1 files changed, 67 insertions, 0 deletions
diff --git a/log.c b/log.c
new file mode 100644
index 0000000..a4e585d
--- /dev/null
+++ b/log.c
@@ -0,0 +1,67 @@
+#include "log.h"
+#include <stdbool.h>
+#include <unistd.h>
+
+static FILE *log_file = NULL;
+
+static void get_timestamp(char timestamp[24]) {
+	struct tm tm = {0};
+	localtime_r((const time_t[1]) { time(NULL) }, &tm);
+	strftime(timestamp, 24, "[%Y-%m-%d %H:%M:%S]", &tm);
+}
+
+void log_init(const char *out) {
+	assert(!log_file);
+	log_file = fopen(out, "a");
+	if (log_file) {
+		char timestamp[24] = {0};
+		get_timestamp(timestamp);
+		fprintf(log_file, "\n\n--- new session %s ---\n", timestamp);
+	} else {
+		perror("fopen");
+	}
+}
+
+void log_message(int severity, const char *fmt, va_list args) {
+	char *message = va_sprintf(fmt, args);
+	if (!message) return;
+	if (log_file) {
+		char timestamp[24] = {0};
+		get_timestamp(timestamp);
+		fprintf(log_file, "%s ", timestamp);
+	}
+	const char *color_start = "", *severity_str = "???";
+	switch (severity) {
+	case LOG_ERROR:
+		color_start = "\x1b[91m";
+		severity_str = "error";
+		break;
+	case LOG_WARNING:
+		color_start = "\x1b[93m";
+		severity_str = "warning";
+		break;
+	}
+	bool color = isatty(2) == 1;
+	if (color)
+		fprintf(stderr, "%s", color_start);
+	fprintf(stderr, "%s: ", severity_str);
+	if (color)
+		fprintf(stderr, "\x1b[0m");
+	fprintf(stderr, "%s\n", message);
+	if (log_file) fprintf(log_file, "%s: %s\n", severity_str, message);
+	free(message);
+}
+
+void log_error(const char *fmt, ...) {
+	va_list args;
+	va_start(args, fmt);
+	log_message(LOG_ERROR, fmt, args);
+	va_end(args);
+}
+
+void log_warning(const char *fmt, ...) {
+	va_list args;
+	va_start(args, fmt);
+	log_message(LOG_WARNING, fmt, args);
+	va_end(args);
+}