using DD.Persistence.Models;
using DD.Persistence.Models.Common;
using DD.Persistence.Models.Requests;
using DD.Persistence.Models.Requests.ChangeLog;
using DD.Persistence.Repositories;
using Microsoft.Extensions.Caching.Memory;

namespace DD.Persistence.API.Services;

/// <summary>
/// Сервис по работе с журналом изменений
/// </summary>
public class ChangeLogService
{
    private readonly IMemoryCache memoryCache;
    private readonly IChangeLogCommitRepository commitRepository;
    private readonly IChangeLogRepository repository;
    private readonly TimeSpan? AbsoluteExpirationRelativeToNow = TimeSpan.FromMinutes(60);

    /// <summary>
    /// ctor
    /// </summary>
    /// <param name="memoryCache"></param>
    /// <param name="commitRepository"></param>
    /// <param name="repository"></param>
    public ChangeLogService(
        IMemoryCache memoryCache,
        IChangeLogCommitRepository commitRepository,
        IChangeLogRepository repository)
    {
        this.memoryCache = memoryCache;
        this.commitRepository = commitRepository;
        this.repository = repository;
    }

    /// <summary>
    /// Чтение или создание нового коммита
    /// </summary>
    /// <param name="request"></param>
    /// <param name="token"></param>
    /// <returns></returns>
    private async Task<ChangeLogCommitDto> GetOrCreateCommitAsync(CreateChangeLogCommitRequest request, CancellationToken token)
    {
        var key = (request.IdAuthor, request.Comment);
        var commit = await memoryCache.GetOrCreateAsync(key, async (cacheEntry) =>
        {
            cacheEntry.AbsoluteExpirationRelativeToNow = AbsoluteExpirationRelativeToNow;

            var commit = await commitRepository.Add(request, token);

            return commit;
        });
        return commit!;
    }

    /// <summary>
    /// Добавление записи в журнал изменений
    /// </summary>
    /// <param name="idDiscriminator"></param>
    /// <param name="request"></param>
    /// <param name="dtos"></param>
    /// <param name="token"></param>
    /// <returns></returns>
    public async Task<int> AddRange(Guid idDiscriminator, CreateChangeLogCommitRequest request, IEnumerable<ChangeLogValuesDto> dtos, CancellationToken token)
    {
        var commit = await GetOrCreateCommitAsync(request, token);

        var result = await repository.AddRange(idDiscriminator, commit, dtos, token);
        return result;
    }

    /// <summary>
    /// Пометить запись журнала изменений как удаленную
    /// </summary>
    /// <param name="ids"></param>
    /// <param name="request"></param>
    /// <param name="token"></param>
    /// <returns></returns>
    public async Task<int> MarkAsDeleted(IEnumerable<Guid> ids, CreateChangeLogCommitRequest request, CancellationToken token)
    {
        var commit = await GetOrCreateCommitAsync(request, token);

        var result = await repository.MarkAsDeleted(ids, commit, token);

        return result;
    }

    /// <summary>
    /// Очистить старые и добавить новые записи в журнал изменений
    /// </summary>
    /// <param name="idDiscriminator"></param>
    /// <param name="request"></param>
    /// <param name="dtos"></param>
    /// <param name="token"></param>
    /// <returns></returns>
    public async Task<int> ClearAndAddRange(Guid idDiscriminator, CreateChangeLogCommitRequest request, IEnumerable<ChangeLogValuesDto> dtos, CancellationToken token)
    {
        var commit = await GetOrCreateCommitAsync(request, token);

        var result = await repository.ClearAndAddRange(idDiscriminator, commit, dtos, token);

        return result;
    }

    /// <summary>
    /// Обновить записи в журнале изменений
    /// </summary>
    /// <param name="commitRequest"></param>
    /// <param name="dtos"></param>
    /// <param name="token"></param>
    /// <returns></returns>
    public async Task<int> UpdateRange(CreateChangeLogCommitRequest commitRequest, IEnumerable<ChangeLogValuesDto> dtos, CancellationToken token)
    {
        var commit = await GetOrCreateCommitAsync(commitRequest, token);
        var result = await repository.UpdateRange(commit, dtos, token);

        return result;
    }

    /// <summary>
    ///  Получение актуальных записей на определенный момент времени (с пагинацией)
    /// </summary>
    /// <param name="idDiscriminator"></param>
    /// <param name="momentUtc"></param>
    /// <param name="paginationRequest"></param>
    /// <param name="token"></param>
    /// <returns></returns>
    public async Task<PaginationContainer<ChangeLogValuesDto>> GetByDate(
      Guid idDiscriminator,
      DateTimeOffset momentUtc,
      PaginationRequest paginationRequest,
      CancellationToken token)
    {
        var result = await repository.GetByDate(idDiscriminator, momentUtc, paginationRequest, token);

        return result;
    }

    /// <summary>
    /// Получение измененных записей за период времени
    /// </summary>
    /// <param name="idDiscriminator"></param>
    /// <param name="dateBegin"></param>
    /// <param name="dateEnd"></param>
    /// <param name="token"></param>
    /// <returns></returns>
    public async Task<IEnumerable<ChangeLogDto>> GetChangeLogForInterval(Guid idDiscriminator, DateTimeOffset dateBegin, DateTimeOffset dateEnd, CancellationToken token)
    {
        var result = await repository.GetChangeLogForInterval(idDiscriminator, dateBegin, dateEnd, token);

        return result;
    }

    /// <summary>
    /// Получение списка дат, в которые происходили изменения (день, месяц, год, без времени)
    /// </summary>
    /// <param name="idDiscriminator"></param>
    /// <param name="token"></param>
    /// <returns></returns>
    public async Task<IEnumerable<DateOnly>> GetDatesChange(Guid idDiscriminator, CancellationToken token)
    {
        var result = await repository.GetDatesChange(idDiscriminator, token);

        return result;
    }

    /// <summary>
    /// Получить данные, начиная с определенной даты
    /// </summary>
    /// <param name="idDiscriminator"></param>
    /// <param name="dateBegin"></param>
    /// <param name="token"></param>
    /// <returns></returns>
    public async Task<IEnumerable<ChangeLogValuesDto>> GetGtDate(Guid idDiscriminator, DateTimeOffset dateBegin, CancellationToken token)
    {
        var result = await repository.GetGtDate(idDiscriminator, dateBegin, token);

        return result;
    }

    /// <summary>
    /// Получить диапазон дат, для которых есть данные в репозитории
    /// </summary>
    /// <param name="idDiscriminator"></param>
    /// <param name="token"></param>
    /// <returns></returns>
    public async Task<DatesRangeDto?> GetDatesRange(Guid idDiscriminator, CancellationToken token)
    {
        var result = await repository.GetDatesRange(idDiscriminator, token);

        return result;
    }

    /// <summary>
    /// Метод получения статистики пользователя по количеству изменений в разрезе дней
    /// </summary>
    /// <param name="request"></param>
    /// <param name="token"></param>
    /// <returns></returns>
    public async Task<IEnumerable<StatisticsChangeLogDto>> GetUserStatisticsCount(ChangeLogRequest request, CancellationToken token)
    {
        var commitData = await commitRepository.GetCreatedAndObsoleted(request.DiscriminatorId, request.UserId, token);
        var commitCreated = commitData.Item1.OrderBy(c => c.Creation);
        var commitObsoleted = commitData.Item2.OrderBy(c => c.Creation);

        if (!commitCreated.Any())
            return Enumerable.Empty<StatisticsChangeLogDto>();

        var minDateTime = commitCreated.FirstOrDefault()!.Creation;
        var minDate = new DateOnly(minDateTime.Year, minDateTime.Month, minDateTime.Day);

        var lastCommitCreated = commitCreated.Last();
        var lastCommitObsoleted = commitObsoleted.LastOrDefault();

        var maxDateTime = lastCommitCreated.Creation;
        if ((lastCommitObsoleted != null) && (lastCommitObsoleted.Creation > maxDateTime))
            maxDateTime = lastCommitObsoleted.Creation;
        var maxDate = new DateOnly(maxDateTime.Year, maxDateTime.Month, maxDateTime.Day);

        var result = new List<StatisticsChangeLogDto>();
        while (minDate <= maxDate)
        {
            var createdCount = commitCreated
                .Where(c => new DateOnly(c.Creation.Year, c.Creation.Month, c.Creation.Day) == minDate)
                .Count();
            var obsoletedCount = commitObsoleted
               .Where(c => new DateOnly(c.Creation.Year, c.Creation.Month, c.Creation.Day) == minDate)
               .Count();

            result.Add(new StatisticsChangeLogDto()
            {
                Date = minDate,
                CreatedCount = createdCount,
                ObsoletedCount = obsoletedCount,
                Count = createdCount + obsoletedCount
            });
        }

        return result;


    }

    /// <summary>
    /// 
    /// </summary>
    /// <param name="request"></param>
    /// <param name="token"></param>
    /// <returns></returns>
    /// <exception cref="NotImplementedException"></exception>
    public async Task<IEnumerable<HistoryChangeLogDto>> GetHistoryChangeLog(ChangeLogRequest request, CancellationToken token)
    {
        var commits = await commitRepository.Get(request.DiscriminatorId, request.UserId, token);
       
        if (!commits.Any())
            return Enumerable.Empty<HistoryChangeLogDto>();

        var result = commits.Select(c => new HistoryChangeLogDto()
        {
            ChangeLogItems = new List<ChangeLogDto>(),
            Comment = c.Comment ?? string.Empty,
            DateTime = c.Creation,
            User = new UserDto() { 
                DisplayName = "",
                Id = c.IdAuthor,
            }
        });

        return result;
    }
}