using System.Text;
using UnityEngine;
using UnityEngine.TerrainTools;
using System;


namespace UnityEditor.TerrainTools
{
    internal class BrushStrengthVariator : BaseBrushVariator, IBrushStrengthController
    {

        const float kMinBrushStrength = 0.0f;
        const float kMaxBrushStrength = 1.0f;
        const float kDefaultBrushStrength = kMaxBrushStrength;

        private float defaultBrushStrength;

        class Styles
        {
            public readonly GUIContent brushStrength = EditorGUIUtility.TrTextContent("Brush Strength");
        }

        static readonly Styles styles = new Styles();

        private readonly TerrainFloatMinMaxValue m_BrushStrength = new TerrainFloatMinMaxValue(styles.brushStrength, kDefaultBrushStrength, kMinBrushStrength, kMaxBrushStrength, true);
        private readonly BrushJitterHandler m_JitterHandler = new BrushJitterHandler(0.0f, kMinBrushStrength, kMaxBrushStrength);

        private bool m_AdjustingStrength;
        public override bool isInUse => m_AdjustingStrength;

        private RaycastHit m_LastRaycastHit;

        public float brushStrength {
            get
            {
                return m_JitterHandler.CalculateValue(m_BrushStrength.value);
            }
            set { m_BrushStrength.value = Mathf.Clamp(value, brushStrengthMin, brushStrengthMax); }
        }
        
        public float brushStrengthVal
        {
            get
            { return m_BrushStrength.value; }
        }

        public float brushStrengthMin
        {
            get { return m_BrushStrength.minValue;  }
            set { m_BrushStrength.minValue = value;  }
        }
        
        public float brushStrengthMax
        {
            get { return m_BrushStrength.maxValue;  }
            set { m_BrushStrength.maxValue = value;  }
        }
        
        public float brushStrengthJitter
        {
            get { return m_JitterHandler.jitter;  }
            set { m_JitterHandler.jitter = value;  }
        }

        
        public float brushStrengthUI => Mathf.Clamp(m_BrushStrength.value, kMinBrushStrength, kMaxBrushStrength);

        public BrushStrengthVariator(string toolName, IBrushEventHandler eventHandler, IBrushTerrainCache terrainCache, float defaultValue = kDefaultBrushStrength) : base(toolName, eventHandler, terrainCache)
        {
            this.defaultBrushStrength = defaultValue;
        }

        private void BeginAdjustingStrength()
        {
            LockTerrainUnderCursor(true);
            m_AdjustingStrength = true;
        }

        private void EndAdjustingStrength()
        {
            m_AdjustingStrength = false;
            UnlockTerrainUnderCursor();
        }

        public override void OnEnterToolMode(BrushShortcutHandler<BrushShortcutType> shortcutHandler)
        {
            base.OnEnterToolMode(shortcutHandler);

            if (!canUpdateTerrainUnderCursor)
            {
                UnlockTerrainUnderCursor();
            }

            shortcutHandler.AddActions(BrushShortcutType.Strength, BeginAdjustingStrength, EndAdjustingStrength);

            m_BrushStrength.value = GetEditorPrefs("TerrainBrushStrength", defaultBrushStrength);
            m_JitterHandler.jitter = GetEditorPrefs("TerrainBrushRandomStrength", 0.0f);
            m_BrushStrength.minValue = GetEditorPrefs("TerrainBrushStrengthMin", 0.0f);
            m_BrushStrength.maxValue = GetEditorPrefs("TerrainBrushStrengthMax", 1.0f);
        }

        public override void OnExitToolMode(BrushShortcutHandler<BrushShortcutType> shortcutHandler)
        {
            SetEditorPrefs("TerrainBrushStrength", m_BrushStrength.value);
            SetEditorPrefs("TerrainBrushStrengthMouseSensitivity", m_BrushStrength.mouseSensitivity);
            SetEditorPrefs("TerrainBrushRandomStrength", m_JitterHandler.jitter);
            SetEditorPrefs("TerrainBrushStrengthMin", m_BrushStrength.minValue);
            SetEditorPrefs("TerrainBrushStrengthMax", m_BrushStrength.maxValue);

            shortcutHandler.RemoveActions(BrushShortcutType.Strength);

            EndAdjustingStrength();

            base.OnExitToolMode(shortcutHandler);
        }

        public override void OnSceneGUI(Event currentEvent, int controlId, Terrain terrain, IOnSceneGUI editContext)
        {
            Event e = Event.current;

            base.OnSceneGUI(currentEvent, controlId, terrain, editContext);

            m_JitterHandler.Update();

            if (m_AdjustingStrength)
            {
                float strength = m_BrushStrength.value;

                strength += 0.001f * e.delta.x;
                m_BrushStrength.value = strength;

                int strengthPct = Mathf.RoundToInt(100.0f * strength);
                float pixelPointMultiplier = 1.0f / EditorGUIUtility.pixelsPerPoint;
                var pos = editContext.sceneView.camera.WorldToScreenPoint(raycastHitUnderCursor.point) * pixelPointMultiplier;
                Handles.BeginGUI();
                {
                    GUI.matrix = Matrix4x4.identity;
                    var temp = TerrainToolGUIHelper.TempContent($"Strength: {strengthPct}%");
                    GUI.Label(new Rect(pos.x + 10 * pixelPointMultiplier, (Screen.height * pixelPointMultiplier - pos.y - 60 * pixelPointMultiplier) - EditorGUIUtility.singleLineHeight, s_SceneLabelStyle.CalcSize(temp).x, EditorGUIUtility.singleLineHeight), temp, s_SceneLabelStyle);
                }
                Handles.EndGUI();
                RequestRepaint();
            }
            else
            {
                m_LastRaycastHit = editContext.raycastHit;
            }
        }

        public override bool OnPaint(Terrain terrain, IOnPaint editContext)
        {
            m_JitterHandler.RequestRandomization();
            return base.OnPaint(terrain, editContext);
        }

        // for updating condensed slider overlays 
        public static event Action BrushStrengthChanged;
        public static event Action BrushStrengthMinChanged;
        public static event Action BrushStrengthMaxChanged; 
        private float prevBrushStrength = kDefaultBrushStrength;
        private float prevBrushStrengthMin = kMinBrushStrength;
        private float prevBrushStrengthMax = kMaxBrushStrength; 
        
        public override void OnInspectorGUI(Terrain terrain, IOnInspectorGUI editContext)
        {
            base.OnInspectorGUI(terrain, editContext);

            m_BrushStrength.DrawInspectorGUI();
            if (!Mathf.Approximately(m_BrushStrength.value, prevBrushStrength) && BrushStrengthChanged != null)
            {
                BrushStrengthChanged();
                prevBrushStrength = m_BrushStrength.value; 
            }
            if (!Mathf.Approximately(brushStrengthMin, prevBrushStrengthMin) && BrushStrengthMinChanged != null)
            {
                BrushStrengthMinChanged();
                prevBrushStrengthMin = brushStrengthMin; 
            }
            if (!Mathf.Approximately(brushStrengthMax, prevBrushStrengthMax) && BrushStrengthMaxChanged != null)
            {
                BrushStrengthMaxChanged();
                prevBrushStrengthMax = brushStrengthMax; 
            }
            if (m_BrushStrength.expanded)
            {
                EditorGUI.indentLevel++;
                m_JitterHandler.OnGuiLayout("Allow random variation of brush intensity");
                EditorGUI.indentLevel--;
            }

        }

        public override void AppendBrushInfo(Terrain terrain, IOnSceneGUI editContext, StringBuilder builder)
        {
            base.AppendBrushInfo(terrain, editContext, builder);
            builder.AppendLine($"Strength = {m_BrushStrength.value:F3}");
        }

        protected override bool OnBeginModifier()
        {
            base.OnBeginModifier();

            LockTerrainUnderCursor(false);
            return true;
        }

        protected override bool OnModifierUsingMouseWheel(Event mouseEvent, Terrain terrain, IOnSceneGUI editContext)
        {
            base.OnModifierUsingMouseWheel(mouseEvent, terrain, editContext);

            Vector2 delta = CalculateMouseDelta(mouseEvent, m_BrushStrength.mouseSensitivity);
            float strength = m_BrushStrength.value;

            strength += delta.y;
            m_BrushStrength.value = strength;

            return true;
        }

        protected override bool OnEndModifier()
        {
            base.OnEndModifier();

            UnlockTerrainUnderCursor();
            return true;
        }
    }
}