using System;
using System.Collections.Generic;
using System.Drawing;
using GLFW;

namespace OpenGLTutorial.GameLoop {
    public class Input {
        
        /// <summary>
        /// Get the state of a key
        /// Usage: Input.Keys[Keys.W]
        /// </summary>
        public static Dict<Keys, bool> Keys { get; } = new (false);

        /// <summary>
        /// Get the state of a mouse button
        /// Usage: Input.MouseButtons[MouseButton.Button1]
        /// </summary>
        public static Dict<MouseButton, bool> MouseButtons { get; } = new (false);
        
        /// <summary>
        /// The screen position of the Mouse
        /// </summary>
        public static Point MousePosition { get; set; } = new (0, 0);
        
        /// <summary>
        /// The relative scroll offset from last frame
        /// </summary>
        public static float MouseScroll { get; set; } = 0.0f;

        /// <summary>
        /// Get the state of a joystick button
        /// Usage: Input.JoystickButtons[Joystick.Joystick1][JoystickButton.A]
        /// </summary>
        public static Dict<Joystick, Dict<JoystickButton, bool>> JoystickButtons { get; } = new(new Dict<JoystickButton, bool>(false));
        
        /// <summary>
        /// Get the state of a joystick axis
        /// Usage: JoystickAxis[Joystick.Joystick1][JoystickAxis.LeftJoystickX]
        /// </summary>
        public static Dict<Joystick, Dict<JoystickAxis, float>> JoystickAxis { get; } = new(new Dict<JoystickAxis, float>(0.0f));

        /// <summary>
        /// Get the state of the given axis
        /// </summary>
        /// <param name="axis">The axis</param>
        /// <param name="joystick">(OPTIONAL) The joystick to use</param>
        /// <returns>A value between -1 and 1</returns>
        /// <exception cref="GLFW.Exception">Throws an exception if the given axis does not exist</exception>
        public static float GetAxis(Axis axis, Joystick joystick = Joystick.Joystick1) {
            switch (axis) {
                case Axis.Horizontal:
                    float x = JoystickAxis[joystick][GameLoop.JoystickAxis.LeftJoystickX];
                    if (Keys[GLFW.Keys.A]) x += -1.0f;
                    if (Keys[GLFW.Keys.D]) x +=  1.0f;
                    return Math.Clamp(x, -1, 1);
                
                case Axis.Vertical:
                    float y = JoystickAxis[joystick][GameLoop.JoystickAxis.LeftJoystickY];
                    if (Keys[GLFW.Keys.S]) y += -1.0f;
                    if (Keys[GLFW.Keys.W]) y +=  1.0f;
                    return Math.Clamp(y, -1, 1);
                
                case Axis.Junp:
                    float jump = JoystickButtons[joystick][JoystickButton.A] ? 1.0f : 0.0f;
                    if (Keys[GLFW.Keys.Space]) jump = 1.0f;
                    return jump;
                
                default:
                    throw new System.Exception("Unexpected Token: '" + axis + "'. That Axis does not exist");
            }
        }

        /// <summary>
        /// SYSTEM INTERNAL
        /// </summary>
        public static void Update() {
            UpdateJoystick(Joystick.Joystick1);
            UpdateJoystick(Joystick.Joystick2);
            UpdateJoystick(Joystick.Joystick3);
            UpdateJoystick(Joystick.Joystick4);
            UpdateJoystick(Joystick.Joystick5);
            UpdateJoystick(Joystick.Joystick6);
            UpdateJoystick(Joystick.Joystick7);
            UpdateJoystick(Joystick.Joystick8);
            UpdateJoystick(Joystick.Joystick9);
            UpdateJoystick(Joystick.Joystick10);
            UpdateJoystick(Joystick.Joystick11);
            UpdateJoystick(Joystick.Joystick12);
            UpdateJoystick(Joystick.Joystick13);
            UpdateJoystick(Joystick.Joystick14);
            UpdateJoystick(Joystick.Joystick15);
            UpdateJoystick(Joystick.Joystick16);
        }

        private static void UpdateJoystick(Joystick joystick) {
            if (!Glfw.JoystickPresent(joystick)) return;
            float[] axis = Glfw.GetJoystickAxes(joystick);
            JoystickAxis[joystick][GameLoop.JoystickAxis.LeftJoystickX] = ClampAxis(axis[0]);
            JoystickAxis[joystick][GameLoop.JoystickAxis.LeftJoystickY] = -ClampAxis(axis[1]);
            JoystickAxis[joystick][GameLoop.JoystickAxis.RightJoystickX] = ClampAxis(axis[2]);
            JoystickAxis[joystick][GameLoop.JoystickAxis.RightJoystickY] = -ClampAxis(axis[3]);
            JoystickAxis[joystick][GameLoop.JoystickAxis.LeftTrigger] = ClampAxis(axis[4]);
            JoystickAxis[joystick][GameLoop.JoystickAxis.RightTrigger] = ClampAxis(axis[5]);

            InputState[] buttons = Glfw.GetJoystickButtons(joystick);
            JoystickButtons[joystick][JoystickButton.A] = buttons[0] != InputState.Release;
            JoystickButtons[joystick][JoystickButton.B] = buttons[1] != InputState.Release;
            JoystickButtons[joystick][JoystickButton.X] = buttons[2] != InputState.Release;
            JoystickButtons[joystick][JoystickButton.Y] = buttons[3] != InputState.Release;
            JoystickButtons[joystick][JoystickButton.Lb] = buttons[4] != InputState.Release;
            JoystickButtons[joystick][JoystickButton.Rb] = buttons[5] != InputState.Release;
            JoystickButtons[joystick][JoystickButton.Back] = buttons[6] != InputState.Release;
            JoystickButtons[joystick][JoystickButton.Start] = buttons[7] != InputState.Release;
            JoystickButtons[joystick][JoystickButton.Left] = buttons[8] != InputState.Release;
            JoystickButtons[joystick][JoystickButton.Right] = buttons[9] != InputState.Release;
            JoystickButtons[joystick][JoystickButton.DpadUp] = buttons[10] != InputState.Release;
            JoystickButtons[joystick][JoystickButton.DpadRight] = buttons[11] != InputState.Release;
            JoystickButtons[joystick][JoystickButton.DpadDown] = buttons[12] != InputState.Release;
            JoystickButtons[joystick][JoystickButton.DpadLeft] = buttons[13] != InputState.Release;
        }

        private static float ClampAxis(float value) {
            if (value < 0.15f && value > -0.15f)
                value = 0;

            return value;
        }
    }

    public class Dict<TKey, TValue> : Dictionary<TKey, TValue> {
        public TValue DefaultValue { get; set; }

        public Dict(TValue defaultValue) => DefaultValue = defaultValue;

        public new TValue this[TKey key] {
            get => TryGetValue(key, out TValue t) ? t : DefaultValue;
            set => base[key] = value;
        }
    }

    public enum JoystickButton {
        A,
        B,
        X,
        Y,
        Start,
        Back,
        Lb,
        Rb,
        Left,
        Right,
        DpadUp,
        DpadDown,
        DpadRight,
        DpadLeft
    }

    public enum JoystickAxis {
        LeftJoystickX,
        LeftJoystickY,
        RightJoystickX,
        RightJoystickY,
        LeftTrigger,
        RightTrigger
    }

    public enum Axis {
        Horizontal,
        Vertical,
        Junp
    }
}