BirthdayBot/Data/GuildConfiguration.cs

using Discord.WebSocket;
using Npgsql;
using NpgsqlTypes;
using System;
using System.Data.Common;
using System.Linq;
using System.Threading.Tasks;

namespace BirthdayBot.Data
{
    /// <summary>
    /// Represents guild-specific configuration as exists in the database.
    /// Updating any property requires a call to <see cref="UpdateAsync"/> for changes to take effect.
    /// </summary>
    class GuildConfiguration
    {
        /// <summary>
        /// Gets this configuration's corresponding guild ID.
        /// </summary>
        public ulong GuildId { get; }

        /// <summary>
        /// Gets or sets the guild's designated usable role ID.
        /// Updating this value requires a call to <see cref="UpdateAsync"/>.
        /// </summary>
        public ulong? RoleId { get; set; }

        /// <summary>
        /// Gets or sets the announcement channel ID.
        /// Updating this value requires a call to <see cref="UpdateAsync"/>.
        /// </summary>
        public ulong? AnnounceChannelId { get; set; }

        /// <summary>
        /// Gets or sets the guild's default time zone ztring.
        /// Updating this value requires a call to <see cref="UpdateAsync"/>.
        /// </summary>
        public string TimeZone { get; set; }

        /// <summary>
        /// Gets or sets the guild's moderated mode setting.
        /// Updating this value requires a call to <see cref="UpdateAsync"/>.
        /// </summary>
        public bool IsModerated { get; set; }

        /// <summary>
        /// Gets or sets the guild's corresponding bot moderator role ID.
        /// Updating this value requires a call to <see cref="UpdateAsync"/>.
        /// </summary>
        public ulong? ModeratorRole { get; set; }

        /// <summary>
        /// Gets or sets the guild-specific birthday announcement message.
        /// Updating this value requires a call to <see cref="UpdateAsync"/>.
        /// </summary>
        public (string, string) AnnounceMessages { get; set; }

        /// <summary>
        /// Gets or sets the announcement ping setting.
        /// Updating this value requires a call to <see cref="UpdateAsync"/>.
        /// </summary>
        public bool AnnouncePing { get; set; }

        // Called by Load. Double-check ordinals when changes are made.
        private GuildConfiguration(DbDataReader reader)
        {
            GuildId = (ulong)reader.GetInt64(0);
            if (!reader.IsDBNull(1)) RoleId = (ulong)reader.GetInt64(1);
            if (!reader.IsDBNull(2)) AnnounceChannelId = (ulong)reader.GetInt64(2);
            TimeZone = reader.IsDBNull(3) ? null : reader.GetString(3);
            IsModerated = reader.GetBoolean(4);
            if (!reader.IsDBNull(5)) ModeratorRole = (ulong)reader.GetInt64(5);
            string announceMsg = reader.IsDBNull(6) ? null : reader.GetString(6);
            string announceMsgPl = reader.IsDBNull(7) ? null : reader.GetString(7);
            AnnounceMessages = (announceMsg, announceMsgPl);
            AnnouncePing = reader.GetBoolean(8);
        }

        /// <summary>
        /// Checks if the given user exists in the block list.
        /// If the server is in moderated mode, this always returns true.
        /// </summary>
        public async Task<bool> IsUserBlockedAsync(ulong userId)
        {
            if (IsModerated) return true;

            using var db = await Database.OpenConnectionAsync();
            using var c = db.CreateCommand();
            c.CommandText = $"select * from {BackingTableBans} "
                + "where guild_id = @Gid and user_id = @Uid";
            c.Parameters.Add("@Gid", NpgsqlDbType.Bigint).Value = (long)GuildId;
            c.Parameters.Add("@Uid", NpgsqlDbType.Bigint).Value = (long)userId;
            c.Prepare();
            using var r = await c.ExecuteReaderAsync();
            if (await r.ReadAsync()) return true;
            return false;
        }

        /// <summary>
        /// Adds the specified user to the block list corresponding to this guild.
        /// </summary>
        public async Task BlockUserAsync(ulong userId)
        {
            using var db = await Database.OpenConnectionAsync();
            using var c = db.CreateCommand();
            c.CommandText = $"insert into {BackingTableBans} (guild_id, user_id) "
                + "values (@Gid, @Uid) "
                + "on conflict (guild_id, user_id) do nothing";
            // There is no validation on whether the requested user is even in the guild. will this be a problem?
            c.Parameters.Add("@Gid", NpgsqlDbType.Bigint).Value = (long)GuildId;
            c.Parameters.Add("@Uid", NpgsqlDbType.Bigint).Value = (long)userId;
            c.Prepare();
            await c.ExecuteNonQueryAsync();
        }

        /// <summary>
        /// Removes the specified user from the block list corresponding to this guild.
        /// </summary>
        /// <returns>True if a user has been removed, false if the requested user was not in this list.</returns>
        public async Task<bool> UnblockUserAsync(ulong userId)
        {
            using var db = await Database.OpenConnectionAsync();
            using var c = db.CreateCommand();
            c.CommandText = $"delete from {BackingTableBans} where "
                + "guild_id = @Gid and user_id = @Uid";
            c.Parameters.Add("@Gid", NpgsqlDbType.Bigint).Value = (long)GuildId;
            c.Parameters.Add("@Uid", NpgsqlDbType.Bigint).Value = (long)userId;
            c.Prepare();
            var result = await c.ExecuteNonQueryAsync();
            return result != 0;
        }

        /// <summary>
        /// Checks if the given user can be considered a bot moderator.
        /// Checks for either the Manage Guild permission or if the user is within a predetermined role.
        /// </summary>
        public bool IsBotModerator(SocketGuildUser user)
            => user.GuildPermissions.ManageGuild || (ModeratorRole.HasValue && user.Roles.Any(r => r.Id == ModeratorRole.Value));

        #region Database
        public const string BackingTable = "settings";
        public const string BackingTableBans = "banned_users";

        internal static async Task DatabaseSetupAsync(NpgsqlConnection db)
        {
            using (var c = db.CreateCommand())
            {
                c.CommandText = $"create table if not exists {BackingTable} ("
                    + "guild_id bigint primary key, "
                    + "role_id bigint null, "
                    + "channel_announce_id bigint null, "
                    + "time_zone text null, "
                    + "moderated boolean not null default FALSE, "
                    + "moderator_role bigint null, "
                    + "announce_message text null, "
                    + "announce_message_pl text null, "
                    + "announce_ping boolean not null default FALSE, "
                    + "last_seen timestamptz not null default NOW()"
                    + ")";
                await c.ExecuteNonQueryAsync();
            }
            using (var c = db.CreateCommand())
            {
                c.CommandText = $"create table if not exists {BackingTableBans} ("
                    + $"guild_id bigint not null references {BackingTable} ON DELETE CASCADE, "
                    + "user_id bigint not null, "
                    + "PRIMARY KEY (guild_id, user_id)"
                    + ")";
                await c.ExecuteNonQueryAsync();
            }
        }

        /// <summary>
        /// Fetches guild settings from the database. If no corresponding entry exists, it will be created.
        /// </summary>
        /// <param name="nullIfUnknown">
        /// If true, this method shall not create a new entry and will return null if the guild does
        /// not exist in the database.
        /// </param>
        public static async Task<GuildConfiguration> LoadAsync(ulong guildId, bool nullIfUnknown)
        {
            using (var db = await Database.OpenConnectionAsync())
            {
                using (var c = db.CreateCommand())
                {
                    // Take note of ordinals for the constructor
                    c.CommandText = "select guild_id, role_id, channel_announce_id, time_zone, "
                        + " moderated, moderator_role, announce_message, announce_message_pl, announce_ping "
                        + $"from {BackingTable} where guild_id = @Gid";
                    c.Parameters.Add("@Gid", NpgsqlDbType.Bigint).Value = (long)guildId;
                    c.Prepare();
                    using var r = await c.ExecuteReaderAsync();
                    if (await r.ReadAsync()) return new GuildConfiguration(r);
                }
                if (nullIfUnknown) return null;

                // If we got here, no row exists. Create it with default values.
                using (var c = db.CreateCommand())
                {
                    c.CommandText = $"insert into {BackingTable} (guild_id) values (@Gid)";
                    c.Parameters.Add("@Gid", NpgsqlDbType.Bigint).Value = (long)guildId;
                    c.Prepare();
                    await c.ExecuteNonQueryAsync();
                }
            }
            // With a new row created, try this again
            return await LoadAsync(guildId, nullIfUnknown);
        }

        /// <summary>
        /// Updates values on the backing database with values from this object instance.
        /// </summary>
        public async Task UpdateAsync()
        {
            using var db = await Database.OpenConnectionAsync();
            using var c = db.CreateCommand();
            c.CommandText = $"update {BackingTable} set "
                + "role_id = @RoleId, "
                + "channel_announce_id = @ChannelId, "
                + "time_zone = @TimeZone, "
                + "moderated = @Moderated, "
                + "moderator_role = @ModRole, "
                + "announce_message = @AnnounceMsg, "
                + "announce_message_pl = @AnnounceMsgPl, "
                + "announce_ping = @AnnouncePing "
                + "where guild_id = @Gid";
            c.Parameters.Add("@Gid", NpgsqlDbType.Bigint).Value = (long)GuildId;
            NpgsqlParameter p;

            p = c.Parameters.Add("@RoleId", NpgsqlDbType.Bigint);
            if (RoleId.HasValue) p.Value = (long)RoleId.Value;
            else p.Value = DBNull.Value;

            p = c.Parameters.Add("@ChannelId", NpgsqlDbType.Bigint);
            if (AnnounceChannelId.HasValue) p.Value = (long)AnnounceChannelId.Value;
            else p.Value = DBNull.Value;

            p = c.Parameters.Add("@TimeZone", NpgsqlDbType.Text);
            if (TimeZone != null) p.Value = TimeZone;
            else p.Value = DBNull.Value;

            c.Parameters.Add("@Moderated", NpgsqlDbType.Boolean).Value = IsModerated;

            p = c.Parameters.Add("@ModRole", NpgsqlDbType.Bigint);
            if (ModeratorRole.HasValue) p.Value = (long)ModeratorRole.Value;
            else p.Value = DBNull.Value;

            p = c.Parameters.Add("@AnnounceMsg", NpgsqlDbType.Text);
            if (AnnounceMessages.Item1 != null) p.Value = AnnounceMessages.Item1;
            else p.Value = DBNull.Value;

            p = c.Parameters.Add("@AnnounceMsgPl", NpgsqlDbType.Text);
            if (AnnounceMessages.Item2 != null) p.Value = AnnounceMessages.Item2;
            else p.Value = DBNull.Value;

            c.Parameters.Add("@AnnouncePing", NpgsqlDbType.Boolean).Value = AnnouncePing;

            c.Prepare();
            c.ExecuteNonQuery();
        }
        #endregion
    }
}