using DD.Persistence.Models.Requests;
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>
    /// Создание или чтение данных коммита
    /// </summary>
    /// <param name="commitDto"></param>
    /// <param name="token"></param>
    /// <returns></returns>
    private async Task<Guid> GetOrCreateCommitAsync(ChangeLogCommitDto commitDto, CancellationToken token)
    {
        var key = (commitDto.IdAuthor, commitDto.Comment);
        var commitId = await memoryCache.GetOrCreateAsync(key, async (cacheEntry) =>
        {
            cacheEntry.AbsoluteExpirationRelativeToNow = AbsoluteExpirationRelativeToNow;

            var commitId = await commitRepository.Add(commitDto, token);

            return commitId;
        });
        return commitId;
    }

    /// <summary>
    /// Добавление записи в журнал изменений
    /// </summary>
    /// <param name="idDiscriminator"></param>
    /// <param name="commitDto"></param>
    /// <param name="token"></param>
    /// <returns></returns>
    public async Task<int> AddRange(Guid idDiscriminator, ChangeLogCommitDto commitDto, CancellationToken token)
    {
        var commitId = await GetOrCreateCommitAsync(commitDto, token);
        commitDto.Id = commitId;

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

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

        var result = await repository.MarkAsDeleted(commitId, ids, commitDto.Creation, token);

        return result;
    }

    /// <summary>
    /// Очистить старые и добавить новые записи в журнал изменений
    /// </summary>
    /// <param name="idDiscriminator"></param>
    /// <param name="commitDto"></param>
    /// <param name="token"></param>
    /// <returns></returns>
    public async Task<int> ClearAndAddRange(Guid idDiscriminator, ChangeLogCommitDto commitDto, CancellationToken token)
    {
        var commitId = await GetOrCreateCommitAsync(commitDto, token);
        commitDto.Id = commitId;

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

        return result;
    }

    /// <summary>
    /// Обновить записи в журнале изменений
    /// </summary>
    /// <param name="changeLogCommit"></param>
    /// <param name="token"></param>
    /// <returns></returns>
    public async Task<int> UpdateRange(ChangeLogCommitDto changeLogCommit, CancellationToken token)
    {
        var commitId = await GetOrCreateCommitAsync(changeLogCommit, token);
        changeLogCommit.Id = commitId;

        var result = await repository.UpdateRange(changeLogCommit, token);

        return result;
    }
}