using FarseerPhysics;
using Microsoft.Xna.Framework;
using System;
using System.Linq;

namespace Barotrauma
{
    class AIObjectiveGoTo : AIObjective
    {
        public override string DebugTag => "go to";

        private AIObjectiveFindDivingGear findDivingGear;
        private Vector2 targetPos;
        private bool repeat;
        //how long until the path to the target is declared unreachable
        private float waitUntilPathUnreachable;
        private bool getDivingGearIfNeeded;

        public Func<bool> customCondition;

        /// <summary>
        /// Sim units
        /// </summary>
        public float CloseEnough { get; set; } = 0.5f;
        public bool IgnoreIfTargetDead { get; set; }
        public bool AllowGoingOutside { get; set; }
        public bool CheckVisibility { get; set; }

        public override float GetPriority()
        {
            if (FollowControlledCharacter && Character.Controlled == null) { return 0.0f; }
            if (Target != null && Target.Removed) { return 0.0f; }
            if (IgnoreIfTargetDead && Target is Character character && character.IsDead) { return 0.0f; }                     
            if (objectiveManager.CurrentOrder == this)
            {
                return AIObjectiveManager.OrderPriority;
            }
            return 1.0f;
        }

        public Entity Target { get; private set; }

        public Vector2 TargetPos => Target != null ? Target.SimPosition : targetPos;

        public bool FollowControlledCharacter;

        public AIObjectiveGoTo(Entity target, Character character, AIObjectiveManager objectiveManager, bool repeat = false, bool getDivingGearIfNeeded = true, float priorityModifier = 1) 
            : base (character, objectiveManager, priorityModifier)
        {
            this.Target = target;
            this.repeat = repeat;

            waitUntilPathUnreachable = 2.0f;
            this.getDivingGearIfNeeded = getDivingGearIfNeeded;
            CalculateCloseEnough();
        }


        public AIObjectiveGoTo(Vector2 simPos, Character character, AIObjectiveManager objectiveManager, bool repeat = false, bool getDivingGearIfNeeded = true, float priorityModifier = 1) 
            : base(character, objectiveManager, priorityModifier)
        {
            this.targetPos = simPos;
            this.repeat = repeat;

            waitUntilPathUnreachable = 5.0f;
            this.getDivingGearIfNeeded = getDivingGearIfNeeded;
            CalculateCloseEnough();
        }

        protected override void Act(float deltaTime)
        {
            if (FollowControlledCharacter)
            {
                if (Character.Controlled == null)
                {
                    abandon = true;
                    return;
                }
                Target = Character.Controlled;
            }
            if (Target == character)
            {
                character.AIController.SteeringManager.Reset();
                abandon = true;
                return;
            }           
            waitUntilPathUnreachable -= deltaTime;
            if (!character.IsClimbing)
            {
                character.SelectedConstruction = null;
            }
            if (Target != null)
            {
                if (Target.Removed)
                {
                    abandon = true;
                }
                else
                {
                    character.AIController.SelectTarget(Target.AiTarget);
                }
            }
            Vector2 currTargetPos = Vector2.Zero;
            if (Target == null)
            {
                currTargetPos = targetPos;
            }
            else
            {
                currTargetPos = Target.SimPosition;
                
                //if character is inside the sub and target isn't, transform the position
                if (character.Submarine != null && Target.Submarine == null)
                {
                    currTargetPos -= character.Submarine.SimPosition;
                }
            }
            bool sightCheck = true;
            if (CheckVisibility && Target != null)
            {
                sightCheck = Target is Character ch ? character.CanSeeCharacter(ch) : character.CanSeeTarget(Target);
            }
            if (sightCheck && Vector2.DistanceSquared(currTargetPos, character.SimPosition) < CloseEnough * CloseEnough)
            {
                character.AIController.SteeringManager.Reset();
                character.AnimController.TargetDir = currTargetPos.X > character.SimPosition.X ? Direction.Right : Direction.Left;
            }
            else
            {
                bool isInside = character.CurrentHull != null;
                bool insideSteering = SteeringManager == PathSteering && PathSteering.CurrentPath != null && !PathSteering.IsPathDirty;
                var targetHull = Target is Hull h ? h : Target is Item i ? i.CurrentHull : Target is Character c ? c.CurrentHull : character.CurrentHull;
                bool targetIsOutside = (Target != null && targetHull == null) || (insideSteering && PathSteering.CurrentPath.HasOutdoorsNodes);
                if (isInside && targetIsOutside && !AllowGoingOutside)
                {
                    abandon = true;
                }
                else if (!repeat && waitUntilPathUnreachable < 0)
                {
                    if (SteeringManager == PathSteering && PathSteering.CurrentPath != null)
                    {
                        abandon = PathSteering.CurrentPath.Unreachable;
                    }
                }
                if (abandon)
                {
#if DEBUG
                    DebugConsole.NewMessage($"{character.Name}: Cannot reach the target: {(Target != null ? Target.ToString() : TargetPos.ToString())}", Color.Yellow);
#endif
                    if (objectiveManager.CurrentOrder != null)
                    {
                        character.Speak(TextManager.Get("DialogCannotReach"), identifier: "cannotreach", minDurationBetweenSimilar: 10.0f);
                    }
                    character.AIController.SteeringManager.Reset();
                }
                else
                {
                    character.AIController.SteeringManager.SteeringSeek(currTargetPos);
                    if (getDivingGearIfNeeded)
                    {
                        bool needsDivingGear = HumanAIController.NeedsDivingGear(targetHull);
                        bool needsDivingSuit = needsDivingGear && (targetHull == null || targetIsOutside || targetHull.WaterPercentage > 90);
                        bool needsEquipment = false;
                        if (needsDivingSuit)
                        {
                            needsEquipment = !HumanAIController.HasDivingSuit(character);
                        }
                        else if (needsDivingGear)
                        {
                            needsEquipment = !HumanAIController.HasDivingMask(character);
                        }
                        if (needsEquipment)
                        {
                            TryAddSubObjective(ref findDivingGear, () => new AIObjectiveFindDivingGear(character, needsDivingSuit, objectiveManager));
                        }
                    }
                }
            }
        }

        private bool isCompleted;
        public override bool IsCompleted()
        {
            // First check the distance
            // Then the custom condition
            // And finally check if can interact (heaviest)
            if (repeat) { return false; }
            if (isCompleted) { return true; }
            bool closeEnough = Vector2.DistanceSquared(Target != null ? Target.SimPosition : targetPos, character.SimPosition) < CloseEnough * CloseEnough;
            if (closeEnough)
            {
                if (customCondition == null || customCondition())
                {
                    if (Target is Item item)
                    {
                        if (character.CanInteractWith(item, out _, checkLinked: false)) { isCompleted = true; }
                    }
                    else if (Target is Character targetCharacter)
                    {
                        if (character.CanInteractWith(targetCharacter, ConvertUnits.ToDisplayUnits(CloseEnough))) { isCompleted = true; }
                    }
                    else
                    {
                        isCompleted = true;
                    }
                }
            }
            if (isCompleted)
            {
                character.AIController.SteeringManager.Reset();
            }
            return isCompleted;
        }

        public override bool IsDuplicate(AIObjective otherObjective)
        {
            if (!(otherObjective is AIObjectiveGoTo objective)) { return false; }
            if (objective.Target == Target) { return true; }
            return objective.targetPos == targetPos;
        }

        private void CalculateCloseEnough()
        {
            float interactionDistance = Target is Item i ? ConvertUnits.ToSimUnits(i.InteractDistance * 0.9f) : 0;
            CloseEnough = Math.Max(interactionDistance, CloseEnough);
        }
    }
}