using LehrerApp.Core.Importing;
using LehrerApp.Core.Models;
using LehrerApp.Core.Services;
using LehrerApp.Desktop.ViewModels.Students;
using Xunit;

namespace LehrerApp.Desktop.Tests;

public sealed class StudentImportDialogViewModelTests
{
    [Fact]
    public async Task Vorschau_ZeigtZusammenfassungUndImportiertNeueSchueler()
    {
        var stored = new List<Student>();
        var service = Service(stored,
        [
            new ImportedStudent
            {
                FirstName = "Max",
                LastName = "Beispiel",
                Gender = Gender.M,
            },
        ]);
        var preview = await service.AnalyzeAsync(File());
        var vm = new StudentImportDialogViewModel(service, preview, "students.csv");

        Assert.Contains("1 erkannt", vm.Summary);
        Assert.Equal(1, vm.NewStudents);
        Assert.True(vm.IsReadyWithoutConflicts);

        Assert.True(await vm.TryApplyAsync());
        Assert.Equal(1, vm.Result?.CreatedStudents);
        Assert.Single(stored);
    }

    [Fact]
    public async Task Konflikt_VerwendetDieSichereStandardoptionUeberspringen()
    {
        var stored = new List<Student>
        {
            new() { FirstName = "Max", LastName = "Beispiel" },
        };
        var service = Service(stored,
        [
            new ImportedStudent { FirstName = "Max", LastName = "Beispiel" },
        ]);
        var preview = await service.AnalyzeAsync(File());
        var vm = new StudentImportDialogViewModel(service, preview, "students.csv");

        var conflict = Assert.Single(vm.Conflicts);
        Assert.Equal("skip", conflict.SelectedOption.Id);
        Assert.Equal("skip", Assert.Single(vm.BuildDecisions()).SelectedOptionId);

        Assert.True(await vm.TryApplyAsync());
        Assert.Equal(1, vm.Result?.SkippedStudents);
        Assert.Single(stored);
    }

    private static StudentImportService Service(
        List<Student> stored,
        IReadOnlyList<ImportedStudent> imported) => new(
        [new FakeImportHandler(imported)],
        new FakeStudents(stored),
        new FakeGroups([]),
        new FakeMemberships([]),
        new SchoolYearService());

    private static ImportFile File() => new("students.csv", "test"u8.ToArray());

    private sealed class FakeImportHandler(IReadOnlyList<ImportedStudent> imported)
        : IImportHandler<ImportedStudent>
    {
        public ImportFormatId FormatId { get; } = new("test.students");
        public string DisplayName => "Testformat";
        public IReadOnlyCollection<string> SupportedExtensions { get; } = [".csv"];

        public ValueTask<ImportDetection> DetectAsync(
            ImportFile file,
            CancellationToken cancellationToken = default) =>
            ValueTask.FromResult(ImportDetection.Match(100));

        public ValueTask<ImportParseResult<ImportedStudent>> ParseAsync(
            ImportFile file,
            CancellationToken cancellationToken = default) =>
            ValueTask.FromResult(new ImportParseResult<ImportedStudent>(imported));
    }
}