﻿// 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.

#nullable disable

using System.Collections.Generic;
using System.Linq;
using Roslyn.Utilities;

namespace Microsoft.CodeAnalysis.ExtractMethod
{
    internal partial class OperationStatus
    {
        public OperationStatus(OperationStatusFlag flag, string reason)
        {
            Contract.ThrowIfTrue(flag.Succeeded() && flag.HasBestEffort());

            Flag = flag;
            Reasons = reason == null ? SpecializedCollections.EmptyEnumerable<string>() : SpecializedCollections.SingletonEnumerable(reason);
        }

        private OperationStatus(OperationStatusFlag flag, IEnumerable<string> reasons)
        {
            Contract.ThrowIfNull(reasons);
            Contract.ThrowIfTrue(flag.Succeeded() && flag.HasBestEffort());

            Flag = flag;
            Reasons = reasons;
        }

        public OperationStatus With(OperationStatusFlag flag, string reason)
        {
            var newFlag = Flag | flag;

            newFlag = (this.Failed() || flag.Failed()) ? newFlag.RemoveFlag(OperationStatusFlag.Succeeded) : newFlag;
            newFlag = newFlag.Succeeded() ? newFlag.RemoveFlag(OperationStatusFlag.BestEffort) : newFlag;

            var reasons = reason == null ? Reasons : Reasons.Concat(reason);
            return new OperationStatus(newFlag, reasons);
        }

        public OperationStatus With(OperationStatus operationStatus)
        {
            var newFlag = Flag | operationStatus.Flag;

            newFlag = (this.Failed() || operationStatus.Failed()) ? newFlag.RemoveFlag(OperationStatusFlag.Succeeded) : newFlag;
            newFlag = newFlag.Succeeded() ? newFlag.RemoveFlag(OperationStatusFlag.BestEffort) : newFlag;

            var reasons = Reasons.Concat(operationStatus.Reasons);
            return new OperationStatus(newFlag, reasons);
        }

        public OperationStatus MakeFail()
            => new(OperationStatusFlag.None, Reasons);

        public OperationStatus MarkSuggestion()
            => new(Flag | OperationStatusFlag.Suggestion, Reasons);

        public OperationStatus<T> With<T>(T data)
            => Create(this, data);

        public OperationStatusFlag Flag { get; }
        public IEnumerable<string> Reasons { get; }
    }
}
