package liquibase.sqlgenerator.core;

 import liquibase.database.Database;

 import liquibase.database.core.DB2Database;

 import liquibase.database.core.InformixDatabase;

 import liquibase.database.core.MSSQLDatabase;

 import liquibase.database.core.OracleDatabase;

 import liquibase.database.core.SQLiteDatabase;

 import liquibase.database.core.SybaseASADatabase;

 import liquibase.database.core.SybaseDatabase;

 import liquibase.exception.ValidationErrors;

 import liquibase.sql.Sql;

 import liquibase.sql.UnparsedSql;

 import liquibase.sqlgenerator.SqlGeneratorChain;

 import liquibase.statement.core.AddUniqueConstraintStatement;

 import liquibase.util.StringUtils;

 public class AddUniqueConstraintGenerator extends AbstractSqlGenerator<AddUniqueConstraintStatement> {

     @Override

     public boolean supports(AddUniqueConstraintStatement statement, Database database) {

         return !(database instanceof SQLiteDatabase) && !(database instanceof MSSQLDatabase)

                 && !(database instanceof SybaseDatabase) && !(database instanceof SybaseASADatabase)

                 && !(database instanceof InformixDatabase);

     }

     @Override

     public ValidationErrors validate(AddUniqueConstraintStatement addUniqueConstraintStatement, Database database,

             SqlGeneratorChain sqlGeneratorChain) {

         ValidationErrors validationErrors = new ValidationErrors();

         validationErrors.checkRequiredField("columnNames", addUniqueConstraintStatement.getColumnNames());

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

         return validationErrors;

     }

     @Override

     public Sql[] generateSql(AddUniqueConstraintStatement statement, Database database,

             SqlGeneratorChain sqlGeneratorChain) {

         String sql = null;

         if (statement.getConstraintName() == null) {

             sql = String.format("ALTER TABLE %s ADD UNIQUE (%s)",

                     database.escapeTableName(statement.getSchemaName(), statement.getTableName()),

                     database.escapeColumnNameList(statement.getColumnNames()));

         } else {

             sql = String.format("ALTER TABLE %s ADD CONSTRAINT %s UNIQUE (%s)",

                     database.escapeTableName(statement.getSchemaName(), statement.getTableName()),

                     database.escapeConstraintName(statement.getConstraintName()),

                     database.escapeColumnNameList(statement.getColumnNames()));

         }

         if (database instanceof OracleDatabase) {

             if (statement.isDeferrable() || statement.isInitiallyDeferred()) {

                 if (statement.isDeferrable()) {

                     sql += " DEFERRABLE";

                 }

                 if (statement.isInitiallyDeferred()) {

                     sql += " INITIALLY DEFERRED";

                 }

             }

             if (statement.isDisabled()) {

                 sql += " DISABLE";

             }

         }

         if (StringUtils.trimToNull(statement.getTablespace()) != null && database.supportsTablespaces()) {

             if (database instanceof MSSQLDatabase) {

                 sql += " ON " + statement.getTablespace();

             } else if (database instanceof DB2Database || database instanceof SybaseASADatabase

                     || database instanceof InformixDatabase) {

                 ; // not supported

             } else {

                 sql += " USING INDEX TABLESPACE " + statement.getTablespace();

             }

         }

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

     }

 }