//
//  ServiceCollectionExtensions.cs
//
//  Copyright (c) František Boháček. All rights reserved.
//  Licensed under the MIT license. See LICENSE file in the project root for full license information.

using System;
using System.Linq;
using System.Reflection;
using Microsoft.Extensions.DependencyInjection;
using NosSmooth.Packets.Converters;
using NosSmooth.Packets.Converters.Basic;
using NosSmooth.Packets.Converters.Special;
using NosSmooth.Packets.Packets;

namespace NosSmooth.Packets.Extensions;

/// <summary>
/// Extensions for <see cref="IServiceCollection"/>.
/// </summary>
public static class ServiceCollectionExtensions
{
    /// <summary>
    /// Add packet serialization classes.
    /// </summary>
    /// <remarks>
    /// All generic implementations of ITypeConverter the class
    /// implements will be registered.
    /// </remarks>
    /// <param name="serviceCollection">The service collection.</param>
    /// <returns>The collection.</returns>
    public static IServiceCollection AddPacketSerialization(this IServiceCollection serviceCollection)
    {
        return serviceCollection
            .AddSingleton<ITypeConverterRepository, TypeConverterRepository>()
            .AddSingleton<IPacketSerializer, PacketSerializer>()
            .AddSingleton<IPacketTypesRepository>(p =>
            {
                var repository = new PacketTypesRepository(p.GetRequiredService<ITypeConverterRepository>());
                var packetTypes = typeof(ServiceCollectionExtensions).Assembly
                    .GetExportedTypes()
                    .Where(x => x != typeof(UnresolvedPacket) && !x.IsAbstract && typeof(IPacket).IsAssignableFrom(x));
                foreach (var packetType in packetTypes)
                {
                    var result = repository.AddPacketType(packetType);
                    if (!result.IsSuccess)
                    {
                        // TODO: figure out how to handle this.
                        throw new Exception(result.Error.Message);
                    }
                }

                return repository;
            })
            .AddGeneratedSerializers(typeof(ServiceCollectionExtensions).Assembly)
            .AddBasicConverters();
    }

    /// <summary>
    /// Adds all generated serializers from the given assembly.
    /// </summary>
    /// <param name="serviceCollection">The service collection.</param>
    /// <param name="assembly">The assembly.</param>
    /// <returns>The collection.</returns>
    public static IServiceCollection AddGeneratedSerializers(this IServiceCollection serviceCollection, Assembly assembly)
    {
        var types = assembly.GetExportedTypes()
            .Where(x => x.Namespace?.Contains("Generated") ?? false)
            .Where(x => x.GetInterfaces().Any(
                i => i.IsGenericType && i.GetGenericTypeDefinition() == typeof(ITypeConverter<>)
            ));
        foreach (var type in types)
        {
            serviceCollection.AddTypeConverter(type);
        }

        return serviceCollection;
    }

    /// <summary>
    /// Adds basic converters for int, uint, short, ushort, long, ulong, char, string
    /// and special converters for lists and enums.
    /// </summary>
    /// <param name="serviceCollection">The service collection.</param>
    /// <returns>The collection.</returns>
    public static IServiceCollection AddBasicConverters(this IServiceCollection serviceCollection)
    {
        return serviceCollection
            .AddSpecialConverter<ListTypeConverter>()
            .AddSpecialConverter<EnumTypeConverter>()
            .AddTypeConverter<IntTypeConverter>()
            .AddTypeConverter<UIntTypeConverter>()
            .AddTypeConverter<ShortTypeConverter>()
            .AddTypeConverter<UShortTypeConverter>()
            .AddTypeConverter<ByteTypeConverter>()
            .AddTypeConverter<ULongTypeConverter>()
            .AddTypeConverter<LongTypeConverter>()
            .AddTypeConverter<StringTypeConverter>()
            .AddTypeConverter<CharTypeConverter>();
    }

    /// <summary>
    /// Add generic type converter.
    /// </summary>
    /// <remarks>
    /// All generic implementations of ITypeConverter the class
    /// implements will be registered.
    /// </remarks>
    /// <param name="serviceCollection">The service collection.</param>
    /// <typeparam name="TConverter">The type of the converter.</typeparam>
    /// <returns>The collection.</returns>
    public static IServiceCollection AddTypeConverter<TConverter>(this IServiceCollection serviceCollection)
        where TConverter : ITypeConverter
        => serviceCollection.AddTypeConverter(typeof(TConverter));

    /// <summary>
    /// Add generic type converter.
    /// </summary>
    /// <remarks>
    /// All generic implementations of ITypeConverter the class
    /// implements will be registered.
    /// </remarks>
    /// <param name="serviceCollection">The service collection.</param>
    /// <param name="converterType">The type of the converter.</param>
    /// <returns>The collection.</returns>
    public static IServiceCollection AddTypeConverter(this IServiceCollection serviceCollection, Type converterType)
    {
        if (!converterType.GetInterfaces().Any(
                i => i.IsGenericType && i.GetGenericTypeDefinition() == typeof(ITypeConverter<>)
            ))
        {
            throw new ArgumentException(
                $"{nameof(converterType)} should implement ITypeConverter.",
                nameof(converterType));
        }

        var handlerTypeInterfaces = converterType.GetInterfaces();
        var handlerInterfaces = handlerTypeInterfaces.Where
        (
            r => r.IsGenericType && r.GetGenericTypeDefinition() == typeof(ITypeConverter<>)
        );

        foreach (var handlerInterface in handlerInterfaces)
        {
            serviceCollection.AddSingleton(handlerInterface, converterType);
        }

        return serviceCollection;
    }

    /// <summary>
    /// Add the specified converter as a special converter.
    /// </summary>
    /// <param name="serviceCollection">The service collection.</param>
    /// <typeparam name="TSpecialConverter">The type to add as a special converter.</typeparam>
    /// <returns>The collection.</returns>
    public static IServiceCollection AddSpecialConverter<TSpecialConverter>(this IServiceCollection serviceCollection)
        where TSpecialConverter : class, ISpecialTypeConverter
    {
        return serviceCollection.AddSingleton<ISpecialTypeConverter, TSpecialConverter>();
    }
}