using MySqlConnector;
using System;

namespace SharpChat.EventStorage {
    public partial class MariaDBEventStorage {
        private void DoMigration(string name, Action action) {
            bool done = (long?)RunQueryValue(
                "SELECT COUNT(*) FROM `sqc_migrations` WHERE `migration_name` = @name",
                new MySqlParameter("name", name)
            ) > 0;
            if(!done) {
                Logger.Write($"Running migration '{name}'...");
                action();
                RunMigrationCommand(
                    "INSERT INTO `sqc_migrations` (`migration_name`) VALUES (@name)",
                    new MySqlParameter("name", name)
                );
            }
        }

        public void RunMigrations() {
            RunMigrationCommand(
                "CREATE TABLE IF NOT EXISTS `sqc_migrations` ("
                + "`migration_name` VARCHAR(255) NOT NULL,"
                + "`migration_completed` TIMESTAMP NOT NULL DEFAULT current_timestamp(),"
                + "UNIQUE INDEX `migration_name` (`migration_name`),"
                + "INDEX `migration_completed` (`migration_completed`)"
                + ") COLLATE='utf8mb4_unicode_ci' ENGINE=InnoDB;"
            );

            DoMigration("create_events_table", CreateEventsTable);
            DoMigration("allow_null_target", AllowNullTarget);
            DoMigration("update_event_type_names", UpdateEventTypeNames);
            DoMigration("deprecate_event_flags", DeprecateEventFlags);
            DoMigration("update_collations_and_use_json_type", UpdateCollationsAndUseJsonType);
        }

        private void UpdateCollationsAndUseJsonType() {
            RunMigrationCommand("UPDATE sqc_events SET event_target = LOWER(event_target)");
            RunMigrationCommand("UPDATE sqc_events SET event_sender_nick = NULL WHERE event_sender_nick = ''");
            RunMigrationCommand(
                "ALTER TABLE `sqc_events` COLLATE='utf8mb4_unicode_520_ci',"
                + " CHANGE COLUMN `event_type` `event_type` VARCHAR(255) NOT NULL COLLATE 'ascii_general_ci' AFTER `event_id`,"
                + " CHANGE COLUMN `event_created` `event_created` TIMESTAMP NOT NULL DEFAULT current_timestamp() AFTER `event_type`,"
                + " CHANGE COLUMN `event_deleted` `event_deleted` TIMESTAMP NULL DEFAULT NULL AFTER `event_created`,"
                + " CHANGE COLUMN `event_target` `event_channel` VARCHAR(255) NULL DEFAULT NULL COLLATE 'ascii_general_ci' AFTER `event_deleted`,"
                + " CHANGE COLUMN `event_sender_name` `event_sender_name` VARCHAR(255) NULL DEFAULT NULL COLLATE 'utf8mb4_unicode_520_ci' AFTER `event_sender`,"
                + " CHANGE COLUMN `event_sender_nick` `event_sender_nick` VARCHAR(255) NULL DEFAULT NULL COLLATE 'utf8mb4_unicode_520_ci' AFTER `event_sender_rank`,"
                + " CHANGE COLUMN `event_data` `event_data` JSON NOT NULL DEFAULT '{}' AFTER `event_sender_perms`,"
                + " DROP INDEX `event_target`, ADD INDEX `event_channel` (`event_channel`)"
            );
        }

        private void DeprecateEventFlags() {
            // StoredEventFlags.Action is just a field in the data object
            RunMigrationCommand(@"UPDATE sqc_events SET event_data = JSON_MERGE_PATCH(event_data, JSON_OBJECT('action', true)) WHERE event_flags & 1");

            // StoredEventFlags.Broadcast can be implied by just having a NULL as the channel name
            RunMigrationCommand(@"UPDATE sqc_events SET event_target = NULL WHERE event_flags & 2");

            // StoredEventFlags.Log was never meaningfully used by anything and basically just meant "not-msg:add"
            // StoredEventFlags.Private was also never meaningfully used, can be determined by checking if the channel name starts with @
            RunMigrationCommand(@"ALTER TABLE sqc_events DROP COLUMN event_flags");
        }

        private void UpdateEventTypeNames() {
            RunMigrationCommand(@"UPDATE sqc_events SET event_type = ""msg:add"" WHERE event_type = ""SharpChat.Events.ChatMessage""");
            RunMigrationCommand(@"UPDATE sqc_events SET event_type = ""user:connect"" WHERE event_type = ""SharpChat.Events.UserConnectEvent""");
            RunMigrationCommand(@"UPDATE sqc_events SET event_type = ""user:disconnect"" WHERE event_type = ""SharpChat.Events.UserDisconnectEvent""");
            RunMigrationCommand(@"UPDATE sqc_events SET event_type = ""chan:join"" WHERE event_type = ""SharpChat.Events.UserChannelJoinEvent""");
            RunMigrationCommand(@"UPDATE sqc_events SET event_type = ""chan:leave"" WHERE event_type = ""SharpChat.Events.UserChannelLeaveEvent""");
        }

        private void AllowNullTarget() {
            RunMigrationCommand(
                "ALTER TABLE `sqc_events`"
                + " CHANGE COLUMN `event_target` `event_target` VARBINARY(255) NULL AFTER `event_type`;"
            );
        }

        private void CreateEventsTable() {
            RunMigrationCommand(
                "CREATE TABLE `sqc_events` ("
                + "`event_id` BIGINT(20) NOT NULL,"
                + "`event_sender` BIGINT(20) UNSIGNED NULL DEFAULT NULL,"
                + "`event_sender_name` VARCHAR(255) NULL DEFAULT NULL,"
                + "`event_sender_colour` INT(11) NULL DEFAULT NULL,"
                + "`event_sender_rank` INT(11) NULL DEFAULT NULL,"
                + "`event_sender_nick` VARCHAR(255) NULL DEFAULT NULL,"
                + "`event_sender_perms` INT(11) NULL DEFAULT NULL,"
                + "`event_created` TIMESTAMP NOT NULL DEFAULT current_timestamp(),"
                + "`event_deleted` TIMESTAMP NULL DEFAULT NULL,"
                + "`event_type` VARBINARY(255) NOT NULL,"
                + "`event_target` VARBINARY(255) NOT NULL,"
                + "`event_flags` TINYINT(3) UNSIGNED NOT NULL,"
                + "`event_data` BLOB NULL DEFAULT NULL,"
                + "PRIMARY KEY (`event_id`),"
                + "INDEX `event_target` (`event_target`),"
                + "INDEX `event_type` (`event_type`),"
                + "INDEX `event_sender` (`event_sender`),"
                + "INDEX `event_datetime` (`event_created`),"
                + "INDEX `event_deleted` (`event_deleted`)"
                + ") COLLATE='utf8mb4_unicode_ci' ENGINE=InnoDB;"
            );
        }
    }
}