sharp-chat/SharpChatCommon/Users/UsersContext.cs

using SharpChat.Auth;

namespace SharpChat.Users;

public class UsersContext {
    private readonly Dictionary<string, User> Users = [];
    private readonly Lock @lock = new();

    public bool UserExists(string id) {
        lock(@lock)
            return Users.ContainsKey(id);
    }

    public bool UserExists(Func<User, bool> predicate) {
        lock(@lock)
            return Users.Values.Any(predicate);
    }

    public User? GetUser(string id) {
        lock(@lock)
            return Users.TryGetValue(id, out User? user) ? user : null;
    }

    public User? GetUser(Func<User, bool> predicate) {
        lock(@lock)
            return Users.Values.FirstOrDefault(predicate);
    }

    public IEnumerable<User> GetUsers() {
        lock(@lock)
            return [.. Users.Values];
    }

    public IEnumerable<User> GetUsers(IEnumerable<string> ids) {
        return [.. ids.Select(GetUser).Where(u => u is not null).Cast<User>()];
    }

    public IEnumerable<User> GetUsers(Func<User, bool> predicate) {
        lock(@lock)
            return [.. Users.Values.Where(predicate)];
    }

    public IEnumerable<User> GetUsersWithStatus(UserStatus status) {
        return GetUsers(u => u.Status == status);
    }

    public IEnumerable<User> GetUsersOfMinimumRank(int minRank) {
        return GetUsers(u => u.Rank >= minRank);
    }

    public User CreateOrUpdateUser(AuthResult authResult) {
        lock(@lock) {
            User? user = GetUser(authResult.UserId);
            return user is null ? CreateUserInternal(
                authResult.UserId,
                authResult.UserName,
                authResult.UserColour,
                authResult.UserRank,
                authResult.UserPermissions
            ) : UpdateUserInternal(
                user,
                authResult.UserId,
                authResult.UserName,
                authResult.UserColour,
                authResult.UserRank,
                authResult.UserPermissions
            ).User;
        }
    }

    public User CreateUser(
        string id,
        string name,
        ColourInheritable colour,
        int rank,
        UserPermissions perms,
        string nick = "",
        UserStatus status = UserStatus.Online,
        string statusText = ""
    ) {
        lock(@lock)
            return UserExists(id)
                ? throw new UserExistsException(nameof(id))
                : CreateUserInternal(id, name, colour, rank, perms, nick, status, statusText);
    }

    private User CreateUserInternal(
        string id,
        string name,
        ColourInheritable colour,
        int rank,
        UserPermissions perms,
        string nick = "",
        UserStatus status = UserStatus.Online,
        string statusText = ""
    ) {
        User user = new(id, name, colour, rank, perms, nick, status, statusText);
        Users.Add(id, user);
        return user;
    }

    public UserDiff UpdateUser(
        User user,
        string? name = null,
        ColourInheritable? colour = null,
        int? rank = null,
        UserPermissions? perms = null,
        string? nick = null,
        UserStatus? status = null,
        string? statusText = null
    ) => UpdateUser(user.UserId, name, colour, rank, perms, nick, status, statusText);

    public UserDiff UpdateUser(
        string id,
        string? name = null,
        ColourInheritable? colour = null,
        int? rank = null,
        UserPermissions? perms = null,
        string? nick = null,
        UserStatus? status = null,
        string? statusText = null
    ) {
        lock(@lock)
            return UpdateUserInternal(
                GetUser(id) ?? throw new UserNotFoundException(nameof(id)),
                id, name, colour, rank, perms, nick, status, statusText
            );
    }

    private static UserDiff UpdateUserInternal(
        User user,
        string id,
        string? name = null,
        ColourInheritable? colour = null,
        int? rank = null,
        UserPermissions? perms = null,
        string? nick = null,
        UserStatus? status = null,
        string? statusText = null
    ) {
        StringDiff nameDiff = new(user.UserName, name);
        if(nameDiff.Changed)
            user.UserName = nameDiff.After;

        ValueDiff<ColourInheritable> colourDiff = new(user.Colour, colour);
        if(colourDiff.Changed)
            user.Colour = colourDiff.After;

        ValueDiff<int> rankDiff = new(user.Rank, rank);
        if(rankDiff.Changed)
            user.Rank = rankDiff.After;

        ValueDiff<UserPermissions> permsDiff = new(user.Permissions, perms);
        if(permsDiff.Changed)
            user.Permissions = permsDiff.After;

        StringDiff nickDiff = new(user.NickName, nick);
        if(nickDiff.Changed)
            user.NickName = nickDiff.After;

        ValueDiff<UserStatus> statusDiff = new(user.Status, status);
        if(statusDiff.Changed)
            user.Status = statusDiff.After;

        StringDiff statusTextDiff = new(user.StatusText, statusText);
        if(statusTextDiff.Changed)
            user.StatusText = statusTextDiff.After;

        return new(
            user,
            id,
            nameDiff,
            colourDiff,
            rankDiff,
            permsDiff,
            nickDiff,
            statusDiff,
            statusTextDiff
        );
    }

    public void RemoveUser(User user)
        => RemoveUserInternal(user.UserId, nameof(user));

    public void RemoveUser(string id)
        => RemoveUserInternal(id, nameof(id));

    private void RemoveUserInternal(string id, string argName) {
        lock(@lock)
            if(!Users.Remove(id))
                throw new UserNotFoundException(argName);
    }
}