MLEM/MLEM/Input/GenericInput.cs

using System;
using System.Runtime.Serialization;
using Microsoft.Xna.Framework.Input;

namespace MLEM.Input {
    /// <summary>
    /// A generic input represents any kind of input key.
    /// This includes <see cref="Keys"/> for keyboard keys, <see cref="MouseButton"/> for mouse buttons and <see cref="Buttons"/> for gamepad buttons.
    /// For creating and extracting inputs from a generic input, the implicit operators and <see cref="Type"/> can be used.
    /// Note that this type is serializable using <see cref="DataContractAttribute"/>.
    /// </summary>
    [DataContract]
    public readonly struct GenericInput {

        /// <summary>
        /// The <see cref="InputType"/> of this generic input's current <see cref="value"/>.
        /// </summary>
        [DataMember]
        public readonly InputType Type;
        [DataMember]
        private readonly int value;

        private GenericInput(InputType type, int value) {
            this.Type = type;
            this.value = value;
        }

        /// <inheritdoc />
        public override string ToString() {
            switch (this.Type) {
                case InputType.Mouse:
                    return ((MouseButton) this).ToString();
                case InputType.Keyboard:
                    return ((Keys) this).ToString();
                case InputType.Gamepad:
                    return ((Buttons) this).ToString();
                default:
                    throw new ArgumentOutOfRangeException(nameof(this.Type));
            }
        }

        /// <summary>
        /// Converts a <see cref="Keys"/> to a generic input.
        /// </summary>
        /// <param name="keys">The keys to convert</param>
        /// <returns>The resulting generic input</returns>
        public static implicit operator GenericInput(Keys keys) {
            return new GenericInput(InputType.Keyboard, (int) keys);
        }

        /// <summary>
        /// Converts a <see cref="MouseButton"/> to a generic input.
        /// </summary>
        /// <param name="button">The button to convert</param>
        /// <returns>The resulting generic input</returns>
        public static implicit operator GenericInput(MouseButton button) {
            return new GenericInput(InputType.Mouse, (int) button);
        }

        /// <summary>
        /// Converts a <see cref="Buttons"/> to a generic input.
        /// </summary>
        /// <param name="buttons">The buttons to convert</param>
        /// <returns>The resulting generic input</returns>
        public static implicit operator GenericInput(Buttons buttons) {
            return new GenericInput(InputType.Gamepad, (int) buttons);
        }

        /// <summary>
        /// Converts a generic input to a <see cref="Keys"/>.
        /// </summary>
        /// <param name="input">The input to convert</param>
        /// <returns>The resulting keys</returns>
        /// <exception cref="ArgumentException">If the given generic input's <see cref="Type"/> is not <see cref="InputType.Keyboard"/></exception>
        public static implicit operator Keys(GenericInput input) {
            if (input.Type != InputType.Keyboard)
                throw new ArgumentException();
            return (Keys) input.value;
        }

        /// <summary>
        /// Converts a generic input to a <see cref="MouseButton"/>.
        /// </summary>
        /// <param name="input">The input to convert</param>
        /// <returns>The resulting button</returns>
        /// <exception cref="ArgumentException">If the given generic input's <see cref="Type"/> is not <see cref="InputType.Mouse"/></exception>
        public static implicit operator MouseButton(GenericInput input) {
            if (input.Type != InputType.Mouse)
                throw new ArgumentException();
            return (MouseButton) input.value;
        }

        /// <summary>
        /// Converts a generic input to a <see cref="Buttons"/>.
        /// </summary>
        /// <param name="input">The input to convert</param>
        /// <returns>The resulting buttons</returns>
        /// <exception cref="ArgumentException">If the given generic input's <see cref="Type"/> is not <see cref="InputType.Gamepad"/></exception>
        public static implicit operator Buttons(GenericInput input) {
            if (input.Type != InputType.Gamepad)
                throw new ArgumentException();
            return (Buttons) input.value;
        }

        /// <summary>
        /// A type of input button.
        /// </summary>
        [DataContract]
        public enum InputType {

            /// <summary>
            /// A type representing <see cref="MouseButton"/>
            /// </summary>
            [EnumMember]
            Mouse,
            /// <summary>
            /// A type representing <see cref="Keys"/>
            /// </summary>
            [EnumMember]
            Keyboard,
            /// <summary>
            /// A type representing <see cref="Buttons"/>
            /// </summary>
            [EnumMember]
            Gamepad

        }

    }
}