using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Xml.Linq;
using FarseerPhysics;
using Lidgren.Network;
using Microsoft.Xna.Framework;
using FarseerPhysics.Dynamics;
using Microsoft.Xna.Framework.Graphics;

namespace Barotrauma
{
    
    class EnemyAIController : AIController
    {
        private const float UpdateTargetsInterval = 5.0f;

        private const float RaycastInterval = 1.0f;

        private bool attackWhenProvoked;
        
        //the preference to attack a specific type of target (-1.0 - 1.0)
        //0.0 = doesn't attack targets of the type
        //positive values = attacks targets of this type
        //negative values = escapes targets of this type        
        private float attackRooms, attackHumans, attackWeaker, attackStronger;

        private SteeringManager outsideSteering, insideSteering;

        private float updateTargetsTimer;

        private float raycastTimer;

        private Vector2 prevPosition;
        private float distanceAccumulator;

        //a timer for attacks such as biting that last for a specific amount of time
        //the duration is determined by the attackDuration of the attacking limb
        private float attackTimer;
        
        //a "cooldown time" after an attack during which the Character doesn't try to attack again
        private float attackCoolDown;
        private float coolDownTimer;
        
        //a point in a wall which the Character is currently targeting
        private Vector2 wallAttackPos;
        //the entity (a wall) which the Character is targeting
        private IDamageable targetEntity;

        //the limb selected for the current attack
        private Limb attackingLimb;
        
        private AITarget selectedAiTarget;
        private AITargetMemory selectedTargetMemory;
        private float targetValue;
        
        private Dictionary<AITarget, AITargetMemory> targetMemories;

        //the eyesight of the NPC (0.0 = blind, 1.0 = sees every target within sightRange)
        private float sight;
        //how far the NPC can hear targets from (0.0 = deaf, 1.0 = hears every target within soundRange)
        private float hearing;

        public AITarget SelectedAiTarget
        {
            get { return selectedAiTarget; }
        }
                        
        public EnemyAIController(Character c, string file) : base(c)
        {
            if (GameMain.Client != null && GameMain.Server == null) c.Enabled = false;

            targetMemories = new Dictionary<AITarget, AITargetMemory>();

            XDocument doc = ToolBox.TryLoadXml(file);
            if (doc == null || doc.Root == null) return;

            XElement aiElement = doc.Root.Element("ai");
            if (aiElement == null) return;

            attackRooms     = ToolBox.GetAttributeFloat(aiElement, "attackrooms", 0.0f) / 100.0f;
            attackHumans    = ToolBox.GetAttributeFloat(aiElement, "attackhumans", 0.0f) / 100.0f;
            attackWeaker    = ToolBox.GetAttributeFloat(aiElement, "attackweaker", 0.0f) / 100.0f;
            attackStronger  = ToolBox.GetAttributeFloat(aiElement, "attackstronger", 0.0f) / 100.0f;

            attackCoolDown  = ToolBox.GetAttributeFloat(aiElement, "attackcooldown", 5.0f);

            sight           = ToolBox.GetAttributeFloat(aiElement, "sight", 0.0f);
            hearing         = ToolBox.GetAttributeFloat(aiElement, "hearing", 0.0f);

            attackWhenProvoked = ToolBox.GetAttributeBool(aiElement, "attackwhenprovoked", false);

            outsideSteering = new SteeringManager(this);
            insideSteering = new IndoorsSteeringManager(this, false);

            steeringManager = outsideSteering;

            state = AiState.None;
        }

        public override void SelectTarget(AITarget target)
        {
            selectedAiTarget = target;
            selectedTargetMemory = FindTargetMemory(target);

            targetValue = 100.0f;
        }
        
        public override void Update(float deltaTime)
        {
            UpdateDistanceAccumulator();

            bool ignorePlatforms = (-Character.AnimController.TargetMovement.Y > Math.Abs(Character.AnimController.TargetMovement.X));

            if (steeringManager is IndoorsSteeringManager)
            {
                var currPath = ((IndoorsSteeringManager)steeringManager).CurrentPath;
                if (currPath != null && currPath.CurrentNode != null)
                {
                    if (currPath.CurrentNode.SimPosition.Y < Character.AnimController.GetColliderBottom().Y)
                    {
                        ignorePlatforms = true;
                    }
                }
            }
            
            Character.AnimController.IgnorePlatforms = ignorePlatforms;

            if (Character.AnimController is HumanoidAnimController)
            {
                if (Math.Abs(Character.AnimController.movement.X) > 0.1f && !Character.AnimController.InWater)
                {
                    Character.AnimController.TargetDir = Character.AnimController.movement.X > 0.0f ? Direction.Right : Direction.Left;
                }
            }

            if (updateTargetsTimer > 0.0)
            {
                updateTargetsTimer -= deltaTime;
            }
            else
            {
                UpdateTargets(Character);
                updateTargetsTimer = UpdateTargetsInterval;

                if (selectedAiTarget == null)
                {
                    state = AiState.None;
                }
                else
                {
                    state = (targetValue > 0.0f) ? AiState.Attack : AiState.Escape;
                }
                //if (coolDownTimer >= 0.0f) return;
            }

            steeringManager = Character.Submarine == null ? outsideSteering : insideSteering;

            switch (state)
            {
                case AiState.None:
                    UpdateNone(deltaTime);
                    break;
                case AiState.Attack:
                    UpdateAttack(deltaTime);
                    break;
            }

            steeringManager.Update();
        }

        private void UpdateNone(float deltaTime)
        {
            //wander around randomly
            if (Character.Submarine==null && SimPosition.Y < ConvertUnits.ToSimUnits(SubmarineBody.DamageDepth*0.5f))
            {
                steeringManager.SteeringManual(deltaTime, Vector2.UnitY);
            }
            else
            {
                steeringManager.SteeringAvoid(deltaTime, 0.1f);
                steeringManager.SteeringWander(0.5f);
            }

            attackingLimb = null;
            attackTimer = 0.0f;

            coolDownTimer -= deltaTime;  
        }

        private void UpdateDistanceAccumulator()
        {
            Limb limb = Character.AnimController.Limbs[0];
            distanceAccumulator += (limb.SimPosition - prevPosition).Length();

            prevPosition = limb.body.SimPosition;
        }
        
        private void UpdateAttack(float deltaTime)
        {
            if (selectedAiTarget == null) 
            {
                state = AiState.None;
                return;
            }
            
            selectedTargetMemory.Priority -= deltaTime;
            
            Vector2 attackSimPosition = Character.Submarine==null ? ConvertUnits.ToSimUnits(selectedAiTarget.WorldPosition) : selectedAiTarget.SimPosition;
            if (wallAttackPos != Vector2.Zero && targetEntity != null)
            {
                attackSimPosition = wallAttackPos;

                if (selectedAiTarget.Entity != null && Character.Submarine==null && selectedAiTarget.Entity.Submarine != null) attackSimPosition += ConvertUnits.ToSimUnits(selectedAiTarget.Entity.Submarine.Position);
            }

            if (coolDownTimer>0.0f)
            {
                UpdateCoolDown(attackSimPosition, deltaTime);
                return;
            }

            if (raycastTimer > 0.0)
            {
                raycastTimer -= deltaTime;
            }
            else
            {
                GetTargetEntity();

                raycastTimer = RaycastInterval;
            }

            //steeringManager.SteeringAvoid(deltaTime, 1.0f);

            Limb attackLimb = attackingLimb;
            //check if any of the limbs is close enough to attack the target
            if (attackingLimb == null)
            {
                foreach (Limb limb in Character.AnimController.Limbs)
                {
                    if (limb.attack==null) continue;
                    attackLimb = limb;

                    if (ConvertUnits.ToDisplayUnits(Vector2.Distance(limb.SimPosition, attackSimPosition)) > limb.attack.Range) continue;
                                        
                    attackingLimb = limb;
                    break;   
                }
            }
            if (attackLimb != null)
            {
                steeringManager.SteeringSeek(attackSimPosition - (attackLimb.SimPosition - SimPosition));

                if (steeringManager is IndoorsSteeringManager)
                {
                    var indoorsSteering = (IndoorsSteeringManager)steeringManager;
                    if (indoorsSteering.CurrentPath!=null && (indoorsSteering.CurrentPath.Finished || indoorsSteering.CurrentPath.Unreachable))
                    {
                        steeringManager.SteeringManual(deltaTime, attackSimPosition - attackLimb.SimPosition);
                    }
                }

                if (attackingLimb != null) UpdateLimbAttack(deltaTime, attackingLimb, attackSimPosition);
            }   
        }

        private void UpdateCoolDown(Vector2 attackPosition, float deltaTime)
        {
            coolDownTimer -= deltaTime;
            attackingLimb = null;
            
            if (selectedAiTarget.Entity is Hull ||
                Vector2.Distance(attackPosition, Character.AnimController.Limbs[0].SimPosition) < ConvertUnits.ToSimUnits(500.0f))
            {
                steeringManager.SteeringSeek(attackPosition, -0.8f);
                steeringManager.SteeringAvoid(deltaTime, 1.0f);
            }
            else
            {
                steeringManager.SteeringSeek(attackPosition, -0.5f);
                steeringManager.SteeringAvoid(deltaTime, 1.0f);
            }
        }

        private void GetTargetEntity()
        {
            targetEntity = null;

            if (Character.AnimController.CurrentHull != null)
            {
                wallAttackPos = Vector2.Zero;
                return;
            }
            
            //check if there's a wall between the target and the Character   
            Vector2 rayStart = Character.SimPosition;
            Vector2 rayEnd = selectedAiTarget.SimPosition;

            if (selectedAiTarget.Entity.Submarine!=null && Character.Submarine==null)
            {
                rayStart -= ConvertUnits.ToSimUnits(selectedAiTarget.Entity.Submarine.Position);
            }

            Body closestBody = Submarine.CheckVisibility(rayStart, rayEnd);

            if (Submarine.LastPickedFraction == 1.0f || closestBody == null)
            {
                wallAttackPos = Vector2.Zero;
                return;
            }
            
            Structure wall = closestBody.UserData as Structure;
            if (wall == null)
            {
                wallAttackPos = Submarine.LastPickedPosition;
                if (selectedAiTarget.Entity.Submarine!=null && Character.Submarine == null) wallAttackPos -= ConvertUnits.ToSimUnits(selectedAiTarget.Entity.Submarine.Position);
            
            }
            else
            {
                int sectionIndex = wall.FindSectionIndex(ConvertUnits.ToDisplayUnits(Submarine.LastPickedPosition));

                float sectionDamage = wall.SectionDamage(sectionIndex);
                for (int i = sectionIndex - 2; i <= sectionIndex + 2; i++)
                {
                    if (wall.SectionBodyDisabled(i))
                    {
                        sectionIndex = i;
                        break;
                    }
                    if (wall.SectionDamage(i) > sectionDamage) sectionIndex = i;
                }
                wallAttackPos = wall.SectionPosition(sectionIndex);
                //if (wall.Submarine != null) wallAttackPos += wall.Submarine.Position;
                wallAttackPos = ConvertUnits.ToSimUnits(wallAttackPos);
            }
            
            targetEntity = closestBody.UserData as IDamageable;            
        }

        public override void OnAttacked(IDamageable attacker, float amount)
        {
            updateTargetsTimer = Math.Min(updateTargetsTimer, 0.1f);
            coolDownTimer *= 0.1f;

            if (amount > 0.1f && attackWhenProvoked)
            {
                attackHumans = 100.0f;
                attackRooms = 100.0f;
            }

            if (attacker==null || attacker.AiTarget==null) return;
            AITargetMemory targetMemory = FindTargetMemory(attacker.AiTarget);
            targetMemory.Priority += amount;
        }

        private void UpdateLimbAttack(float deltaTime, Limb limb, Vector2 attackPosition)
        {
            var damageTarget = (wallAttackPos != Vector2.Zero && targetEntity != null) ? targetEntity : selectedAiTarget.Entity as IDamageable;

            limb.UpdateAttack(deltaTime, attackPosition, damageTarget);

            if (limb.AttackTimer >= limb.attack.Duration)
            {
                wallAttackPos = Vector2.Zero;
                limb.AttackTimer = 0.0f;
                coolDownTimer = attackCoolDown;                
            }
        }
        
        //goes through all the AItargets, evaluates how preferable it is to attack the target,
        //whether the Character can see/hear the target and chooses the most preferable target within
        //sight/hearing range
        public void UpdateTargets(Character character)
        {
            if (distanceAccumulator<5.0f && Rand.Range(1,3)==1)
            {
                selectedAiTarget = null;
                character.AnimController.TargetMovement = -character.AnimController.TargetMovement;
                state = AiState.None;
                return;
            }
            distanceAccumulator = 0.0f;

            wallAttackPos = Vector2.Zero;

            selectedAiTarget = null;
            selectedTargetMemory = null;
            targetValue = 0.0f;

            UpdateTargetMemories();
            
            foreach (AITarget target in AITarget.List)
            {
                if (Level.Loaded != null && target.WorldPosition.Y > Level.Loaded.Size.Y)
                {
                    continue;
                }

                float valueModifier = 0.0f;
                float dist = 0.0f;
                
                IDamageable targetDamageable = target.Entity as IDamageable;
                if (targetDamageable!=null && targetDamageable.Health <= 0.0f) continue;

                Character targetCharacter = target.Entity as Character;

                //ignore the aitarget if it is the Character itself
                if (targetCharacter == character) continue;
                                
                if (targetCharacter!=null)
                {
                    if (attackHumans == 0.0f || targetCharacter.SpeciesName != "human") continue;
                    
                    valueModifier = attackHumans;                  
                }
                else if (target.Entity!=null && attackRooms != 0.0f)
                {
                    //skip the target if it's the room the Character is inside of
                    if (character.AnimController.CurrentHull != null && character.AnimController.CurrentHull == target.Entity as Hull) continue;

                    valueModifier = attackRooms;
                }

                dist = Vector2.Distance(
                    character.WorldPosition,
                    target.WorldPosition);

                //if the target has been within range earlier, the character will notice it more easily
                //(i.e. remember where the target was)
                if (targetMemories.ContainsKey(target)) dist *= 0.5f;

                //ignore target if it's too far to see or hear
                if (dist > target.SightRange * sight && dist > target.SoundRange * hearing) continue;

                AITargetMemory targetMemory = FindTargetMemory(target);
                valueModifier = valueModifier * targetMemory.Priority / dist;

                if (Math.Abs(valueModifier) > Math.Abs(targetValue))
                {                  
                    Vector2 rayStart = character.AnimController.Limbs[0].SimPosition;
                    Vector2 rayEnd = target.SimPosition;

                    if (target.Entity.Submarine != null && character.Submarine==null)
                    {
                        rayStart -= ConvertUnits.ToSimUnits(target.Entity.Submarine.Position);
                    }

                    Body closestBody = Submarine.CheckVisibility(rayStart, rayEnd);
                    Structure closestStructure = (closestBody == null) ? null : closestBody.UserData as Structure;

                    if (targetDamageable != null)
                    {
                        valueModifier = valueModifier / targetDamageable.Health;                            
                    }
                    else if (closestStructure!=null)
                    {
                        valueModifier = valueModifier / ((IDamageable)closestStructure).Health;
                    }
                    else
                    {
                        valueModifier = valueModifier / 1000.0f;
                    }

                    if (selectedAiTarget == null || Math.Abs(valueModifier) > Math.Abs(targetValue))
                    {
                        selectedAiTarget = target;
                        selectedTargetMemory = targetMemory;

                        targetValue = valueModifier;
                    }
                }
            }
           
        }

        //find the targetMemory that corresponds to some AItarget or create if there isn't one yet
        private AITargetMemory FindTargetMemory(AITarget target)
        {
            AITargetMemory memory = null;
            if (targetMemories.TryGetValue(target, out memory))
            {
                return memory;
            }

            memory = new AITargetMemory(100.0f);
            targetMemories.Add(target, memory);

            return memory;
        }

        //go through all the targetmemories and delete ones that don't
        //have a corresponding AItarget or whose priority is 0.0f
        private void UpdateTargetMemories()
        {

            List<AITarget> toBeRemoved = new List<AITarget>();
            foreach(KeyValuePair<AITarget, AITargetMemory> memory in targetMemories)
            {
                memory.Value.Priority += 0.5f;
                if (Math.Abs(memory.Value.Priority) < 1.0f || !AITarget.List.Contains(memory.Key)) toBeRemoved.Add(memory.Key);
            }

            foreach (AITarget target in toBeRemoved)
            {
                targetMemories.Remove(target);
            }
        }

        public override void DebugDraw(SpriteBatch spriteBatch)
        {
            if (Character.IsDead) return;

            Vector2 pos = Character.WorldPosition;
            pos.Y = -pos.Y;

            if (selectedAiTarget!=null)
            {
                GUI.DrawLine(spriteBatch, pos, new Vector2(selectedAiTarget.WorldPosition.X, -selectedAiTarget.WorldPosition.Y), Color.Red);

                if (wallAttackPos!=Vector2.Zero)
                {
                    GUI.DrawRectangle(spriteBatch, ConvertUnits.ToDisplayUnits(new Vector2(wallAttackPos.X, -wallAttackPos.Y)) - new Vector2(10.0f, 10.0f), new Vector2(20.0f, 20.0f), Color.Red, false);
                }

                spriteBatch.DrawString(GUI.Font, targetValue.ToString(), pos - Vector2.UnitY*20.0f, Color.Red);
            }

            if (selectedAiTarget != null)
            {
                GUI.DrawLine(spriteBatch,
                    new Vector2(Character.DrawPosition.X, -Character.DrawPosition.Y),
                    new Vector2(selectedAiTarget.WorldPosition.X, -selectedAiTarget.WorldPosition.Y), Color.Red);
            }

            spriteBatch.DrawString(GUI.Font, targetValue.ToString(), pos - Vector2.UnitY * 80.0f, Color.Red);

            spriteBatch.DrawString(GUI.Font, "updatetargets: "+updateTargetsTimer, pos - Vector2.UnitY * 100.0f, Color.Red);
            spriteBatch.DrawString(GUI.Font, "cooldown: " + coolDownTimer, pos - Vector2.UnitY * 120.0f, Color.Red);


            IndoorsSteeringManager pathSteering = steeringManager as IndoorsSteeringManager;
            if (pathSteering == null || pathSteering.CurrentPath == null || pathSteering.CurrentPath.CurrentNode == null) return;

            GUI.DrawLine(spriteBatch,
                new Vector2(Character.DrawPosition.X, -Character.DrawPosition.Y),
                new Vector2(pathSteering.CurrentPath.CurrentNode.DrawPosition.X, -pathSteering.CurrentPath.CurrentNode.DrawPosition.Y),
                Color.LightGreen);


            for (int i = 1; i < pathSteering.CurrentPath.Nodes.Count; i++)
            {
                GUI.DrawLine(spriteBatch,
                    new Vector2(pathSteering.CurrentPath.Nodes[i].DrawPosition.X, -pathSteering.CurrentPath.Nodes[i].DrawPosition.Y),
                    new Vector2(pathSteering.CurrentPath.Nodes[i - 1].DrawPosition.X, -pathSteering.CurrentPath.Nodes[i - 1].DrawPosition.Y),
                    Color.LightGreen);

                spriteBatch.DrawString(GUI.SmallFont,
                    pathSteering.CurrentPath.Nodes[i].ID.ToString(),
                    new Vector2(pathSteering.CurrentPath.Nodes[i].DrawPosition.X, -pathSteering.CurrentPath.Nodes[i].DrawPosition.Y - 10),
                    Color.LightGreen);
            }
        }

        public override void FillNetworkData(NetBuffer message)
        {
            message.WriteRangedInteger(0, Enum.GetValues(typeof(AiState)).Length-1, (int)state);

            //bool wallAttack = (wallAttackPos != Vector2.Zero && state == AiState.Attack);

            //message.Write(wallAttack);

            message.Write(MathUtils.AngleToByte(steeringManager.WanderAngle));

            coolDownTimer = MathHelper.Clamp(coolDownTimer, 0.0f, 30.0f);
            message.WriteRangedSingle(coolDownTimer, 0.0f, 30.0f, 8);

            message.Write(targetEntity==null ? (ushort)0 : (targetEntity as Entity).ID);
        }

        public override void ReadNetworkData(NetIncomingMessage message)
        {
            if (GameMain.Server != null) return;

            AiState newState = AiState.None;
            float wanderAngle;

            ushort targetID;

            try
            {

                newState =  (AiState)message.ReadRangedInteger(0, Enum.GetValues(typeof(AiState)).Length - 1);

                //bool wallAttack = message.ReadBoolean();

                //if (wallAttack)
                //{
                //    newWallAttackPos = new Vector2(
                //        message.ReadRangedSingle(-50.0f, 50.0f, 10),
                //        message.ReadRangedSingle(-50.0f, 50.0f, 10));

                //    newWallAttackPos += Submarine.Loaded.SimPosition;
                //}

                //newVelocity = new Vector2(message.ReadFloat(), message.ReadFloat());

                //targetPosition = new Vector2(message.ReadFloat(), message.ReadFloat());   

                wanderAngle = MathUtils.ByteToAngle(message.ReadByte());
                
                coolDownTimer = message.ReadRangedSingle(0.0f, 30.0f, 8);

                targetID = message.ReadUInt16();
            }

            catch (Exception e)
            {
#if DEBUG
                DebugConsole.ThrowError("Failed to read enemy ai update message", e);
#endif


                return;
            }

            steeringManager.WanderAngle = wanderAngle;

            state = newState;
                
            if (targetID > 0) targetEntity = Entity.FindEntityByID(targetID) as IDamageable;
            //updateTargetsTimer = UpdateTargetsInterval;
            
        }
    }

    //the "memory" of the Character 
    //keeps track of how preferable it is to attack a specific target
    //(if the Character can't inflict much damage the target, the priority decreases
    //and if the target attacks the Character, the priority increases)
    class AITargetMemory
    {
        private float priority;
        
        public float Priority
        {
            get { return priority; }
            set { priority = MathHelper.Clamp(value, 1.0f, 100.0f); }
        }

        public AITargetMemory(float priority)
        {
            this.priority = priority;
        }

    }
}