#include <sys/stat.h>

#include <time.h> // clock_*
#include <stdio.h> // rename is in here... also remove
#include <dirent.h>
#include <string.h>
#include <stdbool.h>
#include <stdlib.h> // mkstemp

bool older_than(const struct timespec older, const struct timespec newer) {
	if(older.tv_sec < newer.tv_sec) return true;
	if(older.tv_sec > newer.tv_sec) return false;
	if(older.tv_nsec < newer.tv_nsec) return true;
	return false;
}

int main(int argc, char *argv[])
{
	if(argc != 2) return 1;
	const char* destname = argv[1];
	size_t destlen = strlen(argv[1]);
	{
		/* Only rebuild .generated.mk once every 60 seconds at most */
		struct stat statinfo;
		if(0 == stat(destname, &statinfo)) {
			struct timespec then;
			clock_gettime(CLOCK_REALTIME, &then);
			then.tv_sec -= 60;
			if(older_than(statinfo.st_mtim, then)) {
				puts("Skipping.");
				exit(0);
			}
		}
	}
	
	char tempname[] = ".tmpXXXXXX";
#define tempnamelen (sizeof(tempname)-1)
	int tempfd = mkstemp(tempname);
	FILE* out = fdopen(tempfd,"wt");
	if(!out) return 2;
#define PUTS(s, len) fwrite(s, len, 1, out)
#define PUTLIT(lit) PUTS(lit, sizeof(lit)-1)
	PUTLIT("PRODUCTS :=");
	bool started = false;
	DIR* d = opendir(".");
	struct dirent* e;
	while((e = readdir(d))) {
		size_t len = strlen(e->d_name);
		if(len < 4) continue;
		if(e->d_name[0] == '.' &&
			 e->d_name[0] == 't' &&
			 e->d_name[0] == 'm' &&
			 e->d_name[0] == 'p') {
			if(!(len == tempnamelen &&
					 (0 == memcmp(e->d_name, tempname, tempnamelen)))) {
				remove(e->d_name);
				continue;
			}
		}
		if(e->d_name[len-3] != '.') continue;
		if(e->d_name[len-2] != 'm') continue;
		if(e->d_name[len-1] != 'd') continue;
		PUTLIT(" \\\n\thtml/");
		PUTS(e->d_name, len - 3);
		PUTLIT(".html");
	}
	fclose(out);
	rename(tempname,destname);
	return 0;
}