Adapter

using UnityEngine;

namespace Patterns.Structural.Adapter
{
    /// <summary>
    /// Client. Only knows about IInputProvider, so it works with any
    /// input backend that has an adapter.
    /// </summary>
    [RequireComponent(typeof(Rigidbody))]
    public class PlayerController : MonoBehaviour
    {
        [SerializeField] private float moveSpeed = 6f;
        [SerializeField] private float jumpForce = 7f;
        [SerializeField] private bool useGamepadSdk;

        private IInputProvider input;
        private Rigidbody body;

        private void Awake()
        {
            body = GetComponent<Rigidbody>();

            // Pick a backend once; nothing below this line cares which.
            input = useGamepadSdk
                ? new GamepadAdapter(new ThirdPartyGamepad(0))
                : new LegacyInputAdapter();
        }

        public void SetInput(IInputProvider provider) => input = provider;

        private void Update()
        {
            input.Tick();

            Vector2 move = input.Move * moveSpeed;
            body.velocity = new Vector3(move.x, body.velocity.y, move.y);

            if (input.JumpPressed)
                body.AddForce(Vector3.up * jumpForce, ForceMode.VelocityChange);
        }
    }
}

using UnityEngine;

namespace Patterns.Structural.Adapter
{
    /// <summary>
    /// Target interface. Game-shaped, deliberately small, and owned by
    /// our project rather than by any input SDK.
    /// </summary>
    public interface IInputProvider
    {
        /// <summary>Called once per frame before values are read.</summary>
        void Tick();

        /// <summary>Movement on the XZ plane, each axis in [-1, 1].</summary>
        Vector2 Move { get; }

        /// <summary>True only on the frame jump was pressed.</summary>
        bool JumpPressed { get; }
    }
}

using UnityEngine;

namespace Patterns.Structural.Adapter
{
    /// <summary>
    /// Adapter for the built-in Input Manager. Translates our interface
    /// into Input.GetAxis / Input.GetButtonDown calls.
    /// </summary>
    public class LegacyInputAdapter : IInputProvider
    {
        private readonly string horizontalAxis;
        private readonly string verticalAxis;
        private readonly string jumpButton;

        public LegacyInputAdapter(string horizontal = "Horizontal",
                                  string vertical = "Vertical",
                                  string jump = "Jump")
        {
            horizontalAxis = horizontal;
            verticalAxis = vertical;
            jumpButton = jump;
        }

        public Vector2 Move { get; private set; }
        public bool JumpPressed { get; private set; }

        public void Tick()
        {
            var raw = new Vector2(Input.GetAxis(horizontalAxis), Input.GetAxis(verticalAxis));
            Move = Vector2.ClampMagnitude(raw, 1f);
            JumpPressed = Input.GetButtonDown(jumpButton);
        }
    }
}

using UnityEngine;

namespace Patterns.Structural.Adapter
{
    /// <summary>
    /// Adaptee: a vendor SDK we cannot modify. It reports sticks as raw
    /// shorts and buttons as a bitmask.
    /// </summary>
    public class ThirdPartyGamepad
    {
        public const uint ButtonA = 1u << 0;

        public ThirdPartyGamepad(int slot) => Slot = slot;
        public int Slot { get; }

        public uint PollButtons() => 0u;          // native call in the real SDK
        public short ReadStick(int axis) => 0;    // -32768..32767
    }

    /// <summary>
    /// Adapter: makes ThirdPartyGamepad look like an IInputProvider by
    /// normalising sticks and turning the bitmask into a "pressed this frame" edge.
    /// </summary>
    public class GamepadAdapter : IInputProvider
    {
        private readonly ThirdPartyGamepad pad;
        private uint previousButtons;

        public GamepadAdapter(ThirdPartyGamepad pad) => this.pad = pad;

        public Vector2 Move { get; private set; }
        public bool JumpPressed { get; private set; }

        public void Tick()
        {
            Move = new Vector2(pad.ReadStick(0) / 32767f, pad.ReadStick(1) / 32767f);

            uint buttons = pad.PollButtons();
            bool down = (buttons & ThirdPartyGamepad.ButtonA) != 0;
            bool wasDown = (previousButtons & ThirdPartyGamepad.ButtonA) != 0;
            JumpPressed = down && !wasDown;
            previousButtons = buttons;
        }
    }
}