#include "globals.h"
#include "flags.h"
#include "fluxmap.h"
#include "sql.h"
#include "bytes.h"
#include "protocol.h"
#include "fluxsink/fluxsink.h"
#include "decoders/fluxmapreader.h"
#include "lib/fluxsink/fluxsink.pb.h"
#include "proto.h"
#include "fmt/format.h"
#include "scp.h"
#include <fstream>
#include <sys/stat.h>
#include <sys/types.h>

static int strackno(int track, int side)
{
	return (track << 1) | side;
}

static void write_le32(uint8_t dest[4], uint32_t v)
{
    dest[0] = v;
    dest[1] = v >> 8;
    dest[2] = v >> 16;
    dest[3] = v >> 24;
}

static void appendChecksum(uint32_t& checksum, const Bytes& bytes)
{
	ByteReader br(bytes);
	while (!br.eof())
		checksum += br.read_8();
}

class ScpFluxSink : public FluxSink
{
public:
	ScpFluxSink(const ScpFluxSinkProto& lconfig):
		_config(lconfig)
	{
		bool singlesided = config.heads().start() == config.heads().end();

		_fileheader.file_id[0] = 'S';
		_fileheader.file_id[1] = 'C';
		_fileheader.file_id[2] = 'P';
		_fileheader.version = 0x18; /* Version 1.8 of the spec */
		_fileheader.type = _config.type_byte();
		_fileheader.start_track = strackno(config.cylinders().start(), config.heads().start());
		_fileheader.end_track = strackno(config.cylinders().end(), config.heads().end());
		_fileheader.flags = (_config.align_with_index() ? SCP_FLAG_INDEXED : 0)
				| SCP_FLAG_96TPI;
		_fileheader.cell_width = 0;
		_fileheader.heads = singlesided;

		std::cout << fmt::format("SCP: writing 96 tpi {} file containing {} tracks\n",
			singlesided ? "single sided" : "double sided",
			_fileheader.end_track - _fileheader.start_track + 1
		);

	}

	~ScpFluxSink()
	{
		uint32_t checksum = 0;
		appendChecksum(checksum,
			Bytes((const uint8_t*) &_fileheader, sizeof(_fileheader))
				.slice(0x10));
		appendChecksum(checksum, _trackdata);
		write_le32(_fileheader.checksum, checksum);

		std::cout << "SCP: writing output file...\n";
		std::ofstream of(_config.filename(), std::ios::out | std::ios::binary);
		if (!of.is_open())
			Error() << "cannot open output file";
		of.write((const char*) &_fileheader, sizeof(_fileheader));
		_trackdata.writeTo(of);
		of.close();
	}

public:
	void writeFlux(int cylinder, int head, Fluxmap& fluxmap)
	{
		ByteWriter trackdataWriter(_trackdata);
		trackdataWriter.seekToEnd();
		int strack = strackno(cylinder, head);

		ScpTrack trackheader = {0};
		trackheader.header.track_id[0] = 'T';
		trackheader.header.track_id[1] = 'R';
		trackheader.header.track_id[2] = 'K';
		trackheader.header.strack = strack;

		FluxmapReader fmr(fluxmap);
		Bytes fluxdata;
		ByteWriter fluxdataWriter(fluxdata);

		if (_config.align_with_index())
			fmr.skipToEvent(F_BIT_INDEX);

		int revolution = 0;
		unsigned revTicks = 0;
		unsigned totalTicks = 0;
		unsigned ticksSinceLastPulse = 0;
		uint32_t startOffset = 0;
		while (revolution < 5)
		{
			unsigned ticks;
			int event;
			fmr.getNextEvent(event, ticks);

			ticksSinceLastPulse += ticks;
			totalTicks += ticks;
			revTicks += ticks;

			if (fmr.eof() || (event & F_BIT_INDEX))
			{
				auto* revheader = &trackheader.revolution[revolution];
				write_le32(revheader->offset, startOffset + sizeof(ScpTrack));
				write_le32(revheader->length, (fluxdataWriter.pos - startOffset) / 2);
				write_le32(revheader->index, revTicks * NS_PER_TICK / 25);
				revolution++;
				revheader++;
				revTicks = 0;
				startOffset = fluxdataWriter.pos;
			}

			if (event & F_BIT_PULSE)
			{
				unsigned t = ticksSinceLastPulse * NS_PER_TICK / 25;
				while (t >= 0x10000)
				{
					fluxdataWriter.write_be16(0);
					t -= 0x10000;
				}
				fluxdataWriter.write_be16(t);
				ticksSinceLastPulse = 0;
			}
		}

		_fileheader.revolutions = revolution - 1;
		write_le32(_fileheader.track[strack], trackdataWriter.pos + sizeof(ScpHeader));
		trackdataWriter += Bytes((uint8_t*)&trackheader, sizeof(trackheader));
		trackdataWriter += fluxdata;
	}

	operator std::string () const
	{
		return fmt::format("scp({})", _config.filename());
	}

private:
	const ScpFluxSinkProto& _config;
	ScpHeader _fileheader = {0};
	Bytes _trackdata;
};

std::unique_ptr<FluxSink> FluxSink::createScpFluxSink(const ScpFluxSinkProto& config)
{
    return std::unique_ptr<FluxSink>(new ScpFluxSink(config));
}