using Cronos;
using Mirea.Api.Endpoint.Configuration.Model.GeneralSettings;
using System;
using System.Collections.Generic;
using System.Linq;

namespace Mirea.Api.Endpoint.Common.Services;

public static class CronUpdateSkipService
{
    public static ScheduleSettings.CronUpdateSkip Get(this Dto.Common.CronUpdateSkip date)
    {
        if (date.Date.HasValue)
            return new ScheduleSettings.CronUpdateSkip(date.Date.Value);
        if (date is { Start: not null, End: not null })
            return new ScheduleSettings.CronUpdateSkip(date.Start.Value, date.End.Value);

        throw new ArgumentException("It is impossible to create a structure because it has incorrect values.");
    }

    public static List<ScheduleSettings.CronUpdateSkip> Filter(this List<ScheduleSettings.CronUpdateSkip> data, DateOnly? currentDate = null)
    {
        currentDate ??= DateOnly.FromDateTime(DateTime.Now);
        return data.OrderBy(x => x.End ?? x.Date)
            .Where(x => x.Date == currentDate || (x.Start <= currentDate && x.End >= currentDate))
            .ToList();
    }

    public static List<ScheduleSettings.CronUpdateSkip> Filter(this List<ScheduleSettings.CronUpdateSkip> data, DateTime? currentDate = null) =>
        data.Filter(DateOnly.FromDateTime(currentDate ?? DateTime.Now));

    public static List<DateTimeOffset> GetNextTask(this List<ScheduleSettings.CronUpdateSkip> data,
        CronExpression expression, int depth = 1, DateOnly? currentDate = null)
    {
        if (depth <= 0)
            return [];

        currentDate ??= DateOnly.FromDateTime(DateTime.UtcNow);
        DateTimeOffset nextRunTime = currentDate.Value.ToDateTime(new TimeOnly(0, 0, 0));

        List<DateTimeOffset> result = [];

        do
        {
            var lastSkip = data.Filter(nextRunTime.DateTime).LastOrDefault();

            if (lastSkip is { Start: not null, End: not null })
                nextRunTime = new DateTimeOffset(lastSkip.End.Value.AddDays(1), new TimeOnly(0, 0, 0), TimeSpan.Zero);
            else if (lastSkip.Date.HasValue)
                nextRunTime = new DateTimeOffset(lastSkip.Date.Value.AddDays(1), new TimeOnly(0, 0, 0), TimeSpan.Zero);

            var next = expression.GetNextOccurrence(nextRunTime, TimeZoneInfo.Local);

            if (!next.HasValue)
                return result;

            nextRunTime = next.Value;

            if (!data.Filter(nextRunTime.DateTime).Any())
                continue;

            result.Add(nextRunTime);
            nextRunTime = nextRunTime.AddMinutes(1);

        } while (result.Count < depth);

        return result;
    }
}