package liquibase.sqlgenerator.core;

 import java.util.Arrays;

 import java.util.Iterator;

 import java.util.List;

 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.SybaseASADatabase;

 import liquibase.database.structure.Index;

 import liquibase.exception.ValidationErrors;

 import liquibase.sql.Sql;

 import liquibase.sql.UnparsedSql;

 import liquibase.sqlgenerator.SqlGeneratorChain;

 import liquibase.statement.core.CreateIndexStatement;

 import liquibase.util.StringUtils;

 public class CreateIndexGenerator extends AbstractSqlGenerator<CreateIndexStatement> {

     @Override

     public ValidationErrors validate(CreateIndexStatement createIndexStatement, Database database,

             SqlGeneratorChain sqlGeneratorChain) {

         ValidationErrors validationErrors = new ValidationErrors();

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

         validationErrors.checkRequiredField("columns", createIndexStatement.getColumns());

         return validationErrors;

     }

     @Override

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

         if (database instanceof OracleDatabase) {

             // Oracle don't create index when creates foreignKey

             // It means that all indexes associated with foreignKey should be created manualy

             List<String> associatedWith = StringUtils.splitAndTrim(statement.getAssociatedWith(), ",");

             if (associatedWith != null

                     && (associatedWith.contains(Index.MARK_PRIMARY_KEY) || associatedWith

                             .contains(Index.MARK_UNIQUE_CONSTRAINT))) {

                 return new Sql[0];

             }

         } else {

             // Default filter of index creation:

             // creation of all indexes with associations are switched off.

             List<String> associatedWith = StringUtils.splitAndTrim(statement.getAssociatedWith(), ",");

             if (associatedWith != null

                     && (associatedWith.contains(Index.MARK_PRIMARY_KEY)

                             || associatedWith.contains(Index.MARK_UNIQUE_CONSTRAINT) || associatedWith

                                 .contains(Index.MARK_FOREIGN_KEY))) {

                 return new Sql[0];

             }

         }

         StringBuffer buffer = new StringBuffer();

         buffer.append("CREATE ");

         if (statement.isUnique() != null && statement.isUnique()) {

             buffer.append("UNIQUE ");

         }

         buffer.append("INDEX ");

         if (statement.getIndexName() != null) {

             String indexSchema = statement.getTableSchemaName();

             buffer.append(database.escapeIndexName(indexSchema, statement.getIndexName())).append(" ");

         }

         buffer.append("ON ");

         buffer.append(database.escapeTableName(statement.getTableSchemaName(), statement.getTableName())).append("(");

         Iterator<String> iterator = Arrays.asList(statement.getColumns()).iterator();

         while (iterator.hasNext()) {

             String column = iterator.next();

             buffer.append(database.escapeColumnName(statement.getTableSchemaName(), statement.getTableName(), column));

             if (iterator.hasNext()) {

                 buffer.append(", ");

             }

         }

         buffer.append(")");

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

             if (database instanceof MSSQLDatabase || database instanceof SybaseASADatabase) {

                 buffer.append(" ON ").append(statement.getTablespace());

             } else if (database instanceof DB2Database || database instanceof InformixDatabase) {

                 buffer.append(" IN ").append(statement.getTablespace());

             } else {

                 buffer.append(" TABLESPACE ").append(statement.getTablespace());

             }

         }

         return new Sql[] { new UnparsedSql(buffer.toString()) };

     }

 }