using System.Collections.Generic;
using System.Linq;
using Comal.Classes;
using InABox.Core;

namespace PRS.Shared
{

    public class RosterBlock
    {
        public DateTime Date { get; }
        public TimeSpan Start { get; }
        public TimeSpan Finish { get; }
        public TimeSpan Duration { get; }

        public RosterBlock(DateTime date, TimeSpan start, TimeSpan finish)
        {
            Date = date;
            Start = start;
            Finish = finish;
            Duration = TimeSpan.FromTicks(Math.Max(0L, finish.Ticks - start.Ticks));
        }
    }
    
    public static class RosterUtils
    {
        
        public static RosterBlock[] GetBlocks(this EmployeeRosterItem roster, DateTime date, TimeSpan start, TimeSpan finish)
        {
            var result = new List<RosterBlock>();
            
            if (roster.Enabled && (roster.Finish > start) && (roster.Start <= finish))
            {
                result.Add(new RosterBlock(
                    date,
                    start < roster.Start ? roster.Start : start,
                    finish > roster.Finish ? roster.Finish : finish
                ));
            }
            
            if ( roster.Enabled && roster.SplitShift && (roster.Finish2 > start) && (roster.Start2 <= finish))
            {
                result.Add(new RosterBlock(
                    date,
                    start < roster.Start2 ? roster.Start2 : start,
                    finish > roster.Finish2 ? roster.Finish2 : finish
                ));
            }
            
            return result.ToArray();
        }

        public static EmployeeRosterItem? GetRoster(IList<EmployeeRosterItem>? roster, DateTime? startdate, DateTime currentdate)
        {
            if (startdate > currentdate)
                return null;
            
            if ((roster == null) || !roster.Any())
                roster = DefaultRoster();

            if ((startdate == null) ||  startdate.Value.IsEmpty())
                startdate = currentdate.StartOfWeek(DayOfWeek.Monday);
            
            while (startdate.Value.AddDays(roster.Count) <= currentdate)
                startdate = startdate.Value.AddDays(roster.Count);                
            
            int rosterday = (int)((currentdate.Date - startdate.Value.Date).TotalDays) % roster.Count;
            return roster[rosterday];
            
        }
        
        
        
        private static readonly EmployeeRosterItem[] DEFAULT_ROSTER = new EmployeeRosterItem[]
        {
            new EmployeeRosterItem()
                { Day = 1, Start = new TimeSpan(8, 0, 0), Finish = new TimeSpan(16, 30, 0), Break = new TimeSpan(0, 30, 0), Enabled = true },
            new EmployeeRosterItem()
                { Day = 2, Start = new TimeSpan(8, 0, 0), Finish = new TimeSpan(16, 30, 0), Break = new TimeSpan(0, 30, 0), Enabled = true },
            new EmployeeRosterItem()
                { Day = 3, Start = new TimeSpan(8, 0, 0), Finish = new TimeSpan(16, 30, 0), Break = new TimeSpan(0, 30, 0), Enabled = true },
            new EmployeeRosterItem()
                { Day = 4, Start = new TimeSpan(8, 0, 0), Finish = new TimeSpan(16, 30, 0), Break = new TimeSpan(0, 30, 0), Enabled = true },
            new EmployeeRosterItem()
                { Day = 5, Start = new TimeSpan(8, 0, 0), Finish = new TimeSpan(16, 30, 0), Break = new TimeSpan(0, 30, 0), Enabled = true },
            new EmployeeRosterItem()
                { Day = 6, Enabled = false },
            new EmployeeRosterItem()
                { Day = 7, Enabled = false },
        };

        public static EmployeeRosterItem[] DefaultRoster() => DEFAULT_ROSTER;
        
        public static TimeSheet[] CreateLeaveTimesheets(Employee employee, EmployeeRosterItem[]? roster, DateTime from, TimeSpan fromtime, DateTime to, TimeSpan totime, Guid activityid, Action<TimeSheet> customise)
        {
            
            var result = new List<TimeSheet>();
            
            DateTime rosterstart = employee.RosterStart.IsEmpty()
                ? from.StartOfWeek(DayOfWeek.Monday)
                : employee.RosterStart;
            
            if ((roster == null) || !roster.Any())
                roster = DefaultRoster();
            
            while (rosterstart.AddDays(roster.Length) <= from)
                rosterstart = rosterstart.AddDays(roster.Length);
            
            DateTime currentdate = from;
            while (currentdate <= to)
            {
                if (
                    (employee.StartDate.IsEmpty() || (employee.StartDate <= currentdate))
                    && (employee.FinishDate.IsEmpty() || (employee.FinishDate >= currentdate))
                )
                {
                    var currentroster = GetRoster(roster, rosterstart, currentdate);
                    if (currentroster?.Enabled == true)
                    {

                        TimeSpan currentfrom = (currentdate.Date == from.Date) ? fromtime : new TimeSpan(0);
                        TimeSpan currentto = (currentdate.Date == to.Date) ? totime : new TimeSpan(1, 0, 0, 0);

                        var shifts = currentroster.GetBlocks(currentdate, currentfrom, currentto);
                        foreach (var shift in shifts)
                        {
                            DateTime now = DateTime.Now;
                            var timesheet = new TimeSheet();

                            timesheet.EmployeeLink.ID = employee.ID;
                            timesheet.Date = currentdate;
                            
                            timesheet.Start = shift.Start;
                            timesheet.Finish = shift.Finish;
                            //timesheet.Duration = shift.Item2 - shift.Item1;
                            
                            timesheet.ApprovedStart = timesheet.Start;
                            timesheet.ApprovedFinish = timesheet.Finish;
                            //timesheet.ApprovedDuration = timesheet.Finish - timesheet.Start;
                            timesheet.Confirmed = now;
                            timesheet.Approved = now;

                            timesheet.ActivityLink.ID = activityid;
                            
                            customise?.Invoke(timesheet);
                            
                            result.Add(timesheet);
                        }
                    }
                }

                currentdate = currentdate.AddDays(1);
            }

            return result.ToArray();
            
        }
        
        
    }
}