using Azure.Core;
using Biskilog_Accounting.Server.POSModels;
using Biskilog_Accounting.ServiceRepo;
using Biskilog_Accounting.Shared.CustomModels;
using Biskilog_Accounting.Shared.Interfaces;
using Biskilog_Accounting.Shared.POSModels;
using Microsoft.EntityFrameworkCore;
using Microsoft.Net.Http.Headers;
using System.Data.Entity;
using System.Runtime.CompilerServices;
using static Microsoft.EntityFrameworkCore.DbLoggerCategory;

namespace Biskilog_Accounting.Server.Services
{
    /// <summary>
    /// Gets the KPIs/ Analysis of operations made with the software
    /// </summary>
    public class AnalyticalService : IAnalytics
    {
        private readonly BiskAcdbContext m_context;
        private readonly ITokenService m_tokenService;
        private bool m_comparisonMode;
        private string m_activeBranch;
        public AnalyticalService(BiskAcdbContext a_context, ITokenService a_tokenService)
        {
            m_context = a_context;
            m_tokenService = a_tokenService;
        }
        public IEnumerable<CancelledSales> GetCancelledSales(DateTime a_start, DateTime a_end)
        {
            //If in comparison mode, the list is fetched from all branchid of the business
            if (m_comparisonMode)
            {
                return from cSale in m_context.Tblcancelledtransactions
                       join aSale in m_context.Tblcarts on cSale.Transno equals aSale.Transno into activeSale
                       join cPurchase in m_context.Tblcustomerpurchases on cSale.Transno equals cPurchase.TransactionId into customerSales
                       from c in customerSales.DefaultIfEmpty()
                       join customer in m_context.Tblcustomers on c.CustomerId equals customer.CustomerId into Customers
                       from cc in Customers.DefaultIfEmpty()
                       where cSale.DateCancelled >= a_start && cSale.DateCancelled <= a_end
                       select new CancelledSales
                       {
                           CancelledTransaction = cSale,
                           Value = activeSale.Sum(s => s.Total),
                           Customer = !String.IsNullOrEmpty(cc.CustomerId) ? $"{cc.Firstname} {cc.Surname}" : "Walk-IN Purchase"
                       };
            }
            else
            {
                return from cSale in m_context.Tblcancelledtransactions
                       join aSale in m_context.Tblcarts on cSale.Transno equals aSale.Transno into activeSale
                       join cPurchase in m_context.Tblcustomerpurchases on cSale.Transno equals cPurchase.TransactionId into customerSales
                       from c in customerSales.DefaultIfEmpty()
                       join customer in m_context.Tblcustomers on c.CustomerId equals customer.CustomerId into Customers
                       from cc in Customers.DefaultIfEmpty()
                       where cSale.DateCancelled >= a_start && cSale.DateCancelled <= a_end && cSale.BranchId == m_activeBranch
                       select new CancelledSales
                       {
                           CancelledTransaction = cSale,
                           Value = (from a in activeSale where a.BranchId == m_activeBranch select a.Total).Sum(),
                           Customer = !String.IsNullOrEmpty(cc.CustomerId) ? $"{cc.Firstname} {cc.Surname}" : "Walk-IN Purchase"
                       };

            }
        }

        public Dictionary<string, List<SaleItem>> GetEmployeeSales(DateTime a_start, DateTime a_end)
        {
            Dictionary<string, List<SaleItem>> sales = new Dictionary<string, List<SaleItem>>();
            if (m_comparisonMode)
            {
                var employeeSales = m_context.Tblcarts.Where(c => c.Date >= a_start && c.Date <= a_end).Select(e => e.Cashier).Distinct();

                foreach (string employeeName in employeeSales)
                {
                    var list = (from a in employeeSales
                                join c in m_context.Tblcarts on a equals c.Cashier into Sales
                                from s in Sales
                                group s by s.Transno into saleItem
                                select new SaleItem
                                {
                                    Total = saleItem.Sum(c => c.Total),
                                    Transno = saleItem.Key,
                                    Cashier = employeeName,
                                    Date = saleItem.First().Date,
                                    Status = saleItem.First().Status,
                                    BranchId = saleItem.First().BranchId
                                }).ToList();
                    sales.Add(employeeName, list);

                }
            }
            else
            {
                var employeeSales = m_context.Tblcarts.Where(c => c.Date >= a_start && c.Date <= a_end && c.BranchId == m_activeBranch).Select(e => e.Cashier).Distinct().ToList();

                foreach (var employeeName in employeeSales)
                {
                    var list = (from a in employeeSales
                                join c in m_context.Tblcarts on a equals c.Cashier into Sales
                                from s in Sales
                                group s by s.Transno into saleItem
                                select new SaleItem
                                {
                                    Total = saleItem.Sum(c => c.Total),
                                    Transno = saleItem.Key,
                                    Cashier = employeeName,
                                    Date = saleItem.First().Date,
                                    Status = saleItem.First().Status,
                                    BranchId = saleItem.First().BranchId
                                }).ToList();
                    sales.Add(employeeName, list);
                }
            }
            return sales;
        }

        public IEnumerable<InDebtCustomers> GetInDebtCustomers()
        {
            if (m_comparisonMode)
            {
                var listDebts = m_context.Customeraccounts.Where(t => t.Balance < 0).OrderByDescending(d => d.Date).Select(t => t.CustomerId).Distinct().ToList();
                foreach (var customerId in listDebts)
                {
                    yield return new InDebtCustomers
                    {
                        Customer = m_context.Tblcustomers.FirstOrDefault(i => i.CustomerId == customerId),
                        Debt = m_context.Customeraccounts.OrderByDescending(d => d.Date).FirstOrDefault(t => t.Balance < 0 && t.CustomerId == customerId).Balance,
                    };
                }
            }
            else
            {
                var listDebts = m_context.Customeraccounts.Where(t => t.Balance < 0 && t.BranchId == m_activeBranch).OrderByDescending(d => d.Date).Select(t => t.CustomerId).Distinct().ToList();
                foreach (var customerId in listDebts)
                {
                    yield return new InDebtCustomers
                    {
                        Customer = m_context.Tblcustomers.FirstOrDefault(i => i.CustomerId == customerId),
                        Debt = m_context.Customeraccounts.OrderByDescending(d => d.Date).FirstOrDefault(t => t.Balance < 0 && t.CustomerId == customerId).Balance,
                    };
                }
            }
        }

        public IEnumerable<MostPurchasedItem> GetMostPurchasedItem(DateTime a_start, DateTime a_end)
        {
            var items = (from s in m_context.Tblcarts
                         join p in m_context.Tblproducts on s.Id equals p.Pcode
                         where s.Date >= a_start && s.Date <= a_end
                         group s by p into g
                         orderby g.Count() descending
                         select new MostPurchasedItem
                         {
                             ProductId = g.Key.Pcode,
                             ProductName = g.Key.ProductName,
                             NbrTimesSold = g.Count(),
                             Revenue = g.Sum(s => s.Price)
                         }).Take(50).ToList();
            return items;
        }

        public IEnumerable<ProductItem> GetOutOfStockItems()
        {
            if (m_comparisonMode)
            {
                return (from item in m_context.Tblinventories
                        join p in m_context.Tblproducts on item.Pcode equals p.Pcode
                        join pu in m_context.Productaltunits on item.Pcode equals pu.Pcode into AltUnit
                        from au in AltUnit.DefaultIfEmpty()
                        join rs in m_context.Restocklevels on item.Pcode equals rs.ProductId
                        join un in m_context.Unitofmeasures on p.BaseUnit equals un.UnitCode
                        where p.Status!.ToLower() != "inactive" &&
                        ((rs.WarnLevel >= item.Quantity && rs.Unit == p.BaseUnit) || (rs.WarnLevel >= (item.Quantity / au.QuantityUnit) &&
                       rs.Unit == au.UnitCode)
                        )
                        select new ProductItem
                        {
                            Product = p,
                            Stock = item,
                            BaseUnit = un.Unitshort!
                        });
            }
            else
            {
                return (from item in m_context.Tblinventories
                        join p in m_context.Tblproducts on item.Pcode equals p.Pcode
                        join pu in m_context.Productaltunits on item.Pcode equals pu.Pcode into AltUnit
                        from au in AltUnit.DefaultIfEmpty()
                        join rs in m_context.Restocklevels on item.Pcode equals rs.ProductId
                        join un in m_context.Unitofmeasures on p.BaseUnit equals un.UnitCode
                        where p.Status!.ToLower() != "inactive" && item.BranchId == m_activeBranch &&
                        ((rs.WarnLevel >= item.Quantity && rs.Unit == p.BaseUnit) || (rs.WarnLevel >= (item.Quantity / au.QuantityUnit) &&
                       rs.Unit == au.UnitCode)
                        )
                        select new ProductItem
                        {
                            Product = p,
                            Stock = item,
                            BaseUnit = un.Unitshort!
                        });
            }
            //return null;
        }

        public IEnumerable<ProductPriceChange> GetPriceChanges(DateTime a_start, DateTime a_end)
        {
            if (m_comparisonMode)
            {
                return from change in m_context.Tblpricechanges
                       join p in m_context.Tblproducts on change.Pcode equals p.Pcode
                       where change.ChangeDate >= a_start && change.ChangeDate <= a_end
                       select new ProductPriceChange
                       {
                           BranchId = change.BranchId,
                           ChangeDate = change.ChangeDate,
                           Pcode = change.Pcode,
                           CountId = change.CountId,
                           CurrentPrice = change.CurrentPrice,
                           PreviousPrice = change.PreviousPrice,
                           ProductName = p.ProductName
                       };
            }
            else
            {
                return from change in m_context.Tblpricechanges
                       join p in m_context.Tblproducts on change.Pcode equals p.Pcode
                       where change.ChangeDate >= a_start && change.ChangeDate <= a_end && change.BranchId == m_activeBranch
                       select new ProductPriceChange
                       {
                           BranchId = change.BranchId,
                           ChangeDate = change.ChangeDate,
                           Pcode = change.Pcode,
                           CountId = change.CountId,
                           CurrentPrice = change.CurrentPrice,
                           PreviousPrice = change.PreviousPrice,
                           ProductName = p.ProductName
                       };
            }
        }

        public IEnumerable<Tblcart> GetSalesTransaction(DateTime a_start, DateTime a_end)
        {
            //If in comparison mode, the list is fetched from all branchid of the business
            if (m_comparisonMode)
            {
                return m_context.Tblcarts.Where(t => t.Date >= a_start && t.Date <= a_end);
            }
            else
            {
                return m_context.Tblcarts.Where(t => t.Date >= a_start && t.Date <= a_end && t.BranchId == m_activeBranch);
            }
        }

        public void SetContraints(string a_token)
        {
            m_comparisonMode = m_tokenService.GetComparison(a_token)!.Value;
            m_activeBranch = m_tokenService.GetBaseBranch(a_token)!;
        }
    }
}