using DocumentService.Application.Common.DTOs;
using DocumentService.Client.Clients;
using DocumentService.Client.Interfaces;
using FluentAssertions;
using Moq;
using System.Net.Http;
using System.Reflection;

namespace DocumentService.Tests.Unit.Client;

/// <summary>
/// Unit tests for <see cref="WorkflowsClient"/>.
/// Both <see cref="IPdfValidationClient"/> and <see cref="ISwissQrCodeClient"/> are mocked –
/// no real HTTP calls are made. Tests cover every overload, every branch, and all edge cases.
/// </summary>
public class WorkflowsClientTests
{
    // ─── test doubles ────────────────────────────────────────────────────────

    private readonly Mock<IPdfValidationClient> _validation = new();
    private readonly Mock<ISwissQrCodeClient>   _swissQrCode = new();
    private WorkflowsClient Sut => new(_validation.Object, _swissQrCode.Object);
    // Extension methods are defined on IWorkflowsClient — use this for filePath overload tests.
    private IWorkflowsClient SutAsInterface => Sut;

    // ─── fixture data ─────────────────────────────────────────────────────────

    private static byte[] ValidPdfBytes()    => LoadTestPdf("valid.pdf");
    private static byte[] EncryptedPdfBytes() => LoadTestPdf("encryptedPdf.pdf");
    private static byte[] QrPdfBytes()       => LoadTestPdf("pdfWithSwissQRCode.pdf");

    private static byte[] LoadTestPdf(string filename)
    {
        var assembly = Assembly.GetExecutingAssembly();
        var resourceName = $"DocumentService.Tests.TestData.Pdfs.{filename}";
        using var stream = assembly.GetManifestResourceStream(resourceName)
            ?? throw new FileNotFoundException(
                $"Embedded resource '{resourceName}' not found. " +
                $"Available: {string.Join(", ", assembly.GetManifestResourceNames())}");
        using var ms = new MemoryStream();
        stream.CopyTo(ms);
        return ms.ToArray();
    }

    // ─── valid PdfValidationResult helpers ───────────────────────────────────

    private static PdfValidationResult ValidResult() =>
        new(PageCount: 1, FileSizeBytes: 1024, FileSizeMB: 0.001,
            PdfVersion: "1.4", HasAttachments: false, AttachmentCount: 0,
            IsEncrypted: false);

    private static PdfValidationResult InvalidResult_Encrypted() =>
        new(PageCount: 1, FileSizeBytes: 1024, FileSizeMB: 0.001,
            PdfVersion: "1.4", HasAttachments: false, AttachmentCount: 0,
            IsEncrypted: true);

    private static PdfValidationResult InvalidResult_EmptyFile() =>
        new(PageCount: 0, FileSizeBytes: 0, FileSizeMB: 0,
            PdfVersion: "", HasAttachments: false, AttachmentCount: 0,
            IsEncrypted: false);

    private static SwissQrCodeExtractionResult QrResult() =>
        new(
            Bill: new SwissQrBillDto
            {
                Version      = "V2_0",
                Currency     = "CHF",
                Amount       = 630.20m,
                Account      = "CH9300762011623852957",
                Creditor     = new AddressDto { Name = "ALMAT AG", Town = "Tagelswangen", CountryCode = "CH", Type = "S", PostalCode = "8317" },
                ReferenceType = "QRR",
                Reference    = "000000000000000000252080824"
            },
            RawLines: ["SPC", "0200", "1"]
        );

    private static SwissQrCodeExtractionResult RawQrResult() =>
        new(Bill: (SwissQrBillDto?)null, RawLines: ["SPC", "0200", "1", "CH9300762011623852957"]);


    [Fact]
    public async Task Inspect_Bytes_ValidPdf_ReturnsBothValidationAndQrCode()
    {
        // Arrange
        var pdfBytes = ValidPdfBytes();
        _validation.Setup(v => v.ValidateAsync(pdfBytes, It.IsAny<CancellationToken>()))
                   .ReturnsAsync(ValidResult());
        _swissQrCode.Setup(q => q.ExtractAsync(pdfBytes, false, It.IsAny<CancellationToken>()))
                    .ReturnsAsync(QrResult());

        // Act
        var result = await Sut.InspectSwissQrCodeAsync(pdfBytes);

        // Assert
        result.Validation.IsValid.Should().BeTrue();
        result.QrCode.Should().NotBeNull();
        result.QrCode!.Bill!.Currency.Should().Be("CHF");
        _validation.Verify(v => v.ValidateAsync(pdfBytes, It.IsAny<CancellationToken>()), Times.Once);
        _swissQrCode.Verify(q => q.ExtractAsync(pdfBytes, false, It.IsAny<CancellationToken>()), Times.Once);
    }

    [Fact]
    public async Task Inspect_Bytes_InvalidPdf_ReturnsValidationWithNullQrCode_NeverThrows()
    {
        // Arrange
        var pdfBytes = EncryptedPdfBytes();
        _validation.Setup(v => v.ValidateAsync(pdfBytes, It.IsAny<CancellationToken>()))
                   .ReturnsAsync(InvalidResult_Encrypted());

        // Act
        var result = await Sut.InspectSwissQrCodeAsync(pdfBytes);

        // Assert – no exception, validation details always available
        result.Validation.IsValid.Should().BeFalse();
        result.Validation.IsEncrypted.Should().BeTrue();
        result.QrCode.Should().BeNull("extraction must not run on an invalid document");
        _swissQrCode.Verify(q => q.ExtractAsync(It.IsAny<byte[]>(), It.IsAny<bool>(), It.IsAny<CancellationToken>()), Times.Never);
    }

    [Fact]
    public async Task Inspect_Bytes_ValidationAlwaysPopulated_RegardlessOfQrOutcome()
    {
        // Arrange – valid PDF but QR extraction returns empty lines (no QR code found)
        var pdfBytes = ValidPdfBytes();
        var emptyQr = new SwissQrCodeExtractionResult(Bill: (SwissQrBillDto?)null, RawLines: []);
        _validation.Setup(v => v.ValidateAsync(pdfBytes, It.IsAny<CancellationToken>()))
                   .ReturnsAsync(ValidResult());
        _swissQrCode.Setup(q => q.ExtractAsync(pdfBytes, false, It.IsAny<CancellationToken>()))
                    .ReturnsAsync(emptyQr);

        // Act
        var result = await Sut.InspectSwissQrCodeAsync(pdfBytes);

        // Assert – validation is always there even when QR is empty
        result.Validation.Should().NotBeNull();
        result.Validation.PageCount.Should().Be(1);
        result.QrCode.Should().NotBeNull(); // extraction was attempted
    }

    [Fact]
    public async Task Inspect_Bytes_RawMode_PassesRawFlagToExtraction()
    {
        // Arrange
        var pdfBytes = QrPdfBytes();
        _validation.Setup(v => v.ValidateAsync(pdfBytes, It.IsAny<CancellationToken>()))
                   .ReturnsAsync(ValidResult());
        _swissQrCode.Setup(q => q.ExtractAsync(pdfBytes, true, It.IsAny<CancellationToken>()))
                    .ReturnsAsync(RawQrResult());

        // Act
        var result = await Sut.InspectSwissQrCodeAsync(pdfBytes, raw: true);

        // Assert
        result.QrCode!.RawLines.Should().Contain("SPC");
        _swissQrCode.Verify(q => q.ExtractAsync(pdfBytes, true, It.IsAny<CancellationToken>()), Times.Once);
    }

    [Fact]
    public async Task Inspect_Bytes_CancellationToken_ForwardedToBothClients()
    {
        // Arrange
        var pdfBytes = ValidPdfBytes();
        var cts = new CancellationTokenSource();
        var token = cts.Token;
        _validation.Setup(v => v.ValidateAsync(pdfBytes, token)).ReturnsAsync(ValidResult());
        _swissQrCode.Setup(q => q.ExtractAsync(pdfBytes, false, token)).ReturnsAsync(QrResult());

        // Act
        await Sut.InspectSwissQrCodeAsync(pdfBytes, cancellationToken: token);

        // Assert
        _validation.Verify(v => v.ValidateAsync(pdfBytes, token), Times.Once);
        _swissQrCode.Verify(q => q.ExtractAsync(pdfBytes, false, token), Times.Once);
    }

    [Fact]
    public async Task Inspect_Stream_ValidPdf_ReturnsBothResults()
    {
        // Arrange
        _validation.Setup(v => v.ValidateAsync(It.IsAny<Stream>(), It.IsAny<CancellationToken>()))
                   .ReturnsAsync(ValidResult());
        _swissQrCode.Setup(q => q.ExtractAsync(It.IsAny<Stream>(), false, It.IsAny<CancellationToken>()))
                    .ReturnsAsync(QrResult());

        using var pdfStream = new MemoryStream(ValidPdfBytes());

        // Act
        var result = await Sut.InspectSwissQrCodeAsync(pdfStream);

        // Assert
        result.Validation.IsValid.Should().BeTrue();
        result.QrCode.Should().NotBeNull();
    }

    [Fact]
    public async Task Inspect_Stream_InvalidPdf_ReturnsValidationWithNullQrCode_NeverThrows()
    {
        // Arrange
        _validation.Setup(v => v.ValidateAsync(It.IsAny<Stream>(), It.IsAny<CancellationToken>()))
                   .ReturnsAsync(InvalidResult_Encrypted());

        using var pdfStream = new MemoryStream(EncryptedPdfBytes());

        // Act
        var result = await Sut.InspectSwissQrCodeAsync(pdfStream);

        // Assert
        result.Validation.IsValid.Should().BeFalse();
        result.QrCode.Should().BeNull();
        _swissQrCode.Verify(q => q.ExtractAsync(It.IsAny<Stream>(), It.IsAny<bool>(), It.IsAny<CancellationToken>()), Times.Never);
    }

    [Fact]
    public async Task Inspect_FilePath_ValidPdf_ReturnsBothResults()
    {
        // Arrange – extension opens a FileStream so mock expects Stream overload
        var tempPath = Path.GetTempFileName();
        try
        {
            await File.WriteAllBytesAsync(tempPath, ValidPdfBytes());
            _validation.Setup(v => v.ValidateAsync(It.IsAny<Stream>(), It.IsAny<CancellationToken>()))
                       .ReturnsAsync(ValidResult());
            _swissQrCode.Setup(q => q.ExtractAsync(It.IsAny<Stream>(), false, It.IsAny<CancellationToken>()))
                        .ReturnsAsync(QrResult());

            // Act – calls extension method which opens a FileStream and delegates to Stream overload
            var result = await SutAsInterface.InspectSwissQrCodeAsync(tempPath);

            // Assert
            result.Validation.IsValid.Should().BeTrue();
            result.QrCode.Should().NotBeNull();
        }
        finally { File.Delete(tempPath); }
    }

    [Fact]
    public async Task Inspect_FilePath_InvalidPdf_ReturnsValidationWithNullQrCode_NeverThrows()
    {
        // Arrange
        var tempPath = Path.GetTempFileName();
        try
        {
            await File.WriteAllBytesAsync(tempPath, EncryptedPdfBytes());
            _validation.Setup(v => v.ValidateAsync(It.IsAny<Stream>(), It.IsAny<CancellationToken>()))
                       .ReturnsAsync(InvalidResult_Encrypted());

            // Act
            var result = await SutAsInterface.InspectSwissQrCodeAsync(tempPath);

            // Assert – never throws, validation details always populated
            result.Validation.IsValid.Should().BeFalse();
            result.QrCode.Should().BeNull();
        }
        finally { File.Delete(tempPath); }
    }

}