using System;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Globalization;
using System.Linq;
using System.Reflection;
using System.Threading;
using System.Threading.Tasks;
using PoweredSoft.DynamicQuery;
using PoweredSoft.DynamicQuery.Core;
using Svrnty.CQRS.DynamicQuery.Abstractions;

namespace Svrnty.CQRS.DynamicQuery;

public abstract class DynamicQueryHandlerBase<TSource, TDestination>
    where TSource : class
    where TDestination : class
{
    private readonly IQueryHandlerAsync _queryHandlerAsync;
    private readonly IEnumerable<IQueryableProvider<TSource>> _queryableProviders;
    private readonly IEnumerable<IAlterQueryableService<TSource, TDestination>> _alterQueryableServices;

    private readonly IEnumerable<IDynamicQueryInterceptorProvider<TSource, TDestination>>
        _dynamicQueryInterceptorProviders;

    private readonly IServiceProvider _serviceProvider;

    public DynamicQueryHandlerBase(IQueryHandlerAsync queryHandlerAsync,
        IEnumerable<IQueryableProvider<TSource>> queryableProviders,
        IEnumerable<IAlterQueryableService<TSource, TDestination>> alterQueryableServices,
        IEnumerable<IDynamicQueryInterceptorProvider<TSource, TDestination>> dynamicQueryInterceptorProviders,
        IServiceProvider serviceProvider)
    {
        _queryHandlerAsync = queryHandlerAsync;
        _queryableProviders = queryableProviders;
        _alterQueryableServices = alterQueryableServices;
        _dynamicQueryInterceptorProviders = dynamicQueryInterceptorProviders;
        _serviceProvider = serviceProvider;
    }

    protected virtual Task<IQueryable<TSource>> GetQueryableAsync(IDynamicQuery query,
        CancellationToken cancellationToken = default)
    {
        if (_queryableProviders.Any())
        {
            // Use Last() to prefer closed generic registrations (overrides) over open generic (default)
            // Registration order: open generic first, closed generic (override) last
            return _queryableProviders.Last().GetQueryableAsync(query, cancellationToken);
        }

        throw new Exception($"You must provide a QueryableProvider<TSource> for {typeof(TSource).Name}");
    }

    public virtual IQueryExecutionOptions GetQueryExecutionOptions(IQueryable<TSource> source, IDynamicQuery query)
    {
        return new QueryExecutionOptions();
    }

    public virtual IEnumerable<IQueryInterceptor> GetInterceptors()
    {
        var types = _dynamicQueryInterceptorProviders.SelectMany(t => t.GetInterceptorsTypes()).Distinct();
        foreach (var type in types)
            yield return _serviceProvider.GetService(type) as IQueryInterceptor;
    }

    protected async Task<IQueryExecutionResult<TDestination>> ProcessQueryAsync(IDynamicQuery query,
        CancellationToken cancellationToken = default)
    {
        var source = await GetQueryableAsync(query, cancellationToken);
        source = await AlterSourceAsync(source, query, cancellationToken);
        var options = GetQueryExecutionOptions(source, query);
        var interceptors = GetInterceptors();

        foreach (var interceptor in interceptors)
            _queryHandlerAsync.AddInterceptor(interceptor);

        var criteria = CreateCriteriaFromQuery(query);
        var result =
            await _queryHandlerAsync.ExecuteAsync<TSource, TDestination>(source, criteria, options, cancellationToken);
        return result;
    }

    protected virtual async Task<IQueryable<TSource>> AlterSourceAsync(IQueryable<TSource> source, IDynamicQuery query,
        CancellationToken cancellationToken)
    {
        foreach (var t in _alterQueryableServices)
            source = await t.AlterQueryableAsync(source, query, cancellationToken);

        return source;
    }

    protected virtual IQueryCriteria CreateCriteriaFromQuery(IDynamicQuery query)
    {
        var filters = query?.GetFilters() ?? new List<IFilter>();
        ConvertFilterValuesToPropertyTypes(filters);
        var criteria = new QueryCriteria
        {
            Page = query?.GetPage(),
            PageSize = query?.GetPageSize(),
            Filters = filters,
            Sorts = query?.GetSorts() ?? new List<ISort>(),
            Groups = query?.GetGroups() ?? new List<IGroup>(),
            Aggregates = query?.GetAggregates() ?? new List<IAggregate>()
        };
        return criteria;
    }

    /// <summary>
    /// Converts string filter values to the correct CLR type based on TSource property types.
    /// This handles the case where transport layers (e.g. gRPC) pass all values as strings,
    /// but PoweredSoft.DynamicLinq needs the actual type to build LINQ expressions.
    /// </summary>
    [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2087",
        Justification = "TSource properties are preserved by EF Core and DynamicLinq usage")]
    private static void ConvertFilterValuesToPropertyTypes(List<IFilter> filters)
    {
        for (var i = filters.Count - 1; i >= 0; i--)
        {
            var filter = filters[i];
            if (filter is SimpleFilter simpleFilter)
            {
                if (simpleFilter.Value == null)
                {
                    filters.RemoveAt(i);
                    continue;
                }

                if (simpleFilter.Value is string strValue && !string.IsNullOrEmpty(strValue))
                {
                    var propertyType = ResolvePropertyType(typeof(TSource), simpleFilter.Path);
                    if (propertyType == null)
                        continue;

                    var targetType = Nullable.GetUnderlyingType(propertyType) ?? propertyType;

                    if (targetType == typeof(DateTime))
                    {
                        if (DateTime.TryParse(strValue, CultureInfo.InvariantCulture, DateTimeStyles.AdjustToUniversal,
                                out var dt))
                        {
                            simpleFilter.Value = DateTime.SpecifyKind(dt, DateTimeKind.Utc);
                        }
                    }
                    else if (targetType == typeof(DateTimeOffset))
                    {
                        if (DateTimeOffset.TryParse(strValue, CultureInfo.InvariantCulture, DateTimeStyles.None,
                                out var dto))
                        {
                            simpleFilter.Value = dto;
                        }
                    }
                }
            }
            else if (filter is CompositeFilter compositeFilter && compositeFilter.Filters != null)
            {
                ConvertFilterValuesToPropertyTypes(compositeFilter.Filters);
            }
        }

        [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2070",
            Justification = "Property types are preserved by EF Core and DynamicLinq usage")]
        [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2075",
            Justification = "Nested property type resolution is inherently dynamic")]
        static Type? ResolvePropertyType(
            [DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicProperties)] Type type, string? path)
        {
            if (string.IsNullOrEmpty(path))
                return null;

            var currentType = type;
            foreach (var part in path.Split('.'))
            {
                var property = currentType.GetProperty(part,
                    BindingFlags.Public | BindingFlags.Instance | BindingFlags.IgnoreCase);
                if (property == null)
                    return null;
                currentType = property.PropertyType;
            }

            return currentType;
        }
    }
}