using DocumentService.Application.Common.DTOs;
using DocumentService.Application.Common.Interfaces;
using DocumentService.Application.ValidatePdfA.Queries;
using DocumentService.Domain.Common.Exceptions;
using FluentAssertions;
using Moq;
using Xunit;

namespace DocumentService.Tests.Unit.Application.Features.ValidatePdfA;

public class ValidatePdfAQueryHandlerTests
{
    private readonly Mock<IPdfProcessor> _mockPdfProcessor;
    private readonly ValidatePdfAQueryHandler _handler;

    public ValidatePdfAQueryHandlerTests()
    {
        _mockPdfProcessor = new Mock<IPdfProcessor>();
        _handler = new ValidatePdfAQueryHandler(_mockPdfProcessor.Object);
    }

    [Fact]
    public async Task Handle_ValidCompliantPdfA_ReturnsCompliantResult()
    {
        // Arrange
        var query = new ValidatePdfAQuery { PdfStream = new MemoryStream("%PDF"u8.ToArray()) };
        var expected = new PdfAValidationResult
        {
            IsValid = true, PdfVersion = "1.7", PageCount = 3, FileSize = 2048,
            Encrypted = false, PdfAVersion = "PDF/A-3b", PdfACompliant = true,
            Errors = [], Warnings = []
        };

        _mockPdfProcessor.Setup(x => x.ValidatePdfAAsync(It.IsAny<Stream>())).ReturnsAsync(expected);

        // Act
        var result = await _handler.Handle(query, CancellationToken.None);

        // Assert
        result.IsValid.Should().BeTrue();
        result.PageCount.Should().Be(3);
        result.PdfVersion.Should().Be("1.7");
        result.PdfAVersion.Should().Be("PDF/A-3b");
        result.PdfACompliant.Should().BeTrue();
        result.Encrypted.Should().BeFalse();
        result.Errors.Should().BeEmpty();
        result.Warnings.Should().BeEmpty();
        _mockPdfProcessor.Verify(x => x.ValidatePdfAAsync(It.IsAny<Stream>()), Times.Once);
    }

    [Fact]
    public async Task Handle_NonCompliantPdfA_ReturnsErrorsAndWarnings()
    {
        // Arrange
        var query = new ValidatePdfAQuery { PdfStream = new MemoryStream("%PDF"u8.ToArray()) };
        var expected = new PdfAValidationResult
        {
            IsValid = false, PdfVersion = "1.4", PageCount = 2, FileSize = 1024,
            Encrypted = false, PdfAVersion = null, PdfACompliant = false,
            Errors = ["Missing XMP metadata", "Invalid color space"],
            Warnings = ["Embedded font not subset"]
        };

        _mockPdfProcessor.Setup(x => x.ValidatePdfAAsync(It.IsAny<Stream>())).ReturnsAsync(expected);

        // Act
        var result = await _handler.Handle(query, CancellationToken.None);

        // Assert
        result.IsValid.Should().BeFalse();
        result.PdfACompliant.Should().BeFalse();
        result.PdfAVersion.Should().BeNull();
        result.Errors.Should().HaveCount(2).And.Contain("Missing XMP metadata").And.Contain("Invalid color space");
        result.Warnings.Should().HaveCount(1).And.Contain("Embedded font not subset");
        _mockPdfProcessor.Verify(x => x.ValidatePdfAAsync(It.IsAny<Stream>()), Times.Once);
    }

    [Fact]
    public async Task Handle_EncryptedPdf_ReturnsEncryptedFlagAndErrors()
    {
        // Arrange
        var query = new ValidatePdfAQuery { PdfStream = new MemoryStream("%PDF"u8.ToArray()) };
        var expected = new PdfAValidationResult
        {
            IsValid = false, PdfVersion = "1.7", PageCount = 1, FileSize = 512,
            Encrypted = true, PdfAVersion = null, PdfACompliant = false,
            Errors = ["PDF/A documents cannot be encrypted"],
            Warnings = []
        };

        _mockPdfProcessor.Setup(x => x.ValidatePdfAAsync(It.IsAny<Stream>())).ReturnsAsync(expected);

        // Act
        var result = await _handler.Handle(query, CancellationToken.None);

        // Assert
        result.Encrypted.Should().BeTrue();
        result.IsValid.Should().BeFalse();
        result.PdfACompliant.Should().BeFalse();
        result.Errors.Should().Contain("PDF/A documents cannot be encrypted");
        _mockPdfProcessor.Verify(x => x.ValidatePdfAAsync(It.IsAny<Stream>()), Times.Once);
    }

    [Fact]
    public async Task Handle_ProcessorThrowsBadRequest_PropagatesException()
    {
        // Arrange
        var query = new ValidatePdfAQuery { PdfStream = new MemoryStream("%PDF"u8.ToArray()) };
        _mockPdfProcessor.Setup(x => x.ValidatePdfAAsync(It.IsAny<Stream>()))
            .ThrowsAsync(new BadRequestException("Invalid PDF format"));

        // Act & Assert
        var ex = await Assert.ThrowsAsync<BadRequestException>(
            () => _handler.Handle(query, CancellationToken.None));
        ex.Message.Should().Be("Invalid PDF format");
    }

    [Fact]
    public async Task Handle_ProcessorThrowsGenericException_PropagatesException()
    {
        // Arrange
        var query = new ValidatePdfAQuery { PdfStream = new MemoryStream("%PDF"u8.ToArray()) };
        _mockPdfProcessor.Setup(x => x.ValidatePdfAAsync(It.IsAny<Stream>()))
            .ThrowsAsync(new Exception("Unexpected processing error"));

        // Act & Assert
        await Assert.ThrowsAsync<Exception>(() => _handler.Handle(query, CancellationToken.None));
    }
}