1 files changed, 113 insertions, 0 deletions
diff --git a/src/compgen.c b/src/compgen.c
index b0ea44d..df04386 100644
--- a/src/compgen.c
+++ b/src/compgen.c
@@ -1,14 +1,127 @@
 #include <dirent.h>
+#include <errno.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/stat.h>
+#include "compgen.h"
 #include "history.h"
 #include "log.h"
+#include "mkdirp.h"
 #include "string_vec.h"
 #include "xmalloc.h"
 
+static const char *default_state_dir = ".cache";
+static const char *cache_basename = "tofi-compgen";
+
+[[nodiscard]]
+static char *get_cache_path() {
+	char *cache_name = NULL;
+	const char *state_path = getenv("XDG_CACHE_HOME");
+	if (state_path == NULL) {
+		const char *home = getenv("HOME");
+		if (home == NULL) {
+			log_error("Couldn't retrieve HOME from environment.\n");
+			return NULL;
+		}
+		size_t len = strlen(home) + 1
+			+ strlen(default_state_dir) + 1
+			+ strlen(cache_basename) + 1;
+		cache_name = xmalloc(len);
+		snprintf(
+			cache_name,
+			len,
+			"%s/%s/%s",
+			home,
+			default_state_dir,
+			cache_basename);
+	} else {
+		size_t len = strlen(state_path) + 1
+			+ strlen(cache_basename) + 1;
+		cache_name = xmalloc(len);
+		snprintf(
+			cache_name,
+			len,
+			"%s/%s",
+			state_path,
+			cache_basename);
+	}
+	return cache_name;
+}
+
+struct string_vec compgen_cached()
+{
+	log_debug("Retrieving PATH.\n");
+	const char *env_path = getenv("PATH");
+	if (env_path == NULL) {
+		log_error("Couldn't retrieve PATH from environment.\n");
+		exit(EXIT_FAILURE);
+	}
+
+	log_debug("Retrieving cache location.\n");
+	char *cache_path = get_cache_path();
+
+	struct stat sb;
+	if (cache_path == NULL) {
+		return compgen();
+	}
+
+	/* If the cache doesn't exist, create it and return */
+	errno = 0;
+	if (stat(cache_path, &sb) == -1) {
+		if (errno == ENOENT) {
+			struct string_vec commands = compgen();
+			if (!mkdirp(cache_path)) {
+				free(cache_path);
+				return commands;
+			}
+			FILE *cache = fopen(cache_path, "wb");
+			string_vec_save(&commands, cache);
+			fclose(cache);
+			free(cache_path);
+			return commands;
+		}
+		free(cache_path);
+		return compgen();
+	}
+
+	/* The cache exists, so check if it's still in date */
+	char *path = xstrdup(env_path);
+	char *saveptr = NULL;
+	char *path_entry = strtok_r(path, ":", &saveptr);
+	bool out_of_date = false;
+	while (path_entry != NULL) {
+		struct stat path_sb;
+		if (stat(path_entry, &path_sb) == 0) {
+			if (path_sb.st_mtim.tv_sec > sb.st_mtim.tv_sec) {
+				out_of_date = true;
+				break;
+			}
+		}
+		path_entry = strtok_r(NULL, ":", &saveptr);
+	}
+	free(path);
+
+	struct string_vec commands;
+	if (out_of_date) {
+		log_debug("Cache out of date, updating.\n");
+		log_indent();
+		commands = compgen();
+		log_unindent();
+		FILE *cache = fopen(cache_path, "wb");
+		string_vec_save(&commands, cache);
+		fclose(cache);
+	} else {
+		log_debug("Cache up to date, loading.\n");
+		FILE *cache = fopen(cache_path, "rb");
+		commands = string_vec_load(cache);
+		fclose(cache);
+	}
+	free(cache_path);
+	return commands;
+}
+
 struct string_vec compgen()
 {
 	log_debug("Retrieving PATH.\n");