using System.Diagnostics;
using System.Drawing.Drawing2D;

namespace TempleRun;

/// <summary>
/// 主窗体：负责游戏循环（定时器 + 高精度计时）、键盘输入、双缓冲绘制调度。
/// </summary>
public class GameForm : Form
{
    private readonly GameWorld _world = new();
    private readonly System.Windows.Forms.Timer _timer;
    private readonly Stopwatch _watch = Stopwatch.StartNew();

    private double _lastTime;
    private double _fpsAccum;
    private int _frameCount;
    private bool _showFps;

    public GameForm()
    {
        Text = "神庙逃亡 · Temple Run (WinForms)";
        ClientSize = new Size(1024, 720);
        MinimumSize = new Size(760, 540);
        StartPosition = FormStartPosition.CenterScreen;
        BackColor = Color.FromArgb(12, 12, 20);
        DoubleBuffered = true;
        ResizeRedraw = true;
        AutoScaleMode = AutoScaleMode.None;
        SetStyle(ControlStyles.AllPaintingInWmPaint
               | ControlStyles.UserPaint
               | ControlStyles.OptimizedDoubleBuffer, true);

        try { Icon = BuildIcon(); } catch { /* 图标失败不影响运行 */ }

        _lastTime = _watch.Elapsed.TotalSeconds;

        _timer = new System.Windows.Forms.Timer { Interval = 15 };   // ≈66Hz
        _timer.Tick += OnTick;
        _timer.Start();
    }

    // ------------------------------------------------------------------ 主循环
    private void OnTick(object sender, EventArgs e)
    {
        double now = _watch.Elapsed.TotalSeconds;
        float dt = (float)(now - _lastTime);
        _lastTime = now;

        if (dt <= 0f) return;
        if (dt > 0.06f) dt = 0.06f;      // 卡顿/拖动窗口后不产生穿模

        // FPS 统计
        _frameCount++;
        _fpsAccum += dt;
        if (_fpsAccum >= 0.5)
        {
            _world.Fps = (float)(_frameCount / _fpsAccum);
            _frameCount = 0;
            _fpsAccum = 0;
        }

        _world.Update(dt);
        Invalidate();
    }

    protected override void OnPaint(PaintEventArgs e)
    {
        GameRenderer.Draw(e.Graphics, ClientSize.Width, ClientSize.Height, _world, _showFps);
    }

    // ------------------------------------------------------------------ 输入
    protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
    {
        Keys key = keyData & Keys.KeyCode;

        if (key == Keys.F1) { _showFps = !_showFps; Invalidate(); return true; }
        if (key == Keys.F11)
        {
            WindowState = WindowState == FormWindowState.Maximized
                ? FormWindowState.Normal : FormWindowState.Maximized;
            return true;
        }
        if (key == Keys.F12) { _world.Muted = !_world.Muted; return true; }

        if (_world.HandleKey(key)) return true;

        return base.ProcessCmdKey(ref msg, keyData);
    }

    protected override void OnMouseClick(MouseEventArgs e)
    {
        base.OnMouseClick(e);
        // 鼠标左键也能触发"开始/重开"，方便触屏设备
        if (e.Button == MouseButtons.Left)
        {
            if (_world.State == RunState.Ready) _world.Start();
            else if (_world.State == RunState.GameOver && _world.CanRestart)
            {
                _world.Start();
            }
        }
    }

    protected override void OnFormClosed(FormClosedEventArgs e)
    {
        _timer.Stop();
        _timer.Dispose();
        GameRenderer.ResetCache();
        base.OnFormClosed(e);
    }

    // ------------------------------------------------------------------ 图标
    private static Icon BuildIcon()
    {
        using var bmp = new Bitmap(32, 32);
        using (var g = Graphics.FromImage(bmp))
        {
            g.SmoothingMode = SmoothingMode.AntiAlias;
            g.Clear(Color.Transparent);
            using (var bg = new SolidBrush(Color.FromArgb(46, 34, 28)))
                g.FillEllipse(bg, 0, 0, 31, 31);
            using (var gold = new SolidBrush(Cfg.Gold))
                g.FillEllipse(gold, 7, 7, 18, 18);
            using (var dark = new Pen(Cfg.GoldDark, 2.4f))
                g.DrawEllipse(dark, 7, 7, 18, 18);
            using (var hi = new SolidBrush(Color.FromArgb(230, 255, 250, 220)))
                g.FillEllipse(hi, 11, 10, 5, 4);
        }
        return Icon.FromHandle(bmp.GetHicon());
    }
}