#include <stdio.h>
#include <sys/stat.h>

#define ENCODE
#define VERBOSE
#include "nrv2b.c"
FILE *infile, *outfile;

struct input_file {
	void *buf;
	size_t len;
};

struct output_file {
	void *buf;
	size_t len;
	size_t max_len;
};

struct zinfo_common {
	char type[4];
	char pad[12];
};

struct zinfo_copy {
	char type[4];
	uint32_t offset;
	uint32_t len;
	uint32_t align;
};

struct zinfo_pack {
	char type[4];
	uint32_t offset;
	uint32_t len;
	uint32_t align;
};

struct zinfo_subtract {
	char type[4];
	uint32_t offset;
	uint32_t divisor;
	uint32_t pad;
};

union zinfo_record {
	struct zinfo_common common;
	struct zinfo_copy copy;
	struct zinfo_pack pack;
	struct zinfo_subtract subtract;
};

struct zinfo_file {
	union zinfo_record *zinfo;
	unsigned int num_entries;
};

static int read_file ( const char *filename, void **buf, size_t *len ) {
	FILE *file;
	struct stat stat;

	file = fopen ( filename, "r" );
	if ( ! file ) {
		fprintf ( stderr, "Could not open %s: %s\n", filename,
			  strerror ( errno ) );
		goto err;
	}

	if ( fstat ( fileno ( file ), &stat ) < 0 ) {
		fprintf ( stderr, "Could not stat %s: %s\n", filename,
			  strerror ( errno ) );
		goto err;
	}

	*len = stat.st_size;
	*buf = malloc ( *len );
	if ( ! *buf ) {
		fprintf ( stderr, "Could not malloc() %d bytes for %s: %s\n",
			  *len, filename, strerror ( errno ) );
		goto err;
	}

	if ( fread ( *buf, 1, *len, file ) != *len ) {
		fprintf ( stderr, "Could not read %d bytes from %s: %s\n",
			  *len, filename, strerror ( errno ) );
		goto err;
	}

	fclose ( file );
	return 0;

 err:
	if ( file )
		fclose ( file );
	return -1;
}

static int read_input_file ( const char *filename,
			     struct input_file *input ) {
	return read_file ( filename, &input->buf, &input->len );
}

static int read_zinfo_file ( const char *filename,
			     struct zinfo_file *zinfo ) {
	void *buf;
	size_t len;

	if ( read_file ( filename, &buf, &len ) < 0 )
		return -1;

	if ( ( len % sizeof ( *(zinfo->zinfo) ) ) != 0 ) {
		fprintf ( stderr, ".zinfo file %s has invalid length %d\n",
			  filename, len );
		return -1;
	}

	zinfo->zinfo = buf;
	zinfo->num_entries = ( len / sizeof ( *(zinfo->zinfo) ) );
	return 0;
}

static int alloc_output_file ( size_t max_len, struct output_file *output ) {
	output->len = 0;
	output->max_len = ( max_len );
	output->buf = malloc ( max_len );
	if ( ! output->buf ) {
		fprintf ( stderr, "Could not allocate %d bytes for output\n",
			  max_len );
		return -1;
	}
	memset ( output->buf, 0xff, sizeof ( output->buf ) );
	return 0;
}

static int process_zinfo_copy ( struct input_file *input,
				struct output_file *output,
				union zinfo_record *zinfo ) {
	struct zinfo_copy *copy = &zinfo->copy;
	size_t offset = copy->offset;
	size_t len = copy->len;
	unsigned int align = copy->align;

	if ( ( offset + len ) > input->len ) {
		fprintf ( stderr, "Input buffer overrun on copy\n" );
		return -1;
	}

	output->len = ( ( output->len + align - 1 ) & ~( align - 1 ) );
	if ( ( output->len + len ) > output->max_len ) {
		fprintf ( stderr, "Output buffer overrun on copy\n" );
		return -1;
	}

	memcpy ( ( output->buf + output->len ),
		 ( input->buf + offset ), len );
	output->len += len;
	return 0;
}

static int process_zinfo_pack ( struct input_file *input,
				struct output_file *output,
				union zinfo_record *zinfo ) {
	struct zinfo_pack *pack = &zinfo->pack;
	size_t offset = pack->offset;
	size_t len = pack->len;
	unsigned int align = pack->align;
	unsigned long packed_len;

	if ( ( offset + len ) > input->len ) {
		fprintf ( stderr, "Input buffer overrun on pack\n" );
		return -1;
	}

	output->len = ( ( output->len + align - 1 ) & ~( align - 1 ) );
	if ( output->len > output->max_len ) {
		fprintf ( stderr, "Output buffer overrun on pack\n" );
		return -1;
	}

	if ( ucl_nrv2b_99_compress ( ( input->buf + offset ), len,
				     ( output->buf + output->len ),
				     &packed_len, 0 ) != UCL_E_OK ) {
		fprintf ( stderr, "Compression failure\n" );
		return -1;
	}

	output->len += packed_len;
	if ( output->len > output->max_len ) {
		fprintf ( stderr, "Output buffer overrun on pack\n" );
		return -1;
	}

	return 0;
}

static int process_zinfo_subtract ( struct input_file *input,
				    struct output_file *output,
				    struct zinfo_subtract *subtract,
				    size_t datasize ) {
	size_t offset = subtract->offset;
	void *target;
	long delta;

	if ( ( offset + datasize ) > output->len ) {
		fprintf ( stderr, "Subtract at %#zx outside output buffer\n",
			  offset );
		return -1;
	}

	target = ( output->buf + offset );
	delta = ( ( output->len / subtract->divisor ) -
		  ( input->len / subtract->divisor ) );

	switch ( datasize ) {
	case 1: {
		uint8_t *byte = target;
		*byte += delta;
		break; }
	case 2: {
		uint16_t *word = target;
		*word += delta;
		break; }
	case 4: {
		uint32_t *dword = target;
		*dword += delta;
		break; }
	default:
		fprintf ( stderr, "Unsupported subtract datasize %d\n",
			  datasize );
		return -1;
	}
	return 0;
}

static int process_zinfo_subb ( struct input_file *input,
				struct output_file *output,
				union zinfo_record *zinfo ) {
	return process_zinfo_subtract ( input, output, &zinfo->subtract, 1 );
}

static int process_zinfo_subw ( struct input_file *input,
				struct output_file *output,
				union zinfo_record *zinfo ) {
	return process_zinfo_subtract ( input, output, &zinfo->subtract, 2 );
}

static int process_zinfo_subl ( struct input_file *input,
				struct output_file *output,
				union zinfo_record *zinfo ) {
	return process_zinfo_subtract ( input, output, &zinfo->subtract, 4 );
}

struct zinfo_processor {
	char *type;
	int ( * process ) ( struct input_file *input,
			    struct output_file *output,
			    union zinfo_record *zinfo );
};

static struct zinfo_processor zinfo_processors[] = {
	{ "COPY", process_zinfo_copy },
	{ "PACK", process_zinfo_pack },
	{ "SUBB", process_zinfo_subb },
	{ "SUBW", process_zinfo_subw },
	{ "SUBL", process_zinfo_subl },
};

static int process_zinfo ( struct input_file *input,
			   struct output_file *output,
			   union zinfo_record *zinfo ) {
	struct zinfo_common *common = &zinfo->common;
	struct zinfo_processor *processor;
	char type[ sizeof ( common->type ) + 1 ] = "";
	unsigned int i;

	strncat ( type, common->type, sizeof ( type ) - 1 );
	for ( i = 0 ; i < ( sizeof ( zinfo_processors ) /
			    sizeof ( zinfo_processors[0] ) ) ; i++ ) {
		processor = &zinfo_processors[i];
		if ( strcmp ( processor->type, type ) == 0 )
			return processor->process ( input, output, zinfo );
	}

	fprintf ( stderr, "Unknown zinfo record type \"%s\"\n", &type[0] );
	return -1;
}

static int write_output_file ( struct output_file *output ) {
	if ( fwrite ( output->buf, 1, output->len, stdout ) != output->len ) {
		fprintf ( stderr, "Could not write %d bytes of output: %s\n",
			  output->len, strerror ( errno ) );
		return -1;
	}
	return 0;
}

int main ( int argc, char **argv ) {
	struct input_file input;
	struct output_file output;
	struct zinfo_file zinfo;
	unsigned int i;

	if ( argc != 3 ) {
		fprintf ( stderr, "Syntax: %s file.bin file.zinfo "
			  "> file.zbin\n", argv[0] );
		exit ( 1 );
	}

	if ( read_input_file ( argv[1], &input ) < 0 )
		exit ( 1 );
	if ( read_zinfo_file ( argv[2], &zinfo ) < 0 )
		exit ( 1 );
	if ( alloc_output_file ( ( input.len * 4 ), &output ) < 0 )
		exit ( 1 );

	for ( i = 0 ; i < zinfo.num_entries ; i++ ) {
		if ( process_zinfo ( &input, &output,
				     &zinfo.zinfo[i] ) < 0 )
			exit ( 1 );
	}

	if ( write_output_file ( &output ) < 0 )
		exit ( 1 );

	return 0;
}