// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
 
using System;
using System.Collections.Generic;
using System.Collections.Immutable;
using System.Composition;
using System.Runtime.Serialization;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.Host;
using Microsoft.CodeAnalysis.Host.Mef;
using Roslyn.Utilities;
 
namespace Microsoft.CodeAnalysis.SymbolSearch
{
    internal interface ISymbolSearchService : IWorkspaceService
    {
        /// <summary>
        /// Searches for packages that contain a type with the provided name and arity.
        /// Note: Implementations are free to return the results they feel best for the
        /// given data.  Specifically, they can do exact or fuzzy matching on the name.
        /// They can use or ignore the arity depending on their capabilities. 
        /// 
        /// Implementations should return results in order from best to worst (from their
        /// perspective).
        /// </summary>
        ValueTask<ImmutableArray<PackageWithTypeResult>> FindPackagesWithTypeAsync(
            string source, string name, int arity, CancellationToken cancellationToken);
 
        /// <summary>
        /// Searches for packages that contain an assembly with the provided name.
        /// Note: Implementations are free to return the results they feel best for the
        /// given data.  Specifically, they can do exact or fuzzy matching on the name.
        /// 
        /// Implementations should return results in order from best to worst (from their
        /// perspective).
        /// </summary>
        ValueTask<ImmutableArray<PackageWithAssemblyResult>> FindPackagesWithAssemblyAsync(
            string source, string assemblyName, CancellationToken cancellationToken);
 
        /// <summary>
        /// Searches for reference assemblies that contain a type with the provided name and arity.
        /// Note: Implementations are free to return the results they feel best for the
        /// given data.  Specifically, they can do exact or fuzzy matching on the name.
        /// They can use or ignore the arity depending on their capabilities. 
        /// 
        /// Implementations should return results in order from best to worst (from their
        /// perspective).
        /// </summary>
        ValueTask<ImmutableArray<ReferenceAssemblyWithTypeResult>> FindReferenceAssembliesWithTypeAsync(
            string name, int arity, CancellationToken cancellationToken);
    }
 
    [DataContract]
    internal abstract class PackageResult
    {
        [DataMember(Order = 0)]
        public readonly string PackageName;
 
        [DataMember(Order = 1)]
        public readonly int Rank;
 
        protected PackageResult(string packageName, int rank)
        {
            PackageName = packageName;
            Rank = rank;
        }
    }
 
    [DataContract]
    internal sealed class PackageWithTypeResult : PackageResult
    {
        [DataMember(Order = 2)]
        public readonly string TypeName;
 
        [DataMember(Order = 3)]
        public readonly string? Version;
 
        [DataMember(Order = 4)]
        public readonly ImmutableArray<string> ContainingNamespaceNames;
 
        public PackageWithTypeResult(
            string packageName,
            int rank,
            string typeName,
            string? version,
            ImmutableArray<string> containingNamespaceNames)
            : base(packageName, rank)
        {
            TypeName = typeName;
            Version = version;
            ContainingNamespaceNames = containingNamespaceNames;
        }
    }
 
    [DataContract]
    internal sealed class PackageWithAssemblyResult : PackageResult, IEquatable<PackageWithAssemblyResult?>, IComparable<PackageWithAssemblyResult?>
    {
        [DataMember(Order = 2)]
        public readonly string? Version;
 
        public PackageWithAssemblyResult(
            string packageName,
            int rank,
            string version)
            : base(packageName, rank)
        {
            Version = version;
        }
 
        public override int GetHashCode()
            => PackageName.GetHashCode();
 
        public override bool Equals(object? obj)
            => Equals(obj as PackageWithAssemblyResult);
 
        public bool Equals(PackageWithAssemblyResult? other)
            => PackageName.Equals(other?.PackageName);
 
        public int CompareTo(PackageWithAssemblyResult? other)
        {
            if (other is null)
                return 1;
 
            return ComparerWithState.CompareTo(this, other, s_comparers);
        }
 
        private static readonly ImmutableArray<Func<PackageWithAssemblyResult, IComparable>> s_comparers =
            ImmutableArray.Create<Func<PackageWithAssemblyResult, IComparable>>(p => p.Rank, p => p.PackageName);
    }
 
    [DataContract]
    internal sealed class ReferenceAssemblyWithTypeResult
    {
        [DataMember(Order = 0)]
        public readonly string AssemblyName;
 
        [DataMember(Order = 1)]
        public readonly string TypeName;
 
        [DataMember(Order = 2)]
        public readonly ImmutableArray<string> ContainingNamespaceNames;
 
        public ReferenceAssemblyWithTypeResult(
            string assemblyName,
            string typeName,
            ImmutableArray<string> containingNamespaceNames)
        {
            AssemblyName = assemblyName;
            TypeName = typeName;
            ContainingNamespaceNames = containingNamespaceNames;
        }
    }
 
    [ExportWorkspaceService(typeof(ISymbolSearchService)), Shared]
    internal class DefaultSymbolSearchService : ISymbolSearchService
    {
        [ImportingConstructor]
        [Obsolete(MefConstruction.ImportingConstructorMessage, error: true)]
        public DefaultSymbolSearchService()
        {
        }
 
        public ValueTask<ImmutableArray<PackageWithTypeResult>> FindPackagesWithTypeAsync(string source, string name, int arity, CancellationToken cancellationToken)
            => ValueTaskFactory.FromResult(ImmutableArray<PackageWithTypeResult>.Empty);
 
        public ValueTask<ImmutableArray<PackageWithAssemblyResult>> FindPackagesWithAssemblyAsync(string source, string assemblyName, CancellationToken cancellationToken)
            => ValueTaskFactory.FromResult(ImmutableArray<PackageWithAssemblyResult>.Empty);
 
        public ValueTask<ImmutableArray<ReferenceAssemblyWithTypeResult>> FindReferenceAssembliesWithTypeAsync(string name, int arity, CancellationToken cancellationToken)
            => ValueTaskFactory.FromResult(ImmutableArray<ReferenceAssemblyWithTypeResult>.Empty);
    }
}