using SQLInsight.Agent.Reports;

namespace SQLInsight.Agent.Tests;

public class MonthlyReportTests
{
    private static readonly TimeZoneInfo Copenhagen = TimeZoneInfo.FindSystemTimeZoneById("Europe/Copenhagen");

    [Fact]
    public void Previous_month_is_due_after_the_send_hour_across_a_daylight_saving_change()
    {
        var period = MonthlyReportService.DuePeriod(new DateTimeOffset(2026, 11, 1, 7, 30, 0, TimeSpan.FromHours(1)), Copenhagen, day: 1, hour: 7, lastSent: "2026-10");

        Assert.NotNull(period);
        Assert.Equal("2026-11", period.Key);
        Assert.Equal(new DateTimeOffset(2026, 10, 1, 0, 0, 0, TimeSpan.FromHours(2)), period.From);
        Assert.Equal(new DateTimeOffset(2026, 11, 1, 0, 0, 0, TimeSpan.FromHours(1)), period.To);
    }

    [Fact]
    public void Nothing_is_due_before_the_send_time_or_after_it_was_sent()
    {
        Assert.Null(MonthlyReportService.DuePeriod(new DateTimeOffset(2026, 11, 1, 6, 59, 0, TimeSpan.FromHours(1)), Copenhagen, 1, 7, "2026-10"));
        Assert.Null(MonthlyReportService.DuePeriod(new DateTimeOffset(2026, 11, 3, 6, 0, 0, TimeSpan.FromHours(1)), Copenhagen, 5, 7, "2026-10"));
        Assert.Null(MonthlyReportService.DuePeriod(new DateTimeOffset(2026, 11, 20, 12, 0, 0, TimeSpan.FromHours(1)), Copenhagen, 1, 7, "2026-11"));
    }

    [Fact]
    public void A_report_missed_while_the_agent_was_down_is_sent_later_in_the_month()
    {
        var period = MonthlyReportService.DuePeriod(new DateTimeOffset(2027, 1, 14, 9, 0, 0, TimeSpan.FromHours(1)), Copenhagen, 1, 7, lastSent: null);

        Assert.Equal(new DateTimeOffset(2026, 12, 1, 0, 0, 0, TimeSpan.FromHours(1)), period!.From);
    }
}