#ifndef PROTOCOL_MP1
#define PROTOCOL_MP1

#include <cfg/compiler.h>
#include <io/kfile.h>

// Options
#define MP1_ENABLE_TCP_COMPATIBILITY false
#if MP1_ENABLE_TCP_COMPATIBILITY
	#define MP1_ENABLE_COMPRESSION false
#endif
#define MP1_ENABLE_CSMA true

// Frame sizing & checksum
#define MP1_INTERLEAVE_SIZE 12
#if MP1_ENABLE_COMPRESSION
	#define MP1_MAX_FRAME_LENGTH 22 * MP1_INTERLEAVE_SIZE
#else
	#define MP1_MAX_FRAME_LENGTH 25 * MP1_INTERLEAVE_SIZE
	#define MP1_USE_TX_QUEUE true
	#define MP1_TX_QUEUE_LENGTH 2
	#define MP1_QUEUE_TX_WAIT 16UL
#endif
#define MP1_HEADER_SIZE 1
#define MP1_CHECKSUM_SIZE 1
#define MP1_MAX_DATA_SIZE MP1_MAX_FRAME_LENGTH - MP1_HEADER_SIZE - MP1_CHECKSUM_SIZE
#define MP1_MIN_FRAME_LENGTH MP1_INTERLEAVE_SIZE
#define MP1_DATA_BLOCK_SIZE ((MP1_INTERLEAVE_SIZE/3)*2)
#define MP1_CHECKSUM_INIT 0xAA

// These two parameters are used for 
// P-persistent CSMA
#define MP1_SETTLE_TIME 175UL		// The minimum wait time before considering sending
#define MP1_SLOT_TIME 100UL			// The time to wait if deciding not to send
#define MP1_P_PERSISTENCE 85UL		// The probability (between 0 and 255) for sending
#define MP1_TXDELAY 0UL			// Delay between turning on the transmitter and sending

// We need to know some basic HDLC flag bytes
#define HDLC_FLAG  0x7E
#define HDLC_RESET 0x7F
#define AX25_ESC   0x1B

// We also define a few header flags and what
// to send as padding if we need to pad a
// packet. Due to forward error correction,
// packets must have an even number of bytes.
#define MP1_PADDING 			0x55
#define MP1_HEADER_PADDED		0x01
#define MP1_HEADER_COMPRESSION 	0x02

// Just a forward declaration that this struct exists
struct MP1Packet;

// The type of a callback function for passing
// back a decoded packet
typedef void (*mp1_callback_t)(struct MP1Packet *packet);

// Struct for a protocol context
typedef struct MP1 {
	uint8_t buffer[MP1_MAX_FRAME_LENGTH+MP1_INTERLEAVE_SIZE];			// A buffer for incoming packets
	KFile *modem;									// KFile access to the modem
	size_t packetLength;							// Counter for received packet length
	size_t readLength;								// This is the full read length, including parity bytes
	uint8_t calculatedParity;						// Calculated parity for incoming data block
	mp1_callback_t callback;						// The function to call when a packet has been received
	uint8_t checksum_in;							// Rolling checksum for incoming packets
	uint8_t checksum_out;							// Rolling checksum for outgoing packets
	bool reading;									// True when we have seen a HDLC flag
	bool escape;									// We need to know if we are in an escape sequence
	ticks_t settleTimer;							// Timer used for carrier sense settling
	long correctionsMade;							// A counter for how many corrections were made to a packet
	uint8_t interleaveCounter;						// Keeps track of when we have received an entire interleaved block
	uint8_t interleaveOut[MP1_INTERLEAVE_SIZE]; 	// A buffer for interleaving bytes before they are sent
	uint8_t interleaveIn[MP1_INTERLEAVE_SIZE];		// A buffer for storing interleaved bytes before they are deinterleaved
	uint8_t randomSeed;								// A seed for the pseudo-random number generator
	#if MP1_USE_TX_QUEUE
		bool queueProcessing;						// For sending queued frames without preamble after first one
		size_t queueLength;							// The length of the transmission queue
		size_t frameLengths[MP1_TX_QUEUE_LENGTH];	// The lengths of the frames in the queue
	    uint8_t frameQueue[MP1_TX_QUEUE_LENGTH]		// A buffer for a queued frame
	  						[MP1_MAX_DATA_SIZE];
	#endif
} MP1;

// A struct encapsulating a network packet
typedef struct MP1Packet {
	const uint8_t *data;					// Pointer to the actual data in the packet
	size_t dataLength;						// The length of the received data
} MP1Packet;

// Declarations of functions
void mp1Init(MP1 *mp1, KFile *modem, mp1_callback_t callback);
void mp1Read(MP1 *mp1, int byte);
void mp1Poll(MP1 *mp1);
void mp1Send(MP1 *mp1, void *_buffer, size_t length);
void mp1QueueFrame(MP1 *mp1, void *_buffer, size_t length);
void mp1ProcessQueue(MP1 *mp1);
bool mp1CarrierSense(MP1 *mp1);

int freeRam(void);
size_t compress(uint8_t *input, size_t length);
size_t decompress(uint8_t *input, size_t length);
void mp1Deinterleave(MP1 *mp1);
void mp1Interleave(MP1 *mp1, uint8_t byte);

#endif