package liquibase.sqlgenerator.core;

 import liquibase.database.Database;

 import liquibase.database.core.MySQLDatabase;

 import liquibase.database.core.OracleDatabase;

 import liquibase.database.core.PostgresDatabase;

 import liquibase.exception.ValidationErrors;

 import liquibase.sql.Sql;

 import liquibase.sql.UnparsedSql;

 import liquibase.sqlgenerator.SqlGenerator;

 import liquibase.sqlgenerator.SqlGeneratorChain;

 import liquibase.statement.core.SetTableRemarksStatement;

 public class SetTableRemarksGenerator extends AbstractSqlGenerator<SetTableRemarksStatement> {

     @Override

     public boolean supports(SetTableRemarksStatement statement, Database database) {

         return database instanceof MySQLDatabase || database instanceof OracleDatabase

                 || database instanceof PostgresDatabase;

     }

     public ValidationErrors validate(SetTableRemarksStatement setTableRemarksStatement, Database database,

             SqlGeneratorChain sqlGeneratorChain) {

         ValidationErrors validationErrors = new ValidationErrors();

         validationErrors.checkRequiredField("tableName", setTableRemarksStatement.getTableName());

         validationErrors.checkRequiredField("remarks", setTableRemarksStatement.getRemarks());

         return validationErrors;

     }

     public Sql[] generateSql(SetTableRemarksStatement statement, Database database, SqlGeneratorChain sqlGeneratorChain) {

         String sql;

         String remarks = database.escapeStringForDatabase(statement.getRemarks());

         if (database instanceof MySQLDatabase) {

             sql = "ALTER TABLE " + database.escapeTableName(statement.getSchemaName(), statement.getTableName())

                     + " COMMENT = '" + remarks + "'";

         } else {

             sql = "COMMENT ON TABLE " + database.escapeTableName(statement.getSchemaName(), statement.getTableName())

                     + " IS '" + remarks + "'";

         }

         return new Sql[] { new UnparsedSql(sql) };

     }

 }