// ReSharper disable VirtualMemberNeverOverriden.Global
// ReSharper disable MemberCanBePrivate.Global
// ReSharper disable VirtualMemberNeverOverridden.Global

using System.Collections.Generic;
using System.Linq;

namespace RGB.NET.Core
{
    /// <inheritdoc cref="AbstractDecoratable{T}" />
    /// <inheritdoc cref="IBrush" />
    /// <summary>
    /// Represents a basic brush.
    /// </summary>
    public abstract class AbstractBrush : AbstractDecoratable<IBrushDecorator>, IBrush
    {
        #region Properties & Fields

        /// <inheritdoc />
        public bool IsEnabled { get; set; } = true;

        /// <inheritdoc />
        public RenderMode CalculationMode { get; set; } = RenderMode.Relative;

        /// <inheritdoc />
        public float Brightness { get; set; }

        /// <inheritdoc />
        public float Opacity { get; set; }

        #endregion

        #region Constructors

        /// <summary>
        /// Initializes a new instance of the <see cref="AbstractBrush"/> class.
        /// </summary>
        /// <param name="brightness">The overall percentage brightness of the brush. (default: 1.0)</param>
        /// <param name="opacity">The overall percentage opacity of the brush. (default: 1.0)</param>
        protected AbstractBrush(float brightness = 1, float opacity = 1)
        {
            this.Brightness = brightness;
            this.Opacity = opacity;
        }

        #endregion

        #region Methods

        public IEnumerable<(RenderTarget renderTarget, Color color)> Render(Rectangle rectangle, IEnumerable<RenderTarget> renderTargets)
        {
            foreach (RenderTarget renderTarget in renderTargets)
            {
                Color color = GetColorAtPoint(rectangle, renderTarget);
                ApplyDecorators(rectangle, renderTarget, ref color);
                FinalizeColor(ref color);
                yield return (renderTarget, color);
            }
        }

        /// <summary>
        /// Applies all attached and enabled decorators to the brush.
        /// </summary>
        /// <param name="rectangle">The rectangle in which the brush should be drawn.</param>
        /// <param name="renderTarget">The target (key/point) from which the color should be taken.</param>
        /// <param name="color">The <see cref="Color"/> to be modified.</param>
        protected virtual void ApplyDecorators(in Rectangle rectangle, in RenderTarget renderTarget, ref Color color)
        {
            lock (Decorators)
                foreach (IBrushDecorator decorator in Decorators)
                    if (decorator.IsEnabled)
                        decorator.ManipulateColor(rectangle, renderTarget, ref color);
        }

        /// <summary>
        /// Gets the color at an specific point assuming the brush is drawn into the given rectangle.
        /// </summary>
        /// <param name="rectangle">The rectangle in which the brush should be drawn.</param>
        /// <param name="renderTarget">The target (key/point) from which the color should be taken.</param>
        /// <returns>The color at the specified point.</returns>
        protected abstract Color GetColorAtPoint(in Rectangle rectangle, in RenderTarget renderTarget);

        /// <summary>
        /// Finalizes the color by appliing the overall brightness and opacity.<br/>
        /// </summary>
        /// <param name="color">The color to finalize.</param>
        /// <returns>The finalized color.</returns>
        protected virtual void FinalizeColor(ref Color color)
        {
            // Since we use HSV to calculate there is no way to make a color 'brighter' than 100%
            // Be carefull with the naming: Since we use HSV the correct term is 'value' but outside we call it 'brightness'
            // THIS IS NOT A HSB CALCULATION!!!
            if (Brightness < 1)
                color = color.MultiplyHSV(value: Brightness.Clamp(0, 1));

            if (Opacity < 1)
                color = color.MultiplyA(Opacity.Clamp(0, 1));
        }

        #endregion
    }
}