#include <stdlib.h>
#include <stdbool.h>
#include <archive.h>
#include <archive_entry.h>

#include "vieter_package_internal.h"
#include "sha256.h"

#define ADD_STRING(section, field) if (pkg_info->field != 0) { \
	size_to_be_written = snprintf(aux, small_buff_size, section, pkg_info->field); \
	if (size_to_be_written > small_buff_size) { \
		aux = realloc(aux, size_to_be_written + 1); \
		small_buff_size = size_to_be_written + 1; \
		snprintf(aux, small_buff_size, section, pkg_info->field); \
	} \
	if (buff_size < strlen(description) + small_buff_size + 1) { \
		description = realloc(description, buff_size * 2); \
		buff_size *= 2; \
	} \
	strcat(description, aux); \
}

#define ADD_ARRAY(section, field) i = 0; if (pkg_info->field != NULL) { \
	ADD_STRING(section, field->array[i]); i++; \
	while (pkg_info->field->array[i] != NULL) { \
		ADD_STRING("\n%s", field->array[i]); i++; \
	} \
}

static char *ignored_names[5] = {
	".BUILDINFO",
	".INSTALL",
	".MTREE",
	".PKGINFO",
	".CHANGELOG"
};
static size_t ignored_words_len = sizeof(ignored_names) / sizeof(char *);

vieter_package *vieter_package_init() {
	return calloc(sizeof(vieter_package_info), 1);
}

vieter_package_error vieter_package_read_archive(vieter_package *pkg, const char *pkg_path) {
	struct archive *a = archive_read_new();
	struct archive_entry *entry = archive_entry_new();

	// These three are the most commonly used compression methods
	archive_read_support_filter_zstd(a);
	archive_read_support_filter_gzip(a);
	archive_read_support_filter_xz(a);

	// Contents should always be a tarball
	archive_read_support_format_tar(a);

	// TODO where does this 10240 come from?
	int r = archive_read_open_filename(a, pkg_path, 10240);

	// Exit early if we weren't able to successfully open the archive for reading
	if (r != ARCHIVE_OK) {
		return vieter_package_unarchive_error;
	}

	int compression_code = archive_filter_code(a, 0);
	const char *path_name;

	vieter_package_info *pkg_info;
	vieter_package_dynarray *files = vieter_package_dynarray_init(16);
	vieter_package_dynarray_add(files, "%FILES%");

	while (archive_read_next_header(a, &entry) == ARCHIVE_OK) {
		path_name = archive_entry_pathname(entry);

		bool ignore = false;

		for (size_t i = 0; i < ignored_words_len; i++) {
			if (strcmp(path_name, ignored_names[i]) == 0) {
				ignore = true;
				break;
			}
		}

		if (!ignore) {
			vieter_package_dynarray_add(files, path_name);
		}

		if (strcmp(path_name, ".PKGINFO") == 0) {
			// Read data of file into memory buffer
			int size = archive_entry_size(entry);
			char *buf = malloc(size);
			archive_read_data(a, buf, size);

			// Parse package vieter_package_info string into a struct
			pkg_info = vieter_package_info_init();
			vieter_package_info_parse(pkg_info, buf);

			free(buf);
		} else {
			archive_read_data_skip(a);
		}
	}

	// Get size of file
	struct stat stats;

	if (stat(pkg_path, &stats) != 0) {
		// errno is set if stat() fails; the calling function should check
		// the value of errno in case vieter_package_stat_error is returned
		return vieter_package_stat_error;
	}

	pkg_info->csize = stats.st_size;

	archive_read_free(a);

	// Create final return value
	pkg->path = strdup(pkg_path);
	pkg->info = pkg_info;
	pkg->files = files;
	pkg->compression = compression_code;

	return vieter_package_ok;
}

void vieter_package_sha256sum(vieter_package *pkg, char *res) {
	FILE *f = fopen(pkg->path, "r");
	fseek(f, 0, SEEK_END);
	size_t size = ftell(f);
	rewind(f);
	unsigned char *in = malloc(size);
	fread(in, 1, size, f);
	fclose(f);

	unsigned char hash[32];
	SHA256_CTX *ctx = malloc(sizeof(SHA256_CTX));

	sha256_init(ctx);
	sha256_update(ctx, in, size);
	sha256_final(ctx, hash);

	free(in);
	free(ctx);

	// We need to convert the bytes in the hash to get a string representation of its hex values
	// i.e. turn 1001 1111 into the string "9f"
	// Each byte of the hash is going to turn into two bytes in the final string
	// so we are going to convert each half byte into a char
	unsigned int half_byte = 0;
	int j = 0;

	// We advance in the string 2 bytes for every one byte of the hash
	for (int i = 0; i < 32; i++) {
		// We transform the first half byte into the second character to keep
		// each byte from becoming reversed in the final string
		half_byte = hash[i] & 0b1111;
		if (half_byte < 10) {
			res[j+1] = half_byte + 48;
		} else {
			res[j+1] = half_byte + 87;
		}
		hash[i] = hash[i] >> 4;
		half_byte = hash[i] & 0b1111;
		if (half_byte < 10) {
			res[j] = half_byte + 48;
		} else {
			res[j] = half_byte + 87;
		}

		j += 2;
	}
	res[j] = '\0';
}



char *vieter_package_to_description(vieter_package *pkg) {
	vieter_package_info *pkg_info = pkg->info;

	size_t buff_size = 1024;
	int small_buff_size = 128;
	int size_to_be_written;
	char *aux = malloc(sizeof(char) * small_buff_size);
	char *description = malloc(sizeof(char) * buff_size);
	// Helper variable for ADD_ARRAY macro
	int i;

	// special case for FILENAME
	// assuming .pkg.tar.zst; other formats are valid, this should account for that
	size_to_be_written = snprintf(aux, small_buff_size, "%%FILENAME%%\n%s-%s-%s.pkg.tar.zst", pkg_info->name,
			pkg_info->version, pkg_info->arch);

	// We neither want to let an arbritrarily long input to overflow the buffer
	// nor to truncate perfectly valid inputs
	if (size_to_be_written > small_buff_size) {
		aux = realloc(aux, size_to_be_written + 1);
		small_buff_size = size_to_be_written + 1;
		snprintf(aux, small_buff_size, "%%FILENAME%%\n%s-%s-%s.pkg.tar.zst", pkg_info->name,
				pkg_info->version, pkg_info->arch);
	}
	strcpy(description, aux);

	ADD_STRING("\n\n%%NAME%%\n%s", name);
	ADD_STRING("\n\n%%BASE%%\n%s", base);
	ADD_STRING("\n\n%%VERSION%%\n%s", version);
	ADD_STRING("\n\n%%DESC%%\n%s", description);
	ADD_ARRAY("\n\n%%GROUPS%%\n%s", groups);
	ADD_STRING("\n\n%%CSIZE%%\n%ld", csize);
	ADD_STRING("\n\n%%ISIZE%%\n%ld", size);

	char checksum[65];
	vieter_package_sha256sum(pkg, checksum);

	snprintf(aux, SMALL_BUFF_SIZE, "\n\n%%SHA256SUM%%\n%s", checksum);
	if (buff_size < strlen(description) + SMALL_BUFF_SIZE + 1) {
		description = realloc(description, buff_size * 2);
		buff_size *= 2;
	}
	strcat(description, aux);

	ADD_STRING("\n\n%%URL%%\n%s", url);
	ADD_ARRAY("\n\n%%LICENSE%%\n%s", licenses);
	ADD_STRING("\n\n%%ARCH%%\n%s", arch);
	ADD_STRING("\n\n%%BUILDDATE%%\n%ld", build_date);
	ADD_STRING("\n\n%%PACKAGER%%\n%s", packager);
	ADD_ARRAY("\n\n%%REPLACES%%\n%s", replaces);
	ADD_ARRAY("\n\n%%CONFLICTS%%\n%s", conflicts);
	ADD_ARRAY("\n\n%%PROVIDES%%\n%s", provides);
	ADD_ARRAY("\n\n%%DEPENDS%%\n%s", depends);
	ADD_ARRAY("\n\n%%OPTDEPENDS%%\n%s", optdepends);
	ADD_ARRAY("\n\n%%MAKEDEPENDS%%\n%s", makedepends);
	ADD_ARRAY("\n\n%%CHECKDEPENDS%%\n%s", checkdepends);

	strcat(description, "\n\n");

	return description;
}

void vieter_package_free(vieter_package **ptp) {
	FREE_STRING((*ptp)->path);
	vieter_package_info_free((*ptp)->info);
	vieter_package_dynarray_free((*ptp)->files);
	free(*ptp);
	*ptp = NULL;

}