#include "reader.h"

#include "debug.h"

#include <algorithm>
#include <cstddef>
#include <cstdint>
#include <cstring>
#include <iostream>

namespace TehImage
{

	Reader::Reader(std::string filename, FileEndianness fileEndianness)
	{
		file = fopen(filename.c_str(), "rb");
		refreshBuffer();
		ready = true;
		this->fileEndianness = fileEndianness;
	}
	Reader::~Reader()
	{
		if(ready)
			fclose(file);
	}

	char Reader::readByte()
	{
		if(pos == BUFFER_SIZE)
			refreshBuffer();
		return buffer[pos++];
	}

	void Reader::refreshBuffer()
	{
		fread(buffer, sizeof(buffer), 1, file);
		pos = 0;
	}

	void Reader::convertEndian(uint8_t* out, size_t bytes)
	{
		constexpr bool LE = std::endian::native == std::endian::little;
		constexpr bool BE = !LE;
		if(fileEndianness == NO_CONVERT || (fileEndianness == BIG && BE) || (fileEndianness == LITTLE && LE))
		{
			for(int i = 0; i < bytes; i++)
			{
				out[i] = readByte();
			}
			return;
		}
		for(int i = 0; i < bytes; i++)
		{
			out[bytes - 1 - i] = readByte();
		}
	}

	template<> uint8_t Reader::readData<uint8_t>()
	{
		return readByte();
	}

	template<> uint16_t Reader::readData<uint16_t>()
	{
		uint16_t num = 0;
		convertEndian((uint8_t*)&num, 2);
		// for(int i = 0; i < 2; i++)
		// {
		// 	num += readByte() << (8 * (1-i));
		// }
		return num;
	}

	template<> uint32_t Reader::readData<uint32_t>()
	{
		uint32_t num = 0;
		convertEndian((uint8_t*)&num, 4);
		// for(int i = 0; i < 4; i++)
		// {
		// 	// uint8_t byte = readByte();
		// 	// debug(std::cout << std::hex << 0+byte << " ");
		// 	num += ((uint8_t) readByte()) << (8 * (3-i));
		// }
		// // debug(std::cout << std::dec << std::endl);
		return num;
	}

	template<> uint64_t Reader::readData<uint64_t>()
	{
		uint64_t num = 0;
		convertEndian((uint8_t*)&num, 8);
		// for(int i = 0; i < 8; i++)
		// {
		// 	num += readByte() << (8 * (7-i));
		// }
		return num;
	}

	void Reader::readBytes(char* out, size_t len)
	{
		while(len > 0)
		{
			size_t bytesToRead = std::min(len, BUFFER_SIZE - pos);
			if(bytesToRead == 0)
			{
				refreshBuffer();
				continue;
			}
			memcpy(out, buffer + pos, bytesToRead);
			out += bytesToRead;
			len -= bytesToRead;
			pos += bytesToRead;
		}
	}

	void Reader::skipBytes(size_t len)
	{
		while(len > 0)
		{
			size_t bytesToRead = std::min(len, BUFFER_SIZE - pos);
			if(bytesToRead == 0)
			{
				refreshBuffer();
				continue;
			}
			len -= bytesToRead;
			pos += bytesToRead;
		}
	}

	void Reader::close()
	{
		fclose(file);
		ready = false;
	}

}