using System.Data;
using JdeScoping.DataSync.Etl.Transformers;
using NSubstitute;

namespace JdeScoping.DataSync.Tests.Etl.Transformers;

public class TransformingDataReaderTests
{
    [Fact]
    public void Read_DelegatesToSourceReader()
    {
        var source = Substitute.For<IDataReader>();
        source.Read().Returns(true, true, false);
        var transformer = new PassThroughTransformer();

        var reader = transformer.Transform(source);

        Assert.True(reader.Read());
        Assert.True(reader.Read());
        Assert.False(reader.Read());
    }

    [Fact]
    public void FieldCount_DelegatesToTransformer()
    {
        var source = Substitute.For<IDataReader>();
        source.FieldCount.Returns(5);
        var transformer = new PassThroughTransformer();

        var reader = transformer.Transform(source);

        Assert.Equal(5, reader.FieldCount);
    }

    [Fact]
    public void GetName_DelegatesToTransformer()
    {
        var source = Substitute.For<IDataReader>();
        source.GetName(0).Returns("OriginalName");
        var transformer = new PassThroughTransformer();

        var reader = transformer.Transform(source);

        Assert.Equal("OriginalName", reader.GetName(0));
    }

    [Fact]
    public void GetValue_DelegatesToTransformer()
    {
        var source = Substitute.For<IDataReader>();
        source.GetValue(0).Returns("TestValue");
        var transformer = new PassThroughTransformer();

        var reader = transformer.Transform(source);

        Assert.Equal("TestValue", reader.GetValue(0));
    }

    [Fact]
    public void GetOrdinal_DelegatesToTransformer()
    {
        var source = Substitute.For<IDataReader>();
        source.GetOrdinal("TestField").Returns(3);
        var transformer = new PassThroughTransformer();

        var reader = transformer.Transform(source);

        Assert.Equal(3, reader.GetOrdinal("TestField"));
    }

    [Fact]
    public void GetFieldType_DelegatesToTransformer()
    {
        var source = Substitute.For<IDataReader>();
        source.GetFieldType(0).Returns(typeof(string));
        var transformer = new PassThroughTransformer();

        var reader = transformer.Transform(source);

        Assert.Equal(typeof(string), reader.GetFieldType(0));
    }

    [Fact]
    public void IsDBNull_DelegatesToTransformer()
    {
        var source = Substitute.For<IDataReader>();
        source.IsDBNull(0).Returns(true);
        var transformer = new PassThroughTransformer();

        var reader = transformer.Transform(source);

        Assert.True(reader.IsDBNull(0));
    }

    [Fact]
    public void Indexer_ByOrdinal_UsesGetValue()
    {
        var source = Substitute.For<IDataReader>();
        source.GetValue(1).Returns("IndexedValue");
        var transformer = new PassThroughTransformer();

        var reader = transformer.Transform(source);

        Assert.Equal("IndexedValue", reader[1]);
    }

    [Fact]
    public void Indexer_ByName_UsesGetOrdinalAndGetValue()
    {
        var source = Substitute.For<IDataReader>();
        source.GetOrdinal("TestColumn").Returns(2);
        source.GetValue(2).Returns("NamedValue");
        var transformer = new PassThroughTransformer();

        var reader = transformer.Transform(source);

        Assert.Equal("NamedValue", reader["TestColumn"]);
    }

    [Fact]
    public void GetValues_PopulatesArrayWithTransformedValues()
    {
        var source = Substitute.For<IDataReader>();
        source.FieldCount.Returns(3);
        source.GetValue(0).Returns("Value0");
        source.GetValue(1).Returns("Value1");
        source.GetValue(2).Returns("Value2");
        var transformer = new PassThroughTransformer();

        var reader = transformer.Transform(source);
        var values = new object[3];
        var count = reader.GetValues(values);

        Assert.Equal(3, count);
        Assert.Equal("Value0", values[0]);
        Assert.Equal("Value1", values[1]);
        Assert.Equal("Value2", values[2]);
    }

    [Fact]
    public void Dispose_DisposesSourceReader()
    {
        var source = Substitute.For<IDataReader>();
        var transformer = new PassThroughTransformer();

        var reader = transformer.Transform(source);
        reader.Dispose();

        source.Received(1).Dispose();
    }

    [Fact]
    public void Close_ClosesSourceReader()
    {
        var source = Substitute.For<IDataReader>();
        var transformer = new PassThroughTransformer();

        var reader = transformer.Transform(source);
        reader.Close();

        source.Received(1).Close();
    }

    [Fact]
    public void NextResult_DelegatesToSourceReader()
    {
        var source = Substitute.For<IDataReader>();
        source.NextResult().Returns(true);
        var transformer = new PassThroughTransformer();

        var reader = transformer.Transform(source);

        Assert.True(reader.NextResult());
    }

    [Fact]
    public void Depth_DelegatesToSourceReader()
    {
        var source = Substitute.For<IDataReader>();
        source.Depth.Returns(2);
        var transformer = new PassThroughTransformer();

        var reader = transformer.Transform(source);

        Assert.Equal(2, reader.Depth);
    }

    [Fact]
    public void IsClosed_DelegatesToSourceReader()
    {
        var source = Substitute.For<IDataReader>();
        source.IsClosed.Returns(true);
        var transformer = new PassThroughTransformer();

        var reader = transformer.Transform(source);

        Assert.True(reader.IsClosed);
    }

    [Fact]
    public void RecordsAffected_DelegatesToSourceReader()
    {
        var source = Substitute.For<IDataReader>();
        source.RecordsAffected.Returns(42);
        var transformer = new PassThroughTransformer();

        var reader = transformer.Transform(source);

        Assert.Equal(42, reader.RecordsAffected);
    }

    [Fact]
    public void Transform_ThrowsOnNullSource()
    {
        var transformer = new PassThroughTransformer();

        Assert.Throws<ArgumentNullException>(() => transformer.Transform(null!));
    }

    [Fact]
    public void TransformerName_ReturnsExpectedName()
    {
        var transformer = new PassThroughTransformer();

        Assert.Equal("PassThrough", transformer.TransformerName);
    }

    [Fact]
    public void GetBytes_ComputedColumn_ThrowsNotSupportedException()
    {
        // Arrange - transformer that returns -1 for ordinal 0 (computed)
        var source = Substitute.For<IDataReader>();
        source.FieldCount.Returns(2);
        source.GetName(0).Returns("Computed");
        source.GetName(1).Returns("B");
        var transformer = new ComputedColumnTransformer();
        var reader = transformer.Transform(source);

        // Act & Assert
        Assert.Throws<NotSupportedException>(() =>
            reader.GetBytes(0, 0, null, 0, 0));
    }

    [Fact]
    public void GetChars_ComputedColumn_ThrowsNotSupportedException()
    {
        // Arrange - transformer that returns -1 for ordinal 0 (computed)
        var source = Substitute.For<IDataReader>();
        source.FieldCount.Returns(2);
        source.GetName(0).Returns("Computed");
        source.GetName(1).Returns("B");
        var transformer = new ComputedColumnTransformer();
        var reader = transformer.Transform(source);

        // Act & Assert
        Assert.Throws<NotSupportedException>(() =>
            reader.GetChars(0, 0, null, 0, 0));
    }

    [Fact]
    public void GetData_ComputedColumn_ThrowsNotSupportedException()
    {
        // Arrange - transformer that returns -1 for ordinal 0 (computed)
        var source = Substitute.For<IDataReader>();
        source.FieldCount.Returns(2);
        source.GetName(0).Returns("Computed");
        source.GetName(1).Returns("B");
        var transformer = new ComputedColumnTransformer();
        var reader = transformer.Transform(source);

        // Act & Assert
        Assert.Throws<NotSupportedException>(() =>
            reader.GetData(0));
    }

    [Fact]
    public void GetDataTypeName_ComputedColumn_ThrowsNotSupportedException()
    {
        // Arrange - transformer that returns -1 for ordinal 0 (computed)
        var source = Substitute.For<IDataReader>();
        source.FieldCount.Returns(2);
        source.GetName(0).Returns("Computed");
        source.GetName(1).Returns("B");
        var transformer = new ComputedColumnTransformer();
        var reader = transformer.Transform(source);

        // Act & Assert
        Assert.Throws<NotSupportedException>(() =>
            reader.GetDataTypeName(0));
    }

    [Fact]
    public void GetBytes_NonComputedColumn_DelegatesToSource()
    {
        // Arrange
        var source = Substitute.For<IDataReader>();
        source.FieldCount.Returns(2);
        source.GetName(0).Returns("A");
        source.GetName(1).Returns("B");
        var expectedBytes = new byte[] { 1, 2, 3 };
        source.GetBytes(1, 0, Arg.Any<byte[]?>(), 0, 3).Returns(3L);
        var transformer = new PassThroughTransformer();
        var reader = transformer.Transform(source);

        // Act
        var buffer = new byte[3];
        var result = reader.GetBytes(1, 0, buffer, 0, 3);

        // Assert
        Assert.Equal(3L, result);
        source.Received(1).GetBytes(1, 0, buffer, 0, 3);
    }

    [Fact]
    public void GetChars_NonComputedColumn_DelegatesToSource()
    {
        // Arrange
        var source = Substitute.For<IDataReader>();
        source.FieldCount.Returns(2);
        source.GetName(0).Returns("A");
        source.GetName(1).Returns("B");
        source.GetChars(1, 0, Arg.Any<char[]?>(), 0, 3).Returns(3L);
        var transformer = new PassThroughTransformer();
        var reader = transformer.Transform(source);

        // Act
        var buffer = new char[3];
        var result = reader.GetChars(1, 0, buffer, 0, 3);

        // Assert
        Assert.Equal(3L, result);
        source.Received(1).GetChars(1, 0, buffer, 0, 3);
    }

    [Fact]
    public void GetData_NonComputedColumn_DelegatesToSource()
    {
        // Arrange
        var source = Substitute.For<IDataReader>();
        source.FieldCount.Returns(2);
        source.GetName(0).Returns("A");
        source.GetName(1).Returns("B");
        var nestedReader = Substitute.For<IDataReader>();
        source.GetData(1).Returns(nestedReader);
        var transformer = new PassThroughTransformer();
        var reader = transformer.Transform(source);

        // Act
        var result = reader.GetData(1);

        // Assert
        Assert.Same(nestedReader, result);
        source.Received(1).GetData(1);
    }

    [Fact]
    public void GetDataTypeName_NonComputedColumn_DelegatesToSource()
    {
        // Arrange
        var source = Substitute.For<IDataReader>();
        source.FieldCount.Returns(2);
        source.GetName(0).Returns("A");
        source.GetName(1).Returns("B");
        source.GetDataTypeName(1).Returns("nvarchar");
        var transformer = new PassThroughTransformer();
        var reader = transformer.Transform(source);

        // Act
        var result = reader.GetDataTypeName(1);

        // Assert
        Assert.Equal("nvarchar", result);
        source.Received(1).GetDataTypeName(1);
    }

    private class PassThroughTransformer : DataTransformerBase
    {
        public override string TransformerName => "PassThrough";
    }

    private class ComputedColumnTransformer : DataTransformerBase
    {
        public override string TransformerName => "Computed";
        public override int MapOrdinal(int ordinal, IDataReader source) => ordinal == 0 ? -1 : ordinal;
    }
}