using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using LCU.API.Collections.CollectionsApiLib.Models;
using LCU.API.Collections.RepoApi.DataAccess;
using LCU.API.Collections.RepoApi.Exceptions;
using LCU.Shared.Collections.RepoApiLib.Models;
using LCU.Shared.Collections.RepoApiLib.Repositories;
using Serilog;

namespace LCU.API.Collections.RepoApi.Services
{
    public class RepoLetterService : IRepoLetterService
    {
        private readonly ILetterRepository _letterRepository;
        private readonly ICollectionsDao _collectionsDao;

        public RepoLetterService(ILetterRepository letterRepository,
            ICollectionsDao collectionsDao)
        {
            _letterRepository = letterRepository;
            _collectionsDao = collectionsDao;
        }

        public async Task<IReadOnlyCollection<RepoLetter>> ListByAccountIdAsync(int accountId)
        {
            try
            {
                var collectionsHistory = await _collectionsDao.RetrieveHistoryAsync(accountId);
                var collectionsLetters =
                    collectionsHistory.Where(history => history.Type == HistoryType.Letter).ToList();

                if (!collectionsLetters.Any())
                {
                    return new List<RepoLetter>();
                }

                var letters = await _letterRepository.ListAsync();
                return ProcessLetters(collectionsLetters, letters.ToList());
            }
            catch (MissingRequirementException ex)
            {
                throw;
            }
            catch (Exception ex)
            {
                Log.Error(ex, "Failure retrieving Letter List");
                throw new ServerErrorException();
            }
        }

        public static IReadOnlyCollection<RepoLetter> ProcessLetters(List<TemenosHistory> collectionsLetters,
            List<Letter> letters)
        {
            // GJF: Are you here to fix a bug? Probably. These don't match up, who wrote this?!?! This code is fueled by hope.
            // Ok, so you really need to fix it. Go out to Temenos, go to System Management (the button is labelled 'tools'!)
            // Find the Communication section, expand it and choose 'letters & forms'. Now find the right Letter and
            // update the LetterDescription column in the Letters table of RepoDb for the correct letter.
            var resultList = new List<RepoLetter>();
            foreach (var letter in letters)
            {
                foreach (var collectionsLetter in collectionsLetters)
                {
                    if (string.IsNullOrWhiteSpace(letter.LetterDescription))
                    {
                        // If this exception is happening, see LetterUpdate.sql. Also See Above.
                        throw new MissingRequirementException("LetterDescription", "Letter table requires LetterDescription Column entry.");
                    }
                    
                    if (collectionsLetter.Message.Trim().ToUpper()
                        .Contains(letter.LetterDescription.Trim().ToUpper()))
                    {
                        resultList.Add(new RepoLetter
                        {
                            NoticeType = collectionsLetter.Message,
                            DateSent = collectionsLetter.Created,
                            DateExpired = collectionsLetter.Created.AddDays(letter.DaysToWait ?? 0),
                            DaysToRedeem = letter.DaysToWait ?? 0,
                            ActionCode = letter.ActionCode.Trim()
                        });
                    }
                }
            }

            return resultList
                .GroupBy(x => x.NoticeType.Trim(),
                    (key, g) => g.OrderByDescending(x => x.DateSent).FirstOrDefault())
                .OrderByDescending(x => x.DateSent).ToList();
        }
    }
}