using System.Collections.Generic;
using System.Linq;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp;
using XamlX.TypeSystem;

namespace Robust.Client.NameGenerator
{
    /// <summary>
    /// Taken from https://github.com/AvaloniaUI/Avalonia.NameGenerator/blob/ecc9677a23de5cbc90af07ccac14e31c0da41d6a/src/Avalonia.NameGenerator/Infrastructure/RoslynTypeSystem.cs
    /// </summary>
     public class RoslynTypeSystem : IXamlTypeSystem
    {
        private readonly List<IXamlAssembly> _assemblies = new List<IXamlAssembly>();

        public RoslynTypeSystem(CSharpCompilation compilation)
        {
            _assemblies.Add(new RoslynAssembly(compilation.Assembly));

            var assemblySymbols = compilation
                .References
                .Select(compilation.GetAssemblyOrModuleSymbol)
                .OfType<IAssemblySymbol>()
                .Select(assembly => new RoslynAssembly(assembly))
                .ToList();

            _assemblies.AddRange(assemblySymbols);
        }

        public IReadOnlyList<IXamlAssembly> Assemblies => _assemblies;

        public IXamlAssembly FindAssembly(string substring) => _assemblies[0];

        public IXamlType FindType(string name)
        {
            foreach (var assembly in _assemblies)
            {
                var type = assembly.FindType(name);
                if (type != null)
                    return type;
            }

            return null;
        }

        public IXamlType FindType(string name, string assembly)
        {
            foreach (var assemblyInstance in _assemblies)
            {
                var type = assemblyInstance.FindType(name);
                if (type != null)
                    return type;
            }

            return null;
        }
    }

    public class RoslynAssembly : IXamlAssembly
    {
        private readonly IAssemblySymbol _symbol;

        public RoslynAssembly(IAssemblySymbol symbol) => _symbol = symbol;

        public bool Equals(IXamlAssembly other) =>
            other is RoslynAssembly roslynAssembly &&
            SymbolEqualityComparer.Default.Equals(_symbol, roslynAssembly._symbol);

        public string Name => _symbol.Name;

        public IReadOnlyList<IXamlCustomAttribute> CustomAttributes =>
            _symbol.GetAttributes()
                .Select(data => new RoslynAttribute(data, this))
                .ToList();

        public IXamlType FindType(string fullName)
        {
            var type = _symbol.GetTypeByMetadataName(fullName);
            return type is null ? null : new RoslynType(type, this);
        }
    }

    public class RoslynAttribute : IXamlCustomAttribute
    {
        private readonly AttributeData _data;
        private readonly RoslynAssembly _assembly;

        public RoslynAttribute(AttributeData data, RoslynAssembly assembly)
        {
            _data = data;
            _assembly = assembly;
        }

        public bool Equals(IXamlCustomAttribute other) =>
            other is RoslynAttribute attribute &&
            _data == attribute._data;

        public IXamlType Type => new RoslynType(_data.AttributeClass, _assembly);

        public List<object> Parameters =>
            _data.ConstructorArguments
                .Select(argument => argument.Value)
                .ToList();

        public Dictionary<string, object> Properties =>
            _data.NamedArguments.ToDictionary(
                pair => pair.Key,
                pair => pair.Value.Value);
    }

    public class RoslynType : IXamlType
    {
        private static readonly SymbolDisplayFormat SymbolDisplayFormat = new SymbolDisplayFormat(
            typeQualificationStyle: SymbolDisplayTypeQualificationStyle.NameAndContainingTypesAndNamespaces,
            genericsOptions: SymbolDisplayGenericsOptions.IncludeTypeParameters |
                             SymbolDisplayGenericsOptions.IncludeTypeConstraints |
                             SymbolDisplayGenericsOptions.IncludeVariance);

        private readonly RoslynAssembly _assembly;
        private readonly INamedTypeSymbol _symbol;

        public RoslynType(INamedTypeSymbol symbol, RoslynAssembly assembly)
        {
            _symbol = symbol;
            _assembly = assembly;
        }

        public bool Equals(IXamlType other) =>
            other is RoslynType roslynType &&
            SymbolEqualityComparer.Default.Equals(_symbol, roslynType._symbol);

        public object Id => _symbol;

        public string Name => _symbol.Name;

        public string Namespace => _symbol.ContainingNamespace.ToDisplayString(SymbolDisplayFormat);

        public string FullName => $"{Namespace}.{Name}";

        public IXamlAssembly Assembly => _assembly;

        public IReadOnlyList<IXamlProperty> Properties =>
            _symbol.GetMembers()
                .Where(member => member.Kind == SymbolKind.Property)
                .OfType<IPropertySymbol>()
                .Select(property => new RoslynProperty(property, _assembly))
                .ToList();

        public IReadOnlyList<IXamlEventInfo> Events { get; } = new List<IXamlEventInfo>();

        public IReadOnlyList<IXamlField> Fields { get; } = new List<IXamlField>();

        public IReadOnlyList<IXamlMethod> Methods { get; } = new List<IXamlMethod>();

        public IReadOnlyList<IXamlConstructor> Constructors =>
            _symbol.Constructors
                .Select(method => new RoslynConstructor(method, _assembly))
                .ToList();

        public IReadOnlyList<IXamlCustomAttribute> CustomAttributes { get; } = new List<IXamlCustomAttribute>();

        public IReadOnlyList<IXamlType> GenericArguments { get; } = new List<IXamlType>();

        public bool IsAssignableFrom(IXamlType type) => type == this;

        public IXamlType MakeGenericType(IReadOnlyList<IXamlType> typeArguments) => this;

        public IXamlType GenericTypeDefinition => this;

        public bool IsArray => false;

        public IXamlType ArrayElementType { get; } = null;

        public IXamlType MakeArrayType(int dimensions) => null;

        public IXamlType BaseType => _symbol.BaseType == null ? null : new RoslynType(_symbol.BaseType, _assembly);

        public bool IsValueType { get; } = false;

        public bool IsEnum { get; } = false;

        public IReadOnlyList<IXamlType> Interfaces =>
            _symbol.AllInterfaces
                .Select(abstraction => new RoslynType(abstraction, _assembly))
                .ToList();

        public bool IsInterface => _symbol.IsAbstract;

        public IXamlType GetEnumUnderlyingType() => null;

        public IReadOnlyList<IXamlType> GenericParameters { get; } = new List<IXamlType>();
    }

    public class RoslynConstructor : IXamlConstructor
    {
        private readonly IMethodSymbol _symbol;
        private readonly RoslynAssembly _assembly;

        public RoslynConstructor(IMethodSymbol symbol, RoslynAssembly assembly)
        {
            _symbol = symbol;
            _assembly = assembly;
        }

        public bool Equals(IXamlConstructor other) =>
            other is RoslynConstructor roslynConstructor &&
            SymbolEqualityComparer.Default.Equals(_symbol, roslynConstructor._symbol);

        public bool IsPublic => true;

        public bool IsStatic => false;

        public IReadOnlyList<IXamlType> Parameters =>
            _symbol.Parameters
                .Select(parameter => parameter.Type)
                .OfType<INamedTypeSymbol>()
                .Select(type => new RoslynType(type, _assembly))
                .ToList();
    }

    public class RoslynProperty : IXamlProperty
    {
        private readonly IPropertySymbol _symbol;
        private readonly RoslynAssembly _assembly;

        public RoslynProperty(IPropertySymbol symbol, RoslynAssembly assembly)
        {
            _symbol = symbol;
            _assembly = assembly;
        }

        public bool Equals(IXamlProperty other) =>
            other is RoslynProperty roslynProperty &&
            SymbolEqualityComparer.Default.Equals(_symbol, roslynProperty._symbol);

        public string Name => _symbol.Name;

        public IXamlType PropertyType =>
            _symbol.Type is INamedTypeSymbol namedTypeSymbol
                ? new RoslynType(namedTypeSymbol, _assembly)
                : null;

        public IXamlMethod Getter => _symbol.GetMethod == null ? null : new RoslynMethod(_symbol.GetMethod, _assembly);

        public IXamlMethod Setter => _symbol.SetMethod == null ? null : new RoslynMethod(_symbol.SetMethod, _assembly);

        public IReadOnlyList<IXamlCustomAttribute> CustomAttributes { get; } = new List<IXamlCustomAttribute>();

        public IReadOnlyList<IXamlType> IndexerParameters { get; } = new List<IXamlType>();
    }

    public class RoslynMethod : IXamlMethod
    {
        private readonly IMethodSymbol _symbol;
        private readonly RoslynAssembly _assembly;

        public RoslynMethod(IMethodSymbol symbol, RoslynAssembly assembly)
        {
            _symbol = symbol;
            _assembly = assembly;
        }

        public bool Equals(IXamlMethod other) =>
            other is RoslynMethod roslynMethod &&
            SymbolEqualityComparer.Default.Equals(roslynMethod._symbol, _symbol);

        public string Name => _symbol.Name;

        public bool IsPublic => true;

        public bool IsStatic => false;

        public IXamlType ReturnType => new RoslynType((INamedTypeSymbol) _symbol.ReturnType, _assembly);

        public IReadOnlyList<IXamlType> Parameters =>
            _symbol.Parameters.Select(parameter => parameter.Type)
                .OfType<INamedTypeSymbol>()
                .Select(type => new RoslynType(type, _assembly))
                .ToList();

        public IXamlType DeclaringType => new RoslynType((INamedTypeSymbol)_symbol.ReceiverType, _assembly);

        public IXamlMethod MakeGenericMethod(IReadOnlyList<IXamlType> typeArguments) => null;

        public IReadOnlyList<IXamlCustomAttribute> CustomAttributes { get; } = new List<IXamlCustomAttribute>();
    }
}