#include "flog.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <time.h>
#include <sys/stat.h>
#include <pthread.h>
#include <unistd.h>

#define FLOG_MAX_CATS 32

static char g_path[512];
static long g_rotate_ms = 3600000;
static long g_max_bytes = 1 << 20;   /* 1 MiB */
static FILE *g_fp = NULL;
static long long g_last_rotate_ms = 0;
static pthread_mutex_t g_mutex = PTHREAD_MUTEX_INITIALIZER;

typedef struct {
    char cat[32];
    long long last_ms;
} FlogThrottle;

static FlogThrottle g_throttle[FLOG_MAX_CATS];
static int g_num_throttle = 0;

static long long now_ms(void) {
    struct timespec ts;
    clock_gettime(CLOCK_MONOTONIC, &ts);
    return (long long)ts.tv_sec * 1000 + ts.tv_nsec / 1000000;
}

int flog_init(const char *path, long rotate_ms, long max_bytes) {
    pthread_mutex_lock(&g_mutex);
    if (g_fp) { fclose(g_fp); g_fp = NULL; }
    g_path[0] = '\0';
    if (path && path[0]) {
        strncpy(g_path, path, sizeof(g_path) - 1);
        g_fp = fopen(path, "a");
        if (!g_fp) {
            pthread_mutex_unlock(&g_mutex);
            fprintf(stderr, "flog: cannot open %s\n", path);
            return -1;
        }
    }
    if (rotate_ms > 0) g_rotate_ms = rotate_ms;
    if (max_bytes > 0) g_max_bytes = max_bytes;
    g_last_rotate_ms = now_ms();
    pthread_mutex_unlock(&g_mutex);
    return 0;
}

void flog_shutdown(void) {
    pthread_mutex_lock(&g_mutex);
    if (g_fp) { fclose(g_fp); g_fp = NULL; }
    pthread_mutex_unlock(&g_mutex);
}

int flog_enabled(void) {
    return g_fp != NULL;
}

void flog(const char *fmt, ...) {
    if (!g_fp) return;
    char msg[1024];
    va_list ap;
    va_start(ap, fmt);
    vsnprintf(msg, sizeof(msg), fmt, ap);
    va_end(ap);

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

    pthread_mutex_lock(&g_mutex);
    if (!g_fp) { pthread_mutex_unlock(&g_mutex); return; }
    fprintf(g_fp, "[%04d-%02d-%02d %02d:%02d:%02d] %s\n",
            tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,
            tm.tm_hour, tm.tm_min, tm.tm_sec, msg);
    fflush(g_fp);
    pthread_mutex_unlock(&g_mutex);
}

void flog_throttled(const char *cat, long min_interval_ms, const char *fmt, ...) {
    if (!g_fp || !cat) return;

    long long now = now_ms();
    int i = 0;
    pthread_mutex_lock(&g_mutex);
    for (i = 0; i < g_num_throttle; i++)
        if (strcmp(g_throttle[i].cat, cat) == 0) break;
    if (i >= FLOG_MAX_CATS) {
        pthread_mutex_unlock(&g_mutex);
        return;
    }
    if (i == g_num_throttle) {
        strncpy(g_throttle[i].cat, cat, sizeof(g_throttle[i].cat) - 1);
        g_throttle[i].cat[sizeof(g_throttle[i].cat) - 1] = '\0';
        g_throttle[i].last_ms = 0;
        g_num_throttle++;
    }
    if (now - g_throttle[i].last_ms < min_interval_ms) {
        pthread_mutex_unlock(&g_mutex);
        return;
    }
    g_throttle[i].last_ms = now;
    pthread_mutex_unlock(&g_mutex);

    char msg[1024];
    va_list ap;
    va_start(ap, fmt);
    vsnprintf(msg, sizeof(msg), fmt, ap);
    va_end(ap);

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

    pthread_mutex_lock(&g_mutex);
    if (!g_fp) { pthread_mutex_unlock(&g_mutex); return; }
    fprintf(g_fp, "[%04d-%02d-%02d %02d:%02d:%02d] %s\n",
            tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,
            tm.tm_hour, tm.tm_min, tm.tm_sec, msg);
    fflush(g_fp);
    pthread_mutex_unlock(&g_mutex);
}

void flog_rotate_check(void) {
    pthread_mutex_lock(&g_mutex);
    if (!g_fp) { pthread_mutex_unlock(&g_mutex); return; }

    long long now = now_ms();
    int do_trunc = 0;
    if (g_rotate_ms > 0 && now - g_last_rotate_ms >= g_rotate_ms) {
        do_trunc = 1;
        g_last_rotate_ms = now;
    }
    if (g_max_bytes > 0) {
        struct stat st;
        if (fstat(fileno(g_fp), &st) == 0 && st.st_size >= g_max_bytes)
            do_trunc = 1;
    }
    if (do_trunc) {
        fclose(g_fp);
        g_fp = fopen(g_path, "w");
        if (!g_fp) {
            pthread_mutex_unlock(&g_mutex);
            fprintf(stderr, "flog: cannot reopen %s\n", g_path);
            return;
        }
        fprintf(g_fp, "--- log cleared at %lld ms ---\n", now);
        fflush(g_fp);
    }
    pthread_mutex_unlock(&g_mutex);
}