using System.Threading.Channels;
using Novelly.Api.Imports;
using Novelly.Api.Projects;

namespace Novelly.Api.Tests;

[TestFixture]
public class ImportServiceTests : ServiceTestFixture
{
    private string _root = null!;
    private Channel<Guid> _queue = null!;
    private ImportService _imports = null!;

    protected override void OnSetUp()
    {
        _root = Directory.CreateTempSubdirectory("novelly-import-test-").FullName;
        _queue = Channel.CreateUnbounded<Guid>();
        _imports = new ImportService(
            Db.Context,
            Projects,
            _queue,
            new CapturingLogger<ImportService>(),
            new InspectImportRequestValidator(),
            new StartImportRequestValidator());
    }

    [TearDown]
    public void CleanUpTempFolder()
    {
        if (Directory.Exists(_root))
        {
            Directory.Delete(_root, recursive: true);
        }
    }

    [Test]
    public async Task Inspecting_a_folder_with_no_ledger_reports_fresh()
    {
        WriteChapterFiles(3);

        var inspection = await _imports.InspectAsync(new InspectImportRequest(_root));

        Assert.Multiple(() =>
        {
            Assert.That(inspection.Readiness, Is.EqualTo(ImportReadiness.Fresh));
            Assert.That(inspection.ProjectId, Is.Null);
            Assert.That(inspection.ChaptersTotal, Is.EqualTo(3));
            Assert.That(inspection.ChaptersCompleted, Is.EqualTo(0));
        });
    }

    [Test]
    public async Task Inspecting_a_folder_with_an_incomplete_ledger_reports_resumable()
    {
        WriteChapterFiles(3);
        WriteLedger("""{"projectId": "11111111-1111-1111-1111-111111111111", "completedPasses": ["project"], "completedChapters": [1]}""");

        var inspection = await _imports.InspectAsync(new InspectImportRequest(_root));

        Assert.Multiple(() =>
        {
            Assert.That(inspection.Readiness, Is.EqualTo(ImportReadiness.Resumable));
            Assert.That(inspection.ChaptersCompleted, Is.EqualTo(1));
            Assert.That(inspection.ChaptersTotal, Is.EqualTo(3));
        });
    }

    [Test]
    public async Task Inspecting_a_folder_whose_ledger_covers_every_pass_and_chapter_reports_complete()
    {
        WriteChapterFiles(2);
        WriteLedger("""
            {
              "projectId": "11111111-1111-1111-1111-111111111111",
              "completedPasses": ["project", "characters", "chapters", "arcs"],
              "completedChapters": [1, 2]
            }
            """);

        var inspection = await _imports.InspectAsync(new InspectImportRequest(_root));

        Assert.That(inspection.Readiness, Is.EqualTo(ImportReadiness.Complete));
    }

    [Test]
    public async Task Starting_an_import_enqueues_a_pending_job()
    {
        var job = await _imports.StartOrResumeAsync(new StartImportRequest(_root));

        Assert.Multiple(() =>
        {
            Assert.That(job.Status, Is.EqualTo(ImportJobStatus.Pending));
            Assert.That(job.SourceRoot, Is.EqualTo(_root));
        });

        Assert.That(_queue.Reader.TryRead(out var queued), Is.True);
        Assert.That(queued, Is.EqualTo(job.Id));
    }

    [Test]
    public async Task Starting_an_import_a_second_time_reuses_the_pending_job_instead_of_duplicating_it()
    {
        var first = await _imports.StartOrResumeAsync(new StartImportRequest(_root));
        var second = await _imports.StartOrResumeAsync(new StartImportRequest(_root));

        Assert.That(second.Id, Is.EqualTo(first.Id));

        // Only one job was ever queued.
        Assert.That(_queue.Reader.TryRead(out _), Is.True);
        Assert.That(_queue.Reader.TryRead(out _), Is.False);
    }

    [Test]
    public async Task Force_restarting_a_completed_import_deletes_the_ledger_and_its_project()
    {
        var project = await Projects.CreateAsync(new CreateProjectRequest("The Blade Itself"));
        WriteLedger($$"""{"projectId": "{{project.Id}}", "completedPasses": ["project", "characters", "chapters", "arcs"], "completedChapters": [1]}""");

        await _imports.StartOrResumeAsync(new StartImportRequest(_root, ForceRestart: true));

        Assert.Multiple(() =>
        {
            Assert.That(File.Exists(Path.Combine(_root, ".novelly-import.json")), Is.False);
            Assert.That(Projects.GetAsync(project.Id).Result, Is.Null);
        });
    }

    private void WriteChapterFiles(int count)
    {
        var outlines = Path.Combine(_root, "outlines");
        Directory.CreateDirectory(outlines);
        for (var i = 1; i <= count; i++)
        {
            File.WriteAllText(Path.Combine(outlines, $"{i:D2}-chapter.md"), $"# Chapter {i}");
        }
    }

    private void WriteLedger(string json) =>
        File.WriteAllText(Path.Combine(_root, ".novelly-import.json"), json);
}