#include"WavFileReader.h"

WavFileReader::WavFileReader(){}

WavFileReader::~WavFileReader()
{
	CloseFile();
}


bool WavFileReader::OpenFile(const std::string& p_fileName)
{
	if (p_fileName == m_fileName) { 
		std::cerr << "已经打开了该WAV文件" << std::endl;
		return true;
	}
	
	m_file = std::ifstream(p_fileName, std::ios::binary);
	if (!m_file) {
		std::cerr << "无法打开WAV文件" << std::endl;
		return false;
	}
	if (ProcessWavFile()) {
		m_fileName = p_fileName;
		return true;
	}
	else {
		m_file.close();
		return false;
	}
}

void WavFileReader::CloseFile()
{
	if (m_file) { m_file.close(); }
	m_fileName = "";
}

bool WavFileReader::ProcessWavFile()
{
	/*处理文件头部分*/
	WavRIFF riff;
	WavFormat format;

	m_file.seekg(0, std::ios::end);
	m_fileSize = m_file.tellg();
	m_file.seekg(0, std::ios::beg);

	m_file.read(reinterpret_cast<char*>(&riff), sizeof(WavRIFF));
	if (strncmp(riff.id, "RIFF", 4) != 0 || strncmp(riff.waveFlag, "WAVE", 4) != 0){
		std::cerr << "不是有效的WAV文件!" << std::endl;
		CloseFile();
		return false;
	}

	m_file.read(reinterpret_cast<char*>(&format), sizeof(WavFormat));
	if (strncmp(format.id, "fmt ", 4) != 0){
		std::cerr << "format读取失败!" << std::endl;
		CloseFile();
		return false;
	}

	if (format.formatTag != 1){
		std::cerr << "数据格式非pcm，程序不支持!" << std::endl;
		CloseFile();
		return false;
	}

	/*处理文件后部数据*/
	while (m_file.tellg() < m_fileSize){
		WavChunk chunk;
		m_file.read(reinterpret_cast<char*>(&chunk), sizeof(WavChunk));
		if (strncmp(chunk.id, "LIST", 4) == 0){
			std::cout << "LIST" << std::endl;
			//ProcessLIST(chunk.dataLength);
			m_file.seekg(chunk.dataLength, std::ios::cur);
			continue;
		}
		else if (strncmp(chunk.id, "data", 4) == 0){
			std::cout << "data" << std::endl;
			m_dataOffset = m_file.tellg();
			m_dataLength = chunk.dataLength;
			m_file.seekg(chunk.dataLength, std::ios::cur);
			continue;
		}
		else{
			m_file.seekg(chunk.dataLength, std::ios::cur);
			continue;
		}
	}
	m_fileLength = riff.fileLength + 8;
	m_channels = format.channels;
	m_sampleRate = format.samplesPerSec;
	m_bitsPerSample = format.bitsPerSample;
	m_bytesPerSec = format.avgBytesPerSec;
	m_lastingTime = (float)m_dataLength / m_bytesPerSec;
	m_sampleNum = m_dataLength / (m_bitsPerSample / 8);
}


//TODO::
void WavFileReader::ProcessLIST(int listLength){
	while (listLength > 0){
		//if (strncmp(id, "INFO", 4) == 0){
			//char* info = new char[chunk.dataLength];
			//m_file.read(info, chunk.dataLength);
			//TODO:处理INFO

			//delete[] info;
		//}
		//else if (strncmp(id, "adtl", 4) == 0) {
			//char* adtl = new char[chunk.dataLength];
			//m_file.read(adtl, chunk.dataLength);
			//TODO:处理adtl

			//delete[] adtl;
		//}
		//else {
			//char* custom = new char[chunk.dataLength];
			//m_file.read(custom, chunk.dataLength);
			//TODO:处理自定义块

			//delete[] custom;
		//}
	}
}



int WavFileReader::ReadData(char* p_buffer, int p_position, int p_readLength){
	if (!m_file) { 
		std::cerr << "该WAV文件不存在" << std::endl;
		return 0; 
	}
	int filePosition = m_dataOffset + p_position;
	if(filePosition>m_fileSize){
		return 0;
	}
	m_file.seekg(m_dataOffset + p_position, std::ios::beg);
	m_file.read(p_buffer, p_readLength);
	int realLength = m_file.gcount();
	return realLength;
}

void WavFileReader::SetPosition(int p_position){
	if (m_file){
		m_file.seekg(p_position, std::ios::beg);
	}
}


int WavFileReader::GetPosition(){
	if (!m_file)
		return -1;
	return m_file.tellg();
}

int WavFileReader::GetFileLength(){
	if (!m_file)
		return -1;
	return m_fileLength;
}

int WavFileReader::GetDataLength()
{
	if (!m_file)
		return -1;
	return m_dataLength;
}

int WavFileReader::GetChannels(){
	if (!m_file)
		return -1;
	return m_channels;
}

int WavFileReader::GetSampleRate(){
	if (!m_file)
		return -1;
	return m_sampleRate;
}

int WavFileReader::GetBytesPerSec(){
	if (!m_file)
		return -1;
	return m_bytesPerSec;
}

int WavFileReader::GetBitsPerSample(){
	if (!m_file)
		return -1;
	return m_bitsPerSample;
}

float WavFileReader::GetLastingTime(){
	if (!m_file)
		return -1;
	return m_lastingTime;
}

int WavFileReader::GetSampleNum(){
	if (!m_file)
		return -1;
	return m_sampleNum;
}

int16_t WavFileReader::GetSampleValue(int p_index) {
	if (p_index >= m_sampleNum || !m_file)
		return -1;
	unsigned int bytesPerSample = m_bitsPerSample / 8;
	char* sampleBytes = new char[bytesPerSample];
	ReadData(sampleBytes, p_index * bytesPerSample, bytesPerSample);
	int16_t sampleValue = 0;
	for (int i = 0; i < bytesPerSample; ++i) {
		sampleValue |= static_cast<int16_t>(static_cast<unsigned char>(sampleBytes[i])) << (8 * i);
	}
	//
	delete[] sampleBytes;
	return sampleValue;
}