using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Diagnostics.CodeAnalysis;
using System.Linq;
using System.Reflection;

using static PKHeX.Core.MessageStrings;
using static PKHeX.Core.BatchModifications;

namespace PKHeX.Core;

/// <summary>
/// Logic for editing many <see cref="PKM"/> with user provided <see cref="StringInstruction"/> list.
/// </summary>
public static class BatchEditing
{
    public static readonly Type[] Types =
    {
        typeof (PK8), typeof (PA8), typeof (PB8),
        typeof (PB7),
        typeof (PK7), typeof (PK6), typeof (PK5), typeof (PK4), typeof(BK4),
        typeof (PK3), typeof (XK3), typeof (CK3),
        typeof (PK2), typeof (SK2), typeof (PK1),
    };

    /// <summary>
    /// Extra properties to show in the list of selectable properties (GUI)
    /// </summary>
    public static readonly List<string> CustomProperties = new()
    {
        PROP_LEGAL, PROP_TYPENAME, PROP_RIBBONS, PROP_CONTESTSTATS, PROP_MOVEMASTERY,
        IdentifierContains, nameof(ISlotInfo.Slot), nameof(SlotInfoBox.Box),
    };

    /// <summary>
    /// Property names, indexed by <see cref="Types"/>.
    /// </summary>
    public static string[][] Properties => GetProperties.Value;

    private static readonly Lazy<string[][]> GetProperties = new(() => GetPropArray(Types, CustomProperties));

    private static readonly Dictionary<string, PropertyInfo>[] Props = GetPropertyDictionaries(Types);

    private static Dictionary<string, PropertyInfo>[] GetPropertyDictionaries(IReadOnlyList<Type> types)
    {
        var result = new Dictionary<string, PropertyInfo>[types.Count];
        for (int i = 0; i < types.Count; i++)
            result[i] = GetPropertyDictionary(types[i], ReflectUtil.GetAllPropertyInfoPublic);
        return result;
    }

    private static Dictionary<string, PropertyInfo> GetPropertyDictionary(Type type, Func<Type, IEnumerable<PropertyInfo>> selector)
    {
        var dict = new Dictionary<string, PropertyInfo>();
        var props = selector(type);
        foreach (var p in props)
        {
            if (!dict.ContainsKey(p.Name))
                dict.Add(p.Name, p);
        }
        return dict;
    }

    internal const string CONST_RAND = "$rand";
    internal const string CONST_SHINY = "$shiny";
    internal const string CONST_SUGGEST = "$suggest";
    private const string CONST_BYTES = "$[]";
    private const char CONST_POINTER = '*';
    internal const char CONST_SPECIAL = '$';

    internal const string PROP_LEGAL = "Legal";
    internal const string PROP_TYPENAME = "ObjectType";
    internal const string PROP_RIBBONS = "Ribbons";
    internal const string PROP_EVS = "EVs";
    internal const string PROP_CONTESTSTATS = "ContestStats";
    internal const string PROP_MOVEMASTERY = "MoveMastery";
    internal const string IdentifierContains = nameof(IdentifierContains);

    private static string[][] GetPropArray(IReadOnlyList<Type> types, IReadOnlyList<string> extra)
    {
        var result = new string[types.Count + 2][];
        var p = result.AsSpan(1, types.Count);

        for (int i = 0; i < p.Length; i++)
        {
            var props = ReflectUtil.GetPropertiesPublic(types[i]);
            p[i] = props.Concat(extra).OrderBy(a => a).ToArray();
        }

        // Properties for any PKM
        // Properties shared by all PKM
        var first = p[0];
        var any = new HashSet<string>(first);
        var all = new HashSet<string>(first);
        for (int i = 1; i < p.Length; i++)
        {
            any.UnionWith(p[i]);
            all.IntersectWith(p[i]);
        }

        result[0] = any.OrderBy(z => z).ToArray();
        result[^1] = all.OrderBy(z => z).ToArray();
        return result;
    }

    /// <summary>
    /// Tries to fetch the <see cref="PKM"/> property from the cache of available properties.
    /// </summary>
    /// <param name="pk">Pokémon to check</param>
    /// <param name="name">Property Name to check</param>
    /// <param name="pi">Property Info retrieved (if any).</param>
    /// <returns>True if has property, false if does not.</returns>
    public static bool TryGetHasProperty(PKM pk, string name, [NotNullWhen(true)] out PropertyInfo? pi)
    {
        var type = pk.GetType();
        return TryGetHasProperty(type, name, out pi);
    }

    /// <summary>
    /// Tries to fetch the <see cref="PKM"/> property from the cache of available properties.
    /// </summary>
    /// <param name="type">Type to check</param>
    /// <param name="name">Property Name to check</param>
    /// <param name="pi">Property Info retrieved (if any).</param>
    /// <returns>True if has property, false if does not.</returns>
    public static bool TryGetHasProperty(Type type, string name, [NotNullWhen(true)] out PropertyInfo? pi)
    {
        var index = Array.IndexOf(Types, type);
        if (index < 0)
        {
            pi = null;
            return false;
        }
        var props = Props[index];
        return props.TryGetValue(name, out pi);
    }

    /// <summary>
    /// Gets a list of <see cref="PKM"/> types that implement the requested <see cref="property"/>.
    /// </summary>
    public static IEnumerable<string> GetTypesImplementing(string property)
    {
        for (int i = 0; i < Types.Length; i++)
        {
            var type = Types[i];
            var props = Props[i];
            if (!props.TryGetValue(property, out var pi))
                continue;
            yield return $"{type.Name}: {pi.PropertyType.Name}";
        }
    }

    /// <summary>
    /// Gets the type of the <see cref="PKM"/> property using the saved cache of properties.
    /// </summary>
    /// <param name="propertyName">Property Name to fetch the type for</param>
    /// <param name="typeIndex">Type index (within <see cref="Types"/>. Leave empty (0) for a nonspecific format.</param>
    /// <returns>Short name of the property's type.</returns>
    public static string? GetPropertyType(string propertyName, int typeIndex = 0)
    {
        if (CustomProperties.Contains(propertyName))
            return "Custom";

        if (typeIndex == 0) // Any
        {
            foreach (var p in Props)
            {
                if (p.TryGetValue(propertyName, out var pi))
                    return pi.PropertyType.Name;
            }
            return null;
        }

        int index = typeIndex - 1 >= Props.Length ? 0 : typeIndex - 1; // All vs Specific
        var pr = Props[index];
        if (!pr.TryGetValue(propertyName, out var info))
            return null;
        return info.PropertyType.Name;
    }

    /// <summary>
    /// Initializes the <see cref="StringInstruction"/> list with a context-sensitive value. If the provided value is a string, it will attempt to convert that string to its corresponding index.
    /// </summary>
    /// <param name="il">Instructions to initialize.</param>
    public static void ScreenStrings(IEnumerable<StringInstruction> il)
    {
        foreach (var i in il.Where(i => !i.PropertyValue.All(char.IsDigit)))
        {
            string pv = i.PropertyValue;
            if (pv.StartsWith(CONST_SPECIAL) && !pv.StartsWith(CONST_BYTES, StringComparison.Ordinal) && pv.Contains(','))
                i.SetRandRange(pv);

            SetInstructionScreenedValue(i);
        }
    }

    /// <summary>
    /// Initializes the <see cref="StringInstruction"/> with a context-sensitive value. If the provided value is a string, it will attempt to convert that string to its corresponding index.
    /// </summary>
    /// <param name="i">Instruction to initialize.</param>
    private static void SetInstructionScreenedValue(StringInstruction i)
    {
        switch (i.PropertyName)
        {
            case nameof(PKM.Species): i.SetScreenedValue(GameInfo.Strings.specieslist); return;
            case nameof(PKM.HeldItem): i.SetScreenedValue(GameInfo.Strings.itemlist); return;
            case nameof(PKM.Ability): i.SetScreenedValue(GameInfo.Strings.abilitylist); return;
            case nameof(PKM.Nature): i.SetScreenedValue(GameInfo.Strings.natures); return;
            case nameof(PKM.Ball): i.SetScreenedValue(GameInfo.Strings.balllist); return;

            case nameof(PKM.Move1) or nameof(PKM.Move2) or nameof(PKM.Move3) or nameof(PKM.Move4):
            case nameof(PKM.RelearnMove1) or nameof(PKM.RelearnMove2) or nameof(PKM.RelearnMove3) or nameof(PKM.RelearnMove4):
                i.SetScreenedValue(GameInfo.Strings.movelist); return;
        }
    }

    /// <summary>
    /// Checks if the object is filtered by the provided <see cref="filters"/>.
    /// </summary>
    /// <param name="filters">Filters which must be satisfied.</param>
    /// <param name="pk">Object to check.</param>
    /// <returns>True if <see cref="pk"/> matches all filters.</returns>
    public static bool IsFilterMatch(IEnumerable<StringInstruction> filters, PKM pk) => filters.All(z => IsFilterMatch(z, pk, Props[Array.IndexOf(Types, pk.GetType())]));

    /// <summary>
    /// Checks if the object is filtered by the provided <see cref="filters"/>.
    /// </summary>
    /// <param name="filters">Filters which must be satisfied.</param>
    /// <param name="pk">Object to check.</param>
    /// <returns>True if <see cref="pk"/> matches all filters.</returns>
    public static bool IsFilterMatchMeta(IEnumerable<StringInstruction> filters, SlotCache pk)
    {
        foreach (var i in filters)
        {
            foreach (var filter in BatchFilters.FilterMeta)
            {
                if (!filter.IsMatch(i.PropertyName))
                    continue;

                if (!filter.IsFiltered(pk, i))
                    return false;

                break;
            }
        }
        return true;
    }

    /// <summary>
    /// Checks if the object is filtered by the provided <see cref="filters"/>.
    /// </summary>
    /// <param name="filters">Filters which must be satisfied.</param>
    /// <param name="obj">Object to check.</param>
    /// <returns>True if <see cref="obj"/> matches all filters.</returns>
    public static bool IsFilterMatch(IEnumerable<StringInstruction> filters, object obj)
    {
        foreach (var cmd in filters)
        {
            if (cmd.PropertyName is PROP_TYPENAME)
            {
                if ((obj.GetType().Name == cmd.PropertyValue) != cmd.Evaluator)
                    return false;
                continue;
            }

            if (!ReflectUtil.HasProperty(obj, cmd.PropertyName, out var pi))
                return false;
            try
            {
                if (pi.IsValueEqual(obj, cmd.PropertyValue) == cmd.Evaluator)
                    continue;
            }
            // User provided inputs can mismatch the type's required value format, and fail to be compared.
            catch (Exception e)
            {
                Debug.WriteLine($"Unable to compare {cmd.PropertyName} to {cmd.PropertyValue}.");
                Debug.WriteLine(e.Message);
            }
            return false;
        }
        return true;
    }

    /// <summary>
    /// Tries to modify the <see cref="PKM"/>.
    /// </summary>
    /// <param name="pk">Object to modify.</param>
    /// <param name="filters">Filters which must be satisfied prior to any modifications being made.</param>
    /// <param name="modifications">Modifications to perform on the <see cref="pk"/>.</param>
    /// <returns>Result of the attempted modification.</returns>
    public static bool TryModify(PKM pk, IEnumerable<StringInstruction> filters, IEnumerable<StringInstruction> modifications)
    {
        var result = TryModifyPKM(pk, filters, modifications);
        return result == ModifyResult.Modified;
    }

    /// <summary>
    /// Tries to modify the <see cref="BatchInfo"/>.
    /// </summary>
    /// <param name="pk">Command Filter</param>
    /// <param name="filters">Filters which must be satisfied prior to any modifications being made.</param>
    /// <param name="modifications">Modifications to perform on the <see cref="pk"/>.</param>
    /// <returns>Result of the attempted modification.</returns>
    internal static ModifyResult TryModifyPKM(PKM pk, IEnumerable<StringInstruction> filters, IEnumerable<StringInstruction> modifications)
    {
        if (!pk.ChecksumValid || pk.Species == 0)
            return ModifyResult.Invalid;

        var info = new BatchInfo(pk);
        var pi = Props[Array.IndexOf(Types, pk.GetType())];
        foreach (var cmd in filters)
        {
            try
            {
                if (!IsFilterMatch(cmd, info, pi))
                    return ModifyResult.Filtered;
            }
            // Swallow any error because this can be malformed user input.
            catch (Exception ex)
            {
                Debug.WriteLine(MsgBEModifyFailCompare + " " + ex.Message, cmd.PropertyName, cmd.PropertyValue);
                return ModifyResult.Error;
            }
        }

        ModifyResult result = ModifyResult.Modified;
        foreach (var cmd in modifications)
        {
            try
            {
                var tmp = SetPKMProperty(cmd, info, pi);
                if (tmp != ModifyResult.Modified)
                    result = tmp;
            }
            // Swallow any error because this can be malformed user input.
            catch (Exception ex)
            {
                Debug.WriteLine(MsgBEModifyFail + " " + ex.Message, cmd.PropertyName, cmd.PropertyValue);
            }
        }
        return result;
    }

    /// <summary>
    /// Sets the if the <see cref="BatchInfo"/> should be filtered due to the <see cref="StringInstruction"/> provided.
    /// </summary>
    /// <param name="cmd">Command Filter</param>
    /// <param name="info">Pokémon to check.</param>
    /// <param name="props">PropertyInfo cache (optional)</param>
    /// <returns>True if filtered, else false.</returns>
    private static ModifyResult SetPKMProperty(StringInstruction cmd, BatchInfo info, IReadOnlyDictionary<string, PropertyInfo> props)
    {
        var pk = info.Entity;
        if (cmd.PropertyValue.StartsWith(CONST_BYTES, StringComparison.Ordinal))
            return SetByteArrayProperty(pk, cmd);

        if (cmd.PropertyValue.StartsWith(CONST_SUGGEST, StringComparison.OrdinalIgnoreCase))
            return SetSuggestedPKMProperty(cmd.PropertyName, info, cmd.PropertyValue);
        if (cmd.PropertyValue == CONST_RAND && cmd.PropertyName == nameof(PKM.Moves))
            return SetMoves(pk, info.Legality.GetMoveSet(true));

        if (SetComplexProperty(pk, cmd))
            return ModifyResult.Modified;

        if (!props.TryGetValue(cmd.PropertyName, out var pi))
            return ModifyResult.Error;

        if (!pi.CanWrite)
            return ModifyResult.Error;

        object val;
        if (cmd.Random)
            val = cmd.RandomValue;
        else if (cmd.PropertyValue.StartsWith(CONST_POINTER) && props.TryGetValue(cmd.PropertyValue[1..], out var opi))
            val = opi.GetValue(pk);
        else
            val = cmd.PropertyValue;

        ReflectUtil.SetValue(pi, pk, val);
        return ModifyResult.Modified;
    }

    /// <summary>
    /// Checks if the <see cref="BatchInfo"/> should be filtered due to the <see cref="StringInstruction"/> provided.
    /// </summary>
    /// <param name="cmd">Command Filter</param>
    /// <param name="info">Pokémon to check.</param>
    /// <param name="props">PropertyInfo cache (optional)</param>
    /// <returns>True if filter matches, else false.</returns>
    private static bool IsFilterMatch(StringInstruction cmd, BatchInfo info, IReadOnlyDictionary<string, PropertyInfo> props)
    {
        var match = BatchFilters.FilterMods.Find(z => z.IsMatch(cmd.PropertyName));
        if (match != null)
            return match.IsFiltered(info, cmd);
        return IsPropertyFiltered(cmd, info.Entity, props);
    }

    /// <summary>
    /// Checks if the <see cref="PKM"/> should be filtered due to the <see cref="StringInstruction"/> provided.
    /// </summary>
    /// <param name="cmd">Command Filter</param>
    /// <param name="pk">Pokémon to check.</param>
    /// <param name="props">PropertyInfo cache (optional)</param>
    /// <returns>True if filter matches, else false.</returns>
    private static bool IsFilterMatch(StringInstruction cmd, PKM pk, IReadOnlyDictionary<string, PropertyInfo> props)
    {
        var match = BatchFilters.FilterMods.Find(z => z.IsMatch(cmd.PropertyName));
        if (match != null)
            return match.IsFiltered(pk, cmd);
        return IsPropertyFiltered(cmd, pk, props);
    }

    /// <summary>
    /// Checks if the <see cref="PKM"/> should be filtered due to the <see cref="StringInstruction"/> provided.
    /// </summary>
    /// <param name="cmd">Command Filter</param>
    /// <param name="pk">Pokémon to check.</param>
    /// <param name="props">PropertyInfo cache</param>
    /// <returns>True if filtered, else false.</returns>
    private static bool IsPropertyFiltered(StringInstruction cmd, PKM pk, IReadOnlyDictionary<string, PropertyInfo> props)
    {
        if (!props.TryGetValue(cmd.PropertyName, out var pi))
            return false;
        if (!pi.CanRead)
            return false;
        return pi.IsValueEqual(pk, cmd.PropertyValue) == cmd.Evaluator;
    }

    /// <summary>
    /// Sets the <see cref="PKM"/> data with a suggested value based on its <see cref="LegalityAnalysis"/>.
    /// </summary>
    /// <param name="name">Property to modify.</param>
    /// <param name="info">Cached info storing Legal data.</param>
    /// <param name="propValue">Suggestion string which starts with <see cref="CONST_SUGGEST"/></param>
    private static ModifyResult SetSuggestedPKMProperty(string name, BatchInfo info, string propValue)
    {
        var first = BatchMods.SuggestionMods.Find(z => z.IsMatch(name, propValue, info));
        if (first != null)
            return first.Modify(name, propValue, info);
        return ModifyResult.Error;
    }

    /// <summary>
    /// Sets the <see cref="PKM"/> byte array property to a specified value.
    /// </summary>
    /// <param name="pk">Pokémon to modify.</param>
    /// <param name="cmd">Modification</param>
    private static ModifyResult SetByteArrayProperty(PKM pk, StringInstruction cmd)
    {
        switch (cmd.PropertyName)
        {
            case nameof(PKM.Nickname_Trash): ConvertToBytes(cmd.PropertyValue).CopyTo(pk.Nickname_Trash); return ModifyResult.Modified;
            case nameof(PKM.OT_Trash):       ConvertToBytes(cmd.PropertyValue).CopyTo(pk.OT_Trash);       return ModifyResult.Modified;
            case nameof(PKM.HT_Trash):       ConvertToBytes(cmd.PropertyValue).CopyTo(pk.HT_Trash);       return ModifyResult.Modified;
            default:
                return ModifyResult.Error;
        }
        static byte[] ConvertToBytes(string str)
        {
            var arr = str[CONST_BYTES.Length..].Split(',');
            return Array.ConvertAll(arr, z => Convert.ToByte(z.Trim(), 16));
        }
    }

    /// <summary>
    /// Sets the <see cref="PKM"/> property to a non-specific smart value.
    /// </summary>
    /// <param name="pk">Pokémon to modify.</param>
    /// <param name="cmd">Modification</param>
    /// <returns>True if modified, false if no modifications done.</returns>
    private static bool SetComplexProperty(PKM pk, StringInstruction cmd)
    {
        if (cmd.PropertyName.StartsWith("IV", StringComparison.Ordinal) && cmd.PropertyValue == CONST_RAND)
        {
            SetRandomIVs(pk, cmd);
            return true;
        }

        var match = BatchMods.ComplexMods.Find(z => z.IsMatch(cmd.PropertyName, cmd.PropertyValue));
        if (match == null)
            return false;

        match.Modify(pk, cmd);
        return true;
    }

    /// <summary>
    /// Sets the <see cref="PKM"/> IV(s) to a random value.
    /// </summary>
    /// <param name="pk">Pokémon to modify.</param>
    /// <param name="cmd">Modification</param>
    private static void SetRandomIVs(PKM pk, StringInstruction cmd)
    {
        if (cmd.PropertyName == nameof(PKM.IVs))
        {
            pk.SetRandomIVs();
            return;
        }

        if (TryGetHasProperty(pk, cmd.PropertyName, out var pi))
            ReflectUtil.SetValue(pi, pk, Util.Rand.Next(pk.MaxIV + 1));
    }
}