using QuestionsApi.Services.Flashcards;
using Xunit;

namespace QuestionsApi.Tests;

public sealed class FlashcardSchedulingTests
{
    [Fact]
    public void NextStudyDayStart_IsMidnightOfTheFollowingDay()
    {
        var studyDayStart = new DateTime(2026, 3, 5, 0, 0, 0, DateTimeKind.Utc);

        var next = FlashcardScheduling.NextStudyDayStart(studyDayStart);

        Assert.Equal(new DateTime(2026, 3, 6, 0, 0, 0, DateTimeKind.Utc), next);
    }

    [Fact]
    public void NextStudyDayStart_TruncatesTimeOfDayBeforeAdvancing()
    {
        // A session that started mid-day still buries siblings until the *next calendar day*,
        // not exactly 24h later.
        var studyDayStart = new DateTime(2026, 3, 5, 14, 30, 0, DateTimeKind.Utc);

        var next = FlashcardScheduling.NextStudyDayStart(studyDayStart);

        Assert.Equal(new DateTime(2026, 3, 6, 0, 0, 0, DateTimeKind.Utc), next);
    }

    [Theory]
    [InlineData(20, null, 0, 20)]
    [InlineData(20, null, 15, 5)]
    [InlineData(20, null, 25, 0)]
    [InlineData(20, 5, 0, 5)]
    [InlineData(20, 0, 0, 0)]
    public void ResolveDailyBudget_DeckOverrideWinsOverGlobal_ClampedAtZero(
        int globalLimit, int? deckOverride, int consumedToday, int expected)
    {
        Assert.Equal(expected, FlashcardScheduling.ResolveDailyBudget(globalLimit, deckOverride, consumedToday));
    }
}