// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System.Collections.Generic;
using System.IO;
using System.Reflection.Metadata;
using System.Runtime.Serialization.BinaryFormat.Utils;
 
namespace System.Runtime.Serialization.BinaryFormat;
 
/// <summary>
/// Represents a single dimensional array of <see langword="string" />.
/// </summary>
/// <remarks>
/// ArraySingleString records are described in <see href="https://learn.microsoft.com/openspecs/windows_protocols/ms-nrbf/3d98fd60-d2b4-448a-ac0b-3cd8dea41f9d">[MS-NRBF] 2.4.3.4</see>.
/// </remarks>
internal sealed class ArraySingleStringRecord : ArrayRecord<string?>
{
    private static TypeName? s_elementTypeName;
 
    private ArraySingleStringRecord(ArrayInfo arrayInfo) : base(arrayInfo) => Records = [];
 
    public override RecordType RecordType => RecordType.ArraySingleString;
 
    public override TypeName ElementTypeName
        => s_elementTypeName ??= TypeName.Parse(typeof(string).FullName.AsSpan()).WithCoreLibAssemblyName();
 
    private List<SerializationRecord> Records { get; }
 
    public override bool IsTypeNameMatching(Type type) => type == typeof(string[]);
 
    internal override bool IsElementType(Type typeElement) => typeElement == typeof(string);
 
    internal static ArraySingleStringRecord Decode(BinaryReader reader)
        => new(ArrayInfo.Decode(reader));
 
    internal override (AllowedRecordTypes allowed, PrimitiveType primitiveType) GetAllowedRecordType()
    {
        // An array of string can consist of string(s), null(s) and reference(s) to string(s).
        const AllowedRecordTypes AllowedTypes = AllowedRecordTypes.BinaryObjectString
            | AllowedRecordTypes.Nulls | AllowedRecordTypes.MemberReference;
 
        return (AllowedTypes, default);
    }
 
    private protected override void AddValue(object value) => Records.Add((SerializationRecord)value);
 
    /// <inheritdoc/>
    public override string?[] GetArray(bool allowNulls = true)
        => (string?[])(allowNulls ? _arrayNullsAllowed ??= ToArray(true) : _arrayNullsNotAllowed ??= ToArray(false));
 
    private string?[] ToArray(bool allowNulls)
    {
        string?[] values = new string?[Length];
 
        for (int recordIndex = 0, valueIndex = 0; recordIndex < Records.Count; recordIndex++)
        {
            SerializationRecord record = Records[recordIndex];
 
            if (record is MemberReferenceRecord memberReference)
            {
                record = memberReference.GetReferencedRecord();
 
                if (record is not BinaryObjectStringRecord)
                {
                    ThrowHelper.ThrowInvalidReference();
                }
            }
 
            if (record is BinaryObjectStringRecord stringRecord)
            {
                values[valueIndex++] = stringRecord.Value;
                continue;
            }
 
            if (!allowNulls)
            {
                ThrowHelper.ThrowArrayContainedNulls();
            }
 
            int nullCount = ((NullsRecord)record).NullCount;
            do
            {
                values[valueIndex++] = null;
                nullCount--;
            }
            while (nullCount > 0);
        }
 
        return values;
    }
}