import { Director, director, game } from 'cc';
import { ThermalProfile } from './ThermalProfile';
import { PerfReport } from './PerfReport';

/** 战斗内 FPS 滑动窗口（帧数，约 1s@60） */
const WINDOW_FRAMES = 60;

/**
 * 战斗 FPS 采样：窗口上报 PF-BTL-FPS，离局汇总 PF-BTL-SESS（含目标帧率 gap）。
 */
export class PerfSampler {
    private static _active = false;
    private static _targetFps = 60;
    private static _windowBuf: number[] = [];
    private static _windowLeft = 0;
    private static _sessionBuf: number[] = [];

    /** 地图可交互后开始采样 */
    static beginBattle(): void {
        if (PerfSampler._active) return;
        ThermalProfile.resolve();
        PerfSampler._targetFps = ThermalProfile.current.battleFrameRate;
        PerfReport.reportBattleRuntimeConfig();
        PerfSampler._active = true;
        PerfSampler._windowBuf = [];
        PerfSampler._sessionBuf = [];
        PerfSampler._windowLeft = WINDOW_FRAMES;
        director.on(Director.EVENT_AFTER_UPDATE, PerfSampler._onFrame, PerfSampler);
    }

    /** 战斗 UI teardown：汇总并上报 */
    static endBattle(): void {
        if (!PerfSampler._active) return;
        director.off(Director.EVENT_AFTER_UPDATE, PerfSampler._onFrame, PerfSampler);
        PerfSampler._active = false;
        PerfSampler._flushWindow(true);
        PerfSampler._flushSession();
        PerfReport.resetBattlePerfSession();
    }

    private static _onFrame(): void {
        const dt = game.deltaTime || 0;
        if (dt <= 0) return;
        const fps = 1 / dt;
        PerfSampler._windowBuf.push(fps);
        PerfSampler._sessionBuf.push(fps);
        PerfSampler._windowLeft--;
        if (PerfSampler._windowLeft <= 0) {
            PerfSampler._flushWindow(false);
            PerfSampler._windowLeft = WINDOW_FRAMES;
            PerfSampler._windowBuf = [];
        }
    }

    private static _flushWindow(force: boolean): void {
        if (PerfSampler._windowBuf.length === 0) return;
        if (!force && PerfSampler._windowBuf.length < WINDOW_FRAMES / 2) return;
        const stats = PerfSampler._stats(PerfSampler._windowBuf);
        PerfReport.reportBattleFps(stats.avg, stats.p10, PerfSampler._targetFps);
    }

    private static _flushSession(): void {
        if (PerfSampler._sessionBuf.length === 0) return;
        const stats = PerfSampler._stats(PerfSampler._sessionBuf);
        PerfReport.reportBattleSessionFps(
            stats.avg,
            stats.p10,
            PerfSampler._targetFps,
            PerfSampler._sessionBuf.length,
        );
        PerfSampler._sessionBuf = [];
    }

    private static _stats(buf: number[]): { avg: number; p10: number } {
        const sorted = [...buf].sort((a, b) => a - b);
        const sum = sorted.reduce((a, b) => a + b, 0);
        const avg = sum / sorted.length;
        const p10Idx = Math.floor(sorted.length * 0.1);
        const p10 = sorted[p10Idx] ?? avg;
        return { avg, p10 };
    }
}