using Microsoft.EntityFrameworkCore;
using System;
using System.Linq;
using System.Threading.Tasks;
using Timeline.Entities;
using Timeline.Models.Validation;
using Timeline.Services.Exceptions;
namespace Timeline.Services
{
///
/// This service provide some basic user features, which should be used internally for other services.
///
public interface IBasicUserService
{
///
/// Check if a user exists.
///
/// The id of the user.
/// True if exists. Otherwise false.
Task CheckUserExistence(long id);
///
/// Get the user id of given username.
///
/// Username of the user.
/// The id of the user.
/// Thrown when is null.
/// Thrown when is of bad format.
/// Thrown when the user with given username does not exist.
Task GetUserIdByUsername(string username);
}
public class BasicUserService : IBasicUserService
{
private readonly DatabaseContext _database;
private readonly UsernameValidator _usernameValidator = new UsernameValidator();
public BasicUserService(DatabaseContext database)
{
_database = database;
}
public async Task CheckUserExistence(long id)
{
return await _database.Users.AnyAsync(u => u.Id == id);
}
public async Task GetUserIdByUsername(string username)
{
if (username == null)
throw new ArgumentNullException(nameof(username));
if (!_usernameValidator.Validate(username, out var message))
throw new ArgumentException(message);
var entity = await _database.Users.Where(user => user.Username == username).Select(u => new { u.Id }).SingleOrDefaultAsync();
if (entity == null)
throw new UserNotExistException(username);
return entity.Id;
}
}
}