using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Comal.Classes;
using Comal.Stores;
using InABox.Core;
using InABox.Scripting;

namespace PRSStores
{
    internal class LeaveRequestStore : BaseStore<LeaveRequest>
    {
 
        protected override void OnSave(LeaveRequest entity, ref string auditnote)
        {
            base.OnSave(entity, ref auditnote);
            
            if (entity.HasOriginalValue(c => c.Status))
                NotifyEmployee(
                    entity,
                    x => x.EmployeeLink.ID,
                    e => e.HasOriginalValue(x => x.Status),
                    e => $"Leave Request {e.Status}",
                    e =>
                    {
                        var sb = new StringBuilder();

                        sb.AppendLine(
                            $"Your Leave Request submitted {e.Created:dd MMM yyy} for {e.From:dd MMM yy} - {e.To:dd MMM yy} has changed from {e.GetOriginalValue(c => c.Status)} to {e.Status}.");

                        if (!string.IsNullOrWhiteSpace(e.StatusNotes))
                            sb.AppendLine($"\nNotes:\n{e.StatusNotes?.Trim()}");

                        return sb.ToString();
                    }
                );
        }

        protected override void AfterSave(LeaveRequest entity)
        {
            base.AfterSave(entity);
            if (entity.HasOriginalValue(c => c.EmployeeLink.ID) || entity.HasOriginalValue(c=>c.ApprovalSet.ID))
                UpdateLeaveRequestApprovals(entity);
        }

        private void ClearLeaveRequestApprovals(LeaveRequest request)
        {
            // We need to clear all automatic bill approvals.
            var approvals = Provider.Query(
                    new Filter<LeaveRequestApproval>(x => x.LeaveRequest.ID).IsEqualTo(request.ID)
                        .And(x => x.IsCustom).IsEqualTo(false),
                    Columns.Required<LeaveRequestApproval>().Add(x => x.ID))
                .ToList<LeaveRequestApproval>();
            Provider.Delete(approvals, UserID);
        }
        
        private void UpdateLeaveRequestApprovals(LeaveRequest request)
        {

            if (request.ID == Guid.Empty) return;

            if(request.ApprovalSet.ID == Guid.Empty)
            {
                ClearLeaveRequestApprovals(request);
                return;
            }

            var setEmployees = Provider.Query(
                new Filter<LeaveRequestApprovalSetEmployee>(x => x.ApprovalSet.ID).IsEqualTo(request.ApprovalSet.ID),
                Columns.None<LeaveRequestApprovalSetEmployee>().Add(x => x.Employee.ID),
                new SortOrder<LeaveRequestApprovalSetEmployee>(x => x.Sequence))
                .ToArray<LeaveRequestApprovalSetEmployee>();
            var approvals = Provider.Query(
                new Filter<LeaveRequestApproval>(x => x.LeaveRequest.ID).IsEqualTo(request.ID),
                Columns.Required<LeaveRequestApproval>().Add(x => x.Employee.ID).Add(x => x.IsCustom).Add(x => x.Status))
                .ToList<LeaveRequestApproval>();

            try
            {
                var customApprovals = new List<LeaveRequestApproval>();
                foreach(var approval in approvals)
                {
                    if (approval.IsCustom)
                    {
                        customApprovals.Add(approval);
                    }
                    else
                    {
                        if(approval.Status != LeaveRequestApprovalStatus.NotYetApproved)
                        {
                            // These really are custom approvals for our purposes, since they've been modified.
                            customApprovals.Add(approval);
                    }
                        }
                }

                // Build up the automatic list.
                var autoApprovals = new List<LeaveRequestApproval>();
                foreach(var employee in setEmployees)
                {
                    var approval = new LeaveRequestApproval();
                    approval.Employee.CopyFrom(employee.Employee);
                    approval.IsCustom = false;
                    autoApprovals.Add(approval);
                }
                if(LeaveRequestApprovalSetStore.GetUpdateApprovalsScript(request.ApprovalSet.ID) is ScriptDocument script)
                {
                    script.Execute(methodname: LeaveRequestApprovalSet.UpdateApprovalsMethodName, parameters: [request, autoApprovals]);
                }

                // Now, we have to merge the custom and auto lists, only saving auto approvals if there are no custom ones for that employee.
                var toAdd = new List<LeaveRequestApproval>();
                var toRemove = new List<LeaveRequestApproval>();

                var newList = customApprovals.ToList();
                foreach(var approval in autoApprovals)
                {
                    newList.Add(approval);
                    if (!approvals.Any(x => x.Employee.ID == approval.Employee.ID))
                    {
                        toAdd.Add(approval);
                    }
                }
                foreach(var approval in approvals)
                {
                    if (!newList.Any(x => x.Employee.ID == approval.Employee.ID))
                    {
                        toRemove.Add(approval);
                    }
                }
                foreach(var approval in toAdd)
                {
                    approval.LeaveRequest.ID = request.ID;
                }
                Provider.Save(toAdd);
                Provider.Delete(toRemove, UserID);
            }
            catch(Exception e)
            {
                CoreUtils.LogException(UserID, e, "Error running leave request approval script");
            }
        }
    }
}