using System.Runtime.CompilerServices;
using UnityEngine.InputSystem.LowLevel;
using UnityEngine.Scripting;

////REVIEW: introduce separate base class for ButtonControl and AxisControl instead of deriving ButtonControl from AxisControl?

namespace UnityEngine.InputSystem.Controls
{
    /// <summary>
    /// An axis that has a trigger point beyond which it is considered to be pressed.
    /// </summary>
    /// <remarks>
    /// By default stored as a single bit. In that format, buttons will only yield 0
    /// and 1 as values. However, buttons return are <see cref="AxisControl"/>s and
    /// yield full floating-point values and may thus have a range of values. See
    /// <see cref="pressPoint"/> for how button presses on such buttons are handled.
    /// </remarks>
    public class ButtonControl : AxisControl
    {
        ////REVIEW: are per-control press points really necessary? can we just drop them?
        /// <summary>
        /// The minimum value the button has to reach for it to be considered pressed.
        /// </summary>
        /// <value>Button press threshold.</value>
        /// <remarks>
        /// The button is considered pressed, if it has a value equal to or greater than
        /// this value.
        ///
        /// By default, this property is set to -1. If the value of the property is negative,
        /// <see cref="InputSettings.defaultButtonPressPoint"/> is used.
        ///
        /// The value can be configured as a parameter in a layout.
        ///
        /// <example>
        /// <code>
        /// public class MyDevice : InputDevice
        /// {
        ///     [InputControl(parameters = "pressPoint=0.234")]
        ///     public ButtonControl button { get; private set; }
        ///
        ///     //...
        /// }
        /// </code>
        /// </example>
        /// </remarks>
        /// <seealso cref="InputSettings.defaultButtonPressPoint"/>
        /// <seealso cref="pressPointOrDefault"/>
        /// <seealso cref="isPressed"/>
        public float pressPoint = -1;

        /// <summary>
        /// Return <see cref="pressPoint"/> if set, otherwise return <see cref="InputSettings.defaultButtonPressPoint"/>.
        /// </summary>
        /// <value>Effective value to use for press point thresholds.</value>
        /// <seealso cref="InputSettings.defaultButtonPressPoint"/>
        public float pressPointOrDefault => pressPoint > 0 ? pressPoint : s_GlobalDefaultButtonPressPoint;

        /// <summary>
        /// Default-initialize the control.
        /// </summary>
        /// <remarks>
        /// The default format for the control is <see cref="InputStateBlock.FormatBit"/>.
        /// The control's minimum value is set to 0 and the maximum value to 1.
        /// </remarks>
        public ButtonControl()
        {
            m_StateBlock.format = InputStateBlock.FormatBit;
            m_MinValue = 0f;
            m_MaxValue = 1f;
        }

        /// <summary>
        /// Whether the given value would be considered pressed for this button.
        /// </summary>
        /// <param name="value">Value for the button.</param>
        /// <returns>True if <paramref name="value"/> crosses the threshold to be considered pressed.</returns>
        /// <seealso cref="pressPoint"/>
        /// <seealso cref="InputSettings.defaultButtonPressPoint"/>
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public new bool IsValueConsideredPressed(float value)
        {
            return value >= pressPointOrDefault;
        }

        /// <summary>
        /// Whether the button is currently pressed.
        /// </summary>
        /// <value>True if button is currently pressed.</value>
        /// <remarks>
        /// A button is considered press if it's value is equal to or greater
        /// than its button press threshold (<see cref="pressPointOrDefault"/>).
        /// </remarks>
        /// <seealso cref="InputSettings.defaultButtonPressPoint"/>
        /// <seealso cref="pressPoint"/>
        /// <seealso cref="InputSystem.onAnyButtonPress"/>
        public bool isPressed => IsValueConsideredPressed(value);

        /// <summary>
        /// Whether the press started this frame.
        /// </summary>
        /// <value>True if the current press of the button started this frame.</value>
        /// <remarks>
        /// <example>
        /// <code>
        /// // An example showing the use of this property on a gamepad button and a keyboard key.
        ///
        /// using UnityEngine;
        /// using UnityEngine.InputSystem;
        ///
        /// public class ExampleScript : MonoBehaviour
        /// {
        ///     void Update()
        ///     {
        ///         bool buttonPressed = Gamepad.current.aButton.wasPressedThisFrame;
        ///         bool spaceKeyPressed = Keyboard.current.spaceKey.wasPressedThisFrame;
        ///     }
        /// }
        /// </code>
        /// </example>
        /// </remarks>
        public bool wasPressedThisFrame => device.wasUpdatedThisFrame && IsValueConsideredPressed(value) && !IsValueConsideredPressed(ReadValueFromPreviousFrame());

        public bool wasReleasedThisFrame => device.wasUpdatedThisFrame && !IsValueConsideredPressed(value) && IsValueConsideredPressed(ReadValueFromPreviousFrame());

        // We make the current global default button press point available as a static so that we don't have to
        // constantly make the hop from InputSystem.settings -> InputManager.m_Settings -> defaultButtonPressPoint.
        internal static float s_GlobalDefaultButtonPressPoint;
        internal static float s_GlobalDefaultButtonReleaseThreshold;

        // We clamp button press points to this value as allowing 0 as the press point causes all buttons
        // to implicitly be pressed all the time. Not useful.
        internal const float kMinButtonPressPoint = 0.0001f;
    }
}