#include <stdio.h>
#include <unistd.h>
#include <sys/timerfd.h>
#include <string.h>

#include "nfcommander.h"
#include "config.h"

#include "libyhy.h"

static int reader_fd = -1;

int init(){
	char reader_version[100];

	char* port = config_get("nfc", "device");
	if(!port){
		printf("Please configure nfc.device to the reader serial port\n");
		return 1;
	}

	//TODO set cloexec, nonblock
	printf("Opening YHY reader on %s\n", port);
	reader_fd = yhy_open(port);
	if(reader_fd < 0){
		printf("Failed to open reader connection at %s\n", port);
		return 1;
	}

	if(yhy_sync_read_version(reader_fd, reader_version, sizeof(reader_version)) > 0){
		printf("Connected YHY reader reports firmware: %s\n", reader_version);
	}

	core_manage_fd(reader_fd, 1, system_reader);
	return 0;
}

int handle(int fd){
	if(fd == reader_fd){
		printf("Unhandled data on YHY fd\n");
	}
	return 0;
}

uint8_t read_ntag(nfc_tag_info_t* tag){
	uint8_t data[16] = "";
	size_t bytes = 0, n = 0;

	//read 16 bytes starting at block 2
	//[0-3] UID, lock bytes
	//[4-7] CC
	//[8-11] Signature
	//[12-15] Data block offsets & lengths
	bytes = yhy_sync_read(reader_fd, 2, data, sizeof(data));
	if(bytes != 16){
		//read failed, probably not a usable tag
		return FLAG_TAG_LOCKED;
	}

	//check for NTAG signature CC bytes
	if(data[4] != 0xE1 || data[5] != 0x10 || data[7]){
		return FLAG_TAG_LOCKED;
	}

	switch(data[6]){
		case 0x12:
			//NTAG213
			tag->bytes_available = 144;
			break;
		case 0x3E:
			//NTAG215
			tag->bytes_available = 496;
			break;
		case 0x6D:
			//NTAG216
			tag->bytes_available = 872;
			break;
		default:
			//unknown
			return FLAG_TAG_LOCKED;
	}

	//TODO check lock bits

	//check nfcommander signature
	if(data[8] != 0xCB || data[9] != 'N' || data[10] != 'F' || data[11] != 'C'){
		return FLAG_TAG_UNPROGRAMMED;
	}

	//sanity check length data
	if(data[12] < 6 || !data[13]){
		return FLAG_TAG_UNPROGRAMMED;
	}

	//read data
	tag->static_length = data[13] * tag->granularity;
	tag->static_data = calloc(tag->static_length, sizeof(uint8_t));
	if(!tag->static_data){
		printf("Failed to allocate memory\n");
		return FLAG_TAG_LOCKED;
	}

	do{
		//each read fetches 4 blocks, but due to a probable firmware bug we cant read blocks 0 or 10
		//so we overwrite 2 bytes per pass and skip the read for 10.
		uint8_t block = data[12] + n * 2;
		if(block != 10){
			bytes = yhy_sync_read(reader_fd, block,
					tag->static_data + n * 2 * 4, 
					tag->static_length - (n * 2 * 4));
		}
		if(bytes <= 0){
			return FLAG_TAG_LOCKED;
		}
		n++;
	} while(n <= data[13] / 2);

	//read dynamic data if present
	tag->dynamic_max = tag->bytes_available - 8 /*4 byte magic, 4 byte length*/ - tag->static_length;
	tag->dynamic_length = data[15] * tag->granularity;
	if(tag->dynamic_length){
		tag->dynamic_data = calloc(tag->dynamic_length, sizeof(uint8_t));
		if(!tag->dynamic_data){
			printf("Failed to allocate memory\n");
			return FLAG_TAG_LOCKED;
		}

		do{
			uint8_t block = data[14] + n * 2;
			if(block != 10){
				bytes = yhy_sync_read(reader_fd, block,
						tag->dynamic_data + n * 2 * 4, 
						tag->dynamic_length - (n * 2 * 4));
			}
			if(bytes <= 0){
				return FLAG_TAG_LOCKED;
			}
			n++;
		} while(n <= data[15] / 2);

	}

	return FLAG_TAG_DATA_VALID;
}

void write_ntag(nfc_tag_info_t* tag, uint8_t flags){
	size_t n = 0;
	size_t static_offset = 6;
	size_t static_blocks = (tag->static_length / tag->granularity) + ((tag->static_length % tag->granularity) ? 1 : 0);
	size_t dynamic_offset = static_offset + static_blocks;
	size_t dynamic_blocks = (tag->dynamic_length / tag->granularity) + ((tag->dynamic_length % tag->granularity) ? 1 : 0);
	uint8_t data[16] = { 0 };

	if(!static_blocks){
		printf("Invalid tag data requested for write (static length is %ld), aborting\n", tag->static_length);
		return;
	}

	//write directory
	data[0] = static_offset;
	data[1] = static_blocks;
	data[2] = dynamic_offset;
	data[3] = dynamic_blocks;
	yhy_sync_write(reader_fd, 5, data);

	if(flags & TAG_WRITE_FULL){
		//write signature
		data[0] = 0xCB;
		data[1] = 'N';
		data[2] = 'F';
		data[3] = 'C';
		yhy_sync_write(reader_fd, 4, data);

		for(n = 0; n < static_blocks; n++){
			memset(data, 0, sizeof(data));
			memcpy(data, tag->static_data + n * tag->granularity, MIN(tag->static_length - n * tag->granularity, 4));
			yhy_sync_write(reader_fd, static_offset + n, data);
		}
	}

	//write dynamic data
	for(n = 0; n < dynamic_blocks; n++){
		memset(data, 0, sizeof(data));
		memcpy(data, tag->dynamic_data + n * tag->granularity, MIN(tag->dynamic_length - n * tag->granularity, 4));
		yhy_sync_write(reader_fd, dynamic_offset + n, data);
	}
}

uint8_t read_mifare(nfc_tag_info_t* tag){
	//TODO
	return FLAG_TAG_LOCKED;
}

void write_mifare(nfc_tag_info_t* tag, uint8_t flags){
	//TODO
}

int scan(){
	nfc_tag_info_t card = {
		0
	};

	uint16_t atqa = 0;
	uint8_t sak = 0;
	uint8_t flags = 0;

	for(yhy_sync_request(reader_fd, 1, &atqa); atqa; yhy_sync_request(reader_fd, 0, &atqa)){
		sak = 0;
		//ATQA should normally not be used as an indicator for UID length
		//However, the YHY UL_SELECT command does not seem to work after CL1 anticollision for some reason

		//extended length UIDs
		if(atqa & 0x00C0){
			card.uid_length = yhy_sync_ulselect(reader_fd, card.uid, sizeof(card.uid));
			//since we dont get either the CL2 SAK or any other method of identifying the particular type of PICC, just guess whether it's an NTAG
			card.type = tag_unknown;
			if(atqa == 0x0044){
				card.type = tag_ntag;
				card.granularity = 4;
			}
			else{
				printf("PICC Parameters: ATQA %04X\n", atqa);
			}
		}
		else{
			card.uid_length = yhy_sync_anticoll(reader_fd, card.uid, sizeof(card.uid));
			yhy_sync_select(reader_fd, card.uid, card.uid_length, &sak);

			card.type = tag_unknown;
			if(atqa == 0x0004 && sak == 0x08){
				card.type = tag_mifare1;
				card.bytes_available = 752;
				card.granularity = 16;
			}
			else{
				printf("PICC Parameters: ATQA %04X SAK %02X\n", atqa, sak);
			}
		}

		flags = TAG_WRITE_FULL;
		switch(reader_tag_present(0, &card)){
			case TAG_READ_REQUESTED:
				//read card data
				if(card.type == tag_ntag){
					flags = read_ntag(&card);
				}
				else if(card.type == tag_mifare1){
					flags = read_mifare(&card);
				}
				reader_tag_present(flags, &card);
				break;
			case TAG_WRITE_DYNAMIC:
				flags = TAG_WRITE_DYNAMIC;
				//fall through
			case TAG_WRITE_FULL:
				//write card data
				if(card.type == tag_ntag){
					write_ntag(&card, flags);
				}
				else if(card.type == tag_mifare1){
					write_mifare(&card, flags);
				}
				break;
		}

		yhy_sync_hlta(reader_fd);
	}

	return 0;
}

static void __attribute__((destructor)) cleanup(){
	core_manage_fd(reader_fd, 0, system_reader);
	close(reader_fd);
	reader_fd = -1;
}