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using Microsoft.AspNetCore.Hosting;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using System;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using Timeline.Entities;
namespace Timeline.Services
{
public class Avatar
{
public string Type { get; set; }
public byte[] Data { get; set; }
}
/// <summary>
/// Thrown when avatar is of bad format.
/// </summary>
[Serializable]
public class AvatarDataException : Exception
{
public AvatarDataException(Avatar avatar, string message) : base(message) { Avatar = avatar; }
public AvatarDataException(Avatar avatar, string message, Exception inner) : base(message, inner) { Avatar = avatar; }
protected AvatarDataException(
System.Runtime.Serialization.SerializationInfo info,
System.Runtime.Serialization.StreamingContext context) : base(info, context) { }
public Avatar Avatar { get; set; }
}
/// <summary>
/// Provider for default user avatar.
/// </summary>
/// <remarks>
/// Mainly for unit tests.
/// </remarks>
public interface IDefaultUserAvatarProvider
{
/// <summary>
/// Get the default avatar.
/// </summary>
Task<Avatar> GetDefaultAvatar();
}
public interface IUserAvatarService
{
/// <summary>
/// Get avatar of a user. If the user has no avatar, a default one is returned.
/// </summary>
/// <param name="username">The username of the user to get avatar of.</param>
/// <returns>The avatar.</returns>
/// <exception cref="ArgumentException">Thrown if <paramref name="username"/> is null or empty.</exception>
/// <exception cref="UserNotExistException">Thrown if the user does not exist.</exception>
Task<Avatar> GetAvatar(string username);
/// <summary>
/// Set avatar for a user.
/// </summary>
/// <param name="username">The username of the user to set avatar for.</param>
/// <param name="avatar">The avatar. Can be null to delete the saved avatar.</param>
/// <exception cref="ArgumentException">Throw if <paramref name="username"/> is null or empty.
/// Or thrown if <paramref name="avatar"/> is not null but <see cref="Avatar.Type"/> is null or empty or <see cref="Avatar.Data"/> is null.</exception>
/// <exception cref="UserNotExistException">Thrown if the user does not exist.</exception>
/// <exception cref="AvatarDataException">Thrown if avatar is of bad format.</exception>
Task SetAvatar(string username, Avatar avatar);
}
public class DefaultUserAvatarProvider : IDefaultUserAvatarProvider
{
private readonly IHostingEnvironment _environment;
public DefaultUserAvatarProvider(IHostingEnvironment environment)
{
_environment = environment;
}
public async Task<Avatar> GetDefaultAvatar()
{
return new Avatar
{
Type = "image/png",
Data = await File.ReadAllBytesAsync(Path.Combine(_environment.ContentRootPath, "default-avatar.png"))
};
}
}
public class UserAvatarService : IUserAvatarService
{
private readonly ILogger<UserAvatarService> _logger;
private readonly DatabaseContext _database;
private readonly IDefaultUserAvatarProvider _defaultUserAvatarProvider;
public UserAvatarService(ILogger<UserAvatarService> logger, DatabaseContext database, IDefaultUserAvatarProvider defaultUserAvatarProvider)
{
_logger = logger;
_database = database;
_defaultUserAvatarProvider = defaultUserAvatarProvider;
}
public async Task<Avatar> GetAvatar(string username)
{
if (string.IsNullOrEmpty(username))
throw new ArgumentException("Username is null or empty.", nameof(username));
var user = await _database.Users.Where(u => u.Name == username).SingleOrDefaultAsync();
if (user == null)
throw new UserNotExistException(username);
await _database.Entry(user).Reference(u => u.Avatar).LoadAsync();
var avatar = user.Avatar;
if (avatar == null)
{
return await _defaultUserAvatarProvider.GetDefaultAvatar();
}
else
{
return new Avatar
{
Type = avatar.Type,
Data = avatar.Data
};
}
}
public async Task SetAvatar(string username, Avatar avatar)
{
if (string.IsNullOrEmpty(username))
throw new ArgumentException("Username is null or empty.", nameof(username));
if (avatar != null)
{
if (string.IsNullOrEmpty(avatar.Type))
throw new ArgumentException("Type of avatar is null or empty.", nameof(avatar));
if (avatar.Data == null)
throw new ArgumentException("Data of avatar is null.", nameof(avatar));
}
var user = await _database.Users.Where(u => u.Name == username).SingleOrDefaultAsync();
if (user == null)
throw new UserNotExistException(username);
await _database.Entry(user).Reference(u => u.Avatar).LoadAsync();
var avatarEntity = user.Avatar;
if (avatar == null)
{
if (avatarEntity == null)
return;
else
{
_database.UserAvatars.Remove(avatarEntity);
await _database.SaveChangesAsync();
}
}
else
{
// TODO: Use image library to check the format to prohibit bad data.
if (avatarEntity == null)
{
user.Avatar = new UserAvatar
{
Type = avatar.Type,
Data = avatar.Data
};
}
else
{
avatarEntity.Type = avatar.Type;
avatarEntity.Data = avatar.Data;
}
await _database.SaveChangesAsync();
}
}
}
public static class UserAvatarServiceCollectionExtensions
{
public static void AddUserAvatarService(this IServiceCollection services)
{
services.AddScoped<IUserAvatarService, UserAvatarService>();
services.AddSingleton<IDefaultUserAvatarProvider, DefaultUserAvatarProvider>();
}
}
}
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