// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
// See the LICENCE file in the repository root for full licence text.

using System;
using osu.Framework.Bindables;
using osu.Game.Beatmaps;

namespace osu.Game.Rulesets.Mods
{
    public class DifficultyBindable : Bindable<float?>
    {
        /// <summary>
        /// Whether the extended limits should be applied to this bindable.
        /// </summary>
        public BindableBool ExtendedLimits { get; } = new BindableBool();

        /// <summary>
        /// An internal numeric bindable to hold and propagate min/max/precision.
        /// The value of this bindable should not be set.
        /// </summary>
        public readonly BindableFloat CurrentNumber = new BindableFloat
        {
            MinValue = 0,
            MaxValue = 10,
        };

        /// <summary>
        /// A function that can extract the current value of this setting from a beatmap difficulty for display purposes.
        /// </summary>
        public Func<BeatmapDifficulty, float> ReadFromDifficulty;

        public float Precision
        {
            set => CurrentNumber.Precision = value;
        }

        public float MinValue
        {
            set => CurrentNumber.MinValue = value;
        }

        private float maxValue;

        public float MaxValue
        {
            set
            {
                if (value == maxValue)
                    return;

                maxValue = value;
                updateMaxValue();
            }
        }

        private float? extendedMaxValue;

        /// <summary>
        /// The maximum value to be used when extended limits are applied.
        /// </summary>
        public float? ExtendedMaxValue
        {
            set
            {
                if (value == extendedMaxValue)
                    return;

                extendedMaxValue = value;
                updateMaxValue();
            }
        }

        public DifficultyBindable()
        {
            ExtendedLimits.BindValueChanged(_ => updateMaxValue());

            BindValueChanged(val =>
            {
                // Ensure that in the case serialisation runs in the wrong order (and limit extensions aren't applied yet) the deserialised value is still propagated.
                if (val.NewValue != null)
                    CurrentNumber.MaxValue = MathF.Max(CurrentNumber.MaxValue, val.NewValue.Value);
            });
        }

        private void updateMaxValue()
        {
            CurrentNumber.MaxValue = ExtendedLimits.Value && extendedMaxValue != null ? extendedMaxValue.Value : maxValue;
        }
    }
}