using System;

using Unity.Collections;
using UnityEngine;
using UnityEngine.UIElements;

namespace BoostComponents {
    public class BoostBar : VisualElement {
        // Need this uxml traits and factory for it to show up in editor
        public new class UxmlTraits : VisualElement.UxmlTraits {
            UxmlDoubleAttributeDescription m_ProgressAttribute = new UxmlDoubleAttributeDescription() {
                name = "progress"
            };

            UxmlIntAttributeDescription m_ChargesAttribute = new UxmlIntAttributeDescription() {
                name = "charges"
            };

            public override void Init(VisualElement ve, IUxmlAttributes bag, CreationContext cc) {
                base.Init(ve, bag, cc);
                (ve as BoostBar).progress = m_ProgressAttribute.GetValueFromBag(bag, cc);
                (ve as BoostBar).charges = m_ChargesAttribute.GetValueFromBag(bag, cc);
            }
        }

        public new class UxmlFactory : UxmlFactory<BoostBar, UxmlTraits> { }

        public static readonly string ussClassName = "boostBar";
        public static readonly string ussLabelClassName = "boostBar";

        double m_Progress = 0f;
        int m_Charges = 2;

        Color strokeColor = Color.white;

        public double progress {
            get => m_Progress;
            set {
                m_Progress = value;
                MarkDirtyRepaint();
            }
        }

        public int charges {
            get => m_Charges;
            set {
                m_Charges = value;
                MarkDirtyRepaint();
            }
        }

        public BoostBar() {
            AddToClassList(ussClassName);
            RegisterCallback<CustomStyleResolvedEvent>(evt => CustomStylesResolved(evt));
            generateVisualContent += GenerateVisualContent;
        }

        static void CustomStylesResolved(CustomStyleResolvedEvent evt) {
            BoostBar element = (BoostBar)evt.currentTarget;
            element.UpdateCustomStyles();
        }

        void UpdateCustomStyles() {
            MarkDirtyRepaint();
        }

        void GenerateVisualContent(MeshGenerationContext context) {
            float width = contentRect.width;
            float height = contentRect.height;

            double length = width * m_Progress;

            Vector2 left = new Vector2(0f, height / 2);
            Vector2 end = new Vector2((float)length, height / 2);

            var painter = context.painter2D;
            painter.lineWidth = 4.0f;
            painter.lineCap = LineCap.Butt;
            painter.strokeColor = strokeColor;

            painter.BeginPath();
            painter.MoveTo(left);
            painter.LineTo(end);
            painter.Stroke();

            float chevGap = width / charges;

            for (int i = 0; i < charges + 1; i++) {
                painter.BeginPath();
                painter.MoveTo(new Vector2(i * chevGap, height));
                painter.LineTo(new Vector2(i * chevGap, 0f));
                painter.Stroke();
            }
        }
    }
}