#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <time.h>
#include <unistd.h>
#include <pthread.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <sys/types.h>

typedef struct f_comp_data {
	char *f1;
	char *f2;
} f_comp_data;

void *f1_newer(void *arg) {
	f_comp_data *files = (f_comp_data *) arg;
	char *f1 = files->f1;
	char *f2 = files->f2;
	struct stat f1_attr;
	struct stat f2_attr;
	stat(f1, &f1_attr);
	stat(f2, &f2_attr);
	int diff = difftime(f1_attr.st_mtime, f2_attr.st_mtime);
	int ret = 0;
	if (diff <= 0) {
		pthread_exit(&ret);
	}
	ret = 1;
	pthread_exit(&ret);
}

void *create_template(void *arg) {
	/* Create simple main.c and makefile boilerplate */
	char *path = (char *) arg;
	int fd = creat(path, 00644);
	FILE *file = fdopen(fd, "w");
	switch(path[2]) {
		case 'i': 
			fprintf(file, "#include <stdio.h>\n\nint main() {\n\tprintf(\"Hello world\\n\");\n}");
			break;
		case 'k':
			fprintf(file, "debug: main.c\n\tgcc -Wall main.c -o ./bin/debug\nrelease: main.c\n\tgcc -O2 -march=native main.c -o ./bin/release");
			break;
		default: break;
	}

	fclose(file);

	return NULL;
}

void new(char *argv[]) {
	char *name = argv[2];
	mkdir(name, 0777);
	chdir(name);
	pthread_t s_thread, m_thread;
	pthread_create(&s_thread, NULL, create_template, (void *) "main.c");
	pthread_create(&m_thread, NULL, create_template, (void *) "makefile");

	pthread_join(s_thread, NULL);
	pthread_join(m_thread, NULL);
	exit(0);
}

int main(int argc, char *argv[]) {
	/* Struct to hold files */
	f_comp_data files;
	files.f1 = "main.c";
	files.f2 = "./bin/debug";

	/* Parse args to determine which mode to run in
	 * Not very robust, needs improvement
	 */
	enum { RUN, BUILD, BUILD_RELEASE, NEW } mode = RUN;
	if (argc > 1) {
		switch(argv[1][0]) {
			case 'r': break;
			case 'b': 
				  if (argc > 2) { 
					  mode = BUILD_RELEASE; 
					  files.f2 = "./bin/release";
					  break; 
				  }
				  mode = BUILD; break;
			case 'n':
				  new(argv); break;
			default: printf("Unknown argument: '%s'\nDefaulting to 'run'\n", argv[1]);
		}
	}

	/* Threads to:
	 * create makefile
	 * check age of source vs. bin
	 */
	pthread_t f_thread, check_thread;
	pthread_create(&f_thread, NULL, create_template, (void *) "makefile");
	pthread_create(&check_thread, NULL, f1_newer, (void *)&files);

	mkdir("./bin", 0777);


	pthread_join(f_thread, NULL);

	/* Get value from thread which checks if the bin
	 * is older than the source code
	 */
	void *newer;
	pthread_join(check_thread, &newer);
	int recomp = *(int *) newer;

	if (recomp) {
		pid_t make_pid;
		if ((make_pid = fork()) == 0) {
			printf("Recompiling...\n");
			switch (mode) {
				case BUILD_RELEASE:
					execl("/usr/bin/make", "make", "release", NULL); 
					break;
				default: 
					execl("/usr/bin/make", "make", "debug", NULL); 
			}
		}
		waitpid(make_pid, NULL, 0);
	}

	if (mode == RUN) {
		pid_t x_pid;
		if ((x_pid = fork()) == 0) {
			execl(files.f2, "tmp", NULL);
		}
		waitpid(x_pid, NULL, 0);
	}

	return 0;
}