#include <opus_types.h>
#include  <opus.h>
#include <cstring>
#include <memory>

#include <vector>
// https://github.com/mackron/dr_libs/blob/master/dr_wav.h
#define DR_WAV_IMPLEMENTATION

#include "dr_wav.h"

#define FRAME_SIZE 480
#define MAX_FRAME_SIZE (6*FRAME_SIZE)

#define MAX_CHANNELS 1
#define MAX_PACKET_SIZE (3*1276)

#pragma pack(push)
#pragma pack(1)

struct WavInfo {
	uint16_t channels;
	uint32_t sampleRate;
	uint32_t bitsPerSample;
};

#pragma pack(pop)

#ifndef  nullptr
#define  nullptr NULL
#endif

class FileStream {
public:
	FileStream() {
		cur_pos = 0;
	}

	void Append(const char *data, size_t size) {
		if (cur_pos + size > Size()) {
			vec.resize(cur_pos + size);
		}
		memcpy(vec.data() + cur_pos, data, size);
		cur_pos += size;
	}

	void AppendU32(uint32_t val) {
		Append((char *)(&val), sizeof(val));
	}

	char *Data() {
		return vec.data();
	}

	size_t Size() {
		return vec.size();
	}

	size_t Read(void *buff, size_t elemSize, size_t elemCount) {
		size_t readed = min((vec.size() - cur_pos), (elemCount * elemSize)) / elemSize;
		if (readed > 0) {
			memcpy(buff, vec.data() + cur_pos, readed * elemSize);
			cur_pos += readed * elemSize;
		}
		return readed;
	}

	bool SeekCur(int offset) {
		if (cur_pos + offset > vec.size()) {
			cur_pos = !vec.empty() ? (vec.size() - 1) : 0;
			return false;
		}
		else {
			cur_pos += offset;
			return true;
		}
	}

	bool SeekBeg(int offset = 0) {
		cur_pos = 0;
		return SeekCur(offset);
	}

	bool WriteToFile(const char *filename) {
		FILE *fin;
		fopen_s(&fin, filename, "wb");
		if (!fin) {
			return false;
		}
		fseek(fin, 0, SEEK_SET);
		fwrite(vec.data(), sizeof(char), vec.size(), fin);
		fclose(fin);
		return true;
	}

	bool ReadFromFile(const char *filename) {
		FILE *fin;
		fopen_s(&fin, filename, "rb");
		if (!fin) {
			return false;
		}
		fseek(fin, 0, SEEK_END);
		long fileSize = ftell(fin);
		vec.resize(static_cast<unsigned long long int>(fileSize));
		fseek(fin, 0, SEEK_SET);
		fread(vec.data(), sizeof(char), vec.size(), fin);
		fclose(fin);
		return true;
	}

private:
	std::vector<char> vec;
	size_t cur_pos;
};

bool Wav2Opus(FileStream *input, FileStream *output);

bool Opus2Wav(FileStream *input, FileStream *output);

bool wav2stream(char *input, FileStream *output);

bool stream2wav(FileStream *input, char *output);


bool wavWrite_int16(char *filename, int16_t *buffer, int sampleRate, uint32_t totalSampleCount) {
	drwav_data_format format = {};
	format.container = drwav_container_riff;     // <-- drwav_container_riff = normal WAV files, drwav_container_w64 = Sony Wave64.
	format.format = DR_WAVE_FORMAT_PCM;          // <-- Any of the DR_WAVE_FORMAT_* codes.
	format.channels = 1;
	format.sampleRate = (drwav_uint32)sampleRate;
	format.bitsPerSample = 16;
	drwav *pWav = drwav_open_file_write(filename, &format);
	if (pWav) {
		drwav_uint64 samplesWritten = drwav_write(pWav, totalSampleCount, buffer);
		drwav_uninit(pWav);
		if (samplesWritten != totalSampleCount) {
			fprintf(stderr, "ERROR\n");
			return false;
		}
		return true;
	}
	return false;
}

int16_t *wavRead_int16(char *filename, uint32_t *sampleRate, uint64_t *totalSampleCount) {
	unsigned int channels;
	int16_t *buffer = drwav_open_and_read_file_s16(filename, &channels, sampleRate, totalSampleCount);
	if (buffer == nullptr) {
		ods("[wavRead_int16() buffer==nullptr]\n");
		fprintf(stderr, "ERROR\n");
		return nullptr;
	}
	if (channels != 1) {
		ods("[wavRead_int16() channels!=1]\n");
		drwav_free(buffer);
		buffer = nullptr;
		*sampleRate = 0;
		*totalSampleCount = 0;
	}
	return buffer;
}

bool wav2stream(char *input, FileStream *output) {
	uint32_t sampleRate = 0;
	uint64_t totalSampleCount = 0;
	int16_t *wavBuffer = wavRead_int16(input, &sampleRate, &totalSampleCount);
	if (wavBuffer == nullptr)
	{
		return false;
	}
	WavInfo info = {};
	info.bitsPerSample = 16;
	info.sampleRate = sampleRate;
	info.channels = 1;
	output->SeekBeg();
	output->Append((char *)&info, sizeof(info));
	output->Append((char *)wavBuffer, (size_t)(totalSampleCount * sizeof(int16_t)));
	free(wavBuffer);
	return true;
}

bool stream2wav(FileStream *input, char *output) {
	WavInfo info = {};
	input->SeekBeg();
	size_t read = input->Read(&info, sizeof(info), 1);
	if (read != 1) {
		return false;
	}
	size_t totalSampleCount = (input->Size() - sizeof(info)) / 2;
	return wavWrite_int16(output, (int16_t *)(input->Data() + sizeof(info)), info.sampleRate,
		static_cast<uint32_t>(totalSampleCount));
}

bool Wav2Opus(FileStream *input, FileStream *output) {
	WavInfo in_info = {};
	input->SeekBeg();
	size_t read = input->Read(&in_info, sizeof(in_info), 1);
	if (read != 1) {
		return false;
	}
	uint32_t bitsPerSample = in_info.bitsPerSample;
	uint32_t sampleRate = in_info.sampleRate;
	uint16_t channels = in_info.channels;
	int err = 0;
	if (channels > MAX_CHANNELS) {
		return false;
	}
	OpusEncoder *encoder = opus_encoder_create(sampleRate, channels, OPUS_APPLICATION_AUDIO, &err);
	if (!encoder || err < 0) {
		fprintf(stderr, "failed to create an encoder: %s\n", opus_strerror(err));
		if (!encoder) {
			opus_encoder_destroy(encoder);
		}
		return false;
	}
	const uint16_t *data = (uint16_t *)(input->Data() + sizeof(in_info));
	size_t size = (input->Size() - sizeof(in_info)) / 2;
	opus_int16 pcm_bytes[FRAME_SIZE * MAX_CHANNELS];
	size_t index = 0;
	size_t step = static_cast<size_t>(FRAME_SIZE * channels);
	FileStream encodedData;
	unsigned char cbits[MAX_PACKET_SIZE];
	size_t frameCount = 0;
	size_t readCount = 0;
	while (index < size) {
		memset(&pcm_bytes, 0, sizeof(pcm_bytes));
		if (index + step <= size) {
			memcpy(pcm_bytes, data + index, step * sizeof(uint16_t));
			index += step;
		}
		else {
			readCount = size - index;
			memcpy(pcm_bytes, data + index, (readCount) * sizeof(uint16_t));
			index += readCount;
		}
		int nbBytes = opus_encode(encoder, pcm_bytes, channels * FRAME_SIZE, cbits, MAX_PACKET_SIZE);
		if (nbBytes < 0) {
			fprintf(stderr, "encode failed: %s\n", opus_strerror(nbBytes));
			break;
		}
		++frameCount;
		encodedData.AppendU32(static_cast<uint32_t>(nbBytes));
		encodedData.Append((char *)cbits, static_cast<size_t>(nbBytes));
	}
	WavInfo info = {};
	info.bitsPerSample = bitsPerSample;
	info.sampleRate = sampleRate;
	info.channels = channels;
	output->SeekBeg();
	output->Append((char *)&info, sizeof(info));
	output->Append(encodedData.Data(), encodedData.Size());
	opus_encoder_destroy(encoder);
	return true;
}

bool Opus2Wav(FileStream *input, FileStream *output) {
	WavInfo info = {};
	input->SeekBeg();
	size_t read = input->Read(&info, sizeof(info), 1);
	if (read != 1) {
		return false;
	}
	int channels = info.channels;
	if (channels > MAX_CHANNELS) {
		return false;
	}
	output->SeekBeg();
	output->Append((char *)&info, sizeof(info));
	int err = 0;
	OpusDecoder *decoder = opus_decoder_create(info.sampleRate, channels, &err);
	if (!decoder || err < 0) {
		fprintf(stderr, "failed to create decoder: %s\n", opus_strerror(err));
		if (!decoder) {
			opus_decoder_destroy(decoder);
		}
		return false;
	}
	unsigned char cbits[MAX_PACKET_SIZE];
	opus_int16 out[MAX_FRAME_SIZE * MAX_CHANNELS];
	int frameCount = 0;
	while (true) {
		uint32_t nbBytes;
		size_t readed = input->Read(&nbBytes, sizeof(uint32_t), 1);
		if (readed == 0) {
			break;
		}

		if (nbBytes > sizeof(cbits)) {
			fprintf(stderr, "nbBytes > sizeof(cbits)\n");
			break;
		}
		readed = input->Read(cbits, sizeof(char), nbBytes);
		if (readed != nbBytes) {
			fprintf(stderr, "readed != nbBytes\n");
			break;
		}
		int frame_size = opus_decode(decoder, cbits, nbBytes, out, MAX_FRAME_SIZE, 0);
		if (frame_size < 0) {
			fprintf(stderr, "decoder failed: %s\n", opus_strerror(frame_size));
			break;
		}
		++frameCount;
		output->Append((char *)out, channels * frame_size * sizeof(out[0]));
	}
	opus_decoder_destroy(decoder);
	return true;
}

void splitpath(const char *path, char *drv, char *dir, char *name, char *ext) {
	const char *end;
	const char *p;
	const char *s;
	if (path[0] && path[1] == ':') {
		if (drv) {
			*drv++ = *path++;
			*drv++ = *path++;
			*drv = '\0';
		}
	}
	else if (drv)
		*drv = '\0';
	for (end = path; *end && *end != ':';)
		end++;
	for (p = end; p > path && *--p != '\\' && *p != '/';)
		if (*p == '.') {
			end = p;
			break;
		}
	if (ext)
		for (s = end; (*ext = *s++);)
			ext++;
	for (p = end; p > path;)
		if (*--p == '\\' || *p == '/') {
			p++;
			break;
		}
	if (name) {
		for (s = p; s < end;)
			*name++ = *s++;
		*name = '\0';
	}
	if (dir) {
		for (s = path; s < p;)
			*dir++ = *s++;
		*dir = '\0';
	}
}

void opus2wav(const char *in_file, char *out_file) {
	FileStream input;
	FileStream output;
	input.ReadFromFile(in_file);
	Opus2Wav(&input, &output);
	stream2wav(&output, out_file);
}

void wav2opus(char *in_file, char *out_file) {
	FileStream input;
	FileStream output;
	if (wav2stream(in_file, &input))
	{
		ods("[wav2stream] OK\n");
	}
	else
	{
		ods("[wav2stream] NG\n");
	}
	if (Wav2Opus(&input, &output))
	{
		ods("[Wav2Opus] OK\n");
	}
	else
	{
		ods("[Wav2Opus] NG\n");
	}
	output.WriteToFile(out_file);
}

#if 0
int convert(char *path) {
	char *in_file = path;
	char drive[3];
	char dir[256];
	char fname[256];
	char ext[256];
	char out_file[1024];
	splitpath(in_file, drive, dir, fname, ext);
	if (memcmp(".wav", ext, strlen(ext)) == 0) {
		sprintf_s(out_file, "%s%s%s.opus", drive, dir, fname);
		wav2opus(in_file, out_file);
	}
	else if (memcmp(".opus", ext, strlen(ext)) == 0) {
		sprintf_s(out_file, "%s%s%s_opus.wav", drive, dir, fname);
		opus2wav(in_file, out_file);
	}
	return 0;
}
#endif