#include <zyb/extract.h>

// libc
#include <stdlib.h>
#include <string.h>
#include <limits.h>

// libzepkg
#include <crypt/sha256.h>

int zyb_extract_leader(FILE *fptr, struct lead *leader) {
	if (fptr == NULL)
		return 1;

	char magic[4];
	size_t bytes = fread(magic, 1, 4, fptr);
	if (bytes != 4)
		return 1;

	if (strcmp(magic, ZYB_MAGIC))
		return 1;

	bytes = fread(&leader + 4, 1, sizeof(struct lead) - 4, fptr);
	if (bytes != sizeof(struct lead) - 4)
		return 1;

	if (leader->version != ZYB_FORMAT_VER)
		return 1;

	return 0;
}

int zyb_extract_dependency(FILE *fptr, struct dependency *dep) {
	if (fptr == NULL)
		return 1;

	char magic[4];
	size_t bytes = fread(magic, 1, 4, fptr);
	if (bytes != 4)
		return 1;

	if (strcmp(magic, ZYB_DEP_MAGIC))
		return 1;

	bytes = fread(&dep + 4, 1, sizeof(struct dependency) - 4, fptr);
	if (bytes != sizeof(struct dependency) - 4)
		return 1;

	return 0;
}

int zyb_extract_header(FILE *fptr, struct zyb_header *header) {
	if (fptr == NULL)
		return 1;

	struct lead leader;
	int ret;
	if ((ret = zyb_extract_leader(fptr, &leader)))
		return ret;
	header->leader = leader;

	if (header->leader.dependencies > 0) {
		for (int i = 0; i < header->leader.dependencies; i++) {
			header = realloc(header, sizeof(header) + sizeof(struct dependency));

			struct dependency dep;
			if ((ret = zyb_extract_dependency(fptr, &dep)))
				return ret;
			header->dependencies[i] = dep;
		}
	}

	return 0;
}

int zyb_extract_file(FILE *fptr, char *dir) {
	if (fptr == NULL)
		return 1;

	char magic[4];
	size_t bytes = fread(magic, 1, 4, fptr);
	if (bytes != 4)
		return 1;

	if (strcmp(magic, ZYB_FILE_MAGIC))
		return 1;

	// Read path in chunks of 2 bytes (to account for alignment)
	char *path = malloc(PATH_MAX);
	for (int i = 0; i < PATH_MAX; i += 2) {
		fread(path + i, 1, 2, fptr);
		if (path[i] == '\0' || path[i + 1] == '\0')
			goto eos;
	}
	// If it reaches this point, means the string is longer than PATH_MAX
	return 1;

eos:	// End of string;
	// Read rest of header
	mode_t permissions;
	bytes = fread(&permissions, sizeof(mode_t), 1, fptr);
	if (bytes != sizeof(mode_t))
		return 1;

	off_t size;
	bytes = fread(&size, sizeof(off_t), 1, fptr);
	if (bytes != sizeof(off_t))
		return 1;

	unsigned char checksum[32];
	bytes = fread(&checksum, 1, 32, fptr);
	if (bytes != 32)
		return 1;

	// Move pointer 2 bytes to account for padding
	fseek(fptr, 2, SEEK_CUR);

	return 0;
}