     2.視頻幀的像素寬
     3.視頻幀的像素高
     4.編碼類型
     5.如果使用指定的視頻編碼器就傳值，NULL表示VideoToolBox自己創建一個
     6.源緩存，NULL表示不使用VideoToolBox創建的，而使用費VTB分配的內存，這樣可以拷貝圖片數據
     7.壓縮數據分配器，NULL表示使用默認的
     8.回調函數（編碼後的視頻幀數據）
     9.回調方法所在的對象類實例，也會傳遞給回調函數（回調函數會被VTCompressionSessionEncodeFrame函數喚醒並且異步執行）
     10.指向編碼器的內存地址
     */
    OSStatus status = VTCompressionSessionCreate(NULL,
                                                 _configuration.videoSize.width,
                                                 _configuration.videoSize.height,
                                                 kCMVideoCodecType_H264,
                                                 NULL,
                                                 NULL,
                                                 NULL,
                                                 VideoCompressonOutputCallback,
                                                 (__bridge void *)self,
                                                 &compressionSession);
    if (status != noErr) {
        return;
    }

    _currentVideoBitRate = _configuration.videoBitRate; // 值越大效果越好，幀數據越大
    VTSessionSetProperty(compressionSession,
                         kVTCompressionPropertyKey_MaxKeyFrameInterval,
                         (__bridge CFTypeRef)@(_configuration.videoMaxKeyframeInterval));
    VTSessionSetProperty(compressionSession,
                         kVTCompressionPropertyKey_MaxKeyFrameIntervalDuration,
                         (__bridge CFTypeRef)@(_configuration.videoMaxKeyframeInterval/_configuration.videoFrameRate));
    VTSessionSetProperty(compressionSession,
                         kVTCompressionPropertyKey_ExpectedFrameRate,
                         (__bridge CFTypeRef)@(_configuration.videoFrameRate));
    VTSessionSetProperty(compressionSession,
                         kVTCompressionPropertyKey_AverageBitRate,
                         (__bridge CFTypeRef)@(_configuration.videoBitRate));
   
    NSArray *limit = @[@(_configuration.videoBitRate * 1.5/8), @(1)]; // 關鍵幀間隔，越低效果越好，幀數據越大
   
    VTSessionSetProperty(compressionSession,
                         kVTCompressionPropertyKey_DataRateLimits,
                         (__bridge CFArrayRef)limit);
    VTSessionSetProperty(compressionSession,
                         kVTCompressionPropertyKey_RealTime, // 實施編碼輸出，降低編碼延遲
                         kCFBooleanTrue);
    VTSessionSetProperty(compressionSession,
                         kVTCompressionPropertyKey_ProfileLevel,
                         kVTProfileLevel_H264_Main_AutoLevel);
    VTSessionSetProperty(compressionSession,
                         kVTCompressionPropertyKey_AllowFrameReordering,
                         kCFBooleanTrue);
    VTSessionSetProperty(compressionSession,
                         kVTCompressionPropertyKey_H264EntropyMode,
                         kVTH264EntropyMode_CABAC);
    VTCompressionSessionPrepareToEncodeFrames(compressionSession);

}

- (void)setVideoBitRate:(NSInteger)videoBitRate {
    if(_isBackGround) return;
    VTSessionSetProperty(compressionSession,
                         kVTCompressionPropertyKey_AverageBitRate,
                         (__bridge CFTypeRef)@(videoBitRate));
    NSArray *limit = @[@(videoBitRate * 1.5/8), @(1)];
    VTSessionSetProperty(compressionSession,
                         kVTCompressionPropertyKey_DataRateLimits,
                         (__bridge CFArrayRef)limit);
    _currentVideoBitRate = videoBitRate;
}

- (NSInteger)videoBitRate {
    return _currentVideoBitRate;
}

- (void)dealloc {
    if (compressionSession != NULL) {
        VTCompressionSessionCompleteFrames(compressionSession, kCMTimeInvalid);

        VTCompressionSessionInvalidate(compressionSession);
        CFRelease(compressionSession);
        compressionSession = NULL;
    }
    [[NSNotificationCenter defaultCenter] removeObserver:self];
}

#pragma mark -- LFVideoEncoder
- (void)encodeVideoData:(CVPixelBufferRef)pixelBuffer timeStamp:(uint64_t)timeStamp {
    if(_isBackGround) return;
    frameCount++;
    
    /*
     CMTime CMTimeMake (
                        int64_t value,    //表示 當前視頻播放到的第幾楨數
                        int32_t timescale //每秒的幀數
     );
     */
    CMTime presentationTimeStamp = CMTimeMake(frameCount, (int32_t)_configuration.videoFrameRate);
    VTEncodeInfoFlags flags;
    
    CMTime duration = CMTimeMake(1, (int32_t)_configuration.videoFrameRate);

    // 設置當前幀為 關鍵幀.關鍵幀間隔在config文件中定義了，是幀率24（fps）*2，即 frameCount % (24*2) = 0就設置為關鍵幀
    NSDictionary *properties = nil;
    if (frameCount % (int32_t)_configuration.videoMaxKeyframeInterval == 0) {
        properties = @{(__bridge NSString *)kVTEncodeFrameOptionKey_ForceKeyFrame: @YES};
    }
    NSNumber *timeNumber = @(timeStamp);

    
    /* 開啟幀編碼
     1.編碼器
     2.一個將要被壓縮的視頻幀，不能為空
     3.展示當前幀的時間戳
     4.播放24幀需要多長時間，默認kCMTimeInvalid
     5.當前幀的屬性（主要判斷是否為關鍵幀）
     6.當前幀關聯的值（時間戳），會傳遞給回調函數
     7.編碼操作的信息
     */
    OSStatus status = VTCompressionSessionEncodeFrame(compressionSession,
                                                      pixelBuffer,
                                                      presentationTimeStamp,
                                                      duration,
                                                      (__bridge CFDictionaryRef)properties,
                                                      (__bridge_retained void *)timeNumber,
                                                      &flags);
    if(status != noErr){
        [self resetCompressionSession];
    }
}

- (void)stopEncoder {
    VTCompressionSessionCompleteFrames(compressionSession, kCMTimeIndefinite);
}

- (void)setDelegate:(id<LFVideoEncodingDelegate>)delegate {
    _h264Delegate = delegate;
}

#pragma mark -- Notification
- (void)willEnterBackground:(NSNotification*)notification{
    _isBackGround = YES;
}

- (void)willEnterForeground:(NSNotification*)notification{
    [self resetCompressionSession];
    _isBackGround = NO;
}

#pragma mark -- VideoCallBack
/*
 1.可以引用到幀編碼函數中的參數
 2.原始幀數據的引用值（未編碼之前）
 3.編碼是否成功
 4.編碼操作的信息
 5.編碼後的幀（如果編碼成功並且沒有丟幀，反之參數為NULL）
 */
static void VideoCompressonOutputCallback(void *VTref,
                                          void *VTFrameRef,
                                          OSStatus status,
                                          VTEncodeInfoFlags infoFlags,
                                          CMSampleBufferRef sampleBuffer){
    // 編碼失敗 或 丟幀
    if (!sampleBuffer) return;
    
    /*
     返回一個不可變數組（元素是dictionary）
     1.訪問的對象
     2.如果樣本為空是否創建一個空數組
     */
    CFArrayRef array = CMSampleBufferGetSampleAttachmentsArray(sampleBuffer, true);
    if (!array) return;
    
    // 獲取數組中第一個dictionary數據
    CFDictionaryRef dic = (CFDictionaryRef)CFArrayGetValueAtIndex(array, 0);
    if (!dic) return;

    // 是否是關鍵幀
    BOOL keyframe = !CFDictionaryContainsKey(dic, kCMSampleAttachmentKey_NotSync);
    
    // 獲取幀編碼函數中的時間戳參數
    uint64_t timeStamp = [((__bridge_transfer NSNumber *)VTFrameRef) longLongValue];

    // 獲取回調函數所在類的實例對象
    LFHardwareVideoEncoder *videoEncoder = (__bridge LFHardwareVideoEncoder *)VTref;
    if (status != noErr) {
        return;
    }

    // 關鍵幀 且 尚未設置sps
    if (keyframe && !videoEncoder->sps) {
        // 獲取樣本緩存中的一個樣本的格式描述（獲取幀描述信息）
        CMFormatDescriptionRef format = CMSampleBufferGetFormatDescription(sampleBuffer);

        // sps和pps一般保存在視頻文件頭中。sps在前pps在後
        
        size_t sparameterSetSize, sparameterSetCount;
        const uint8_t *sparameterSet;
        /*
         獲取sps信息（序列參數集） H.264碼流中第一個NALU單元，保存了一組編碼視頻序列的全局參數.
         1. 格式信息
         2. sps信息在format中的索引
         3. 指向參數集的指針，如果不需要這些信息傳NULL
         4. 指向參數字節多少的指針，
         5. 指向參數數量的指針，
         6.
         */
        OSStatus statusCode = CMVideoFormatDescriptionGetH264ParameterSetAtIndex(format,
                                                                                 0,
                                                                                 &sparameterSet,
                                                                                 &sparameterSetSize,
                                                                                 &sparameterSetCount,
                                                                                 0);
        if (statusCode == noErr) {
            size_t pparameterSetSize, pparameterSetCount;
            const uint8_t *pparameterSet;
            // 獲取pps信息（圖像參數集）H.264碼流中第二個NALU單元，
            OSStatus statusCode = CMVideoFormatDescriptionGetH264ParameterSetAtIndex(format,
                                                                                     1,
                                                                                     &pparameterSet,
                                                                                     &pparameterSetSize,
                                                                                     &pparameterSetCount,
                                                                                     0);
            // 寫入本地
            if (statusCode == noErr) {
                // 設置sps、pps
                videoEncoder->sps = [NSData dataWithBytes:sparameterSet length:sparameterSetSize];
                videoEncoder->pps = [NSData dataWithBytes:pparameterSet length:pparameterSetSize];

                /*
                 處理數據時，sps、pps放在H264視頻流的最前端
                 編碼的視頻寫入本地時，需要添加4個字節的頭信息並且卸載H264文件最前面
                 如果推流，sps、pps、頭信息放入flv數據區即可。
                 */
                if (videoEncoder->enabledWriteVideoFile) {
                    NSMutableData *data = [[NSMutableData alloc] init];
                    uint8_t header[] = {0x00, 0x00, 0x00, 0x01};
                    [data appendBytes:header length:4];
                    [data appendData:videoEncoder->sps];
                    [data appendBytes:header length:4];
                    [data appendData:videoEncoder->pps];
                    fwrite(data.bytes, 1, data.length, videoEncoder->fp);
                }
            }
        }
    }


    
    CMBlockBufferRef dataBuffer = CMSampleBufferGetDataBuffer(sampleBuffer);
    size_t length, totalLength;
    char *dataPointer;
    
    /*
     獲取IDR信息
     1.媒體信息數據
     2.IDR信息在媒體信息數據中的索引
     3.IDR信息數據長度
     4.媒體信息數據長度
     5.媒體信息數據的字節數（前4個字節是數據長度）
     */
    OSStatus statusCodeRet = CMBlockBufferGetDataPointer(dataBuffer,
                                                         0,
                                                         &length,
                                                         &totalLength,
                                                         &dataPointer);
    
    if (statusCodeRet == noErr) {
        size_t bufferOffset = 0;
        static const int AVCCHeaderLength = 4;
        
        // 循環獲取NALU數據，真正用來播放的視頻幀數據
        while (bufferOffset < totalLength - AVCCHeaderLength) {
            // Read the NAL unit length
            uint32_t NALUnitLength = 0;
            memcpy(&NALUnitLength, dataPointer + bufferOffset, AVCCHeaderLength);

            // 大小端轉換
            NALUnitLength = CFSwapInt32BigToHost(NALUnitLength);

            LFVideoFrame *videoFrame = [LFVideoFrame new];
            videoFrame.timestamp = timeStamp;
            videoFrame.data = [[NSData alloc] initWithBytes:(dataPointer + bufferOffset + AVCCHeaderLength) length:NALUnitLength];
            videoFrame.isKeyFrame = keyframe;
            videoFrame.sps = videoEncoder->sps;
            videoFrame.pps = videoEncoder->pps;

            if (videoEncoder.h264Delegate && [videoEncoder.h264Delegate respondsToSelector:@selector(videoEncoder:videoFrame:)]) {
                [videoEncoder.h264Delegate videoEncoder:videoEncoder videoFrame:videoFrame];
            }

            if (videoEncoder->enabledWriteVideoFile) {
                NSMutableData *data = [[NSMutableData alloc] init];
                if (keyframe) {
                    uint8_t header[] = {0x00, 0x00, 0x00, 0x01};
                    [data appendBytes:header length:4];
                } else {
                    uint8_t header[] = {0x00, 0x00, 0x01};
                    [data appendBytes:header length:3];
                }
                [data appendData:videoFrame.data];

                fwrite(data.bytes, 1, data.length, videoEncoder->fp);
            }

            bufferOffset += AVCCHeaderLength + NALUnitLength;
        }
    }
}

- (void)initForFilePath {
    NSString *path = [self GetFilePathByfileName:@"IOSCamDemo.h264"];
    NSLog(@"%@", path);
    self->fp = fopen([path cStringUsingEncoding:NSUTF8StringEncoding], "wb");
}

- (NSString *)GetFilePathByfileName:(NSString*)filename {
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    NSString *writablePath = [documentsDirectory stringByAppendingPathComponent:filename];
    return writablePath;
}

ios 視頻流H264硬編碼---分解LFLiveKit