#pragma once

#include <cstdint>
#include <string>

namespace FAT32 {

	using ClusterNr = uint32_t;
	using AbsOffset = uint32_t;
	using AbsPos = uint32_t;

	struct FSDesc {
		uint16_t bytesPerSector;
		uint8_t sectorsPerCluster;
		uint16_t numReservedSectors;
		uint8_t numberOfFATs;
		uint32_t sectorsPerFAT;
		ClusterNr rootDirFirstCluster;
	};

	struct Precomputed {
		uint32_t bytesPerCluster;
		AbsPos startOfFAT;					// absolute byte offset where the FAT begins
		AbsPos startOfFirstDataCluster;		// absolute byte offset where the first cluster is
		AbsPos startOfFirstRootDirCluster;	// absolute byte offset where the first root dir cluster is
		uint32_t dirEntriesPerSector;
	};

	union Attributes {
		uint8_t raw;
		struct {
			uint8_t readOnly : 1;
			uint8_t hidden : 1;
			uint8_t system : 1;
			uint8_t volumeID : 1;
			uint8_t directory : 1;
			uint8_t archive : 1;
			uint8_t unused1 : 1;
			uint8_t unused2 : 1;
		} bits;
	} __attribute__((packed));

	struct DirEntry {

		unsigned char name[8];
		unsigned char ext[3];
		Attributes attr;
		uint8_t dummy1[8];
		uint16_t firstClusterHi;
		uint8_t dummy2[4];
		uint16_t firstClusterLo;
		uint32_t size;	// file size in bytes

		bool isUnused() const			{return name[0] == 0xE5;}
		bool isDirectory() const		{return attr.bits.directory;}
		bool isEndOfDirectory() const	{return name[0] == 0x00;}
		bool isLongFileName() const		{return (attr.raw & 0b1111) == 0b1111;}

		uint32_t getFirstCluster() const {return firstClusterHi<<16 | firstClusterLo<<0;}

		std::string getName() const {
			char buf[16];
			uint8_t pos = 0;
			for (uint8_t i = 0; i < 8; ++i) {if (name[i] != ' ') {buf[pos++] = name[i];}}
			buf[pos++] = '.';
			for (uint8_t i = 0; i < 8; ++i) {if ( ext[i] != ' ') {buf[pos++] =  ext[i];}}
			buf[pos] = 0;
			return std::string(buf);
		}

	} __attribute__((packed));

	static inline uint16_t getU8(const uint8_t* src)	{return src[0];}
	static inline uint16_t getU16(const uint8_t* src)	{return src[0]<<0 | src[1]<<8;}
	static inline uint32_t getU32(const uint8_t* src)	{return src[0]<<0 | src[1]<<8 | src[2]<<16 | src[3]<<24;}

}