#include <stdio.h>
#include <stdlib.h>

#include "upkg.h"
#include "pack.h"


struct upkg_private {
	FILE *f;


	unsigned long name_offset, export_offset, import_offset;
	unsigned char guid[16];
};

static struct upkg *init_upkg(unsigned char hdr[static UPKG_HDR_SIZE])
{
	struct upkg *pkg;

	pkg = malloc(sizeof *pkg);
	if (!pkg) {
		return NULL;
	}

	pkg->priv = malloc(sizeof *pkg->priv);
	if (!pkg->priv) {
		free(pkg);
		return NULL;
	}

	pkg->version      = unpack_16_le(hdr+4);
	pkg->license      = unpack_16_le(hdr+6);
	pkg->flags        = unpack_32_le(hdr+8);
	pkg->name_count   = unpack_32_le(hdr+12);
	pkg->export_count = unpack_32_le(hdr+20);
	pkg->import_count = unpack_32_le(hdr+28);

	pkg->priv->name_offset   = unpack_32_le(hdr+16);
	pkg->priv->export_offset = unpack_32_le(hdr+24);
	pkg->priv->import_offset = unpack_32_le(hdr+32);

	return pkg;
}

struct upkg *upkg_fopen(const char *path)
{
	unsigned char hdr_buf[UPKG_HDR_SIZE];
	struct upkg *pkg;
	FILE *f;
	
	if (!(f = fopen(path, "rb"))) {
		return NULL;
	}
	if (fread(hdr_buf, sizeof hdr_buf, 1, f) != 1) {
		goto err;
	}
	if (unpack_32_le(hdr_buf) != UPKG_HDR_MAGIC) {
		goto err;
	}

	/* Initialize package structure. */
	pkg = init_upkg(hdr_buf);
	if (!pkg) {
		goto err;
	}
	pkg->priv->f = f;

	return pkg;
err:
	fclose(f);
	return NULL;
}

int upkg_close(struct upkg *pkg)
{
	if (pkg->priv->f)
		return fclose(pkg->priv->f);
	return 0;
}