// Copyright (c) 2007-2008, Niels Martin Hansen
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
//   * Redistributions of source code must retain the above copyright notice,
//     this list of conditions and the following disclaimer.
//   * Redistributions in binary form must reproduce the above copyright notice,
//     this list of conditions and the following disclaimer in the documentation
//     and/or other materials provided with the distribution.
//   * Neither the name of the Aegisub Group nor the names of its contributors
//     may be used to endorse or promote products derived from this software
//     without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
//
// Aegisub Project http://www.aegisub.org/

#include "include/aegisub/audio_provider.h"

#include "audio_controller.h"

#include <libaegisub/file_mapping.h>
#include <libaegisub/fs.h>
#include <libaegisub/make_unique.h>

#include <vector>

class PCMAudioProvider : public AudioProvider {
	void FillBuffer(void *buf, int64_t start, int64_t count) const override;

protected:
	std::unique_ptr<agi::read_file_mapping> file;

	PCMAudioProvider(agi::fs::path const& filename)
	: file(agi::make_unique<agi::read_file_mapping>(filename))
	{
		float_samples = false;
	}

	const char *EnsureRangeAccessible(int64_t start, int64_t length) const {
		try {
			return file->read(start, static_cast<size_t>(length));
		}
		catch (agi::fs::FileSystemError const& e) {
			throw AudioDecodeError(e.GetMessage());
		}
	}

	template<typename T>
	T const& Read(int64_t start) const {
		return *reinterpret_cast<const T *>(EnsureRangeAccessible(start, sizeof(T)));
	}

	struct IndexPoint {
		int64_t start_byte;
		int64_t num_samples;
	};
	std::vector<IndexPoint> index_points;
};

void PCMAudioProvider::FillBuffer(void *buf, int64_t start, int64_t count) const {
	auto write_buf = static_cast<char *>(buf);
	auto bps = bytes_per_sample * channels;
	int64_t pos = 0;

	for (auto const& ip : index_points) {
		if (count == 0) break;
		if (pos + ip.num_samples < start) {
			pos += ip.num_samples;
			continue;
		}

		auto read_offset = start - pos;
		auto read_count = std::min(count, ip.num_samples - read_offset);
		auto bytes = read_count * bps;
		memcpy(write_buf, file->read(ip.start_byte + read_offset * bps, bytes), bytes);

		write_buf += bytes;
		count -= read_count;
		start += read_count;
		pos += ip.num_samples;
	}
}

/// @class RiffWavPCMAudioProvider
/// @brief RIFF WAV PCM provider
///
/// Overview of RIFF WAV: <http://www.sonicspot.com/guide/wavefiles.html>
class  RiffWavPCMAudioProvider : public PCMAudioProvider {
	struct ChunkHeader {
		/// Always "RIFF"
		char type[4];
		/// File size minus sizeof(ChunkHeader) (i.e. 8)
		uint32_t size;
	};

	struct RIFFChunk {
		ChunkHeader ch;
		/// Always "WAVE"
		char format[4];
	};

	struct fmtChunk {
		/// compression format used
		/// We support only PCM (0x1)
		uint16_t compression;

		/// Number of channels
		uint16_t channels;

		/// Samples per second
		uint32_t samplerate;

		/// Bytes per second
		/// can't always be trusted
		uint32_t avg_bytes_sec;

		/// Bytes per sample
		uint16_t block_align;

		/// Bits per sample that are actually used; rest should be ignored
		uint16_t significant_bits_sample;
		// Here was supposed to be some more fields but we don't need them
		// and just skipping by the size of the struct wouldn't be safe
		// either way, as the fields can depend on the compression.
	};

	static bool CheckFourcc(const char (&str1)[4], const char (&str2)[5])
	{
		return str1[0] == str2[0]
			&& str1[1] == str2[1]
			&& str1[2] == str2[2]
			&& str1[3] == str2[3];
	}

public:

	RiffWavPCMAudioProvider(agi::fs::path const& filename)
	: PCMAudioProvider(filename)
	{
		// Read header
		auto const& header = Read<RIFFChunk>(0);

		// Check magic values
		if (!CheckFourcc(header.ch.type, "RIFF"))
			throw agi::AudioDataNotFoundError("File is not a RIFF file");
		if (!CheckFourcc(header.format, "WAVE"))
			throw agi::AudioDataNotFoundError("File is not a RIFF WAV file");

		// How far into the file we have processed.
		// Must be incremented by the riff chunk size fields.
		uint32_t filepos = sizeof(header);
		// Count how much more data we can have in the entire file
		// The first 4 bytes are already eaten by the header.format field
		auto total_data = std::min<uint32_t>(header.ch.size - 4 + filepos, file->size());

		bool got_fmt_header = false;

		// Inherited from AudioProvider
		num_samples = 0;

		// Continue reading chunks until out of data
		while (filepos + sizeof(ChunkHeader) < total_data) {
			auto const& ch = Read<ChunkHeader>(filepos);
			filepos += sizeof(ch);

			if (CheckFourcc(ch.type, "fmt ")) {
				if (got_fmt_header) throw agi::AudioProviderOpenError("Invalid file, multiple 'fmt ' chunks");
				got_fmt_header = true;

				auto const& fmt = Read<fmtChunk>(filepos);

				if (fmt.compression != 1)
					throw agi::AudioProviderOpenError("Can't use file, not PCM encoding");

				// Set stuff inherited from the AudioProvider class
				sample_rate = fmt.samplerate;
				channels = fmt.channels;
				bytes_per_sample = (fmt.significant_bits_sample + 7) / 8; // round up to nearest whole byte
			}
			else if (CheckFourcc(ch.type, "data")) {
				// This won't pick up 'data' chunks inside 'wavl' chunks
				// since the 'wavl' chunks wrap those.

				if (!got_fmt_header) throw agi::AudioProviderOpenError("Found 'data' chunk before 'fmt ' chunk, file is invalid.");

				auto samples = std::min(total_data - filepos, ch.size) / bytes_per_sample / channels;
				index_points.push_back(IndexPoint{filepos, samples});
				num_samples += samples;
			}

			// Support wavl (wave list) chunks too?

			// Update counters
			// Make sure they're word aligned
			filepos += (ch.size + 1) & ~1;
		}

		decoded_samples = num_samples;
	}
};

static const uint8_t w64GuidRIFF[16] = {
	// {66666972-912E-11CF-A5D6-28DB04C10000}
	0x72, 0x69, 0x66, 0x66, 0x2E, 0x91, 0xCF, 0x11, 0xA5, 0xD6, 0x28, 0xDB, 0x04, 0xC1, 0x00, 0x00
};

static const uint8_t w64GuidWAVE[16] = {
	// {65766177-ACF3-11D3-8CD1-00C04F8EDB8A}
	0x77, 0x61, 0x76, 0x65, 0xF3, 0xAC, 0xD3, 0x11, 0x8C, 0xD1, 0x00, 0xC0, 0x4F, 0x8E, 0xDB, 0x8A
};

static const uint8_t w64Guidfmt[16] = {
	// {20746D66-ACF3-11D3-8CD1-00C04F8EDB8A}
	0x66, 0x6D, 0x74, 0x20, 0xF3, 0xAC, 0xD3, 0x11, 0x8C, 0xD1, 0x00, 0xC0, 0x4F, 0x8E, 0xDB, 0x8A
};

static const uint8_t w64Guiddata[16] = {
	// {61746164-ACF3-11D3-8CD1-00C04F8EDB8A}
	0x64, 0x61, 0x74, 0x61, 0xF3, 0xAC, 0xD3, 0x11, 0x8C, 0xD1, 0x00, 0xC0, 0x4F, 0x8E, 0xDB, 0x8A
};

/// @class Wave64AudioProvider
/// @brief Sony Wave64 audio provider
///
/// http://www.vcs.de/fileadmin/user_upload/MBS/PDF/Whitepaper/Informations_about_Sony_Wave64.pdf
class Wave64AudioProvider final : public PCMAudioProvider {
	// Here's some copy-paste from the FFmpegSource2 code

	/// http://msdn.microsoft.com/en-us/library/dd757720(VS.85).aspx
	struct WaveFormatEx {
		uint16_t wFormatTag;
		uint16_t nChannels;
		uint32_t nSamplesPerSec;
		uint32_t nAvgBytesPerSec;
		uint16_t nBlockAlign;
		uint16_t wBitsPerSample;
		uint16_t cbSize;
	};

	struct RiffChunk {
		uint8_t riff_guid[16];
		uint64_t file_size;
		uint8_t format_guid[16];
	};

	struct FormatChunk {
		uint8_t chunk_guid[16];
		uint64_t chunk_size;
		WaveFormatEx format;
		uint8_t padding[6];
	};

	struct DataChunk {
		uint8_t chunk_guid[16];
		uint64_t chunk_size;
	};

	bool CheckGuid(const uint8_t *guid1, const uint8_t *guid2) {
		return memcmp(guid1, guid2, 16) == 0;
	}

public:

	Wave64AudioProvider(agi::fs::path const& filename)
	: PCMAudioProvider(filename)
	{
		size_t smallest_possible_file = sizeof(RiffChunk) + sizeof(FormatChunk) + sizeof(DataChunk);

		if (file->size() < smallest_possible_file)
			throw agi::AudioDataNotFoundError("File is too small to be a Wave64 file");

		// Read header
		auto const& header = Read<RiffChunk>(0);

		// Check magic values
		if (!CheckGuid(header.riff_guid, w64GuidRIFF))
			throw agi::AudioDataNotFoundError("File is not a Wave64 RIFF file");
		if (!CheckGuid(header.format_guid, w64GuidWAVE))
			throw agi::AudioDataNotFoundError("File is not a Wave64 WAVE file");

		// How far into the file we have processed.
		// Must be incremented by the riff chunk size fields.
		uint64_t filepos = sizeof(header);
		// Count how much more data we can have in the entire file
		auto total_data = std::min<uint64_t>(header.file_size, file->size());

		bool got_fmt_header = false;

		// Inherited from AudioProvider
		num_samples = 0;

		// Continue reading chunks until out of data
		while (filepos + 24 < total_data) {
			uint8_t *chunk_guid = (uint8_t*)EnsureRangeAccessible(filepos, 16);
			auto chunk_size = std::min(total_data - filepos, Read<uint64_t>(filepos + 16)) - 24;
			filepos += 24;

			if (CheckGuid(chunk_guid, w64Guidfmt)) {
				if (got_fmt_header)
					throw agi::AudioProviderOpenError("Bad file, found more than one 'fmt' chunk");

				auto const& fmt = Read<FormatChunk>(filepos);
				if (fmt.format.wFormatTag != 1)
					throw agi::AudioProviderOpenError("File is not uncompressed PCM");

				got_fmt_header = true;
				// Set stuff inherited from the AudioProvider class
				sample_rate = fmt.format.nSamplesPerSec;
				channels = fmt.format.nChannels;
				bytes_per_sample = (fmt.format.wBitsPerSample + 7) / 8; // round up to nearest whole byte
			}
			else if (CheckGuid(chunk_guid, w64Guiddata)) {
				if (!got_fmt_header)
					throw agi::AudioProviderOpenError("Found 'data' chunk before 'fmt ' chunk, file is invalid.");

				auto samples = chunk_size / bytes_per_sample / channels;
				index_points.push_back(IndexPoint{
					static_cast<int64_t>(filepos),
					static_cast<int64_t>(samples)});
				num_samples += samples;
			}

			// Update counters
			// Make sure they're 64 bit aligned
			filepos += (chunk_size + 7) & ~7;
		}

		decoded_samples = num_samples;
	}
};

std::unique_ptr<AudioProvider> CreatePCMAudioProvider(agi::fs::path const& filename, agi::BackgroundRunner *) {
	bool wrong_file_type = true;
	std::string msg;

	try {
		return agi::make_unique<RiffWavPCMAudioProvider>(filename);
	}
	catch (agi::AudioDataNotFoundError const& err) {
		msg = "RIFF PCM WAV audio provider: " + err.GetMessage();
	}
	catch (agi::AudioProviderOpenError const& err) {
		wrong_file_type = false;
		msg = "RIFF PCM WAV audio provider: " + err.GetMessage();
	}

	try {
		return agi::make_unique<Wave64AudioProvider>(filename);
	}
	catch (agi::AudioDataNotFoundError const& err) {
		msg += "\nWave64 audio provider: " + err.GetMessage();
	}
	catch (agi::AudioProviderOpenError const& err) {
		wrong_file_type = false;
		msg += "\nWave64 audio provider: " + err.GetMessage();
	}

	if (wrong_file_type)
		throw agi::AudioDataNotFoundError(msg);
	else
		throw agi::AudioProviderOpenError(msg);
}