persistence/DD.Persistence.Database/Repositories/TimestampedValuesRepository.cs

using DD.Persistence.Database.Entity;
using DD.Persistence.Models;
using DD.Persistence.Models.Common;
using DD.Persistence.Repositories;
using Microsoft.EntityFrameworkCore;

namespace DD.Persistence.Database.Postgres.Repositories;
public class TimestampedValuesRepository : ITimestampedValuesRepository
{
    private readonly DbContext db;

    public TimestampedValuesRepository(DbContext db)
    {
        this.db = db;
    }

    protected virtual IQueryable<TimestampedValues> GetQueryReadOnly() => this.db.Set<TimestampedValues>()
        .Include(e => e.DataScheme);

    public async virtual Task<int> AddRange(Guid discriminatorId, IEnumerable<TimestampedValuesDto> dtos, CancellationToken token)
    {
        var timestampedValuesEntities = dtos.Select(dto => new TimestampedValues()
        {
            DiscriminatorId = discriminatorId,
            Timestamp = dto.Timestamp.ToUniversalTime(),
            Values = dto.Values.Values.ToArray()
        });

        await db.Set<TimestampedValues>().AddRangeAsync(timestampedValuesEntities, token);

        var result = await db.SaveChangesAsync(token);

        return result;
    }

    public async virtual Task<IDictionary<Guid, IEnumerable<(DateTimeOffset Timestamp, object[] Values)>>> Get(IEnumerable<Guid> discriminatorIds,
        DateTimeOffset? timestampBegin,
        IEnumerable<string>? columnNames,
        int skip,
        int take,
        CancellationToken token)
    {
        var query = GetQueryReadOnly()
            .Where(entity => discriminatorIds.Contains(entity.DiscriminatorId));

        // Фильтрация по дате
        if (timestampBegin.HasValue)
        {
            query = ApplyGeTimestamp(query, timestampBegin.Value);
        }

        // Группировка отсортированных значений по DiscriminatorId
        var groupQuery = query
            .GroupBy(e => e.DiscriminatorId)
            .Select(g => KeyValuePair.Create(g.Key, g.OrderBy(i => i.Timestamp).Skip(skip).Take(take)));
        var entities = await groupQuery.ToArrayAsync(token);

        var result = entities.ToDictionary(k => k.Key, v => v.Value.Select(e => (
            e.Timestamp,
            e.Values
        )));

        return result;
    }

    public async virtual Task<IEnumerable<(DateTimeOffset Timestamp, object[] Values)>> GetFirst(Guid discriminatorId, int takeCount, CancellationToken token)
    {
        var query = GetQueryReadOnly()
            .OrderBy(e => e.Timestamp)
            .Take(takeCount);
        var entities = await query.ToArrayAsync(token);

        var result = entities.Select(e => (
            e.Timestamp,
            e.Values
        ));

        return result;
    }

    public async virtual Task<IEnumerable<(DateTimeOffset Timestamp, object[] Values)>> GetLast(Guid discriminatorId, int takeCount, CancellationToken token)
    {
        var query = GetQueryReadOnly()
            .OrderByDescending(e => e.Timestamp)
            .Take(takeCount);
        var entities = await query.ToArrayAsync(token);

        var result = entities.Select(e => (
            e.Timestamp,
            e.Values
        ));

        return result;
    }

    // ToDo: прореживание должно осуществляться до материализации
    public async virtual Task<IEnumerable<(DateTimeOffset Timestamp, object[] Values)>> GetResampledData(
        Guid discriminatorId,
        DateTimeOffset dateBegin,
        double intervalSec = 600d,
        int approxPointsCount = 1024,
        CancellationToken token = default)
    {
        var result = await GetGtDate(discriminatorId, dateBegin, token);

        var dateEnd = dateBegin.AddSeconds(intervalSec);
        result = result
            .Where(i => i.Item1 <= dateEnd);

        var ratio = result.Count() / approxPointsCount;
        if (ratio > 1)
            result = result
                .Where((_, index) => index % ratio == 0);

        return result;
    }

    public async virtual Task<IEnumerable<(DateTimeOffset Timestamp, object[] Values)>> GetGtDate(Guid discriminatorId, DateTimeOffset timestampBegin, CancellationToken token)
    {
        var query = GetQueryReadOnly()
            .Where(e => e.Timestamp > timestampBegin);
        var entities = await query.ToArrayAsync(token);

        var result = entities.Select(e => (
            e.Timestamp,
            e.Values
        ));

        return result;
    }

    public async virtual Task<DatesRangeDto?> GetDatesRange(Guid discriminatorId, CancellationToken token)
    {
        var query = GetQueryReadOnly()
            .GroupBy(entity => entity.DiscriminatorId)
            .Select(group => new
            {
                Min = group.Min(entity => entity.Timestamp),
                Max = group.Max(entity => entity.Timestamp),
            });

        var item = await query.FirstOrDefaultAsync(token);
        if (item is null)
        {
            return null;
        }

        var dto = new DatesRangeDto
        {
            From = item.Min,
            To = item.Max,
        };

        return dto;
    }

    public virtual Task<int> Count(Guid discriminatorId, CancellationToken token)
    {
        var dbSet = db.Set<TimestampedValues>();
        var query = dbSet.Where(entity => entity.DiscriminatorId == discriminatorId);

        return query.CountAsync(token);
    }

    /// <summary>
    /// Применить фильтр по дате
    /// </summary>
    /// <param name="query"></param>
    /// <param name="timestampBegin"></param>
    /// <returns></returns>
    private IQueryable<TimestampedValues> ApplyGeTimestamp(IQueryable<TimestampedValues> query, DateTimeOffset timestampBegin)
    {
        var geTimestampUtc = timestampBegin.ToUniversalTime();

        var result = query
            .Where(entity => entity.Timestamp >= geTimestampUtc);

        return result;
    }
}