using System;
using System.Collections.Generic;
using System.Linq;
using Schaad.Accounting.Interfaces;
using Schaad.Accounting.Models;

namespace Schaad.Accounting.Repositories
{
    public class TransactionRepository : BaseRepository, ITransactionRepository
    {
        private readonly IAccountRepository accountRepository;
        private readonly string TRANSACTIONS = "Transactions.xml";

        public TransactionRepository(ISettingsService settingsService, RepositoryCache cache, IAccountRepository accountRepository)
            : base(settingsService, cache)
        {
            this.accountRepository = accountRepository;
        }

        /// <summary>
        /// Get transaction list
        /// </summary>
        public List<Transaction> GetTransactionList() => LoadList<Transaction>(TRANSACTIONS);

        /// <summary>
        /// Save a transaction (insert/update)
        /// </summary>
        public void SaveTransaction(Transaction transaction)
        {
            transaction.Value = Math.Abs(transaction.Value);

            var originIsFx = accountRepository.GetAccount(transaction.OriginAccountId).IsFxAccount;
            var targetIsFx = accountRepository.GetAccount(transaction.TargetAccountId).IsFxAccount;
            var isFxAccount = originIsFx || targetIsFx;

            // user enters amount in the foreign account's currency -> convert to CHF for storage
            if (isFxAccount && transaction.FxRate != 0)
            {
                transaction.Value = transaction.Value * transaction.FxRate.Value;
            }

            if (!isFxAccount)
            {
                transaction.FxRate = null;
            }


            var transactionList = GetTransactionList();
            var existingTransaction = transactionList.FirstOrDefault(a => a.Id == transaction.Id);

            if (existingTransaction == null)
            {
                existingTransaction = new Transaction();
                transactionList.Add(existingTransaction);
                transaction.Id = Guid.NewGuid().ToString();
            }
            transaction.Copy(existingTransaction);
            Save(transactionList, TRANSACTIONS);
        }

        /// <summary>
        /// Get transaction
        /// </summary>
        public Transaction GetTransaction(string id)
        {
            var transactions = GetTransactionList();
            var stored = transactions.FirstOrDefault(t => t.Id == id);
            if (stored == null)
            {
                return null;
            }

            var result = new Transaction();
            stored.Copy(result);

            // value is stored in CHF -> convert back to foreign currency for display/editing
            var isFxAccount = accountRepository.GetAccount(result.OriginAccountId).IsFxAccount
                || accountRepository.GetAccount(result.TargetAccountId).IsFxAccount;
            if (isFxAccount && result.FxRate != 0)
            {
                result.Value = result.Value / result.FxRate.Value;
            }

            return result;
        }
        
        /// <summary>
        /// Delete transaction
        /// </summary>
        public void DeleteTransaction(string id)
        {
            var transactions = GetTransactionList();
            transactions.RemoveAll(t => t.Id == id);
            Save(transactions, TRANSACTIONS);
        }
    }
}