// 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 Roslyn.Utilities;

namespace Microsoft.CodeAnalysis.CSharp
{
    /// <summary>
    /// Structure containing all semantic information about a for each statement.
    /// </summary>
    public readonly struct ForEachStatementInfo : IEquatable<ForEachStatementInfo>
    {
        /// <summary>
        /// Whether this is an asynchronous foreach.
        /// </summary>
        public bool IsAsynchronous { get; }

        /// <summary>
        /// Gets the &quot;GetEnumerator&quot; method.
        /// </summary>
        public IMethodSymbol? GetEnumeratorMethod { get; }

        /// <summary>
        /// Gets the &quot;MoveNext&quot; method (or &quot;MoveNextAsync&quot; in an asynchronous foreach).
        /// </summary>
        public IMethodSymbol? MoveNextMethod { get; }

        /// <summary>
        /// Gets the awaitable info for the <see cref="MoveNextMethod"/> in an asynchronous foreach. <see langword="default"/> if this is a synchronous foreach.
        /// </summary>
        public AwaitExpressionInfo MoveNextAwaitableInfo { get; }

        /// <summary>
        /// Gets the &quot;Current&quot; property.
        /// </summary>
        public IPropertySymbol? CurrentProperty { get; }

        /// <summary>
        /// Gets the &quot;Dispose&quot; method (or &quot;DisposeAsync&quot; in an asynchronous foreach).
        /// </summary>
        public IMethodSymbol? DisposeMethod { get; }

        /// <summary>
        /// Gets the awaitable info for the <see cref="DisposeMethod"/> in an asynchronous foreach. <see langword="default"/> if this is a synchronous foreach.
        /// </summary>
        public AwaitExpressionInfo DisposeAwaitableInfo { get; }

        /// <summary>
        /// The intermediate type to which the output of the <see cref="CurrentProperty"/> is converted
        /// before being converted to the iteration variable type.
        /// </summary>
        /// <remarks>
        /// As you might hope, for an array, it is the element type of the array.
        /// </remarks>
        public ITypeSymbol? ElementType { get; }

        /// <summary>
        /// The conversion from the <see cref="ElementType"/> to the iteration variable type.
        /// </summary>
        /// <remarks>
        /// May be user-defined.
        /// </remarks>
        public Conversion ElementConversion { get; }

        /// <summary>
        /// The conversion from the type of the <see cref="CurrentProperty"/> to the <see cref="ElementType"/>.
        /// </summary>
        public Conversion CurrentConversion { get; }

        /// <summary>
        /// Initializes a new instance of the <see cref="ForEachStatementInfo" /> structure.
        /// </summary>
        internal ForEachStatementInfo(bool isAsync,
                                      IMethodSymbol getEnumeratorMethod,
                                      IMethodSymbol moveNextMethod,
                                      AwaitExpressionInfo moveNextAwaitableInfo,
                                      IPropertySymbol currentProperty,
                                      IMethodSymbol disposeMethod,
                                      AwaitExpressionInfo disposeAwaitableInfo,
                                      ITypeSymbol elementType,
                                      Conversion elementConversion,
                                      Conversion currentConversion)
        {
            this.IsAsynchronous = isAsync;
            this.GetEnumeratorMethod = getEnumeratorMethod;
            this.MoveNextMethod = moveNextMethod;
            this.MoveNextAwaitableInfo = moveNextAwaitableInfo;
            this.CurrentProperty = currentProperty;
            this.DisposeMethod = disposeMethod;
            this.DisposeAwaitableInfo = disposeAwaitableInfo;
            this.ElementType = elementType;
            this.ElementConversion = elementConversion;
            this.CurrentConversion = currentConversion;
        }

        public override bool Equals(object? obj)
        {
            return obj is ForEachStatementInfo && Equals((ForEachStatementInfo)obj);
        }

        public bool Equals(ForEachStatementInfo other)
        {
            return this.IsAsynchronous == other.IsAsynchronous
                && object.Equals(this.GetEnumeratorMethod, other.GetEnumeratorMethod)
                && object.Equals(this.MoveNextMethod, other.MoveNextMethod)
                && this.MoveNextAwaitableInfo.Equals(other.MoveNextAwaitableInfo)
                && object.Equals(this.CurrentProperty, other.CurrentProperty)
                && object.Equals(this.DisposeMethod, other.DisposeMethod)
                && this.DisposeAwaitableInfo.Equals(other.DisposeAwaitableInfo)
                && object.Equals(this.ElementType, other.ElementType)
                && this.ElementConversion == other.ElementConversion
                && this.CurrentConversion == other.CurrentConversion;
        }

        public override int GetHashCode()
        {
            return Hash.Combine(IsAsynchronous,
                   Hash.Combine(GetEnumeratorMethod,
                   Hash.Combine(MoveNextMethod,
                   Hash.Combine(MoveNextAwaitableInfo.GetHashCode(),
                   Hash.Combine(CurrentProperty,
                   Hash.Combine(DisposeMethod,
                   Hash.Combine(DisposeAwaitableInfo.GetHashCode(),
                   Hash.Combine(ElementType,
                   Hash.Combine(ElementConversion.GetHashCode(),
                                CurrentConversion.GetHashCode())))))))));
        }
    }
}