using w4c_workflows.Services.Triggers;
using Xunit;

namespace w4c_workflows.Tests;

public class CronExpressionTests
{
    private static DateTimeOffset Utc(int year, int month, int day, int hour, int minute)
        => new(year, month, day, hour, minute, 0, TimeSpan.Zero);

    [Theory]
    [InlineData("* * * * *", 2026, 8, 28, 14, 21, true)]
    [InlineData("*/15 * * * *", 2026, 8, 28, 14, 0, true)]
    [InlineData("*/15 * * * *", 2026, 8, 28, 14, 1, false)]
    [InlineData("0 */6 * * *", 2026, 8, 28, 6, 0, true)]
    [InlineData("0 */6 * * *", 2026, 8, 28, 12, 0, true)]
    [InlineData("0 */6 * * *", 2026, 8, 28, 13, 0, false)]
    [InlineData("0 9 * * 1-5", 2026, 8, 28, 9, 0, true)]   // Friday
    [InlineData("0 9 * * 1-5", 2026, 8, 29, 9, 0, false)]  // Saturday
    [InlineData("0 0 1 * *", 2026, 8, 1, 0, 0, true)]
    [InlineData("0 0 1 * *", 2026, 8, 2, 0, 0, false)]
    [InlineData("0 9 * * 0", 2026, 8, 30, 9, 0, true)]     // Sunday via 0
    [InlineData("0 9 * * 7", 2026, 8, 30, 9, 0, true)]     // Sunday via alias 7
    [InlineData("30 4,16 * * *", 2026, 8, 28, 16, 30, true)]
    [InlineData("30 4,16 * * *", 2026, 8, 28, 12, 30, false)]
    [InlineData("15-30 * * * *", 2026, 8, 28, 14, 22, true)]
    [InlineData("15-30 * * * *", 2026, 8, 28, 14, 31, false)]
    public void Matches_standard_5_field_expressions(
        string expr, int y, int m, int d, int h, int min, bool expected)
    {
        Assert.True(CronExpression.TryParse(expr, out var cron, out var error), error);
        Assert.Equal(expected, cron!.Matches(new DateTime(y, m, d, h, min, 0, DateTimeKind.Utc)));
    }

    [Fact]
    public void GetNextOccurrence_returns_next_matching_minute()
    {
        Assert.True(CronExpression.TryParse("0 9 * * *", out var cron, out _));
        var next = cron!.GetNextOccurrence(Utc(2026, 8, 28, 10, 0));
        Assert.Equal(Utc(2026, 8, 29, 9, 0), next);
    }

    [Fact]
    public void GetNextOccurrence_skips_to_next_day_for_weekday_schedule()
    {
        Assert.True(CronExpression.TryParse("0 9 * * 1-5", out var cron, out _));
        // Friday 10:00 → next is Monday 09:00.
        var next = cron!.GetNextOccurrence(Utc(2026, 8, 28, 10, 0));
        Assert.Equal(Utc(2026, 8, 31, 9, 0), next);
    }

    [Fact]
    public void GetNextOccurrence_is_strictly_after_the_given_instant()
    {
        Assert.True(CronExpression.TryParse("* * * * *", out var cron, out _));
        var after = Utc(2026, 8, 28, 14, 0);
        var next = cron!.GetNextOccurrence(after);
        Assert.Equal(Utc(2026, 8, 28, 14, 1), next);
    }

    [Theory]
    [InlineData("")]
    [InlineData("   ")]
    [InlineData("0 9 * *")]          // 4 fields
    [InlineData("0 9 * * * *")]      // 6 fields
    [InlineData("60 * * * *")]       // minute out of range
    [InlineData("0 24 * * *")]       // hour out of range
    [InlineData("0 9 32 * *")]       // day-of-month out of range
    [InlineData("0 9 * 13 *")]       // month out of range
    [InlineData("0 9 * * 8")]        // day-of-week out of range
    [InlineData("0 9 * * *")]        // valid — ensure it is NOT rejected
    public void TryParse_validates_field_count_and_ranges(string expr)
    {
        var result = CronExpression.TryParse(expr, out var cron, out _);
        if (expr == "0 9 * * *")
            Assert.True(result);
        else
            Assert.False(result);
    }

    [Fact]
    public void GetNextOccurrence_returns_null_for_unmatchable_schedule()
    {
        // Feb 30 never occurs — no match within the bounded horizon.
        Assert.True(CronExpression.TryParse("0 0 30 2 *", out var cron, out _));
        Assert.Null(cron!.GetNextOccurrence(Utc(2026, 8, 28, 0, 0)));
    }
}