class FirebirdGrammar extends Grammar {

    /**
     * The possible column modifiers.
     *
     * @var array
     */
    protected $modifiers = ['Charset', 'Collate', 'Increment', 'Nullable', 'Default'];

    /**
     * The columns available as serials.
     *
     * @var array
     */
    protected $serials = ['bigInteger', 'integer', 
        'mediumInteger', 'smallInteger', 'tinyInteger'];

// …………………… пропущено ………………

    /**
     * Get the SQL for a character set column modifier.
     *
     * @param  \Illuminate\Database\Schema\Blueprint  $blueprint
     * @param  \Illuminate\Support\Fluent  $column
     * @return string|null
     */
    protected function modifyCharset(Blueprint $blueprint, Fluent $column)
    {
        if (! is_null($column->charset)) {
            return ' character set '.$column->charset;
        }
    }  
    
    /**
     * Get the SQL for a collation column modifier.
     *
     * @param  \Illuminate\Database\Schema\Blueprint  $blueprint
     * @param  \Illuminate\Support\Fluent  $column
     * @return string|null
     */
    protected function modifyCollate(Blueprint $blueprint, Fluent $column)
    {
        if (! is_null($column->collation)) {
            return ' collate '.$column->collation;
        }
    }    

    /**
     * Get the SQL for a nullable column modifier.
     *
     * @param  \Illuminate\Database\Schema\Blueprint  $blueprint
     * @param  \Illuminate\Support\Fluent  $column
     * @return string|null
     */
    protected function modifyNullable(Blueprint $blueprint, Fluent $column) {
        return $column->nullable ? '' : ' not null';
    }

    /**
     * Get the SQL for a default column modifier.
     *
     * @param  \Illuminate\Database\Schema\Blueprint  $blueprint
     * @param  \Illuminate\Support\Fluent  $column
     * @return string|null
     */
    protected function modifyDefault(Blueprint $blueprint, Fluent $column) {
        if (!is_null($column->default)) {
            return ' default ' . $this->getDefaultValue($column->default);
        }
    }

    /**
     * Get the SQL for an auto-increment column modifier.
     *
     * @param  \Illuminate\Database\Schema\Blueprint  $blueprint
     * @param  \Illuminate\Support\Fluent  $column
     * @return string|null
     */
    protected function modifyIncrement(Blueprint $blueprint, Fluent $column) {
        if (in_array($column->type, $this->serials) && $column->autoIncrement) {
            return ' primary key';
        }
    }

// …………………… пропущено ………………

}

    /**
     * Create the column definition for a char type.
     *
     * @param  \Illuminate\Support\Fluent  $column
     * @return string
     */
    protected function typeChar(Fluent $column) {
        return "char({$column->length})";
    }

    /**
     * Create the column definition for a string type.
     *
     * @param  \Illuminate\Support\Fluent  $column
     * @return string
     */
    protected function typeString(Fluent $column) {
        return "varchar({$column->length})";
    }

    /**
     * Create the column definition for a text type.
     *
     * @param  \Illuminate\Support\Fluent  $column
     * @return string
     */
    protected function typeText(Fluent $column) {
        return 'BLOB SUB_TYPE TEXT';
    }

    /**
     * Create the column definition for a medium text type.
     *
     * @param  \Illuminate\Support\Fluent  $column
     * @return string
     */
    protected function typeMediumText(Fluent $column) {
        return 'BLOB SUB_TYPE TEXT';
    }

    /**
     * Create the column definition for a long text type.
     *
     * @param  \Illuminate\Support\Fluent  $column
     * @return string
     */
    protected function typeLongText(Fluent $column) {
        return 'BLOB SUB_TYPE TEXT';
    }

    /**
     * Create the column definition for a integer type.
     *
     * @param  \Illuminate\Support\Fluent  $column
     * @return string
     */
    protected function typeInteger(Fluent $column) {
        return $column->autoIncrement ? 'INTEGER GENERATED BY DEFAULT AS IDENTITY' : 'INTEGER';
    }

    /**
     * Create the column definition for a big integer type.
     *
     * @param  \Illuminate\Support\Fluent  $column
     * @return string
     */
    protected function typeBigInteger(Fluent $column) {
        return $column->autoIncrement ? 'BIGINT GENERATED BY DEFAULT AS IDENTITY' : 'BIGINT';
    }

    /**
     * Create the column definition for a medium integer type.
     *
     * @param  \Illuminate\Support\Fluent  $column
     * @return string
     */
    protected function typeMediumInteger(Fluent $column) {
        return $column->autoIncrement ? 'INTEGER GENERATED BY DEFAULT AS IDENTITY' : 'INTEGER';
    }

    /**
     * Create the column definition for a tiny integer type.
     *
     * @param  \Illuminate\Support\Fluent  $column
     * @return string
     */
    protected function typeTinyInteger(Fluent $column) {
        return $column->autoIncrement ? 'SMALLINT GENERATED BY DEFAULT AS IDENTITY' : 'SMALLINT';
    }

    /**
     * Create the column definition for a small integer type.
     *
     * @param  \Illuminate\Support\Fluent  $column
     * @return string
     */
    protected function typeSmallInteger(Fluent $column) {
        return $column->autoIncrement ? 'SMALLINT GENERATED BY DEFAULT AS IDENTITY' : 'SMALLINT';
    }

    /**
     * Create the column definition for a float type.
     *
     * @param  \Illuminate\Support\Fluent  $column
     * @return string
     */
    protected function typeFloat(Fluent $column) {
        return $this->typeDouble($column);
    }

    /**
     * Create the column definition for a double type.
     *
     * @param  \Illuminate\Support\Fluent  $column
     * @return string
     */
    protected function typeDouble(Fluent $column) {
        return 'double precision';
    }

    /**
     * Create the column definition for a decimal type.
     *
     * @param  \Illuminate\Support\Fluent  $column
     * @return string
     */
    protected function typeDecimal(Fluent $column) {
        return "decimal({$column->total}, {$column->places})";
    }

    /**
     * Create the column definition for a boolean type.
     *
     * @param  \Illuminate\Support\Fluent  $column
     * @return string
     */
    protected function typeBoolean(Fluent $column) {
        return 'boolean';
    }

    /**
     * Create the column definition for an enum type.
     *
     * @param  \Illuminate\Support\Fluent  $column
     * @return string
     */
    protected function typeEnum(Fluent $column) {
        $allowed = array_map(function ($a) {
            return "'" . $a . "'";
        }, $column->allowed);

        return "varchar(255) check (\"{$column->name}\" in (" . implode(', ', $allowed) . '))';
    }

    /**
     * Create the column definition for a json type.
     *
     * @param  \Illuminate\Support\Fluent  $column
     * @return string
     */
    protected function typeJson(Fluent $column) {
        return 'varchar(8191)';
    }

    /**
     * Create the column definition for a jsonb type.
     *
     * @param  \Illuminate\Support\Fluent  $column
     * @return string
     */
    protected function typeJsonb(Fluent $column) {
        return 'varchar(8191)';
    }

    /**
     * Create the column definition for a date type.
     *
     * @param  \Illuminate\Support\Fluent  $column
     * @return string
     */
    protected function typeDate(Fluent $column) {
        return 'date';
    }

    /**
     * Create the column definition for a date-time type.
     *
     * @param  \Illuminate\Support\Fluent  $column
     * @return string
     */
    protected function typeDateTime(Fluent $column) {
        return 'timestamp';
    }

    /**
     * Create the column definition for a date-time type.
     *
     * @param  \Illuminate\Support\Fluent  $column
     * @return string
     */
    protected function typeDateTimeTz(Fluent $column) {
        return 'timestamp';
    }

    /**
     * Create the column definition for a time type.
     *
     * @param  \Illuminate\Support\Fluent  $column
     * @return string
     */
    protected function typeTime(Fluent $column) {
        return 'time';
    }

    /**
     * Create the column definition for a time type.
     *
     * @param  \Illuminate\Support\Fluent  $column
     * @return string
     */
    protected function typeTimeTz(Fluent $column) {
        return 'time';
    }

    /**
     * Create the column definition for a timestamp type.
     *
     * @param  \Illuminate\Support\Fluent  $column
     * @return string
     */
    protected function typeTimestamp(Fluent $column) {
        if ($column->useCurrent) {
            return 'timestamp default CURRENT_TIMESTAMP';
        }

        return 'timestamp';
    }

    /**
     * Create the column definition for a timestamp type.
     *
     * @param  \Illuminate\Support\Fluent  $column
     * @return string
     */
    protected function typeTimestampTz(Fluent $column) {
        if ($column->useCurrent) {
            return 'timestamp default CURRENT_TIMESTAMP';
        }

        return 'timestamp';
    }

    /**
     * Create the column definition for a binary type.
     *
     * @param  \Illuminate\Support\Fluent  $column
     * @return string
     */
    protected function typeBinary(Fluent $column) {
        return 'varchar(8191) CHARACTER SET OCTETS';
    }

    /**
     * Create the column definition for a uuid type.
     *
     * @param  \Illuminate\Support\Fluent  $column
     * @return string
     */
    protected function typeUuid(Fluent $column) {
        return 'char(36)';
    }

    /**
     * Create the column definition for an IP address type.
     *
     * @param  \Illuminate\Support\Fluent  $column
     * @return string
     */
    protected function typeIpAddress(Fluent $column) {
        return 'varchar(45)';
    }

    /**
     * Create the column definition for a MAC address type.
     *
     * @param  \Illuminate\Support\Fluent  $column
     * @return string
     */
    protected function typeMacAddress(Fluent $column) {
        return 'varchar(17)';
    }

    /**
     * Compile a column addition command.
     *
     * @param  \Illuminate\Database\Schema\Blueprint  $blueprint
     * @param  \Illuminate\Support\Fluent  $command
     * @return string
     */
    public function compileAdd(Blueprint $blueprint, Fluent $command) {
        $table = $this->wrapTable($blueprint);

        $columns = $this->prefixArray('add column', $this->getColumns($blueprint));

        return 'alter table ' . $table . ' ' . implode(', ', $columns);
    }

    /**
     * Compile a primary key command.
     *
     * @param  \Illuminate\Database\Schema\Blueprint  $blueprint
     * @param  \Illuminate\Support\Fluent  $command
     * @return string
     */
    public function compilePrimary(Blueprint $blueprint, Fluent $command) {
        $columns = $this->columnize($command->columns);

        return 'alter table ' . $this->wrapTable($blueprint) . " add primary key ({$columns})";
    }

    /**
     * Compile a unique key command.
     *
     * @param  \Illuminate\Database\Schema\Blueprint  $blueprint
     * @param  \Illuminate\Support\Fluent  $command
     * @return string
     */
    public function compileUnique(Blueprint $blueprint, Fluent $command) {
        $table = $this->wrapTable($blueprint);

        $index = $this->wrap($command->index);

        $columns = $this->columnize($command->columns);

        return "alter table $table add constraint {$index} unique ($columns)";
    }

    /**
     * Compile a plain index key command.
     *
     * @param  \Illuminate\Database\Schema\Blueprint  $blueprint
     * @param  \Illuminate\Support\Fluent  $command
     * @return string
     */
    public function compileIndex(Blueprint $blueprint, Fluent $command) {
        $columns = $this->columnize($command->columns);

        $index = $this->wrap($command->index);

        return "create index {$index} on " . $this->wrapTable($blueprint) . " ({$columns})";
    }

    /**
     * Compile a drop column command.
     *
     * @param  \Illuminate\Database\Schema\Blueprint  $blueprint
     * @param  \Illuminate\Support\Fluent  $command
     * @return string
     */
    public function compileDropColumn(Blueprint $blueprint, Fluent $command) {
        $columns = $this->prefixArray('drop column', $this->wrapArray($command->columns));

        $table = $this->wrapTable($blueprint);

        return 'alter table ' . $table . ' ' . implode(', ', $columns);
    }

    /**
     * Compile a drop primary key command.
     *
     * @param  \Illuminate\Database\Schema\Blueprint  $blueprint
     * @param  \Illuminate\Support\Fluent  $command
     * @return string
     */
    public function compileDropPrimary(Blueprint $blueprint, Fluent $command) {
        $table = $blueprint->getTable();

        $index = $this->wrap("{$table}_pkey");

        return 'alter table ' . $this->wrapTable($blueprint) . " drop constraint {$index}";
    }

    /**
     * Compile a drop unique key command.
     *
     * @param  \Illuminate\Database\Schema\Blueprint  $blueprint
     * @param  \Illuminate\Support\Fluent  $command
     * @return string
     */
    public function compileDropUnique(Blueprint $blueprint, Fluent $command) {
        $table = $this->wrapTable($blueprint);

        $index = $this->wrap($command->index);

        return "alter table {$table} drop constraint {$index}";
    }

    /**
     * Compile a drop index command.
     *
     * @param  \Illuminate\Database\Schema\Blueprint  $blueprint
     * @param  \Illuminate\Support\Fluent  $command
     * @return string
     */
    public function compileDropIndex(Blueprint $blueprint, Fluent $command) {
        $index = $this->wrap($command->index);

        return "drop index {$index}";
    }

    /**
     * Compile a drop foreign key command.
     *
     * @param  \Illuminate\Database\Schema\Blueprint  $blueprint
     * @param  \Illuminate\Support\Fluent  $command
     * @return string
     */
    public function compileDropForeign(Blueprint $blueprint, Fluent $command) {
        $table = $this->wrapTable($blueprint);

        $index = $this->wrap($command->index);

        return "alter table {$table} drop constraint {$index}";
    }

    /**
     * Compile a create sequence command.
     *
     * @param  \Illuminate\Database\Schema\SequenceBlueprint  $blueprint
     * @param  \Illuminate\Support\Fluent  $command
     * @return string
     */
    public function compileCreateSequence(SequenceBlueprint $blueprint, Fluent $command) {
        $sql = 'create sequence ';
        $sql .= $this->wrapSequence($blueprint);
        if ($blueprint->getInitialValue() !== 0) {
            $sql .= ' start with ' . $blueprint->getInitialValue();
        }
        if ($blueprint->getIncrement() !== 1) {
            $sql .= ' increment by ' . $blueprint->getIncrement();
        }
        return $sql;
    }

    /**
     * Compile a alter sequence command.
     *
     * @param  \Illuminate\Database\Schema\SequenceBlueprint  $blueprint
     * @param  \Illuminate\Support\Fluent  $command
     * @return string
     */
    public function compileAlterSequence(SequenceBlueprint $blueprint, Fluent $command) {
        $sql = 'alter sequence ';
        $sql .= $this->wrapSequence($blueprint);
        if ($blueprint->isRestart()) {
            $sql .= ' restart';
            if ($blueprint->getInitialValue() !== null) {
                $sql .= ' with ' . $blueprint->getInitialValue();
            }
        }
        if ($blueprint->getIncrement() !== 1) {
            $sql .= ' increment by ' . $blueprint->getIncrement();
        }
        return $sql;
    }

    /**
     * Compile a drop sequence command.
     * 
     * @param \Illuminate\Database\Schema\SequenceBlueprint $blueprint
     * @param \Illuminate\Support\Fluent $command
     * @return string
     */
    public function compileDropSequence(SequenceBlueprint $blueprint, Fluent $command) {
        return 'drop sequence ' . $this->wrapSequence($blueprint);
    }

    /**
     * Compile a drop sequence command.
     * 
     * @param \Illuminate\Database\Schema\SequenceBlueprint $blueprint
     * @param \Illuminate\Support\Fluent $command
     * @return string
     */
    public function compileDropSequenceIfExists(SequenceBlueprint $blueprint, Fluent $command) {
        $sql = 'EXECUTE BLOCK' . "\n";
        $sql .= 'AS' . "\n";
        $sql .= 'BEGIN' . "\n";
        $sql .= "  IF (EXISTS(select * from RDB\$GENERATORS where RDB\$GENERATOR_NAME = '" . $blueprint->getSequence() . "')) THEN" . "\n";
        $sql .= "    EXECUTE STATEMENT 'DROP SEQUENCE " . $this->wrapSequence($blueprint) . "';" . "\n";
        $sql .= 'END';
        return $sql;
    }

    /**
     * Wrap a sequence in keyword identifiers.
     *
     * @param  mixed   $sequence
     * @return string
     */
    public function wrapSequence($sequence) {
        if ($sequence instanceof SequenceBlueprint) {
            $sequence = $sequence->getSequence();
        }

        if ($this->isExpression($sequence)) {
            return $this->getValue($sequence);
        }

        return $this->wrap($this->tablePrefix . $sequence, true);
    }

class CreateUsersTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        // выполнит оператор 
        // CREATE SEQUENCE "seq_users_id"
        Schema::createSequence('seq_users_id');
        // выполнит операторы
        // CREATE TABLE "users" (
        //   "id"              INTEGER NOT NULL,
        //   "name"            VARCHAR(255) NOT NULL,
        //   "email"           VARCHAR(255) NOT NULL,
        //   "password"        VARCHAR(255) NOT NULL,
        //   "remember_token"  VARCHAR(100),
        //   "created_at"      TIMESTAMP,
        //   "updated_at"      TIMESTAMP
        // );
        // ALTER TABLE "users" ADD PRIMARY KEY ("id");
        // ALTER TABLE "users" ADD CONSTRAINT "users_email_unique" UNIQUE ("email");
        Schema::create('users', function (Blueprint $table) {
            //$table->increments('id');
            $table->integer('id')->primary();
            $table->string('name');
            $table->string('email')->unique();
            $table->string('password');
            $table->rememberToken();
            $table->timestamps();
        });
        // выполнит оператор
        // ALTER SEQUENCE "seq_users_id" RESTART WITH 10 INCREMENT BY 5
        Schema::sequence('seq_users_id', function (SequenceBlueprint $sequence) {
            $sequence->increment(5);
            $sequence->restart(10);
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        // выполнит оператор 
        // DROP SEQUENCE "seq_users_id"
        Schema::dropSequence('seq_users_id');
        // выполнит оператор 
        // DROP TABLE "users"        
        Schema::drop('users');
    }
}