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

namespace Barotrauma
{
    partial class EventManager
    {
        const float IntensityUpdateInterval = 5.0f;

        const float CalculateDistanceTraveledInterval = 5.0f;

        private Level level;

        private readonly List<Sprite> preloadedSprites = new List<Sprite>();

        //The "intensity" of the current situation (a value between 0.0 - 1.0).
        //High when a disaster has struck, low when nothing special is going on.
        private float currentIntensity;
        //The exact intensity of the current situation, current intensity is lerped towards this value
        private float targetIntensity;

        //How low the intensity has to be for an event to be triggered. 
        //Gradually increases with time, so additional problems can still appear eventually even if
        //the sub is laying broken on the ocean floor or if the players are trying to abuse the system
        //by intentionally keeping the intensity high by causing breaches, damaging themselves or such
        private float eventThreshold = 0.2f;

        //New events can't be triggered when the cooldown is active.
        private float eventCoolDown;

        private float intensityUpdateTimer;

        private PathFinder pathFinder;
        private float totalPathLength;
        private float calculateDistanceTraveledTimer;
        private float distanceTraveled;

        private float avgCrewHealth, avgHullIntegrity, floodingAmount, fireAmount, enemyDanger;

        private float roundDuration;

        private readonly List<ScriptedEventSet> pendingEventSets = new List<ScriptedEventSet>();

        private readonly Dictionary<ScriptedEventSet, List<ScriptedEvent>> selectedEvents = new Dictionary<ScriptedEventSet, List<ScriptedEvent>>();

        private readonly List<ScriptedEvent> activeEvents = new List<ScriptedEvent>();

#if DEBUG && SERVER
        private DateTime nextIntensityLogTime;
#endif

        private EventManagerSettings settings;

        private readonly bool isClient;
        
        public float CurrentIntensity
        {
            get { return currentIntensity; }
        }

        public List<ScriptedEvent> ActiveEvents
        {
            get { return activeEvents; }
        }
        
        public EventManager()
        {
            isClient = GameMain.NetworkMember != null && GameMain.NetworkMember.IsClient;
        }

        public bool Enabled = true;

        public void StartRound(Level level)
        {
            if (isClient) { return; }

            pendingEventSets.Clear();
            selectedEvents.Clear();

            pathFinder = new PathFinder(WayPoint.WayPointList, indoorsSteering: false);
            var steeringPath = pathFinder.FindPath(ConvertUnits.ToSimUnits(Level.Loaded.StartPosition), ConvertUnits.ToSimUnits(Level.Loaded.EndPosition));
            totalPathLength = steeringPath.TotalLength;

            this.level = level;
            SelectSettings();

            var initialEventSet = SelectRandomEvents(ScriptedEventSet.List);
            if (initialEventSet != null)
            {
                pendingEventSets.Add(initialEventSet);
                CreateEvents(initialEventSet);
            }

            PreloadContent(GetFilesToPreload());

            roundDuration = 0.0f;
            intensityUpdateTimer = 0.0f;
            CalculateCurrentIntensity(0.0f);
            currentIntensity = targetIntensity;
            eventCoolDown = 0.0f;
        }

        private void SelectSettings()
        {
            if (EventManagerSettings.List.Count == 0)
            {
                throw new InvalidOperationException("Could not select EventManager settings (no settings loaded).");
            }
            if (level == null)
            {
                throw new InvalidOperationException("Could not select EventManager settings (level not set).");
            }

            var suitableSettings = EventManagerSettings.List.FindAll(s =>
                level.Difficulty >= s.MinLevelDifficulty &&
                level.Difficulty <= s.MaxLevelDifficulty);

            if (suitableSettings.Count == 0)
            {
                DebugConsole.ThrowError("No suitable event manager settings found for the selected level (difficulty " + level.Difficulty + ")");
                settings = EventManagerSettings.List[Rand.Int(EventManagerSettings.List.Count, Rand.RandSync.Server)];
            }
            else
            {
                settings = suitableSettings[Rand.Int(suitableSettings.Count, Rand.RandSync.Server)];
            }
            if (settings != null)
            {
                eventThreshold = settings.DefaultEventThreshold;
            }
        }

        public IEnumerable<ContentFile> GetFilesToPreload()
        {
            foreach (List<ScriptedEvent> eventList in selectedEvents.Values)
            {
                foreach (ScriptedEvent scriptedEvent in eventList)
                {
                    foreach (ContentFile contentFile in scriptedEvent.GetFilesToPreload())
                    {
                        yield return contentFile;
                    }
                }
            }
        }

        public void PreloadContent(IEnumerable<ContentFile> contentFiles)
        {
            var filesToPreload = new List<ContentFile>(contentFiles);
            foreach (Submarine sub in Submarine.Loaded)
            {
                if (sub.WreckAI == null) { continue; }

                if (!string.IsNullOrEmpty(sub.WreckAI.Config.DefensiveAgent))
                {
                    var prefab = CharacterPrefab.FindBySpeciesName(sub.WreckAI.Config.DefensiveAgent);
                    if (prefab != null && !filesToPreload.Any(f => f.Path == prefab.FilePath))
                    {
                        filesToPreload.Add(new ContentFile(prefab.FilePath, ContentType.Character));
                    }
                }
                foreach (Item item in Item.ItemList)
                {
                    if (item.Submarine != sub) { continue; }
                    foreach (Items.Components.ItemComponent component in item.Components)
                    {
                        if (component.statusEffectLists == null) { continue; }
                        foreach (var statusEffectList in component.statusEffectLists.Values)
                        {
                            foreach (StatusEffect statusEffect in statusEffectList)
                            {
                                foreach (var spawnInfo in statusEffect.SpawnCharacters)
                                {
                                    var prefab = CharacterPrefab.FindBySpeciesName(spawnInfo.SpeciesName);
                                    if (prefab != null && !filesToPreload.Any(f => f.Path == prefab.FilePath))
                                    {
                                        filesToPreload.Add(new ContentFile(prefab.FilePath, ContentType.Character));
                                    }
                                }
                            }
                        }
                    }
                }                
            }

            foreach (ContentFile file in filesToPreload)
            {
                switch (file.Type)
                {
                    case ContentType.Character:
#if CLIENT
                        CharacterPrefab characterPrefab = CharacterPrefab.FindByFilePath(file.Path);
                        if (characterPrefab?.XDocument == null)
                        {
                            throw new Exception($"Failed to load the character config file from {file.Path}!");
                        }
                        var doc = characterPrefab.XDocument;
                        var rootElement = doc.Root;
                        var mainElement = rootElement.IsOverride() ? rootElement.FirstElement() : rootElement;

                        foreach (var soundElement in mainElement.GetChildElements("sound"))
                        {
                            var sound = Submarine.LoadRoundSound(soundElement);
                        }
                        string speciesName = mainElement.GetAttributeString("speciesname", null);
                        if (string.IsNullOrWhiteSpace(speciesName))
                        {
                            speciesName = mainElement.GetAttributeString("name", null);
                            if (!string.IsNullOrWhiteSpace(speciesName))
                            {
                                DebugConsole.NewMessage($"Error in {file.Path}: 'name' is deprecated! Use 'speciesname' instead.", Color.Orange);
                            }
                            else
                            {
                                throw new Exception($"Species name null in {file.Path}");
                            }
                        }

                        bool humanoid = mainElement.GetAttributeBool("humanoid", false);
                        RagdollParams ragdollParams;
                        if (humanoid)
                        {
                            ragdollParams = RagdollParams.GetRagdollParams<HumanRagdollParams>(speciesName);
                        }
                        else
                        {
                            ragdollParams = RagdollParams.GetRagdollParams<FishRagdollParams>(speciesName);
                        }
                        if (ragdollParams != null)
                        {
                            HashSet<string> texturePaths = new HashSet<string>
                            {
                                ragdollParams.Texture
                            };
                            foreach (RagdollParams.LimbParams limb in ragdollParams.Limbs)
                            {
                                if (!string.IsNullOrEmpty(limb.normalSpriteParams?.Texture)) { texturePaths.Add(limb.normalSpriteParams.Texture); }
                                if (!string.IsNullOrEmpty(limb.deformSpriteParams?.Texture)) { texturePaths.Add(limb.deformSpriteParams.Texture); }
                                if (!string.IsNullOrEmpty(limb.damagedSpriteParams?.Texture)) { texturePaths.Add(limb.damagedSpriteParams.Texture); }
                                foreach (var decorativeSprite in limb.decorativeSpriteParams)
                                {
                                    if (!string.IsNullOrEmpty(decorativeSprite.Texture)) { texturePaths.Add(decorativeSprite.Texture); }
                                }
                            }
                            foreach (string texturePath in texturePaths)
                            {
                                preloadedSprites.Add(new Sprite(texturePath, Vector2.Zero));
                            }
                        }
#endif
                        break;
                }
            }
        }

        public void EndRound()
        {
            pendingEventSets.Clear();
            selectedEvents.Clear();

            preloadedSprites.ForEach(s => s.Remove());
            preloadedSprites.Clear();
        }

        private void CreateEvents(ScriptedEventSet eventSet)
        {
            int applyCount = 1;
            if (eventSet.PerRuin)
            {
                applyCount = Level.Loaded.Ruins.Count();
            }
            else if (eventSet.PerWreck)
            {
                applyCount = Submarine.Loaded.Count(s => s.Info.IsWreck && (s.WreckAI == null || !s.WreckAI.IsAlive));
            }
            for (int i = 0; i < applyCount; i++)
            {
                if (eventSet.ChooseRandom)
                {
                    if (eventSet.EventPrefabs.Count > 0)
                    {
                        MTRandom rand = new MTRandom(ToolBox.StringToInt(level.Seed));
                        var eventPrefab = ToolBox.SelectWeightedRandom(eventSet.EventPrefabs, eventSet.EventPrefabs.Select(e => e.Commonness).ToList(), rand);
                        if (eventPrefab != null)
                        {
                            var newEvent = eventPrefab.CreateInstance();
                            newEvent.Init(true);
                            DebugConsole.Log("Initialized event " + newEvent.ToString());
                            if (!selectedEvents.ContainsKey(eventSet))
                            {
                                selectedEvents.Add(eventSet, new List<ScriptedEvent>());
                            }
                            selectedEvents[eventSet].Add(newEvent);
                        }
                    }
                    if (eventSet.ChildSets.Count > 0)
                    {
                        var newEventSet = SelectRandomEvents(eventSet.ChildSets);
                        if (newEventSet != null) { CreateEvents(newEventSet); }
                    }
                }
                else
                {
                    foreach (ScriptedEventPrefab eventPrefab in eventSet.EventPrefabs)
                    {
                        var newEvent = eventPrefab.CreateInstance();
                        newEvent.Init(true);
                        DebugConsole.Log("Initialized event " + newEvent.ToString());
                        if (!selectedEvents.ContainsKey(eventSet))
                        {
                            selectedEvents.Add(eventSet, new List<ScriptedEvent>());
                        }
                        selectedEvents[eventSet].Add(newEvent);
                    }

                    foreach (ScriptedEventSet childEventSet in eventSet.ChildSets)
                    {
                        CreateEvents(childEventSet);
                    }
                }
            }
        }

        private ScriptedEventSet SelectRandomEvents(List<ScriptedEventSet> eventSets)
        {
            MTRandom rand = new MTRandom(ToolBox.StringToInt(level.Seed));

            var allowedEventSets = 
                eventSets.Where(es => level.Difficulty >= es.MinLevelDifficulty && level.Difficulty <= es.MaxLevelDifficulty);

            float totalCommonness = allowedEventSets.Sum(e => e.GetCommonness(level));
            float randomNumber = (float)rand.NextDouble() * totalCommonness;
            foreach (ScriptedEventSet eventSet in allowedEventSets)
            {
                float commonness = eventSet.GetCommonness(level);
                if (randomNumber <= commonness)
                {
                    return eventSet;
                }
                randomNumber -= commonness;
            }

            return null;
        }

        private bool CanStartEventSet(ScriptedEventSet eventSet)
        {
            ISpatialEntity refEntity = GetRefEntity();
            float distFromStart = Vector2.Distance(refEntity.WorldPosition, level.StartPosition);
            float distFromEnd = Vector2.Distance(refEntity.WorldPosition, level.EndPosition);

            //don't create new events if within 50 meters of the start/end of the level
            if (!eventSet.AllowAtStart)
            {
                if (distanceTraveled <= 0.0f ||
                    distFromStart * Physics.DisplayToRealWorldRatio < 50.0f ||
                    distFromEnd * Physics.DisplayToRealWorldRatio < 50.0f)
                {
                    return false;
                }
            }

            if ((Submarine.MainSub == null || distanceTraveled < eventSet.MinDistanceTraveled) &&
                roundDuration < eventSet.MinMissionTime)
            {
                return false;
            }

            if (CurrentIntensity < eventSet.MinIntensity || CurrentIntensity > eventSet.MaxIntensity)
            {
                return false;
            }

            return true;
        }

        
        public void Update(float deltaTime)
        {
            if (!Enabled) { return; }

            //clients only calculate the intensity but don't create any events
            //(the intensity is used for controlling the background music)
            CalculateCurrentIntensity(deltaTime);

#if DEBUG && SERVER
            if (DateTime.Now > nextIntensityLogTime)
            {
                DebugConsole.NewMessage("EventManager intensity: " + (int)Math.Round(currentIntensity * 100) + " %");
                nextIntensityLogTime = DateTime.Now + new TimeSpan(0, minutes: 1, seconds: 0);
            }
#endif

            if (isClient) { return; }

            roundDuration += deltaTime;

            if (settings == null)
            {
                DebugConsole.ThrowError("Event settings not set before updating EventManager. Attempting to select...");
                SelectSettings();
                if (settings == null)
                {
                    DebugConsole.ThrowError("Could not select EventManager settings. Disabling EventManager for the round...");
#if SERVER
                    GameMain.Server?.SendChatMessage("Could not select EventManager settings. Disabling EventManager for the round...", Networking.ChatMessageType.Error);
#endif
                    Enabled = false;
                    return;
                }
            }

            calculateDistanceTraveledTimer -= deltaTime;
            if (calculateDistanceTraveledTimer <= 0.0f)
            {
                distanceTraveled = CalculateDistanceTraveled();
                calculateDistanceTraveledTimer = CalculateDistanceTraveledInterval;
            }

            eventThreshold += settings.EventThresholdIncrease * deltaTime;
            if (eventCoolDown > 0.0f)
            {
                eventCoolDown -= deltaTime;
            }
            else if (currentIntensity < eventThreshold)
            {
                //activate pending event sets that can be activated
                for (int i = pendingEventSets.Count - 1; i >= 0; i--)
                {
                    var eventSet = pendingEventSets[i];
                    if (!CanStartEventSet(eventSet)) { continue; }

                    pendingEventSets.RemoveAt(i);

                    if (selectedEvents.ContainsKey(eventSet))
                    {
                        //start events in this set
                        foreach (ScriptedEvent scriptedEvent in selectedEvents[eventSet])
                        {
                            activeEvents.Add(scriptedEvent);
                        }
                    }

                    //add child event sets to pending
                    foreach (ScriptedEventSet childEventSet in eventSet.ChildSets)
                    {
                        if (selectedEvents.ContainsKey(childEventSet))
                        {
                            pendingEventSets.Add(childEventSet);
                        }
                    }
                }
                eventThreshold = settings.DefaultEventThreshold;
                eventCoolDown = settings.EventCooldown;
            }

            foreach (ScriptedEvent ev in activeEvents)
            {
                if (!ev.IsFinished) { ev.Update(deltaTime); }                             
            }
        }
                
        private void CalculateCurrentIntensity(float deltaTime)
        {
            intensityUpdateTimer -= deltaTime;
            if (intensityUpdateTimer > 0.0f) { return; }
            intensityUpdateTimer = IntensityUpdateInterval;

            // crew health --------------------------------------------------------

            avgCrewHealth = 0.0f;
            int characterCount = 0;
            foreach (Character character in Character.CharacterList)
            {
                if (character.IsDead || character.TeamID == Character.TeamType.FriendlyNPC) { continue; }
                if (character.AIController is HumanAIController || character.IsRemotePlayer)
                {
                    avgCrewHealth += character.Vitality / character.MaxVitality * (character.IsUnconscious ? 0.5f : 1.0f);
                    characterCount++;
                }
            }
            if (characterCount > 0)
            {
                avgCrewHealth /= characterCount;
            }
            else
            {
                avgCrewHealth = 0.5f;
            }

            // enemy amount --------------------------------------------------------

            enemyDanger = 0.0f;
            foreach (Character character in Character.CharacterList)
            {
                if (character.IsDead || character.IsIncapacitated || !character.Enabled) continue;

                EnemyAIController enemyAI = character.AIController as EnemyAIController;
                if (enemyAI == null) continue;
                
                if (character.CurrentHull?.Submarine != null && 
                    (character.CurrentHull.Submarine == Submarine.MainSub || Submarine.MainSub.DockedTo.Contains(character.CurrentHull.Submarine)))
                {
                    //crawler inside the sub adds 0.1f to enemy danger, mantis 0.25f
                    enemyDanger += enemyAI.CombatStrength / 1000.0f;
                }
                else if (enemyAI.SelectedAiTarget?.Entity?.Submarine != null)
                {
                    //enemy outside and targeting the sub or something in it
                    //moloch adds 0.24 to enemy danger, a crawler 0.02
                    enemyDanger += enemyAI.CombatStrength / 5000.0f;
                }
            }
            enemyDanger = MathHelper.Clamp(enemyDanger, 0.0f, 1.0f);

            // hull status (gaps, flooding, fire) --------------------------------------------------------

            float holeCount = 0.0f;
            floodingAmount = 0.0f;
            int hullCount = 0;
            foreach (Hull hull in Hull.hullList)
            {
                if (hull.Submarine == null || hull.Submarine.Info.Type != SubmarineInfo.SubmarineType.Player) { continue; }
                hullCount++;
                foreach (Gap gap in hull.ConnectedGaps)
                {
                    if (!gap.IsRoomToRoom) holeCount += gap.Open;
                }
                floodingAmount += hull.WaterVolume / hull.Volume;
                fireAmount += hull.FireSources.Sum(fs => fs.Size.X);
            }
            if (hullCount > 0)
            {
                floodingAmount = floodingAmount / hullCount;
            }

            //hull integrity at 0.0 if there are 10 or more wide-open holes
            avgHullIntegrity = MathHelper.Clamp(1.0f - holeCount / 10.0f, 0.0f, 1.0f);
            
            //a fire of any size bumps up the fire amount to 20%
            //if the total width of the fires is 1000 or more, the fire amount is considered to be at 100%
            fireAmount = MathHelper.Clamp(fireAmount / 1000.0f, fireAmount > 0.0f ? 0.2f : 0.0f, 1.0f);

            //flooding less than 10% of the sub is ignored 
            //to prevent ballast tanks from affecting the intensity
            if (floodingAmount < 0.1f) floodingAmount = 0.0f;

            // calculate final intensity --------------------------------------------------------

            targetIntensity = 
                ((1.0f - avgCrewHealth) + (1.0f - avgHullIntegrity) + floodingAmount) / 3.0f;
            targetIntensity += fireAmount * 0.5f;
            targetIntensity += enemyDanger;
            targetIntensity = MathHelper.Clamp(targetIntensity, 0.0f, 1.0f);

            if (targetIntensity > currentIntensity)
            {
                //50 seconds for intensity to go from 0.0 to 1.0
                currentIntensity = MathHelper.Min(currentIntensity + 0.02f * IntensityUpdateInterval, targetIntensity);
            }
            else
            {
                //400 seconds for intensity to go from 1.0 to 0.0
                currentIntensity = MathHelper.Max(0.0025f * IntensityUpdateInterval, targetIntensity);
            }
        }

        private float CalculateDistanceTraveled()
        {
            var refEntity = GetRefEntity();
            Vector2 target = ConvertUnits.ToSimUnits(Level.Loaded.EndPosition);
            var steeringPath = pathFinder.FindPath(ConvertUnits.ToSimUnits(refEntity.WorldPosition), target);
            if (steeringPath.Unreachable || float.IsPositiveInfinity(totalPathLength))
            {
                //use horizontal position in the level as a fallback if a path can't be found
                return MathHelper.Clamp((refEntity.WorldPosition.X - level.StartPosition.X) / (level.EndPosition.X - level.StartPosition.X), 0.0f, 1.0f);
            }
            else
            {
                return MathHelper.Clamp(1.0f - steeringPath.TotalLength / totalPathLength, 0.0f, 1.0f);
            }
        }


        /// <summary>
        /// Get the entity that should be used in determining how far the player has progressed in the level.
        /// = The submarine or player character that has progressed the furthest. 
        /// </summary>
        private ISpatialEntity GetRefEntity()
        {
            ISpatialEntity refEntity = Submarine.MainSub;
#if CLIENT
            if (Character.Controlled != null)
            {
                if (Character.Controlled.Submarine != null && 
                    Character.Controlled.Submarine.Info.Type == SubmarineInfo.SubmarineType.Player)
                {
                    refEntity = Character.Controlled.Submarine;
                }
                else
                {
                    refEntity = Character.Controlled;
                }
            }
#else
            foreach (Barotrauma.Networking.Client client in GameMain.Server.ConnectedClients)
            {
                if (client.Character == null) { continue; }
                //only take the players inside a player sub into account. 
                //Otherwise the system could be abused by for example making a respawned player wait
                //close to the destination outpost
                if (client.Character.Submarine != null && 
                    client.Character.Submarine.Info.Type == SubmarineInfo.SubmarineType.Player)
                {
                    if (client.Character.Submarine.WorldPosition.X > refEntity.WorldPosition.X)
                    {
                        refEntity = client.Character.Submarine;
                    }
                }
            }
#endif
            return refEntity;
        }
    }
}