/* redo.c
 *
 * Copyright (c) 2014-2016 Tharre
 *
 * This software may be modified and distributed under the terms
 * of the MIT license.  See the LICENSE file for details.
 */

#define _XOPEN_SOURCE 600
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <time.h>
#include <limits.h>
#include <unistd.h>

#include "build.h"
#include "util.h"
#include "dbg.h"
#include "filepath.h"


/* Returns the amount of digits a number n has in decimal. */
static inline unsigned digits(unsigned n) {
	return n ? 1 + digits(n/10) : n;
}

void prepare_env() {
	if (getenv("REDO_ROOT") && getenv("REDO_PARENT_TARGET")
	    && getenv("REDO_MAGIC"))
		return;

	/* set REDO_ROOT */
	char *cwd = getcwd(NULL, 0);
	if (!cwd)
		fatal("redo: failed to obtain cwd");
	if (setenv("REDO_ROOT", cwd, 0))
		fatal("redo: failed to setenv() REDO_ROOT to %s", cwd);
	free(cwd);

	/* set REDO_MAGIC */
	char magic_str[digits(UINT_MAX) + 1];
	sprintf(magic_str, "%u", rand());
	if (setenv("REDO_MAGIC", magic_str, 0))
		fatal("redo: failed to setenv() REDO_MAGIC to %s", magic_str);
}

int DBG_LVL;

int main(int argc, char *argv[]) {
	srand(time(NULL));
	char *argv_base = xbasename(argv[0]);

	if (!strcmp(argv_base, "redo")) {
		prepare_env();
		if (argc < 2) {
			update_target("all", 'a');
		} else {
			for (int i = 1; i < argc; ++i)
				update_target(argv[i], 'a');
		}
	} else {
		char ident;
		char **temp;
		if      (!strcmp(argv_base, "redo-ifchange"))
			ident = 'c';
		else if (!strcmp(argv_base, "redo-ifcreate"))
			ident = 'e';
		else if (!strcmp(argv_base, "redo-always"))
			ident = 'a';
		else
			die("redo: argv set to unkown value\n");

		/* ensure the environment is correct */
		char *parent = getenv("REDO_PARENT_TARGET");
		char *root = getenv("REDO_ROOT");
		char *magic = getenv("REDO_MAGIC");

		if (!parent || !root || !magic)
			die("%s must be called inside a .do script\n", argv[0]);

		/* set DBG_LVL (for dbg.h) */
		char *env = getenv("REDO_DEBUG");
		if (env)
			DBG_LVL = atoi(env);

		if (ident == 'a')
			add_prereq(parent, parent, ident);
		else
			for (int i = 1; i < argc; ++i) {
				do {
					temp = &argv[rand() % (argc-1) + 1];
				} while (!*temp);

				update_target(*temp, ident);
				add_prereq_path(*temp, xbasename(parent), ident);
				*temp = NULL;
			}
	}

	return EXIT_SUCCESS;
}