#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <spawn.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>

extern char **environ;

static const char *PYTHON = "/usr/bin/python3";
static const char *WATCHER = "/Users/ar/bin/daily_activity_watch.py";
static const char *APP_LOG = "/Users/ar/.daily-activity-watch.app.log";
static const char *CHILD_STDOUT = "/Users/ar/.daily-activity-watch.child.log";
static const char *CHILD_STDERR = "/Users/ar/.daily-activity-watch.err.log";

static volatile sig_atomic_t should_stop = 0;
static volatile sig_atomic_t child_pid = 0;

static void app_log(const char *fmt, ...) {
    FILE *fh = fopen(APP_LOG, "a");
    if (!fh) {
        return;
    }

    time_t now = time(NULL);
    struct tm local_tm;
    localtime_r(&now, &local_tm);

    char ts[32];
    strftime(ts, sizeof(ts), "%Y-%m-%d %H:%M:%S", &local_tm);
    fprintf(fh, "[%s] ", ts);

    va_list args;
    va_start(args, fmt);
    vfprintf(fh, fmt, args);
    va_end(args);

    fputc('\n', fh);
    fclose(fh);
}

static void handle_signal(int signo) {
    should_stop = 1;
    if (child_pid > 0) {
        kill(child_pid, signo);
    }
}

static int spawn_watcher(pid_t *pid) {
    posix_spawn_file_actions_t actions;
    posix_spawn_file_actions_init(&actions);
    posix_spawn_file_actions_addopen(&actions, STDOUT_FILENO, CHILD_STDOUT,
                                     O_CREAT | O_APPEND | O_WRONLY, 0644);
    posix_spawn_file_actions_addopen(&actions, STDERR_FILENO, CHILD_STDERR,
                                     O_CREAT | O_APPEND | O_WRONLY, 0644);

    char *argv[] = {(char *)PYTHON, (char *)WATCHER, NULL};
    int rc = posix_spawn(pid, PYTHON, &actions, NULL, argv, environ);
    posix_spawn_file_actions_destroy(&actions);
    return rc;
}

int main(void) {
    signal(SIGTERM, handle_signal);
    signal(SIGINT, handle_signal);
    signal(SIGHUP, handle_signal);

    app_log("DailyActivityWatch app started");

    while (!should_stop) {
        pid_t pid = 0;
        int rc = spawn_watcher(&pid);
        if (rc != 0) {
            app_log("failed to start watcher: %s", strerror(rc));
            sleep(5);
            continue;
        }

        child_pid = pid;
        app_log("started watcher pid=%d", pid);

        int status = 0;
        while (waitpid(pid, &status, 0) < 0) {
            if (errno == EINTR && should_stop) {
                break;
            }
            if (errno != EINTR) {
                app_log("waitpid failed: %s", strerror(errno));
                break;
            }
        }

        child_pid = 0;
        if (should_stop) {
            break;
        }

        app_log("watcher exited status=%d; restarting in 5s", status);
        sleep(5);
    }

    app_log("DailyActivityWatch app stopped");
    return 0;
}