/*
 * This implementation was written based on information provided by the
 * following documents:
 *
 * Mifare Std as NFC Forum Enabled,
 * Extensions for Mifare standard 1k/4k as NFC Forum Enable Tag
 *   Application note
 *   Revision 1.1 — 21 August 2007
 *
 * NXP Type MF1K/4K Tag Operation, NXP Semiconductors [ANNFC1K4K]
 *   Application Note
 *   Revision 1.1 — 21 August 2007
 *   Document Identifier 130410
 */

#if defined(HAVE_CONFIG_H)
    #include "config.h"
#endif

#include <err.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <unistd.h>

#include <nfc/nfc.h>

#include <freefare.h>

#define MIN(a,b) ((a < b) ? a: b)

struct {
    bool interactive;
} read_options = {
    .interactive = true
};

static void
usage(char *progname)
{
    fprintf(stderr, "usage: %s -o FILE\n", progname);
    fprintf(stderr, "\nOptions:\n");
    fprintf(stderr, "  -y     Do not ask for confirmation\n");
    fprintf(stderr, "  -o     Extract NDEF message if available in FILE\n");
}

int
main(int argc, char *argv[])
{
    int error = 0;
    nfc_device *device = NULL;
    FreefareTag *tags = NULL;
    Mad mad;

    int ch;
    char *ndef_output = NULL;
    while ((ch = getopt(argc, argv, "hyo:")) != -1) {
	switch (ch) {
	case 'h':
	    usage(argv[0]);
	    exit(EXIT_SUCCESS);
	    break;
	case 'y':
	    read_options.interactive = false;
	    break;
	case 'o':
	    ndef_output = optarg;
	    break;
	case '?':
	    if (optopt == 'o')
		fprintf(stderr, "Option -%c requires an argument.\n", optopt);
	/* FALLTHROUGH */
	default:
	    usage(argv[0]);
	    exit(EXIT_FAILURE);
	}
    }

    if (ndef_output == NULL) {
	usage(argv[0]);
	exit(EXIT_FAILURE);
    }
    FILE *message_stream = NULL;
    FILE *ndef_stream = NULL;

    if ((strlen(ndef_output) == 1) && (ndef_output[0] == '-')) {
	message_stream = stderr;
	ndef_stream = stdout;
    } else {
	message_stream = stdout;
	ndef_stream = fopen(ndef_output, "wb");
	if (!ndef_stream) {
	    fprintf(stderr, "Could not open file %s.\n", ndef_output);
	    exit(EXIT_FAILURE);
	}
    }

    nfc_connstring devices[8];
    size_t device_count;

    nfc_context *context;
    nfc_init(&context);
    if (context == NULL)
	errx(EXIT_FAILURE, "Unable to init libnfc (malloc)");

    device_count = nfc_list_devices(context, devices, 8);
    if (device_count <= 0)
	errx(EXIT_FAILURE, "No NFC device found.");

    for (size_t d = 0; d < device_count; d++) {
	device = nfc_open(context, devices[d]);
	if (!device) {
	    warnx("nfc_open() failed.");
	    error = EXIT_FAILURE;
	    continue;
	}

	tags = freefare_get_tags(device);
	if (!tags) {
	    nfc_close(device);
	    errx(EXIT_FAILURE, "Error listing MIFARE classic tag.");
	}

	for (int i = 0; (!error) && tags[i]; i++) {
	    switch (freefare_get_tag_type(tags[i])) {
	    case MIFARE_CLASSIC_1K:
	    case MIFARE_CLASSIC_4K:
		break;
	    default:
		continue;
	    }

	    char *tag_uid = freefare_get_tag_uid(tags[i]);
	    char buffer[BUFSIZ];

	    fprintf(message_stream, "Found %s with UID %s. ", freefare_get_tag_friendly_name(tags[i]), tag_uid);

	    bool read_ndef = true;
	    if (read_options.interactive) {
		fprintf(message_stream, "Read NDEF [yN] ");
		fgets(buffer, BUFSIZ, stdin);
		read_ndef = ((buffer[0] == 'y') || (buffer[0] == 'Y'));
	    } else {
		fprintf(message_stream, "\n");
	    }

	    if (read_ndef) {
		// NFCForum card has a MAD, load it.
		if (0 == mifare_classic_connect(tags[i])) {
		} else {
		    nfc_perror(device, "mifare_classic_connect");
		    error = EXIT_FAILURE;
		    goto error;
		}

		if ((mad = mad_read(tags[i]))) {
		    // Dump the NFCForum application using MAD information
		    uint8_t buffer[4096];
		    ssize_t len;
		    if ((len = mifare_application_read(tags[i], mad, mad_nfcforum_aid, buffer, sizeof(buffer), mifare_classic_nfcforum_public_key_a, MFC_KEY_A)) != -1) {
			uint8_t tlv_type;
			uint16_t tlv_data_len;
			uint8_t *tlv_data;
			uint8_t *pbuffer = buffer;
decode_tlv:
			tlv_data = tlv_decode(pbuffer, &tlv_type, &tlv_data_len);
			switch (tlv_type) {
			case 0x00:
			    fprintf(message_stream, "NFC Forum application contains a \"NULL TLV\", Skipping...\n");	// According to [ANNFC1K4K], we skip this Tag to read further TLV blocks.
			    pbuffer += tlv_record_length(pbuffer, NULL, NULL);
			    if (pbuffer >= buffer + sizeof(buffer)) {
				error = EXIT_FAILURE;
				goto error;
			    }
			    goto decode_tlv;
			    break;
			case 0x03:
			    fprintf(message_stream, "NFC Forum application contains a \"NDEF Message TLV\".\n");
			    break;
			case 0xFD:
			    fprintf(message_stream, "NFC Forum application contains a \"Proprietary TLV\", Skipping...\n");	// According to [ANNFC1K4K], we can skip this TLV to read further TLV blocks.
			    pbuffer += tlv_record_length(pbuffer, NULL, NULL);
			    if (pbuffer >= buffer + sizeof(buffer)) {
				error = EXIT_FAILURE;
				goto error;
			    }
			    goto decode_tlv;
			    break;
			case 0xFE:
			    fprintf(stderr, "NFC Forum application contains a \"Terminator TLV\", no available data.\n");
			    error = EXIT_FAILURE;
			    goto error;
			    break;
			default:
			    fprintf(stderr, "NFC Forum application contains an invalid TLV.\n");
			    error = EXIT_FAILURE;
			    goto error;
			    break;
			}
			if (fwrite(tlv_data, 1, tlv_data_len, ndef_stream) != tlv_data_len) {
			    fprintf(stderr, "Could not write to file.\n");
			    error = EXIT_FAILURE;
			    goto error;
			}
			free(tlv_data);
		    } else {
			fprintf(stderr, "No NFC Forum application.\n");
			error = EXIT_FAILURE;
			goto error;
		    }
		} else {
		    fprintf(stderr, "No MAD detected.\n");
		    error = EXIT_FAILURE;
		    goto error;
		}
		free(mad);
	    }

error:
	    free(tag_uid);
	}
	fclose(ndef_stream);
	freefare_free_tags(tags);
	nfc_close(device);
    }

    nfc_exit(context);
    exit(error);
}