#include "WavWriter.hh"

#include "Mixer.hh"

#include "MSXException.hh"

#include "Math.hh"
#include "endian.hh"
#include "enumerate.hh"
#include "narrow.hh"
#include "ranges.hh"
#include "small_buffer.hh"

#include <array>
#include <vector>

namespace openmsx {

WavWriter::WavWriter(const std::string& filename,
                     unsigned channels, unsigned bits, unsigned frequency)
	: file(filename, "wb")
{
	// write wav header
	struct WavHeader {
		std::array<char, 4> chunkID;       // + 0 'RIFF'
		Endian::L32         chunkSize;     // + 4 total size
		std::array<char, 4> format;        // + 8 'WAVE'
		std::array<char, 4> subChunk1ID;   // +12 'fmt '
		Endian::L32         subChunk1Size; // +16 = 16 (fixed)
		Endian::L16         audioFormat;   // +20 =  1 (fixed)
		Endian::L16         numChannels;   // +22
		Endian::L32         sampleRate;    // +24
		Endian::L32         byteRate;      // +28
		Endian::L16         blockAlign;    // +32
		Endian::L16         bitsPerSample; // +34
		std::array<char, 4> subChunk2ID;   // +36 'data'
		Endian::L32         subChunk2Size; // +40
	} header;

	copy_to_range(std::string_view("RIFF"), header.chunkID);
	header.chunkSize     = 0; // actual value filled in later
	copy_to_range(std::string_view("WAVE"), header.format);
	copy_to_range(std::string_view("fmt "), header.subChunk1ID);
	header.subChunk1Size = 16;
	header.audioFormat   = 1;
	header.numChannels   = narrow<uint16_t>(channels);
	header.sampleRate    = frequency;
	header.byteRate      = (channels * frequency * bits) / 8;
	header.blockAlign    = narrow<uint16_t>((channels * bits) / 8);
	header.bitsPerSample = narrow<uint16_t>(bits);
	copy_to_range(std::string_view("data"), header.subChunk2ID);
	header.subChunk2Size = 0; // actual value filled in later

	file.write(std::span{&header, 1});
}

WavWriter::~WavWriter()
{
	try {
		// data chunk must have an even number of bytes
		if (bytes & 1) {
			std::array<uint8_t, 1> pad = {0};
			file.write(pad);
		}

		flush(); // write header
	} catch (MSXException&) {
		// ignore, can't throw from destructor
	}
}

void WavWriter::flush()
{
	Endian::L32 totalSize((bytes + 44 - 8 + 1) & ~1); // round up to even number
	Endian::L32 wavSize(bytes);

	file.seek(4);
	file.write(std::span{&totalSize, 1});
	file.seek(40);
	file.write(std::span{&wavSize, 1});
	file.seek(file.getSize()); // SEEK_END
	file.flush();
}

void Wav8Writer::write(std::span<const uint8_t> buffer)
{
	file.write(buffer);
	bytes += narrow<uint32_t>(buffer.size_bytes());
}

void Wav16Writer::write(std::span<const int16_t> buffer)
{
	if constexpr (Endian::BIG) {
		small_buffer<Endian::L16, 4096> buf(buffer);
		file.write(std::span{buf});
	} else {
		file.write(buffer);
	}
	bytes += narrow<uint32_t>(buffer.size_bytes());
}

static int16_t float2int16(float f)
{
	return Math::clipToInt16(lrintf(32768.0f * f));
}

void Wav16Writer::write(std::span<const float> buffer, float amp)
{
	std::vector<Endian::L16> buf_(buffer.size());
	std::span buf{buf_};
	std::ranges::transform(buffer, buf.data(), [=](float f) { return float2int16(f * amp); });
	file.write(buf);
	bytes += narrow<uint32_t>(buf.size_bytes());
}

void Wav16Writer::write(std::span<const StereoFloat> buffer, float ampLeft, float ampRight)
{
	std::vector<Endian::L16> buf(buffer.size() * 2);
	for (auto [i, s] : enumerate(buffer)) { // TODO use zip() in the future
		buf[2 * i + 0] = float2int16(s.left  * ampLeft);
		buf[2 * i + 1] = float2int16(s.right * ampRight);
	}
	std::span s{buf};
	file.write(s);
	bytes += narrow<uint32_t>(s.size_bytes());
}

void Wav16Writer::writeSilence(uint32_t samples)
{
	small_buffer<int16_t, 4096> buf_(samples, 0);
	std::span buf{buf_};
	file.write(buf);
	bytes += narrow<uint32_t>(buf.size_bytes());
}

} // namespace openmsx