using Barotrauma.Items.Components;
using Microsoft.Xna.Framework;
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Xml.Linq;

namespace Barotrauma
{
    partial class Gap : MapEntity
    {
        public static List<Gap> GapList = new List<Gap>();

        public static bool ShowGaps = true;

        public readonly bool IsHorizontal;
        
        //a value between 0.0f-1.0f (0.0 = closed, 1.0f = open)
        private float open;           

        //the force of the water flow which is exerted on physics bodies
        private Vector2 flowForce;
        private Hull flowTargetHull;
        
        private float higherSurface;
        private float lowerSurface;
        
        private Vector2 lerpedFlowForce;

        //if set to true, hull connections of this gap won't be updated when changes are being done to hulls
        public bool DisableHullRechecks;
        
        //can ambient light get through the gap even if it's not open
        public bool PassAmbientLight;

        public float Open
        {
            get { return open; }
            set { open = MathHelper.Clamp(value, 0.0f, 1.0f); }
        }

        public Door ConnectedDoor;

        public Structure ConnectedWall;

        public Vector2 LerpedFlowForce
        {
            get { return lerpedFlowForce; }
        }

        public Hull FlowTargetHull
        {
            get { return flowTargetHull; }
        }

        public bool IsRoomToRoom
        {
            get
            {
                return linkedTo.Count == 2;
            }
        }

        public override Rectangle Rect
        {
            get
            {
                return base.Rect;
            }
            set
            {
                base.Rect = value;

                FindHulls();
            }
        }

        public override string Name
        {
            get
            {
                return "Gap";
            }
        }

        public override bool SelectableInEditor
        {
            get
            {
                return ShowGaps;
            }
        }

        public Gap(MapEntityPrefab prefab, Rectangle rectangle)
           : this (rectangle, Submarine.MainSub)
        { }

        public Gap(Rectangle newRect, Submarine submarine)
            : this(newRect, newRect.Width < newRect.Height, submarine)
        { }

        public Gap(Rectangle newRect, bool isHorizontal, Submarine submarine)
            : base (MapEntityPrefab.Find("Gap"), submarine)
        {
            rect = newRect;
            linkedTo = new ObservableCollection<MapEntity>();

            flowForce = Vector2.Zero;

            this.IsHorizontal = isHorizontal;

            open = 1.0f;

            FindHulls();

            GapList.Add(this);
            InsertToList();
        }

        public override MapEntity Clone()
        {
            return new Gap(rect, IsHorizontal, Submarine);
        }

        public override void Move(Vector2 amount)
        {
            base.Move(amount);

            FindHulls();
        }

        public static void UpdateHulls()
        {
            foreach (Gap g in GapList)
            {
                if (g.DisableHullRechecks) continue;
                g.FindHulls();
            }
        }

        public override bool IsMouseOn(Vector2 position)
        {
            return ShowGaps && Submarine.RectContains(WorldRect, position) &&
                !Submarine.RectContains(MathUtils.ExpandRect(WorldRect, -5), position);
        }

        private void FindHulls()
        {
            Hull[] hulls = new Hull[2];

            linkedTo.Clear();

            Vector2[] searchPos = new Vector2[2];
            if (IsHorizontal)
            {
                searchPos[0] = new Vector2(rect.X, rect.Y - rect.Height / 2);
                searchPos[1] = new Vector2(rect.Right, rect.Y - rect.Height / 2);
            }
            else
            {
                searchPos[0] = new Vector2(rect.Center.X, rect.Y);
                searchPos[1] = new Vector2(rect.Center.X, rect.Y - rect.Height);
            }

            for (int i = 0; i < 2; i++)
            {
                hulls[i] = Hull.FindHullOld(searchPos[i], null, false);
                if (hulls[i] == null) hulls[i] = Hull.FindHullOld(searchPos[i], null, false, true);
            }

            if (hulls[0] == null && hulls[1] == null) return;

            if (hulls[0] == null && hulls[1] != null)
            {
                Hull temp = hulls[0];
                hulls[0] = hulls[1];
                hulls[1] = temp;
            }

            flowTargetHull = hulls[0];

            for (int i = 0; i < 2; i++)
            {
                if (hulls[i] == null) continue;
                linkedTo.Add(hulls[i]);
                if (!hulls[i].ConnectedGaps.Contains(this)) hulls[i].ConnectedGaps.Add(this);
            }
        }

        public override void Update(float deltaTime, Camera cam)
        {
            flowForce = Vector2.Zero;

            if (open == 0.0f || linkedTo.Count == 0)
            {
                lerpedFlowForce = Vector2.Zero;
                return;
            }

            UpdateOxygen();

            if (linkedTo.Count == 1)
            {
                //gap leading from a room to outside
                UpdateRoomToOut(deltaTime);
            }
            else
            {
                //gap leading from a room to another
                UpdateRoomToRoom(deltaTime);
            }

            lerpedFlowForce = Vector2.Lerp(lerpedFlowForce, flowForce, deltaTime * 5.0f);

            EmitParticles(deltaTime);

            if (flowTargetHull != null && lerpedFlowForce != Vector2.Zero)
            {
                foreach (Character character in Character.CharacterList)
                {
                    if (character.CurrentHull == null) continue;
                    if (character.CurrentHull != linkedTo[0] as Hull &&
                        (linkedTo.Count < 2 || character.CurrentHull != linkedTo[1] as Hull))
                    {
                        continue;
                    }

                    foreach (Limb limb in character.AnimController.Limbs)
                    {
                        if (!limb.inWater) continue;

                        float dist = Vector2.Distance(limb.WorldPosition, WorldPosition);
                        if (dist > lerpedFlowForce.Length()) continue;

                        Vector2 force = lerpedFlowForce / (float)Math.Max(Math.Sqrt(dist), 20.0f) * 0.025f;

                        //vertical gaps only apply forces if the character is roughly above/below the gap
                        if (!IsHorizontal)
                        {
                            float xDist = Math.Abs(limb.WorldPosition.X - WorldPosition.X);
                            if (xDist > rect.Width || rect.Width == 0) return;

                            force *= 1.0f - xDist / rect.Width;
                        }

                        character.AnimController.Collider.ApplyForce(force * limb.body.Mass);
                    }
                }
            }
        }

        partial void EmitParticles(float deltaTime);

        void UpdateRoomToRoom(float deltaTime)
        {
            if (linkedTo.Count < 2) return;
            Hull hull1 = (Hull)linkedTo[0];
            Hull hull2 = (Hull)linkedTo[1];
            
            Vector2 subOffset = Vector2.Zero;
            if (hull1.Submarine != Submarine)
            {
                subOffset =Submarine.Position - hull1.Submarine.Position;
            }
            else if (hull2.Submarine != Submarine)
            {

                subOffset = hull2.Submarine.Position - Submarine.Position;

            }

            if (hull1.WaterVolume <= 0.0 && hull2.WaterVolume <= 0.0) return;

            float size = IsHorizontal ? rect.Height : rect.Width;

            //a variable affecting the water flow through the gap
            //the larger the gap is, the faster the water flows
            float sizeModifier = size / 100.0f * open;

            //horizontal gap (such as a regular door)
            if (IsHorizontal)
            {
                higherSurface = Math.Max(hull1.Surface, hull2.Surface + subOffset.Y);
                float delta = 0.0f;

                //water level is above the lower boundary of the gap
                if (Math.Max(hull1.Surface + hull1.WaveY[hull1.WaveY.Length - 1], hull2.Surface + subOffset.Y + hull2.WaveY[0]) > rect.Y - size)
                {
                    int dir = (hull1.Pressure > hull2.Pressure + subOffset.Y) ? 1 : -1;

                    //water flowing from the righthand room to the lefthand room
                    if (dir == -1)
                    {
                        if (!(hull2.WaterVolume > 0.0f)) return;
                        lowerSurface = hull1.Surface - hull1.WaveY[hull1.WaveY.Length - 1];
                        //delta = Math.Min((room2.water.pressure - room1.water.pressure) * sizeModifier, Math.Min(room2.water.Volume, room2.Volume));
                        //delta = Math.Min(delta, room1.Volume - room1.water.Volume + Water.MaxCompress);

                        flowTargetHull = hull1;

                        //make sure not to move more than what the room contains
                        delta = Math.Min(((hull2.Pressure + subOffset.Y) - hull1.Pressure) * 5.0f * sizeModifier, Math.Min(hull2.WaterVolume, hull2.Volume));
                        
                        //make sure not to place more water to the target room than it can hold
                        delta = Math.Min(delta, hull1.Volume + Hull.MaxCompress - (hull1.WaterVolume));
                        hull1.WaterVolume += delta;
                        hull2.WaterVolume -= delta;
                        if (hull1.WaterVolume > hull1.Volume)
                        {
                            hull1.Pressure = Math.Max(hull1.Pressure, (hull1.Pressure + hull2.Pressure+subOffset.Y) / 2);
                        }

                        flowForce = new Vector2(-delta, 0.0f);
                    }
                    else if (dir == 1)
                    {
                        if (!(hull1.WaterVolume > 0.0f)) return;
                        lowerSurface = hull2.Surface - hull2.WaveY[hull2.WaveY.Length - 1];

                        flowTargetHull = hull2;

                        //make sure not to move more than what the room contains
                        delta = Math.Min((hull1.Pressure - (hull2.Pressure + subOffset.Y)) * 5.0f * sizeModifier, Math.Min(hull1.WaterVolume, hull1.Volume));

                        //make sure not to place more water to the target room than it can hold
                        delta = Math.Min(delta, hull2.Volume + Hull.MaxCompress - (hull2.WaterVolume));
                        hull1.WaterVolume -= delta;
                        hull2.WaterVolume += delta;
                        if (hull2.WaterVolume > hull2.Volume)
                        {
                            hull2.Pressure = Math.Max(hull2.Pressure, ((hull1.Pressure-subOffset.Y) + hull2.Pressure) / 2);
                        }
                        
                        flowForce = new Vector2(delta, 0.0f);
                    }

                    if (delta > 100.0f && subOffset == Vector2.Zero)
                    {
                        float avg = (hull1.Surface + hull2.Surface) / 2.0f;

                        if (hull1.WaterVolume < hull1.Volume - Hull.MaxCompress &&
                            hull1.Surface + hull1.WaveY[hull1.WaveY.Length - 1] < rect.Y)
                        {
                            hull1.WaveVel[hull1.WaveY.Length - 1] = (avg - (hull1.Surface + hull1.WaveY[hull1.WaveY.Length - 1])) * 0.1f;
                            hull1.WaveVel[hull1.WaveY.Length - 2] = hull1.WaveVel[hull1.WaveY.Length - 1];
                        }

                        if (hull2.WaterVolume < hull2.Volume - Hull.MaxCompress &&
                            hull2.Surface + hull2.WaveY[0] < rect.Y)
                        {
                            hull2.WaveVel[0] = (avg - (hull2.Surface + hull2.WaveY[0])) * 0.1f;
                            hull2.WaveVel[1] = hull2.WaveVel[0];
                        }
                    }
                }

            }
            else
            {
                //lower room is full of water
                if (hull2.Pressure + subOffset.Y > hull1.Pressure)
                {
                    float delta = Math.Min(hull2.WaterVolume - hull2.Volume + Hull.MaxCompress, deltaTime * 8000.0f * sizeModifier);

                    //make sure not to place more water to the target room than it can hold
                    if (hull1.WaterVolume + delta > hull1.Volume + Hull.MaxCompress)
                    {
                        delta -= (hull1.WaterVolume + delta) - (hull1.Volume + Hull.MaxCompress);
                    }

                    delta = Math.Max(delta, 0.0f);
                    hull1.WaterVolume += delta;
                    hull2.WaterVolume -= delta;

                    flowForce = new Vector2(
                        0.0f, 
                        Math.Min(Math.Min((hull2.Pressure + subOffset.Y) - hull1.Pressure, 200.0f), delta));

                    flowTargetHull = hull1;

                    if (hull1.WaterVolume > hull1.Volume)
                    {
                        hull1.Pressure = Math.Max(hull1.Pressure, (hull1.Pressure + (hull2.Pressure + subOffset.Y)) / 2);
                    }                   

                }
                //there's water in the upper room, drop to lower
                else if (hull1.WaterVolume > 0)
                {
                    flowTargetHull = hull2;

                    //make sure the amount of water moved isn't more than what the room contains
                    float delta = Math.Min(hull1.WaterVolume, deltaTime * 25000f * sizeModifier);

                    //make sure not to place more water to the target room than it can hold
                    if (hull2.WaterVolume + delta > hull2.Volume + Hull.MaxCompress)
                    {
                        delta -= (hull2.WaterVolume + delta) - (hull2.Volume + Hull.MaxCompress);
                    }
                    hull1.WaterVolume -= delta;
                    hull2.WaterVolume += delta;

                    flowForce = new Vector2(
                        hull1.WaveY[hull1.GetWaveIndex(rect.X)] - hull1.WaveY[hull1.GetWaveIndex(rect.Right)],
                        Math.Max(Math.Max((hull2.Pressure + subOffset.Y - hull1.Pressure) * 10.0f, -200.0f), -delta));

                    if (hull2.WaterVolume > hull2.Volume)
                    {
                        hull2.Pressure = Math.Max(hull2.Pressure, ((hull1.Pressure - subOffset.Y) + hull2.Pressure) / 2);
                    }
                }
            }

            if (open > 0.0f)
            {
                if (hull1.WaterVolume > hull1.Volume - Hull.MaxCompress && hull2.WaterVolume > hull2.Volume - Hull.MaxCompress)
                {
                    float avgLethality = (hull1.LethalPressure + hull2.LethalPressure) / 2.0f;
                    hull1.LethalPressure = avgLethality;
                    hull2.LethalPressure = avgLethality;
                }
                else 
                {
                    hull1.LethalPressure = 0.0f;
                    hull2.LethalPressure = 0.0f;
                }
            }
        }

        void UpdateRoomToOut(float deltaTime)
        {
            if (linkedTo.Count != 1) return;

            float size = (IsHorizontal) ? rect.Height : rect.Width;

            Hull hull1 = (Hull)linkedTo[0];

            //a variable affecting the water flow through the gap
            //the larger the gap is, the faster the water flows
            float sizeModifier = size * open * open;

            float delta = Hull.MaxCompress * sizeModifier * deltaTime;
            
            //make sure not to place more water to the target room than it can hold
            delta = Math.Min(delta, hull1.Volume + Hull.MaxCompress - hull1.WaterVolume);
            hull1.WaterVolume += delta;

            if (hull1.WaterVolume > hull1.Volume) hull1.Pressure += 0.5f;

            flowTargetHull = hull1;

            if (IsHorizontal)
            {
                //water flowing from right to left
                if (rect.X > hull1.Rect.X + hull1.Rect.Width / 2.0f)
                {
                    flowForce = new Vector2(-delta, 0.0f);
                    
                }
                else
                {
                    flowForce = new Vector2(delta, 0.0f);
                }

                higherSurface = hull1.Surface;
                lowerSurface = rect.Y;

                if (hull1.WaterVolume < hull1.Volume - Hull.MaxCompress &&
                    hull1.Surface < rect.Y)
                {
                    if (rect.X > hull1.Rect.X + hull1.Rect.Width / 2.0f)
                    {
                        float vel = ((rect.Y - rect.Height / 2) - (hull1.Surface + hull1.WaveY[hull1.WaveY.Length - 1])) * 0.1f;
                        vel *= Math.Min(Math.Abs(flowForce.X) / 200.0f, 1.0f);

                        hull1.WaveVel[hull1.WaveY.Length - 1] += vel;
                        hull1.WaveVel[hull1.WaveY.Length - 2] += vel;
                    }
                    else
                    {
                        float vel = ((rect.Y - rect.Height / 2) - (hull1.Surface + hull1.WaveY[0])) * 0.1f;
                        vel *= Math.Min(Math.Abs(flowForce.X) / 200.0f, 1.0f);

                        hull1.WaveVel[0] += vel;
                        hull1.WaveVel[1] += vel;
                    } 
                }
                else
                {
                    hull1.LethalPressure += (Submarine != null && Submarine.AtDamageDepth) ? 100.0f * deltaTime : 10.0f * deltaTime;
                }
            }
            else
            {
                if (rect.Y > hull1.Rect.Y - hull1.Rect.Height / 2.0f)
                {
                    flowForce = new Vector2(0.0f, -delta);
                }
                else
                {
                    flowForce = new Vector2(0.0f, delta);
                }
                if (hull1.WaterVolume >= hull1.Volume - Hull.MaxCompress)
                {
                    hull1.LethalPressure += (Submarine != null && Submarine.AtDamageDepth) ? 100.0f * deltaTime : 10.0f * deltaTime;
                }
            }

        }

        private void UpdateOxygen()
        {
            if (linkedTo.Count < 2) return;
            Hull hull1 = (Hull)linkedTo[0];
            Hull hull2 = (Hull)linkedTo[1];

            if (IsHorizontal)
            {
                if (Math.Max(hull1.Surface + hull1.WaveY[hull1.WaveY.Length - 1], hull2.Surface + hull2.WaveY[0]) > rect.Y) return;
            }

            float totalOxygen = hull1.Oxygen + hull2.Oxygen;
            float totalVolume = (hull1.Volume + hull2.Volume);
            
            float deltaOxygen = (totalOxygen * hull1.Volume / totalVolume) - hull1.Oxygen;
            deltaOxygen = MathHelper.Clamp(deltaOxygen, -Hull.OxygenDistributionSpeed, Hull.OxygenDistributionSpeed);

            hull1.Oxygen += deltaOxygen;
            hull2.Oxygen -= deltaOxygen;            
        }

        public static Gap FindAdjacent(List<Gap> gaps, Vector2 worldPos, float allowedOrthogonalDist)
        {
            foreach (Gap gap in gaps)
            {
                if (gap.Open == 0.0f || gap.IsRoomToRoom) continue;

                if (gap.ConnectedWall != null)
                {
                    int sectionIndex = gap.ConnectedWall.FindSectionIndex(gap.Position);
                    if (sectionIndex > -1 && !gap.ConnectedWall.SectionBodyDisabled(sectionIndex)) continue;
                }

                if (gap.IsHorizontal)
                {
                    if (worldPos.Y < gap.WorldRect.Y && worldPos.Y > gap.WorldRect.Y - gap.WorldRect.Height &&
                        Math.Abs(gap.WorldRect.Center.X - worldPos.X) < allowedOrthogonalDist)
                    {
                        return gap;
                    }
                }
                else
                {
                    if (worldPos.X > gap.WorldRect.X && worldPos.X < gap.WorldRect.Right &&
                        Math.Abs(gap.WorldRect.Y - gap.WorldRect.Height / 2 - worldPos.Y) < allowedOrthogonalDist)
                    {
                        return gap;
                    }
                }
            }

            return null;
        }

        public override void ShallowRemove()
        {
            base.ShallowRemove();
            GapList.Remove(this);

            foreach (Hull hull in Hull.hullList)
            {
                hull.ConnectedGaps.Remove(this);
            }
        }

        public override void Remove()
        {
            base.Remove();
            GapList.Remove(this);

            foreach (Hull hull in Hull.hullList)
            {
                hull.ConnectedGaps.Remove(this);
            }
        }

        public override void OnMapLoaded()
        {
            FindHulls();
        }
        
        public static void Load(XElement element, Submarine submarine)
        {
            Rectangle rect = Rectangle.Empty;

            if (element.Attribute("rect") != null)
            {
                rect = element.GetAttributeRect("rect", Rectangle.Empty);
            }
            else
            {
                //backwards compatibility
                rect = new Rectangle(
                    int.Parse(element.Attribute("x").Value),
                    int.Parse(element.Attribute("y").Value),
                    int.Parse(element.Attribute("width").Value),
                    int.Parse(element.Attribute("height").Value));
            }

            bool isHorizontal = rect.Height > rect.Width;

            var horizontalAttribute = element.Attribute("horizontal");
            if (horizontalAttribute!=null)
            {
                isHorizontal = horizontalAttribute.Value.ToString() == "true";
            }

            Gap g = new Gap(rect, isHorizontal, submarine);
            g.ID = (ushort)int.Parse(element.Attribute("ID").Value);
            
            g.linkedToID = new List<ushort>();
        }

        public override XElement Save(XElement parentElement)
        {
            XElement element = new XElement("Gap");

            element.Add(
                new XAttribute("ID", ID),
                new XAttribute("horizontal", IsHorizontal ? "true" : "false"));

            element.Add(new XAttribute("rect",
                    (int)(rect.X - Submarine.HiddenSubPosition.X) + "," +
                    (int)(rect.Y - Submarine.HiddenSubPosition.Y) + "," +
                    rect.Width + "," + rect.Height));

            parentElement.Add(element);

            return element;
        }
    }
}