// ============================================================================
// timer.c - 高精度计时器实现 (使用 rdtsc.asm)
// ============================================================================

#include "timer.h"
#include "../include/engine_api.h"
#include <Windows.h>

static double g_seconds_per_count = 0.0;
static int64_t g_prev_time = 0;
static int64_t g_curr_time = 0;
static int64_t g_start_time = 0;
static double g_delta_time = 0.0;
static double g_total_time = 0.0;
static double g_fps = 0.0;
static uint64_t g_frame_count = 0;
static double g_fps_accumulator = 0.0;
static uint64_t g_fps_frame_count = 0;

void timer_init(void) {
    // 使用 QueryPerformanceCounter 获取高精度时间
    LARGE_INTEGER freq;
    QueryPerformanceFrequency(&freq);
    g_seconds_per_count = 1.0 / (double)freq.QuadPart;

    LARGE_INTEGER now;
    QueryPerformanceCounter(&now);
    g_start_time = now.QuadPart;
    g_prev_time = now.QuadPart;
    g_curr_time = now.QuadPart;

    g_delta_time = 0.0;
    g_total_time = 0.0;
    g_fps = 0.0;
    g_frame_count = 0;
    g_fps_accumulator = 0.0;
    g_fps_frame_count = 0;
}

void timer_reset(void) {
    timer_init();
}

void timer_tick(void) {
    LARGE_INTEGER now;
    QueryPerformanceCounter(&now);
    g_curr_time = now.QuadPart;

    g_delta_time = (g_curr_time - g_prev_time) * g_seconds_per_count;
    g_total_time = (g_curr_time - g_start_time) * g_seconds_per_count;
    g_prev_time = g_curr_time;

    g_frame_count++;
    g_fps_frame_count++;
    g_fps_accumulator += g_delta_time;

    if (g_fps_accumulator >= 1.0) {
        g_fps = (double)g_fps_frame_count / g_fps_accumulator;
        g_fps_frame_count = 0;
        g_fps_accumulator = 0.0;
    }
}

double timer_get_delta(void) {
    return g_delta_time;
}

double timer_get_total(void) {
    return g_total_time;
}

double timer_get_fps(void) {
    return g_fps;
}

uint64_t timer_get_frame_count(void) {
    return g_frame_count;
}