#include <stdlib.h>
#include <stdio.h>
#include <sys/stat.h>
#include <unistd.h>
#include <string.h>
#include <dirent.h>

#ifdef DEBUG
#define DBG(fmt, ...) fprintf(stderr, fmt, ##__VA_ARGS__)
#else
#define DBG(fmt, ...)
#endif

#define RED "\033[0;31m"
#define GREEN "\033[0;32m"
#define CLEAR "\033[0;0m"

enum destination { HOME, XDG_CONFIG_HOME, UNDEFINED };

int resolve_target_path(const char *file)
{
	struct stat sb;
	char source[512];

	snprintf(source, sizeof(source), "%s/dotfiles/%s", getenv("HOME"),
		 file);

	if (lstat(source, &sb) == -1) {
		return UNDEFINED;
	}

	if (file[0] == '.') {
		return HOME;
	} else if (S_ISDIR(sb.st_mode)) {
		return XDG_CONFIG_HOME;
	}

	return UNDEFINED;
}

int is_link(const char *path)
{
	struct stat sb;

	if (lstat(path, &sb) == 0) {
		if (S_ISLNK(sb.st_mode)) {
			return 1;
		}
	}

	return 0;
}

void create_link(const char *file)
{
	struct stat sb;
	char source[512];
	char target[512];

	switch (resolve_target_path(file)) {
	case HOME:
		snprintf(target, sizeof(target), "%s/%s", getenv("HOME"), file);
		break;
	case XDG_CONFIG_HOME:
		snprintf(target, sizeof(target), "%s/.config/%s",
			 getenv("HOME"), file);
		break;
	default:
		fprintf(stderr,
			"%serror: could not resolve destination for %s%s\n",
			RED, source, CLEAR);
		exit(EXIT_FAILURE);
		break;
	}

	snprintf(source, sizeof(source), "%s/dotfiles/%s", getenv("HOME"),
		 file);

	if (stat(source, &sb) == -1) {
		fprintf(stderr, "%snot found: %s%s\n", RED, source, CLEAR);
		exit(EXIT_FAILURE);
	}

	if (is_link(target)) {
		printf("already linked\n");
		exit(EXIT_SUCCESS);
	}

	if (symlink(source, target) == 0) {
		printf("Changes:\n");
		printf("\t%slinked: %s%s\n", GREEN, file, CLEAR);
		exit(EXIT_SUCCESS);
	}
}

void remove_link(const char *file)
{
	char target[512];

	switch (resolve_target_path(file)) {
	case HOME:
		snprintf(target, sizeof(target), "%s/%s", getenv("HOME"), file);
		break;
	case XDG_CONFIG_HOME:
		snprintf(target, sizeof(target), "%s/.config/%s",
			 getenv("HOME"), file);
		break;
	default:
		fprintf(stderr, "%snot found: %s%s\n", RED, file, CLEAR);
		exit(EXIT_FAILURE);
		break;
	}

	if (!is_link(target)) {
		printf("already unlinked\n");
		exit(EXIT_SUCCESS);
	}

	if (unlink(target) == 0) {
		printf("Changes:\n");
		printf("\t%sunlinked: %s%s\n", RED, file, CLEAR);
		exit(EXIT_SUCCESS);
	}
}
int main(int argc, char *argv[])
{
	char path[512];
	int opt;
	char *arg;

	if (getenv("HOME") == NULL) {
		fprintf(stderr, "%s\n", "variable not set: $HOME");
		exit(EXIT_FAILURE);
	}

	while ((opt = getopt(argc, argv, "f:")) == 0) {
		switch (opt) {
		case 'f':
			break;
		default:
			fprintf(stderr, "usage: pt [link | unlink] <file>\n");
			exit(EXIT_FAILURE);
		}
	}

	if (argv[optind] == NULL) {
		fprintf(stderr, "usage: pt [link | unlink] <file>\n");
		exit(EXIT_FAILURE);
	}

	char *cmd = argv[optind];
	if (strcmp(cmd, "link") == 0) {
		if (argv[optind + 1] == NULL) {
			fprintf(stderr, "missing argument: <file>\n");
			exit(EXIT_FAILURE);
		}
		create_link(argv[optind + 1]);
	} else if (strcmp(cmd, "unlink") == 0) {
		if (argv[optind + 1] == NULL) {
			fprintf(stderr, "missing argument: <file>\n");
			exit(EXIT_FAILURE);
		}
		remove_link(argv[optind + 1]);
	} else if (strcmp(cmd, "status") == 0) {
		char source[512];
		struct dirent *d;

		snprintf(source, sizeof(source), "%s/dotfiles",
			 getenv("HOME"));

		printf("Using directory %s\n\n", source);
		printf("Unlinked files:\n");

		DIR *dir = opendir(source);
		while ((d = readdir(dir)) != NULL) {
			if (strcmp(d->d_name, ".") == 0 ||
			    strcmp(d->d_name, "..") == 0) {
				continue;
			}

			printf("\t%s%s%s\n", RED, d->d_name, CLEAR);
		}
	}
}