/*
   audio/wavfile.cc
   This file is part of the Osirion project and is distributed under
   the terms of the GNU General Public License version 2
*/

#include "string.h"

#include <iostream>
#include <string>

#include "audio/wavfile.h"
#include "filesystem/filesystem.h"
#include "sys/sys.h"

namespace audio
{

PCM *Wav::load(std::string const & filename)
{
	if (!filename.size())
		return 0;

	filesystem::File *wav_file = filesystem::open(filename.c_str());
	if (!wav_file) {
		return 0;
	}

	unsigned char header[44];	
	memset(header, 0, sizeof(header));
	if (!wav_file->read(header, 44)) {
		con_warn << "Error reading " << filename << std::endl;
		filesystem::close(wav_file);
		return 0;
	}
	
	// header RIFF
	if (strncmp((char *)header, "RIFF", 4)) {
		con_warn << "Error reading " << filename << ": invalid RIFF header!" << std::endl;
		filesystem::close(wav_file);
		return 0;
	}

	// format WAVE
	if (strncmp((char *)header + 8, "WAVE", 4) != 0) {
		con_warn << "Error reading " << filename << ": invalid WAVE header!" << std::endl;
		filesystem::close(wav_file);
		return 0;
	}

	// file size
	//size_t chunksize = header[4] + (header[5] << 8) + (header[6] << 16) + (header[7] << 24);

	if (strncmp((char *)header + 12, "fmt ", 4) != 0) {
		con_warn << "Error reading " << filename << ": invalid format header!" << std::endl;
		filesystem::close(wav_file);
		return 0;
	}

	size_t subchunksize1 = header[16] + (header[17] << 8) + (header[18] << 16) + (header[19] << 24);
	size_t audioformat = header[20] + (header[21] << 8);

	if ((subchunksize1 != 16) || (audioformat != 1)) {
		con_warn << "Error reading " << filename << ": unrecognized file format!" << std::endl;
		filesystem::close(wav_file);
		return 0;

	}

	unsigned int channels = header[22] + (header[23] << 8);
	if ((channels < 1) || (channels > 2)) {
		con_warn << "Error reading " << filename << ": invalid number of channels!" << std::endl;
		filesystem::close(wav_file);
		return 0;
	}

	unsigned int samplerate = header[24] + ((size_t)header[25] << 8) + ((size_t)header[26] << 16) + ((size_t)header[27] << 24);
	//size_t byterate  = header[28] + (header[29] << 8) + (header[30] << 16) + (header[31] << 24);
	//size_t blockalign = header[32] + (header[33] << 8);
	size_t bitspersample = header[34] + (header[35] << 8);
	
	if (strncmp((char *)header + 36, "LIST", 4) == 0) {
		// this wav file contains meta data (author, title, ..)
		// byte 40 through 43 contains the metadata length instead of the datasize
		size_t metasize = header[40] + (header[41] << 8) + (header[42] << 16) + (header[43] << 24);
		wav_file->skip(metasize);
		
		// the data header follows the meta data, we overwrite the original metadata header
		if (!wav_file->read(header + 36, 8)) {
			con_warn << "Error reading " << filename << ": unexpected end of file!" << std::endl;
			filesystem::close(wav_file);
			return 0;
		}
	}

	if (strncmp((char *)header + 36, "data", 4) != 0) {
		con_warn << "Error reading " << filename << ": invalid data header!" << std::endl;
		filesystem::close(wav_file);
		return 0;
	}

	size_t datasize = header[40] + (header[41] << 8) + (header[42] << 16) + (header[43] << 24);

	PCM *pcm = new PCM(samplerate, bitspersample, channels, datasize);
	const size_t readblocksize = channels * (bitspersample / 8);
	size_t total_bytes = 0;

	while ((wav_file->read((void *)(*pcm)[total_bytes], readblocksize)) && (total_bytes < datasize)) {
		total_bytes += readblocksize;
	}

	if (total_bytes < datasize) {
		con_warn << "Error reading " << filename << ": file appears to be truncated!" << std::endl;
	}

	con_debug << "  " << filename << " " << pcm->samplerate() << "Hz " << pcm->bitspersample() << "bit " <<
	pcm->channels() << " chan " << pcm->size() << " bytes" << std::endl;

	filesystem::close(wav_file);
	return pcm;
}

}