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

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

        return data.Where(x => x.Date >= currentDate || x.End >= currentDate)
            .OrderBy(x => x.End ?? x.Date)
            .ToList();
    }


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

        DateTimeOffset nextRunTime = (currentDate?.ToDateTime(TimeOnly.MinValue) ?? DateTime.Now).ToUniversalTime();
        List<DateTimeOffset> result = [];

        do
        {
            var lastSkippedEntry = data.FilterDateEntry(nextRunTime.DateTime).LastOrDefault();

            if (lastSkippedEntry is { Start: not null, End: not null })
                nextRunTime = lastSkippedEntry.End.Value.ToDateTime(TimeOnly.MinValue).AddDays(1);
            else if (lastSkippedEntry.Date.HasValue)
                nextRunTime = lastSkippedEntry.Date.Value.ToDateTime(TimeOnly.MinValue).AddDays(1);

            var nextOccurrence = expression.GetNextOccurrence(nextRunTime.AddMinutes(-1), TimeZoneInfo.Local);

            if (!nextOccurrence.HasValue)
                return result;

            if (data.FilterDateEntry(nextOccurrence.Value.DateTime).Count != 0)
            {
                nextRunTime = nextOccurrence.Value.AddDays(1);
                continue;
            }

            result.Add(nextOccurrence.Value.ToLocalTime());
            nextRunTime = nextOccurrence.Value.AddMinutes(1);

        } while (result.Count < depth);

        return result;
    }
}