using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Linq.Expressions;
using InABox.Core;

namespace Comal.Classes
{
    public enum SchedulePeriod
    {
        Minute,
        Hour,
        Day,
        Week,
        Month,
        Year
    }

    public enum ScheduleTrigger
    {
        Distance,
        Usage,
        Counter1,
        Counter2,
        Counter3,
        Counter4,
        Counter5
    }

    public enum ScheduleRollover
    {
        FromDueDate,
        FromActualDate
    }

    public enum ScheduleType
    {
        None,
        Job,
        Task
    }

    public class ScheduleOffset : BaseObject, IPackable
    {
        public ScheduleOffset()
        {
        }

        public ScheduleOffset(int offset, SchedulePeriod period)
        {
            Period = period;
            Offset = offset;
        }

        [EnumLookupEditor(typeof(SchedulePeriod), Visible = Visible.Default)]
        [EditorSequence(1)]
        public SchedulePeriod Period { get; set; }

        [IntegerEditor(Visible = Visible.Default)]
        [EditorSequence(2)]
        public int Offset { get; set; }

        public void Pack(BinaryWriter writer)
        {
            writer.Write((int)Period);
            writer.Write(Offset);
        }

        public void Unpack(BinaryReader reader)
        {
            Period = (SchedulePeriod)reader.ReadInt32();
            Offset = reader.ReadInt32();
        }
    }

    public class ScheduleOffsetList : PackableList<ScheduleOffset>
    {
    }

    public class ScheduleLink : EntityLink<Schedule>
    {
        [NullEditor]
        public override Guid ID { get; set; }

        [TextBoxEditor(Editable = Editable.Hidden)]
        public string Title { get; set; }

        [EnumLookupEditor(typeof(ScheduleRollover), Editable = Editable.Hidden)]
        public ScheduleRollover Rollover { get; set; }
    }

    public class NextScheduleDue : CoreAggregate<Entity, Schedule, DateTime>
    {
        public override Expression<Func<Schedule, DateTime>> Aggregate => x => x.DueDate;
        public override AggregateCalculation Calculation => AggregateCalculation.Minimum;
        public override Filter<Schedule> Filter => new Filter<Schedule>(x => x.IncludeInAggregate).IsEqualTo(true);

        public override Dictionary<Expression<Func<Schedule, object>>, Expression<Func<Entity, object>>> Links =>
            new Dictionary<Expression<Func<Schedule, object>>, Expression<Func<Entity, object>>>()
            {
                { Schedule => Schedule.DocumentID, Entity => Entity.ID }
            };
    }

    public class ActiveSchedules : CoreAggregate<Entity, Schedule, Guid>
    {
        public override Expression<Func<Schedule, Guid>> Aggregate => x => x.ID;

        public override AggregateCalculation Calculation => AggregateCalculation.Count;

        public override Dictionary<Expression<Func<Schedule, object>>, Expression<Func<Entity, object>>> Links =>
            new Dictionary<Expression<Func<Schedule, object>>, Expression<Func<Entity, object>>>()
            {
                { Schedule => Schedule.DocumentID, Entity => Entity.ID }
            };
    }

    [UserTracking("Task Scheduler")]
    public class Schedule : Entity, IPersistent, IRemotable, IOneToMany<Employee>, ILicense<ScheduleEngineLicense>
    {
        #region Public Properties

        [NullEditor]
        public string DocumentClass { get; set; }

        //[NullEditor]
        //[DoNotSerialize]
        public Type? DocumentType()
        {
            try
            {
                return CoreUtils.GetEntityOrNull(DocumentClass);
            }
            catch
            {
                return null;
            }
        }

        [NullEditor]
        public Guid DocumentID { get; set; }

        [TextBoxEditor]
        [EditorSequence(0)]
        public string Title { get; set; }

        [MemoEditor]
        [EditorSequence(1)]
        public string Description { get; set; }

        // Date Based Scheduling

        [IntegerEditor]
        [EditorSequence(2)]
        [Caption("Schedule Frequency")]
        public int Frequency { get; set; } = 1;

        [EnumLookupEditor(typeof(SchedulePeriod))]
        [EditorSequence(3)]
        [Caption("Schedule Type")]
        public SchedulePeriod Period { get; set; } = SchedulePeriod.Month;

        [DateTimeEditor]
        [EditorSequence(4)]
        [Caption("Schedule Due")]
        public DateTime DueDate { get; set; } = DateTime.Today.AddDays(1);

        // Trigger-Based Scheduling

        [IntegerEditor]
        [EditorSequence(5)]
        [Caption("Trigger Frequency")]
        public int Threshold { get; set; }

        [EnumLookupEditor(typeof(ScheduleTrigger))]
        [Caption("Trigger Type")]
        [EditorSequence(6)]
        public ScheduleTrigger Trigger { get; set; }

        [IntegerEditor]
        [EditorSequence(7)]
        [Caption("Trigger Level")]
        public int DueThreshold { get; set; }

        [EnumLookupEditor(typeof(ScheduleType))]
        [EditorSequence(8)]
        [Caption("Scheduled Action")]
        public ScheduleType ScheduleType { get; set; } = ScheduleType.Task;

        //[LookupEditor(typeof(KanbanType))]
        [EditorSequence(9)]
        [Caption("Task Type")]
        public KanbanTypeLink KanbanType { get; set; }

        [IntegerEditor]
        [EditorSequence(10)]
        [Caption("Lead Time")]
        public int LeadTime { get; set; }

        public ScheduleOffsetList Offsets { get; set; } = new ScheduleOffsetList();

        [Caption("Assigned To")]
        [EditorSequence(11)]
        public EmployeeLink EmployeeLink { get; set; }

        [Caption("Managed By")]
        [EditorSequence(12)]
        public EmployeeLink ManagerLink { get; set; }

        [Caption("Report Type")]
        [EditorSequence(13)]
        public DocumentLink Report { get; set; }

        [EnumLookupEditor(typeof(ScheduleRollover))]
        [EditorSequence(14)]
        public ScheduleRollover Rollover { get; set; }

        [TimestampEditor(Editable = Editable.Hidden)]
        public DateTime Completed { get; set; }

        [NullEditor]
        public bool Active { get; set; }

        [CheckBoxEditor]
        [EditorSequence(15)]
        public bool IncludeInAggregate { get; set; } = true;

        #endregion

        #region Public Methods

        private DateTime ApplyPeriod(DateTime date)
        {
            var result = date;
            switch (Period)
            {
                case SchedulePeriod.Year:
                    return date.AddYears(Frequency);
                case SchedulePeriod.Month:
                    return date.AddMonths(Frequency);
                case SchedulePeriod.Week:
                    return date.AddDays(7 * Frequency);
                case SchedulePeriod.Day:
                    return date.AddDays(Frequency);
                case SchedulePeriod.Hour:
                    return date.AddHours(Frequency);
                case SchedulePeriod.Minute:
                    return date.AddMinutes(Frequency);
            }

            return result;
        }

        private DateTime ApplyOffsets(DateTime date, int index)
        {
            if (index >= Offsets.Count)
                return date;

            var offset = Offsets[index];

            var result = date;
            var skip = 1;

            switch (offset.Period)
            {
                case SchedulePeriod.Year:
                    result = date.AddYears(offset.Offset);
                    break;

                case SchedulePeriod.Month:
                    result = date.AddMonths(offset.Offset);
                    break;

                case SchedulePeriod.Week:

                    // First Lets get to the start of the month 
                    var startOfMonth = date.Date.AddDays(1 - date.Day);

                    // Calculate the DOW for the start of the month
                    var dow = (int)startOfMonth.DayOfWeek;

                    // If the next offset is a day-type
                    var tgtdow = 0;
                    if (index < Offsets.Count - 1)
                    {
                        skip++;
                        if (Offsets[index + 1].Period == SchedulePeriod.Day)
                            tgtdow = Offsets[index + 1].Offset;
                        else if (Offsets[index + 1].Period == SchedulePeriod.Hour)
                            tgtdow = Offsets[index + 1].Offset / 24;
                        else if (Offsets[index + 1].Period == SchedulePeriod.Minute)
                            tgtdow = Offsets[index + 1].Offset / (24 * 60);
                        else
                            skip--;
                    }

                    result = startOfMonth.AddDays(0 - dow).AddDays(tgtdow);
                    if (dow > tgtdow)
                        result = result.AddDays(7);

                    result = result.AddDays(Offsets[index].Offset * 7);
                    break;

                case SchedulePeriod.Day:
                    result = date.AddDays(offset.Offset);
                    break;

                case SchedulePeriod.Hour:
                    result = date.AddHours(offset.Offset);
                    break;

                case SchedulePeriod.Minute:
                    result = date.AddMinutes(offset.Offset);
                    break;
            }

            return ApplyOffsets(result, index + skip);
        }

        public DateTime GetNextDate(DateTime last)
        {
            // if this is the first time run, then
            // just return the due date
            if (last.IsEmpty())
                return DueDate;

            // Get the base date for the next scheduled run
            var result = Rollover.Equals(ScheduleRollover.FromDueDate) ? DueDate : last;

            // Roll it forward to the next due date
            result = ApplyPeriod(result);

            // Apply any offsets we need
            if (Offsets != null && Offsets.Any())
                result = ApplyOffsets(result, 0);

            return result;
        }

        #endregion
    }

    public interface ISchedulable
    {
        //bool ScheduleEnabled { get; set; }

        [NullEditor]
        int ActiveSchedules { get; set; }
    }

    public interface IScheduleAction
    {
        DateTime Completed { get; set; }

        ScheduleLink ScheduleLink { get; set; }
    }
}