using DocumentService.Client.Clients;
using DocumentService.Client.Interfaces;
using FluentAssertions;
using Microsoft.Extensions.Logging.Abstractions;
using System.Net;
using System.Net.Http;
using System.Text.Json;
using Xunit;

namespace DocumentService.Tests.Unit.Client;

public class PdfValidationClientTests
{
    private static (PdfValidationClient client, MockHttpMessageHandler handler) Build<T>(T responseBody)
    {
        var handler = MockHttpMessageHandler.ReturningJson(responseBody);
        var httpClient = new HttpClient(handler) { BaseAddress = new Uri("http://localhost") };
        return (new PdfValidationClient(httpClient, NullLogger<PdfValidationClient>.Instance), handler);
    }

    private static (PdfValidationClient client, MockHttpMessageHandler handler) BuildError(HttpStatusCode code)
    {
        var handler = MockHttpMessageHandler.ReturningStatus(code);
        var httpClient = new HttpClient(handler) { BaseAddress = new Uri("http://localhost") };
        return (new PdfValidationClient(httpClient, NullLogger<PdfValidationClient>.Instance), handler);
    }

    private static byte[] FakePdfBytes() => "fake-pdf"u8.ToArray();

    // ── ValidatePdfAsync (Stream) ────────────────────────────────────────────

    [Fact]
    public async Task ValidatePdfAsync_Stream_SendsMultipartPost()
    {
        var expected = new PdfValidationResult { PageCount = 3, PdfVersion = "1.7", FileSizeBytes = 2048, IsEncrypted = false };
        var (client, handler) = Build(expected);

        var result = await client.ValidatePdfAsync(new MemoryStream(FakePdfBytes()));

        result.PageCount.Should().Be(3);
        result.PdfVersion.Should().Be("1.7");
        result.FileSizeBytes.Should().Be(2048);
        result.IsEncrypted.Should().BeFalse();
        handler.LastRequest!.Method.Should().Be(HttpMethod.Post);
        handler.LastRequest.RequestUri!.PathAndQuery.Should().Be("/api/pdf/validation/validate");
        handler.LastRequest.Content.Should().BeOfType<MultipartFormDataContent>();
    }

    [Fact]
    public async Task ValidatePdfAsync_Stream_EncryptedPdf_DeserializesIsEncryptedTrue()
    {
        var expected = new PdfValidationResult { PageCount = 1, IsEncrypted = true, PdfVersion = "1.6" };
        var (client, _) = Build(expected);

        var result = await client.ValidatePdfAsync(new MemoryStream(FakePdfBytes()));

        result.IsEncrypted.Should().BeTrue("encrypted PDFs should surface IsEncrypted=true");
    }

    [Fact]
    public async Task ValidatePdfAsync_Stream_ThrowsWhenApiReturnsNull()
    {
        var handler = MockHttpMessageHandler.ReturningJson<PdfValidationResult?>(null);
        var httpClient = new HttpClient(handler) { BaseAddress = new Uri("http://localhost") };
        var client = new PdfValidationClient(httpClient, NullLogger<PdfValidationClient>.Instance);

        await client.Invoking(c => c.ValidatePdfAsync(new MemoryStream(FakePdfBytes())))
            .Should().ThrowAsync<InvalidOperationException>();
    }

    [Fact]
    public async Task ValidatePdfAsync_Stream_WhenApiReturns400_ThrowsHttpRequestException()
    {
        var (client, _) = BuildError(HttpStatusCode.BadRequest);
        await client.Invoking(c => c.ValidatePdfAsync(new MemoryStream(FakePdfBytes())))
            .Should().ThrowAsync<HttpRequestException>();
    }

    [Fact]
    public async Task ValidatePdfAsync_Stream_WhenApiReturns500_ThrowsHttpRequestException()
    {
        var (client, _) = BuildError(HttpStatusCode.InternalServerError);
        await client.Invoking(c => c.ValidatePdfAsync(new MemoryStream(FakePdfBytes())))
            .Should().ThrowAsync<HttpRequestException>();
    }

    // ── ValidatePdfAsync (byte[]) ────────────────────────────────────────────

    [Fact]
    public async Task ValidatePdfAsync_Bytes_SendsJsonWithBase64()
    {
        var expected = new PdfValidationResult { PageCount = 1, IsEncrypted = false, HasAttachments = true, AttachmentCount = 2 };
        var (client, handler) = Build(expected);

        var result = await client.ValidatePdfAsync(FakePdfBytes());

        result.PageCount.Should().Be(1);
        result.HasAttachments.Should().BeTrue();
        result.AttachmentCount.Should().Be(2);
        handler.LastRequest!.Content!.Headers.ContentType!.MediaType.Should().Be("application/json");
        var body = await handler.LastRequest.Content!.ReadAsStringAsync();
        var doc = JsonDocument.Parse(body);
        doc.RootElement.GetProperty("base64Pdf").GetString().Should().NotBeNullOrEmpty();
    }

    [Fact]
    public async Task ValidatePdfAsync_Bytes_WhenApiReturns400_ThrowsHttpRequestException()
    {
        var (client, _) = BuildError(HttpStatusCode.BadRequest);
        await client.Invoking(c => c.ValidatePdfAsync(FakePdfBytes()))
            .Should().ThrowAsync<HttpRequestException>();
    }

    // ── ValidatePdfAAsync (Stream) ───────────────────────────────────────────

    [Fact]
    public async Task ValidatePdfAAsync_Stream_DeserializesAllFields()
    {
        var expected = new PdfAValidationResult
        {
            IsValid = true, PdfAVersion = "PDF/A-3b", PageCount = 2,
            Errors = [], Warnings = []
        };
        var (client, handler) = Build(expected);

        var result = await client.ValidatePdfAAsync(new MemoryStream(FakePdfBytes()));

        result.IsValid.Should().BeTrue();
        result.PdfAVersion.Should().Be("PDF/A-3b");
        result.PageCount.Should().Be(2);
        result.Errors.Should().BeEmpty();
        handler.LastRequest!.RequestUri!.PathAndQuery.Should().Be("/api/pdf/validation/validate-pdfa");
        handler.LastRequest.Content.Should().BeOfType<MultipartFormDataContent>();
    }

    [Fact]
    public async Task ValidatePdfAAsync_Stream_NonCompliant_ReturnsErrors()
    {
        var expected = new PdfAValidationResult
        {
            IsValid = false,
            Errors = ["Missing embedded font", "Encryption not allowed"],
            Warnings = ["Manual verification recommended"]
        };
        var (client, _) = Build(expected);

        var result = await client.ValidatePdfAAsync(new MemoryStream(FakePdfBytes()));

        result.IsValid.Should().BeFalse();
        result.Errors.Should().HaveCount(2).And.Contain("Missing embedded font");
        result.Warnings.Should().HaveCount(1);
    }

    [Fact]
    public async Task ValidatePdfAAsync_Stream_WhenApiReturns400_ThrowsHttpRequestException()
    {
        var (client, _) = BuildError(HttpStatusCode.BadRequest);
        await client.Invoking(c => c.ValidatePdfAAsync(new MemoryStream(FakePdfBytes())))
            .Should().ThrowAsync<HttpRequestException>();
    }

    // ── ValidatePdfAAsync (byte[]) ───────────────────────────────────────────

    [Fact]
    public async Task ValidatePdfAAsync_Bytes_SendsJsonToCorrectEndpoint()
    {
        var expected = new PdfAValidationResult { IsValid = true };
        var (client, handler) = Build(expected);

        await client.ValidatePdfAAsync(FakePdfBytes());

        handler.LastRequest!.RequestUri!.PathAndQuery.Should().Be("/api/pdf/validation/validate-pdfa");
        handler.LastRequest.Content!.Headers.ContentType!.MediaType.Should().Be("application/json");
    }

    [Fact]
    public async Task ValidatePdfAAsync_Bytes_WhenApiReturns500_ThrowsHttpRequestException()
    {
        var (client, _) = BuildError(HttpStatusCode.InternalServerError);
        await client.Invoking(c => c.ValidatePdfAAsync(FakePdfBytes()))
            .Should().ThrowAsync<HttpRequestException>();
    }
}