const team_size_trigger = `
CREATE OR REPLACE FUNCTION enforce_team_size() RETURNS trigger AS $$
DECLARE
    team_size INTEGER := 3;
    team_count INTEGER := 0;
BEGIN
    IF (TG_OP = 'UPDATE' OR TG_OP = 'INSERT') THEN
        SELECT INTO team_count COUNT(id)
        FROM constructs
        WHERE account = NEW.account
        AND team = true;
    ELSIF (TG_OP = 'DELETE') THEN
        SELECT INTO team_count COUNT(id)
        FROM constructs
        WHERE account = OLD.account
        AND team = true;
    END IF;

    IF team_count != team_size THEN
        RAISE EXCEPTION 'You must have exactly % constructs in your team.', team_size;
    END IF;

    RETURN NEW;
END;
$$ LANGUAGE plpgsql;

CREATE CONSTRAINT TRIGGER check_team_size
    AFTER INSERT OR UPDATE OR DELETE
    ON constructs
    DEFERRABLE INITIALLY DEFERRED
    FOR EACH ROW
    EXECUTE PROCEDURE enforce_team_size();
`;

exports.up = async knex => {
    await knex.schema.createTable('constructs', table => {
        table.uuid('id').primary();
        table.timestamps(true, true);
        table.uuid('account').notNullable()
        table.foreign('account')
            .references('id')
            .inTable('accounts')
            .onDelete('CASCADE');
        table.binary('data').notNullable();

        table.boolean('team')
            .notNullable()
            .defaultTo(false);
    });

    await knex.raw(team_size_trigger);

    return true;
};

exports.down = async () => {};