using bnhtrade.Core.Data.Database.UnitOfWork;
using bnhtrade.Core.Logic.Account;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Transactions;
using static System.Formats.Asn1.AsnWriter;

namespace bnhtrade.Core.Logic.Inventory
{
    public  class StockService : UnitOfWorkBase
    {
        public StockService() : base() { }

        internal StockService(IUnitOfWork unitOfWork) : base(unitOfWork) { }

        public int WIP_StockInsertPurchase(int productId, int conditionId, int accountTaxCodeId, int accountJournalId, int quantity, int statusDebitId)
        {
            DateTime stockJournalEntryDate;
            int stockJournalTypeId = 1;

            return WithUnitOfWork(uow =>
            {
                stockJournalEntryDate = new AccountJournalService(uow).ReadJournalEntryDate(accountJournalId);
                int result = WIP_StockInsertSub(
                    uow, productId, conditionId, accountTaxCodeId, accountJournalId, stockJournalTypeId, stockJournalEntryDate, quantity, statusDebitId);
                CommitIfOwned(uow);
                return result;
            });
        }

        public int WIP_StockInsertOwnerIntroduced(decimal amount, int quantity, int productId, int conditionId, int accountTaxCodeId, DateTime entryDate, int debitStatusId)
        {
            int accountJournalType = 3;
            int stockJournalType = 2;
            string currencyCode = "GBP";

            return WithUnitOfWork(uow =>
            {
                int stockId = WIP_StockInsert(uow, accountJournalType, stockJournalType, currencyCode, amount, quantity, productId, conditionId, accountTaxCodeId, entryDate, debitStatusId);
                CommitIfOwned(uow);
                return stockId;
            });
        }

        private int WIP_StockInsert(IUnitOfWork uow, int accountJournalType, int stockJournalType, string currencyCode, decimal amount,
            int quantity, int productId, int conditionId, int accountTaxCodeId, DateTime entryDate, int debitStatusId)
        {
                // add account journal entry
                int accountJournalId = new Logic.Account.AccountJournalService(uow).JournalInsert(accountJournalType, entryDate, currencyCode, amount);

                // make the stock insert
                int stockId = WIP_StockInsertSub(uow, productId, conditionId, accountTaxCodeId,
                    accountJournalId, stockJournalType, entryDate, quantity, debitStatusId);

                return stockId;
        }

        private int WIP_StockInsertSub(IUnitOfWork uow, int productId, int conditionId, int accountTaxCodeId,
            int accountJournalId, int stockJournalTypeId, DateTime stockJournalEntryDate, int quantity, int statusDebitId)
        {
            stockJournalEntryDate = DateTime.SpecifyKind(stockJournalEntryDate, DateTimeKind.Utc);

            // ensure account journal id hasn't already been added to stock table
            int count = uow.StockRepository.CountStockTableRecords(new List<int> { accountJournalId });

            if (count == 1)
            {
                throw new Exception("Add account journal entry already assigned to stock line.");
            }
            else if (count > 1)
            {
                throw new Exception("Houston we have a problem! An account journal entry is assigned to " + count + " stock lines.");
            }

            // ensure the debit for the account journal transaction is to an 'Asset' account type
            bool isIt = uow.AccountJournalRepository.IsJournalDebitAssetType(accountJournalId);
            if (!isIt)
            {
                throw new Exception("Supplied AccountJournal entry must debit an 'Asset' account type.");
            }

            // get statusCreditId for stock journal type
            int? statusCreditId = uow.StockJournalRepository.ReadTypeIdStatusCreditId(stockJournalTypeId);

            if (statusCreditId == null)
            {
                throw new Exception("Default credit status not set for StockJournalTypeID=" + stockJournalTypeId);
            }

            // get/set an skuId
            int skuId = new Logic.Inventory.SkuService(uow).GetSkuId(productId, conditionId, accountTaxCodeId, true);

            // add the entry to the stock table (minus stockJournalId)
            int stockId = uow.StockRepository.InsertNewStock(skuId, accountJournalId);

            // insert stock journal entry
            var journalPosts = new List<(int statusId, int quantity)>();
            journalPosts.Add((statusDebitId, quantity));
            journalPosts.Add((statusCreditId.Value, (quantity * -1)));
            int stockJournalId = new StockJournalService(uow).StockJournalInsert(stockJournalTypeId, stockId, journalPosts, stockJournalEntryDate, true);

            // update the stock table
            count = uow.StockRepository.UpdateStockJournalId(stockId, stockJournalId);
            if (count < 1)
            {
                throw new Exception("New stock insert cancelled, failed to update StockJournalID");
            }

            return stockId;
        }

        public void WIP_StockDeletePurchase(int stockId)
        {
            WithUnitOfWork(uow =>
            {
                if (stockId <= 0)
                {
                    throw new ArgumentException("Stock ID must be greater than zero", nameof(stockId));
                }
                WIP_StockDelete(uow, stockId);
                CommitIfOwned(uow);
            });
        }

        public void WIP_StockDeleteOwnerIntroduced(int stockId)
        {
            WithUnitOfWork(uow =>
            {
                if (stockId <= 0)
                {
                    throw new ArgumentException("Stock ID must be greater than zero", nameof(stockId));
                }
                WIP_StockDelete(uow, stockId);
                CommitIfOwned(uow);
            });
        }        
        
        private void WIP_StockDelete(IUnitOfWork uow, int stockId)
        {
            int stockJournalType = 0;

            // ensure stockId is owner-introduced
            stockJournalType = uow.StockJournalRepository.ReadJournalTypeIdByStockId(stockId);

            // check stock journal type is not restricted
            // owner inventory introduced
            if (stockJournalType == 2)
            {
                // no dramas
            }
            else
            {
                throw new Exception("Manual delete of this stock type is not supported, use the method that created it!");
            }

            // check there is only one stock journal entry for stock item (i.e. the source entry)
            int count = uow.StockJournalRepository.ReadJournalEntryCountByStockId(stockId);

            if (count > 1)
            {
                throw new Exception("Delete " + count + " stock journal entries (other than source entry), before peforming this operation.");
            }

            // remove account journal entry
            WIP_StockDeleteSubAccountJournalEntry(uow, stockId);

            // remove stock
            WIP_StockDeleteSub(uow, stockId);
        }

        private void WIP_StockDeleteSub(IUnitOfWork uow, int stockId)
        {
            // check for accountJournalId on stock table
            int? accountJournalId = uow.StockRepository.ReadAccountJournalId(stockId);
            if (accountJournalId.HasValue)
            {
                throw new Exception("StockID=" + stockId + " remove account journal entry using method that created it first.");
            }

            // get stockJournalId
            int stockJournalId = uow.StockRepository.ReadStockJournalId(stockId) ?? throw new Exception("StockJournalID not found for StockID=" + stockId);

            // remove stockJournalId from stock table
            int count = uow.StockRepository.UpdateStockJournalId(stockId, null);
            if (count != 2) // we need to count the LastUpdated trigger!
            {
                throw new Exception("Failed to remove StockJournalID from stock table StockID=" + stockId);
            }

            // delete stock journal entry
            new StockJournalService(uow).StockJournalDelete(stockJournalId);

            // delete stock table entry
            count = uow.StockRepository.DeleteStock(stockId);
            if (count != 1)
            {
                throw new Exception("StockID = " + stockId + " delete failed");
            }
        }

        // to be used by other methods within a transaction scope
        private void WIP_StockDeleteSubAccountJournalEntry(IUnitOfWork uow, int stockId)
        {
            // get the account journal id
            int accountJournalId = uow.StockRepository.ReadAccountJournalId(stockId) ?? throw new Exception("AccountJournalID not found for StockID=" + stockId);

            // remove entry from stock table
            int count = uow.StockRepository.UpdateAccountJournalId(stockId, null);

            if (count != 2) // must include last modified trigger
            {
                throw new Exception("Failed to set AccountJournalID to NULL on stock table for StockID=" + stockId);
            }

            // delete account journal entry
            new AccountJournalService(uow).DeleteJournal(accountJournalId);
        }
    }
}