using GmRelay.DiscordBot.Features.Sessions;

namespace GmRelay.Bot.Tests.Discord;

public sealed class DiscordTimeParserTests
{
    [Fact]
    public void ParseTimeInput_ShouldTreatInputAsMoscowTime()
    {
        var future = DateTimeOffset.UtcNow.AddDays(7);
        var result = DiscordTimeParser.ParseTimeInput(
            future.ToString("yyyy-MM-dd '15:00'", System.Globalization.CultureInfo.InvariantCulture));

        Assert.True(result.IsSuccess);
        // 15:00 MSK = 12:00 UTC
        Assert.Equal(12, result.Value.Hour);
        Assert.Equal(0, result.Value.Minute);
        Assert.Equal(TimeSpan.Zero, result.Value.Offset);
    }

    [Fact]
    public void ParseTimeInput_ShouldParseDiscordDateFormat()
    {
        var expected = FutureDateAt1930();
        var result = DiscordTimeParser.ParseTimeInput(
            expected.ToString("yyyy-MM-dd HH:mm", System.Globalization.CultureInfo.InvariantCulture));

        Assert.True(result.IsSuccess);
        Assert.Equal(expected.Year, result.Value.Year);
        Assert.Equal(expected.Month, result.Value.Month);
        Assert.Equal(expected.Day, result.Value.Day);
        // Input is treated as Moscow time; 19:30 MSK = 16:30 UTC
        Assert.Equal(16, result.Value.Hour);
        Assert.Equal(30, result.Value.Minute);
    }

    [Fact]
    public void ParseTimeInput_ShouldRejectPastDate()
    {
        var result = DiscordTimeParser.ParseTimeInput("2020-01-01 00:00");
        Assert.False(result.IsSuccess);
    }

    [Fact]
    public void ParseTimeInput_ShouldParseRussianDateFormat()
    {
        var expected = FutureDateAt1930();
        var result = DiscordTimeParser.ParseTimeInput(
            expected.ToString("dd.MM.yyyy HH:mm", System.Globalization.CultureInfo.InvariantCulture));

        Assert.True(result.IsSuccess);
        Assert.Equal(expected.Year, result.Value.Year);
        Assert.Equal(expected.Month, result.Value.Month);
        Assert.Equal(expected.Day, result.Value.Day);
    }

    [Fact]
    public void ParseTimeInput_ShouldRejectInvalidFormat()
    {
        var result = DiscordTimeParser.ParseTimeInput("not-a-date");
        Assert.False(result.IsSuccess);
        Assert.NotNull(result.Error);
    }

    private static DateTimeOffset FutureDateAt1930()
    {
        var future = DateTimeOffset.UtcNow.AddDays(7);
        return new DateTimeOffset(
            future.Year,
            future.Month,
            future.Day,
            19,
            30,
            0,
            TimeSpan.Zero);
    }
}