using ClaudeDo.Worker.Prime;

namespace ClaudeDo.Worker.Tests.Prime;

public class NextDueCalculatorTests
{
    private static PrimeScheduleDto Schedule(
        DateOnly start, DateOnly end, TimeSpan time,
        bool workdaysOnly = true, bool enabled = true, DateTimeOffset? lastRun = null) =>
        new(Guid.NewGuid(), start, end, time, workdaysOnly, enabled, lastRun, null);

    [Fact]
    public void Disabled_Schedule_Returns_Null()
    {
        var now = new DateTimeOffset(2026, 5, 5, 6, 0, 0, TimeSpan.FromHours(2));
        var s = Schedule(new(2026,5,1), new(2026,5,31), new(7,0,0), enabled: false);
        Assert.Null(NextDueCalculator.Compute(new[]{s}, now, TimeSpan.FromMinutes(30)));
    }

    [Fact]
    public void Future_Same_Day_Returns_Today_At_Target()
    {
        var now = new DateTimeOffset(2026, 5, 5, 6, 0, 0, TimeSpan.FromHours(2));
        var s = Schedule(new(2026,5,1), new(2026,5,31), new(7,0,0));
        var r = NextDueCalculator.Compute(new[]{s}, now, TimeSpan.FromMinutes(30));
        Assert.NotNull(r);
        Assert.Equal(new DateTimeOffset(2026,5,5,7,0,0, now.Offset), r!.At);
        Assert.False(r.FireImmediately);
    }

    [Fact]
    public void Within_CatchUp_Window_Fires_Immediately()
    {
        var now = new DateTimeOffset(2026, 5, 5, 7, 15, 0, TimeSpan.FromHours(2));
        var s = Schedule(new(2026,5,1), new(2026,5,31), new(7,0,0));
        var r = NextDueCalculator.Compute(new[]{s}, now, TimeSpan.FromMinutes(30));
        Assert.NotNull(r);
        Assert.True(r!.FireImmediately);
    }

    [Fact]
    public void Past_CatchUp_Window_Skips_To_Next_Eligible_Day()
    {
        var now = new DateTimeOffset(2026, 5, 5, 9, 0, 0, TimeSpan.FromHours(2));
        var s = Schedule(new(2026,5,1), new(2026,5,31), new(7,0,0));
        var r = NextDueCalculator.Compute(new[]{s}, now, TimeSpan.FromMinutes(30));
        Assert.NotNull(r);
        Assert.Equal(new DateOnly(2026,5,6), DateOnly.FromDateTime(r!.At.LocalDateTime));
    }

    [Fact]
    public void WorkdaysOnly_Skips_Weekend()
    {
        var now = new DateTimeOffset(2026, 5, 8, 8, 0, 0, TimeSpan.FromHours(2));
        var s = Schedule(new(2026,5,1), new(2026,5,31), new(7,0,0), workdaysOnly: true);
        var r = NextDueCalculator.Compute(new[]{s}, now, TimeSpan.FromMinutes(30));
        Assert.NotNull(r);
        Assert.Equal(DayOfWeek.Monday, r!.At.LocalDateTime.DayOfWeek);
        Assert.Equal(new DateOnly(2026,5,11), DateOnly.FromDateTime(r.At.LocalDateTime));
    }

    [Fact]
    public void Already_Fired_Today_Skips_To_Tomorrow()
    {
        var now = new DateTimeOffset(2026, 5, 5, 6, 0, 0, TimeSpan.FromHours(2));
        var lastRun = new DateTimeOffset(2026, 5, 5, 7, 1, 0, TimeSpan.FromHours(2));
        var s = Schedule(new(2026,5,1), new(2026,5,31), new(7,0,0), lastRun: lastRun);
        var r = NextDueCalculator.Compute(new[]{s}, now, TimeSpan.FromMinutes(30));
        Assert.NotNull(r);
        Assert.Equal(new DateOnly(2026,5,6), DateOnly.FromDateTime(r!.At.LocalDateTime));
    }

    [Fact]
    public void Past_EndDate_Returns_Null()
    {
        var now = new DateTimeOffset(2026, 6, 1, 6, 0, 0, TimeSpan.FromHours(2));
        var s = Schedule(new(2026,5,1), new(2026,5,31), new(7,0,0));
        Assert.Null(NextDueCalculator.Compute(new[]{s}, now, TimeSpan.FromMinutes(30)));
    }

    [Fact]
    public void Multiple_Schedules_Returns_Earliest()
    {
        var now = new DateTimeOffset(2026, 5, 5, 6, 0, 0, TimeSpan.FromHours(2));
        var early = Schedule(new(2026,5,1), new(2026,5,31), new(7,0,0));
        var late  = Schedule(new(2026,5,1), new(2026,5,31), new(9,0,0));
        var r = NextDueCalculator.Compute(new[]{late, early}, now, TimeSpan.FromMinutes(30));
        Assert.NotNull(r);
        Assert.Equal(early.Id, r!.Schedule.Id);
    }
}