using System.Numerics;

namespace Examples.Core;
/*******************************************************************************************
 *
 *   raylib [core] example - delta time
 *
 *   Example complexity rating: [★☆☆☆] 1/4
 *
 *   Example originally created with raylib 5.5, last time updated with raylib 6.0
 *
 *   Example contributed by Robin (@RobinsAviary) and reviewed by Ramon Santamaria (@raysan5)
 *
 *   Example licensed under an unmodified zlib/libpng license, which is an OSI-certified,
 *   BSD-like license that allows static linking with closed source software
 *
 *   Copyright (c) 2025 Robin (@RobinsAviary)
 *
 ********************************************************************************************/

using static Raylib_cs.Raylib;

public class DeltaTime
{
    public static int Main()
    {
        // Initialization
        //--------------------------------------------------------------------------------------
        const int screenWidth = 800;
        const int screenHeight = 450;

        InitWindow(screenWidth, screenHeight, "raylib [core] example - delta time");

        int currentFps = 60;

        Vector2 deltaCircle = new Vector2(0, (float)screenHeight / 3.0f);
        Vector2 frameCircle = new Vector2(0, (float)screenHeight * (2.0f / 3.0f));

        SetTargetFPS(60);
        //--------------------------------------------------------------------------------------

        const float speed = 10.0f;
        const float circleRadius = 32.0f;

        // Main game loop
        while (!WindowShouldClose())
        {
            // Update
            //----------------------------------------------------------------------------------
            // Adjust the FPS target based on the mouse wheel
            float mouseWheel = GetMouseWheelMove();
            if (mouseWheel != 0)
            {
                currentFps += (int)mouseWheel;
                if (currentFps < 0)
                {
                    currentFps = 0;
                }
                SetTargetFPS(currentFps);
            }

            // GetFrameTime() returns the time it took to draw the last frame, in seconds (usually called delta time)
            // Uses the delta time to make the circle look like it's moving at a "consistent" speed regardless of FPS

            // Multiply by 6.0 (an arbitrary value) in order to make the speed
            // visually closer to the other circle (at 60 fps), for comparison
            deltaCircle.X += GetFrameTime() * 6.0f * speed;
            // This circle can move faster or slower visually depending on the FPS
            frameCircle.X += 0.1f * speed;

            // If either circle is off the screen, reset it back to the start
            if (deltaCircle.X > screenWidth)
            {
                deltaCircle.X = 0;
            }

            if (frameCircle.X > screenWidth)
            {
                frameCircle.X = 0;
            }

            // Reset both circles positions
            if (IsKeyPressed(KeyboardKey.R))
            {
                deltaCircle.X = 0;
                frameCircle.X = 0;
            }
            //----------------------------------------------------------------------------------

            // Draw
            //----------------------------------------------------------------------------------
            BeginDrawing();
            ClearBackground(Color.RayWhite);

            // Draw both circles to the screen
            DrawCircleV(deltaCircle, circleRadius, Color.Red);
            DrawCircleV(frameCircle, circleRadius, Color.Blue);

            // Draw the help text
            // Determine what help text to show depending on the current FPS target
            var fpsText = "";
            if (currentFps <= 0)
            {
                fpsText = $"FPS: unlimited ({GetFPS()})";
            }
            else
            {
                fpsText = $"FPS: {GetFPS()} (target: {currentFps})";
            }
            DrawText(fpsText, 10, 10, 20, Color.DarkGray);
            DrawText($"Frame time: {GetFrameTime():F2} ms", 10, 30, 20, Color.DarkGray);
            DrawText("Use the scroll wheel to change the fps limit, r to reset", 10, 50, 20, Color.DarkGray);

            // Draw the text above the circles
            DrawText("FUNC: x += GetFrameTime()*speed", 10, 90, 20, Color.Red);
            DrawText("FUNC: x += speed", 10, 240, 20, Color.Blue);

            EndDrawing();
            //----------------------------------------------------------------------------------
        }

        // De-Initialization
        //--------------------------------------------------------------------------------------
        CloseWindow();
        //--------------------------------------------------------------------------------------

        return 0;
    }
}