using System.Drawing.Drawing2D;

namespace TempleRun;

/// <summary>
/// 全局常量与可调参数。想改手感直接改这里。
/// 世界坐标约定：X 向右为正，Y 离地向上为正，Z 玩家前方为正。
/// 玩家永远停在 Z = 0，世界向 Z 负方向滚动。
/// </summary>
public static class Cfg
{
    // ---- 相机（透视投影参数）----
    public const float Focal = 520f;        // 焦距：越大视野越窄、远处物体越大
    public const float CamZ = 235f;         // 相机位于玩家后方多远
    public const float CamHeight = 142f;    // 相机离地高度
    public const float FarZ = 3000f;        // 渲染最远距离
    public const float MinDepth = 45f;      // 相机空间最小深度，防止除零

    // ---- 跑道 ----
    public const int LaneCount = 3;
    public const float LaneWidth = 112f;    // 单条车道宽
    public const float RoadHalfWidth = LaneWidth * 1.5f;

    // ---- 玩家 ----
    public const float PlayerHeight = 62f;  // 站立高度
    public const float SlideHeight = 30f;   // 滑铲高度
    public const float PlayerHalfDepth = 22f;
    public const float JumpSpeed = 430f;
    public const float Gravity = 950f;
    public const float LaneLerp = 13f;      // 换道插值速度
    public const float SlideDuration = 0.55f;

    // ---- 速度与难度 ----
    public const float StartSpeed = 620f;
    public const float MaxSpeed = 1900f;
    public const float SpeedAccel = 3.4f;    // 每秒自然加速
    public const float SpeedPerCoin = 5f;    // 每金币额外加速
    public const float SpawnIntervalMin = 0.62f;  // 相邻障碍组最小时间间隔(秒)
    public const float SpawnIntervalMax = 1.15f;

    // ---- 颜色（丛林日落 + 古神庙）----
    public static readonly Color SkyTop = Color.FromArgb(30, 34, 72);
    public static readonly Color SkyMid = Color.FromArgb(122, 78, 96);
    public static readonly Color SkyHorizon = Color.FromArgb(240, 168, 96);
    public static readonly Color Fog = Color.FromArgb(200, 152, 118);
    public static readonly Color GroundNear = Color.FromArgb(44, 36, 28);
    public static readonly Color GroundFar = Color.FromArgb(122, 100, 78);
    public static readonly Color RoadA = Color.FromArgb(178, 150, 110);
    public static readonly Color RoadB = Color.FromArgb(156, 130, 94);
    public static readonly Color Stone = Color.FromArgb(120, 112, 104);
    public static readonly Color Wood = Color.FromArgb(122, 82, 48);
    public static readonly Color Vine = Color.FromArgb(74, 116, 62);
    public static readonly Color Gold = Color.FromArgb(255, 202, 62);
    public static readonly Color GoldDark = Color.FromArgb(196, 140, 24);
    public static readonly Color Player = Color.FromArgb(226, 92, 62);

    public static float LaneX(int lane) => (lane - 1) * LaneWidth;

    public static Color Lerp(Color a, Color b, float t)
    {
        t = Math.Clamp(t, 0f, 1f);
        return Color.FromArgb(
            (int)(a.R + (b.R - a.R) * t),
            (int)(a.G + (b.G - a.G) * t),
            (int)(a.B + (b.B - a.B) * t));
    }
}

public enum RunState { Ready, Playing, Paused, GameOver }

public enum ObstacleKind
{
    /// <summary>矮障碍：必须跳跃</summary>
    Low,
    /// <summary>悬空横梁：必须滑铲</summary>
    High,
    /// <summary>整道石墙：必须换道</summary>
    Full
}

/// <summary>透视相机：把世界坐标投影到屏幕坐标。</summary>
public static class Cam
{
    public static float CenterX;
    public static float HorizonY;
    public static int Width;
    public static int Height;

    public static void Setup(int w, int h)
    {
        Width = w;
        Height = h;
        CenterX = w * 0.5f;
        HorizonY = h * 0.30f;
    }

    /// <summary>
    /// 投影一个世界点。
    /// scale 为"每世界单位对应多少像素"，用于缩放实体自身尺寸。
    /// </summary>
    public static void Project(float x, float y, float z, out float sx, out float sy, out float scale)
    {
        float depth = z + Cfg.CamZ;
        if (depth < Cfg.MinDepth) depth = Cfg.MinDepth;
        scale = Cfg.Focal / depth;
        sx = CenterX + x * scale;
        sy = HorizonY + (Cfg.CamHeight - y) * scale;
    }

    /// <summary>只投影地面上的点（y = 0）。</summary>
    public static void ProjectGround(float x, float z, out float sx, out float sy, out float scale)
        => Project(x, 0f, z, out sx, out sy, out scale);

    /// <summary>距离雾化系数：0 = 完全清晰，1 = 完全融入雾色。</summary>
    public static float FogAmount(float z)
    {
        float t = Math.Clamp(z / Cfg.FarZ, 0f, 1f);
        return t * t;   // 平方衰减，近处保持通透
    }
}

public class Obstacle
{
    public float Z;
    public int Lane;
    public ObstacleKind Kind;
    public bool Scored;          // 是否已计入"躲避成功"

    public float Width => Kind == ObstacleKind.Full ? 96f : 90f;
    public float Depth => Kind == ObstacleKind.Full ? 54f : 56f;
    public float BottomY => Kind == ObstacleKind.High ? 40f : 0f;
    public float TopY => Kind switch
    {
        ObstacleKind.Low => 46f,        // 低于跳跃高度，跳过去
        ObstacleKind.High => 98f,       // 悬空横梁，滑铲钻过去
        _ => 108f                       // 整道石墙，只能换道
    };
    public float CenterX => Cfg.LaneX(Lane);
}

public class Coin
{
    public float Z;
    public int Lane;
    public float Y = 36f;
    public bool Taken;
    public float Phase;
    public float CenterX => Cfg.LaneX(Lane);
}

public class Particle
{
    public float X, Y, Z;
    public float Vx, Vy, Vz;
    public float Life;
    public float MaxLife;
    public float Size;
    public float GravityScale = 1f;
    public Color Color;
}

/// <summary>路边装饰物：石柱、火把、树、雕像碎块。</summary>
public class SideProp
{
    public float Z;
    public int Side;        // -1 左，+1 右
    public int Type;        // 0=石柱 1=火把 2=枯树 3=碎石
    public float Height;
    public float Phase;

    public float CenterX => Side * (Cfg.RoadHalfWidth + 205f + (Type == 3 ? 40f : 0f));
}

public class Player
{
    public float X;                  // 当前横向世界坐标（插值中）
    public int TargetLane = 1;       // 目标车道 0/1/2
    public float Y;                  // 离地高度
    public float Vy;
    public bool OnGround = true;
    public bool Sliding;
    public float SlideTimer;
    public float RunPhase;           // 跑动动画相位
    public bool Alive = true;
    public float Tilt;               // 换道时的侧倾（视觉）

    public float Height => Sliding ? Cfg.SlideHeight : Cfg.PlayerHeight;

    public void Reset()
    {
        TargetLane = 1;
        X = Cfg.LaneX(1);
        Y = 0;
        Vy = 0;
        OnGround = true;
        Sliding = false;
        SlideTimer = 0;
        RunPhase = 0;
        Alive = true;
        Tilt = 0;
    }
}