using System;
using System.Collections.Generic;
using System.Collections.Immutable;
using System.Linq;
using System.Xml.Linq;
using Barotrauma.Extensions;
using Microsoft.Xna.Framework;

namespace Barotrauma
{
#if CLIENT
    class EventSprite : Prefab
    {
        public readonly static PrefabCollection<EventSprite> Prefabs = new PrefabCollection<EventSprite>();

        public readonly Sprite Sprite;

        public EventSprite(ContentXElement element, RandomEventsFile file) : base(file, element.GetAttributeIdentifier("identifier", Identifier.Empty))
        {
            Sprite = new Sprite(element);
        }

        public override void Dispose() { Sprite?.Remove(); }
    }
#endif

    sealed class EventSet : Prefab
    {
        internal class EventDebugStats
        {
            public readonly EventSet RootSet;
            public readonly Dictionary<Identifier, int> MonsterCounts = new Dictionary<Identifier, int>();
            public float MonsterStrength;

            public EventDebugStats(EventSet rootSet)
            {
                RootSet = rootSet;
            }
        }

        public readonly static PrefabCollection<EventSet> Prefabs = new PrefabCollection<EventSet>();
#if CLIENT
        public static Sprite GetEventSprite(string identifier)
        {
            if (string.IsNullOrWhiteSpace(identifier)) { return null; }

            if (EventSprite.Prefabs.TryGet(identifier.ToIdentifier(), out EventSprite sprite))
            {
                return sprite.Sprite;
            }

#if DEBUG || UNSTABLE
            DebugConsole.ThrowError($"Could not find the event sprite \"{identifier}\"");
#else
            DebugConsole.AddWarning($"Could not find the event sprite \"{identifier}\"");
#endif
            return null;
        }
#endif

        public static List<EventPrefab> GetAllEventPrefabs()
        {
            List<EventPrefab> eventPrefabs = EventPrefab.Prefabs.ToList();
            foreach (var eventSet in Prefabs)
            {
                AddSetEventPrefabsToList(eventPrefabs, eventSet);
            }
            return eventPrefabs;
        }

        public static void AddSetEventPrefabsToList(List<EventPrefab> list, EventSet set)
        {
            list.AddRange(set.EventPrefabs.SelectMany(ep => ep.EventPrefabs));
            foreach (var childSet in set.ChildSets) { AddSetEventPrefabsToList(list, childSet); }
        }

        public static EventPrefab GetEventPrefab(Identifier identifier)
        {
            return GetAllEventPrefabs().Find(prefab => prefab.Identifier == identifier);
        }

        public readonly bool IsCampaignSet;

        //0-100
        public readonly float MinLevelDifficulty, MaxLevelDifficulty;

        public readonly Identifier BiomeIdentifier;

        public readonly LevelData.LevelType LevelType;

        public readonly ImmutableArray<Identifier> LocationTypeIdentifiers;
        
        public readonly bool ChooseRandom;

        private readonly int eventCount = 1;
        private readonly Dictionary<Identifier, int> overrideEventCount = new Dictionary<Identifier, int>();

        /// <summary>
        /// 'Exhaustible' sets won't appear in the same level until after one world step (~10 min, see Map.ProgressWorld) has passed.
        /// </summary>
        public readonly bool Exhaustible;

        public readonly float MinDistanceTraveled;
        public readonly float MinMissionTime;

        //the events in this set are delayed if the current EventManager intensity is not between these values
        public readonly float MinIntensity, MaxIntensity;

        public readonly bool AllowAtStart;

        public readonly bool IgnoreCoolDown;

        public readonly bool PerRuin, PerCave, PerWreck;
        public readonly bool DisableInHuntingGrounds;

        /// <summary>
        /// If true, events from this set can only occur once in the level.
        /// </summary>
        public readonly bool OncePerLevel;

        public readonly bool DelayWhenCrewAway;

        public readonly bool TriggerEventCooldown;

        public readonly bool Additive;
            
        public readonly float DefaultCommonness;
        public readonly ImmutableDictionary<Identifier, float> OverrideCommonness;

        public readonly float ResetTime;

        /// <summary>
        /// Used to force an event set based on how many other locations have been discovered before this. (Used for campaign tutorial event sets.)
        /// </summary>
        public readonly int ForceAtDiscoveredNr;

        /// <summary>
        /// Used to force an event set based on how many other outposts have been visited before this. (Used for campaign tutorial event sets.)
        /// </summary>
        public readonly int ForceAtVisitedNr;

        public readonly bool CampaignTutorialOnly;

        public readonly struct SubEventPrefab
        {
            public SubEventPrefab(Either<Identifier[], EventPrefab> prefabOrIdentifiers, float? commonness, float? probability)
            {
                PrefabOrIdentifier = prefabOrIdentifiers;
                SelfCommonness = commonness;
                SelfProbability = probability;
            }

            public readonly Either<Identifier[], EventPrefab> PrefabOrIdentifier;
            public IEnumerable<EventPrefab> EventPrefabs
            {
                get
                {
                    if (PrefabOrIdentifier.TryGet(out EventPrefab p))
                    {
                        yield return p;
                    }
                    else
                    {
                        foreach (var id in (Identifier[])PrefabOrIdentifier)
                        {
                            if (EventPrefab.Prefabs.TryGet(id, out EventPrefab prefab))
                            {
                                yield return prefab;
                            }
                        }
                    }
                }
            }

            public readonly float? SelfCommonness;
            public float Commonness => SelfCommonness ?? EventPrefabs.MaxOrNull(p => p.Commonness) ?? 0.0f;

            public readonly float? SelfProbability;
            public float Probability => SelfProbability ?? EventPrefabs.MaxOrNull(p => p.Probability) ?? 0.0f;

            public void Deconstruct(out IEnumerable<EventPrefab> eventPrefabs, out float commonness, out float probability)
            {
                eventPrefabs = EventPrefabs;
                commonness = Commonness;
                probability = Probability;
            }

            public IEnumerable<Identifier> GetMissingIdentifiers()
            {
                if (PrefabOrIdentifier.TryCast<Identifier[]>(out var ids))
                {
                    foreach (var id in ids)
                    {
                        if (!EventPrefab.Prefabs.ContainsKey(id))
                        {
                            yield return id;
                        }
                    }
                }
            }        
        }
        public readonly ImmutableArray<SubEventPrefab> EventPrefabs;

        public readonly ImmutableArray<EventSet> ChildSets;

        private static Identifier DetermineIdentifier(EventSet parent, XElement element, RandomEventsFile file)
        {
            Identifier retVal = element.GetAttributeIdentifier("identifier", Identifier.Empty);

            if (retVal.IsEmpty)
            {
                if (parent is null)
                {
                    if (file.ContentPackage is CorePackage)
                    {
                        throw new Exception($"Error in {file.Path}: All root EventSets in a core package must have identifiers");
                    }
                    else
                    {
                        DebugConsole.AddWarning($"{file.Path}: All root EventSets should have an identifier");
                    }
                }

                XElement currElement = element;
                string siblingIndices = "";
                while (currElement.Parent != null)
                {
                    int siblingIndex = currElement.ElementsBeforeSelf().Count();
                    siblingIndices = $"-{siblingIndex}{siblingIndices}";
                    if (parent != null) { break; }
                    currElement = currElement.Parent;
                }

                retVal =
                    ((parent != null
                        ? parent.Identifier.Value
                        : $"{file.ContentPackage.Name}-{file.Path}")
                    + siblingIndices)
                        .ToIdentifier();
            }
            return retVal;
        }

        public EventSet(ContentXElement element, RandomEventsFile file, EventSet parentSet = null)
            : base(file, DetermineIdentifier(parentSet, element, file))
        {
            var eventPrefabs = new List<SubEventPrefab>();
            var childSets = new List<EventSet>();
            var overrideCommonness = new Dictionary<Identifier, float>();

            BiomeIdentifier = element.GetAttributeIdentifier("biome", Barotrauma.Identifier.Empty);
            MinLevelDifficulty = element.GetAttributeFloat("minleveldifficulty", 0);
            MaxLevelDifficulty = Math.Max(element.GetAttributeFloat("maxleveldifficulty", 100), MinLevelDifficulty);

            Additive = element.GetAttributeBool("additive", false);

            string levelTypeStr = element.GetAttributeString("leveltype", parentSet?.LevelType.ToString() ?? "LocationConnection");
            if (!Enum.TryParse(levelTypeStr, true, out LevelType))
            {
                DebugConsole.ThrowError($"Error in event set \"{Identifier}\". \"{levelTypeStr}\" is not a valid level type.");
            }

            Identifier[] locationTypeStr = element.GetAttributeIdentifierArray("locationtype", null);
            if (locationTypeStr != null)
            {
                LocationTypeIdentifiers = locationTypeStr.ToImmutableArray();
                //if (LocationType.List.Any()) { CheckLocationTypeErrors(); } //TODO: perform validation elsewhere
            }

            MinIntensity = element.GetAttributeFloat("minintensity", 0.0f);
            MaxIntensity = Math.Max(element.GetAttributeFloat("maxintensity", 100.0f), MinIntensity);

            ChooseRandom = element.GetAttributeBool("chooserandom", false);
            eventCount = element.GetAttributeInt("eventcount", 1);
            Exhaustible = element.GetAttributeBool("exhaustible", false);
            MinDistanceTraveled = element.GetAttributeFloat("mindistancetraveled", 0.0f);
            MinMissionTime = element.GetAttributeFloat("minmissiontime", 0.0f);

            AllowAtStart = element.GetAttributeBool("allowatstart", false);
            PerRuin = element.GetAttributeBool("perruin", false);
            PerCave = element.GetAttributeBool("percave", false);
            PerWreck = element.GetAttributeBool("perwreck", false);
            DisableInHuntingGrounds = element.GetAttributeBool("disableinhuntinggrounds", false);
            IgnoreCoolDown = element.GetAttributeBool("ignorecooldown", parentSet?.IgnoreCoolDown ?? (PerRuin || PerCave || PerWreck));
            DelayWhenCrewAway = element.GetAttributeBool("delaywhencrewaway", !PerRuin && !PerCave && !PerWreck);
            OncePerLevel = element.GetAttributeBool("onceperlevel", element.GetAttributeBool("onceperoutpost", false));
            TriggerEventCooldown = element.GetAttributeBool("triggereventcooldown", true);
            IsCampaignSet = element.GetAttributeBool("campaign", LevelType == LevelData.LevelType.Outpost || (parentSet?.IsCampaignSet ?? false));
            ResetTime = element.GetAttributeFloat("resettime", 0);
            CampaignTutorialOnly = element.GetAttributeBool(nameof(CampaignTutorialOnly), false);

            ForceAtDiscoveredNr = element.GetAttributeInt(nameof(ForceAtDiscoveredNr), -1);
            ForceAtVisitedNr = element.GetAttributeInt(nameof(ForceAtVisitedNr), -1);
            if (ForceAtDiscoveredNr >= 0 && ForceAtVisitedNr >= 0)
            {
                DebugConsole.ThrowError($"Error with event set \"{Identifier}\" - both ForceAtDiscoveredNr and ForceAtVisitedNr are defined, this could lead to unexpected behavior");
            }

            DefaultCommonness = element.GetAttributeFloat("commonness", 1.0f);
            foreach (var subElement in element.Elements())
            {
                switch (subElement.Name.ToString().ToLowerInvariant())
                {
                    case "commonness":
                        DefaultCommonness = subElement.GetAttributeFloat("commonness", DefaultCommonness);
                        foreach (XElement overrideElement in subElement.Elements())
                        {
                            if (overrideElement.NameAsIdentifier() == "override")
                            {
                                Identifier levelType = overrideElement.GetAttributeIdentifier("leveltype", "");
                                if (!overrideCommonness.ContainsKey(levelType))
                                {
                                    overrideCommonness.Add(levelType, overrideElement.GetAttributeFloat("commonness", 0.0f));
                                }
                            }
                        }
                        break;
                    case "eventset":
                        childSets.Add(new EventSet(subElement, file, this));
                        break;
                    case "overrideeventcount":
                        Identifier locationType = subElement.GetAttributeIdentifier("locationtype", "");
                        if (!overrideEventCount.ContainsKey(locationType))
                        {
                            overrideEventCount.Add(locationType, subElement.GetAttributeInt("eventcount", eventCount));
                        }
                        break;
                    default:
                        //an element with just an identifier = reference to an event prefab
                        if (!subElement.HasElements && subElement.Attributes().First().Name.ToString().Equals("identifier", StringComparison.OrdinalIgnoreCase))
                        {
                            Identifier[] identifiers = subElement.GetAttributeIdentifierArray("identifier", Array.Empty<Identifier>());
                            float commonness = subElement.GetAttributeFloat("commonness", -1f);
                            float probability = subElement.GetAttributeFloat("probability", -1f);
                            eventPrefabs.Add(new SubEventPrefab(
                                identifiers,
                                commonness >= 0f ? commonness : (float?)null,
                                probability >= 0f ? probability : (float?)null));
                        }
                        else
                        {
                            var prefab = new EventPrefab(subElement, file, $"{Identifier}-{subElement.ElementsBeforeSelf().Count()}".ToIdentifier());
                            eventPrefabs.Add(new SubEventPrefab(prefab, prefab.Commonness, prefab.Probability));
                        }
                        break;
                }
            }

            EventPrefabs = eventPrefabs.ToImmutableArray();
            ChildSets = childSets.ToImmutableArray();
            OverrideCommonness = overrideCommonness.ToImmutableDictionary();
        }

        public void CheckLocationTypeErrors()
        {
            if (LocationTypeIdentifiers == null) { return; }
            foreach (Identifier locationTypeId in LocationTypeIdentifiers)
            {
                if (!LocationType.Prefabs.ContainsKey(locationTypeId))
                {
                    DebugConsole.ThrowError($"Error in event set \"{Identifier}\". Location type \"{locationTypeId}\" not found.");
                }
            }
        }

        public float GetCommonness(Level level)
        {
            Identifier key = level.GenerationParams?.Identifier ?? Identifier.Empty;
            return OverrideCommonness.ContainsKey(key) ? OverrideCommonness[key] : DefaultCommonness;
        }

        public int GetEventCount(Level level)
        {
            if (level?.StartLocation == null || !overrideEventCount.TryGetValue(level.StartLocation.Type.Identifier, out int count)) { return eventCount; }
            return count;
        }

        public static List<string> GetDebugStatistics(int simulatedRoundCount = 100, Func<MonsterEvent, bool> filter = null, bool fullLog = false)
        {
            List<string> debugLines = new List<string>();

            foreach (var eventSet in Prefabs)
            {
                List<EventDebugStats> stats = new List<EventDebugStats>();
                for (int i = 0; i < simulatedRoundCount; i++)
                {
                    var newStats = new EventDebugStats(eventSet);
                    CheckEventSet(newStats, eventSet, filter);
                    stats.Add(newStats);
                }
                debugLines.Add($"Event stats ({eventSet.Identifier}): ");
                LogEventStats(stats, debugLines, fullLog);
            }

            return debugLines;

            static void CheckEventSet(EventDebugStats stats, EventSet thisSet, Func<MonsterEvent, bool> filter = null)
            {
                if (thisSet.ChooseRandom)
                {
                    var unusedEvents = thisSet.EventPrefabs.ToList();
                    if (unusedEvents.Any())
                    {
                        for (int i = 0; i < thisSet.eventCount; i++)
                        {
                            var eventPrefab = ToolBox.SelectWeightedRandom(unusedEvents, unusedEvents.Select(e => e.Commonness).ToList(), Rand.RandSync.Unsynced);
                            if (eventPrefab.EventPrefabs.Any(p => p != null))
                            {
                                AddEvents(stats, eventPrefab.EventPrefabs, filter);
                                unusedEvents.Remove(eventPrefab);
                            }
                        }
                    }
                    List<float> values = thisSet.ChildSets
                        .SelectMany(s => s.DefaultCommonness.ToEnumerable().Concat(s.OverrideCommonness.Values))
                        .ToList();
                    EventSet childSet = ToolBox.SelectWeightedRandom(thisSet.ChildSets, values, Rand.RandSync.Unsynced);
                    if (childSet != null)
                    {
                        CheckEventSet(stats, childSet, filter);
                    }
                }
                else
                {
                    foreach (var eventPrefab in thisSet.EventPrefabs)
                    {
                        AddEvents(stats, eventPrefab.EventPrefabs, filter);
                    }
                    foreach (var childSet in thisSet.ChildSets)
                    {
                        CheckEventSet(stats, childSet, filter);
                    }
                }
            }

            static void AddEvents(EventDebugStats stats, IEnumerable<EventPrefab> eventPrefabs, Func<MonsterEvent, bool> filter = null)
                => eventPrefabs.ForEach(p => AddEvent(stats, p, filter));
            
            static void AddEvent(EventDebugStats stats, EventPrefab eventPrefab, Func<MonsterEvent, bool> filter = null)
            {
                if (eventPrefab.EventType == typeof(MonsterEvent) && eventPrefab.TryCreateInstance(out MonsterEvent monsterEvent))
                {
                    if (filter != null && !filter(monsterEvent)) { return; }
                    float spawnProbability = monsterEvent.Prefab.Probability;
                    if (Rand.Value() > spawnProbability) { return; }
                    int count = Rand.Range(monsterEvent.MinAmount, monsterEvent.MaxAmount + 1);
                    if (count <= 0) { return; }
                    Identifier character = monsterEvent.SpeciesName;
                    if (stats.MonsterCounts.TryGetValue(character, out int currentCount))
                    {
                        if (currentCount >= monsterEvent.MaxAmountPerLevel) { return; }
                    }
                    else
                    {
                        stats.MonsterCounts[character] = 0;
                    }
                    stats.MonsterCounts[character] += count;
                    
                    var aiElement = CharacterPrefab.FindBySpeciesName(character)?.ConfigElement?.GetChildElement("ai");
                    if (aiElement != null)
                    {
                        stats.MonsterStrength += aiElement.GetAttributeFloat("combatstrength", 0) * count;
                    }
                }
            }

            static void LogEventStats(List<EventDebugStats> stats, List<string> debugLines, bool fullLog)
            {
                if (stats.Count == 0 || stats.All(s => s.MonsterCounts.Values.Sum() == 0))
                {
                    debugLines.Add("  No monster spawns");
                    debugLines.Add($" ");
                }
                else
                {
                    var allMonsters = new Dictionary<Identifier, int>();
                    foreach (var stat in stats)
                    {
                        foreach (var monster in stat.MonsterCounts)
                        {
                            if (!allMonsters.TryAdd(monster.Key, monster.Value))
                            {
                                allMonsters[monster.Key] += monster.Value;
                            }
                        }
                    }
                    allMonsters = allMonsters.OrderBy(m => m.Key).ToDictionary(m => m.Key, m => m.Value);
                    stats.Sort((s1, s2) => s1.MonsterCounts.Values.Sum().CompareTo(s2.MonsterCounts.Values.Sum()));
                    debugLines.Add($"  Average monster count: {StringFormatter.FormatZeroDecimal((float)stats.Average(s => s.MonsterCounts.Values.Sum()))} (Min: {stats.First().MonsterCounts.Values.Sum()}, Max: {stats.Last().MonsterCounts.Values.Sum()})");
                    debugLines.Add($"     {LogMonsterCounts(allMonsters, divider: stats.Count)}");
                    if (fullLog)
                    {
                        debugLines.Add($"  All samples:");
                        stats.ForEach(s => debugLines.Add($"     {LogMonsterCounts(s.MonsterCounts)}"));
                    }
                    stats.Sort((s1, s2) => s1.MonsterStrength.CompareTo(s2.MonsterStrength));
                    debugLines.Add($"  Average monster strength: {StringFormatter.FormatZeroDecimal(stats.Average(s => s.MonsterStrength))} (Min: {StringFormatter.FormatZeroDecimal(stats.First().MonsterStrength)}, Max: {StringFormatter.FormatZeroDecimal(stats.Last().MonsterStrength)})");
                    debugLines.Add($" ");
                }
            }

            static string LogMonsterCounts(Dictionary<Identifier, int> stats, float divider = 0)
            {
                if (divider > 0)
                {
                    return string.Join("\n     ", stats.Select(mc => mc.Key + " x " + (mc.Value / divider).FormatSingleDecimal()));
                }
                else
                {
                    return string.Join(", ", stats.Select(mc => mc.Key + " x " + mc.Value));
                }      
            }
        }

        public override string ToString()
        {
            return $"{base.ToString()} ({Identifier.Value})";
        }

        public override void Dispose() { }
    }
}