#define _GNU_SOURCE

#include <lua.h>
#include <lualib.h>
#include <lauxlib.h>

#include <stdlib.h>
#include <stdbool.h>
#include <string.h>

#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <errno.h>
#include <err.h>

#include "lib.h"

static const char *fs_check_path(lua_State *ctx, int i, size_t *psize) {
	size_t n;
	const char *path = luaL_checklstring(ctx, 1, &n);

	size_t real_len = strlen(path);
	if (n != real_len) {
		luaL_error(ctx, "path may not contain \\0");
		return NULL;
	}

	if (psize) *psize = n;

	return path;
}

static int lib_fs_mkdir(lua_State *ctx) {
	size_t path_size;
	const char *ro_path = fs_check_path(ctx, 1, &path_size);
	bool recursive = lua_toboolean(ctx, 2);

	if (recursive) {
		char path[path_size + 1];
		memcpy(path, ro_path, path_size + 1);

		for (size_t i = 0; i <= path_size ; i++) {
			if (path[i] == '/' || path[i] == '\0') {
				path[i] = '\0';

				if (mkdir(path, 0755) < 0 && errno != EEXIST) {
					lua_pushnil(ctx);
					lua_pushfstring(ctx, "can't make directory: %s", strerror(errno));
					return 12;
				}

				if (i < path_size) path[i] = '/';
			}
		}
	}
	else {
		if (mkdir(ro_path, 0755) < 0) {
			lua_pushnil(ctx);
			lua_pushfstring(ctx, "can't make directory: %s", strerror(errno));
			return 12;
		}
	}

	lua_pushboolean(ctx, true);
	return 1;
}
static int lib_fs_symlink(lua_State *ctx) {
	const char *src = fs_check_path(ctx, 1, NULL);
	const char *dst = fs_check_path(ctx, 2, NULL);

	if (symlink(src, dst) < 0) {
		lua_pushnil(ctx);
		lua_pushfstring(ctx, "failed to chmod: %s", strerror(errno));
		return 2;
	}

	lua_pushboolean(ctx, true);
	return 1;
}
static int lib_fs_chmod(lua_State *ctx) {
	const char *path = fs_check_path(ctx, 1, NULL);
	int mode;

	if (lua_isinteger(ctx, 2)) {
		mode = lua_tointeger(ctx, 2);
		mode = mode & 0xFFF;
	}
	else {
		const char *strmode = luaL_checkstring(ctx, 2);

		mode = 0;

		for (size_t i = 0; strmode[i]; i++) {
			char c = strmode[i];
			if (c >= '0' && c <= '7') {
				mode <<= 3;
				mode |= c - '0';
			}
			else {
				return luaL_error(ctx, "invalid mode '%s' - must be an octal integer", strmode);
			}
		}
	}

	if (chmod(path, mode) < 0) {
		lua_pushnil(ctx);
		lua_pushfstring(ctx, "failed to chmod: %s", strerror(errno));
		return 2;
	}

	lua_pushboolean(ctx, true);
	return 1;
}

int fs_open_lib(lua_State *ctx) {
	luaL_newlib(ctx, ((luaL_Reg[]) {
		{ "mkdir", lib_fs_mkdir },
		{ "chmod", lib_fs_chmod },
		{ "symlink", lib_fs_symlink },
		{ NULL, NULL },
	}));

	return 1;
}