package liquibase.precondition.core;

 import liquibase.changelog.ChangeSet;

 import liquibase.changelog.DatabaseChangeLog;

 import liquibase.database.Database;

 import liquibase.exception.DatabaseException;

 import liquibase.exception.PreconditionErrorException;

 import liquibase.exception.PreconditionFailedException;

 import liquibase.exception.ValidationErrors;

 import liquibase.exception.Warnings;

 import liquibase.precondition.Precondition;

 import liquibase.snapshot.DatabaseSnapshotGeneratorFactory;

 import liquibase.util.StringUtils;

 public class IndexExistsPrecondition implements Precondition {

     private String schemaName;

     private String tableName;

     private String columnNames;

     private String indexName;

     public String getSchemaName() {

         return schemaName;

     }

     public void setSchemaName(String schemaName) {

         this.schemaName = StringUtils.trimToNull(schemaName);

     }

     public String getTableName() {

         return tableName;

     }

     public void setTableName(String tableName) {

         this.tableName = tableName;

     }

     public String getIndexName() {

         return indexName;

     }

     public void setIndexName(String indexName) {

         this.indexName = indexName;

     }

     public String getColumnNames() {

         return columnNames;

     }

     public void setColumnNames(String columnNames) {

         this.columnNames = columnNames;

     }

     @Override

     public Warnings warn(Database database) {

         return new Warnings();

     }

     @Override

     public ValidationErrors validate(Database database) {

         ValidationErrors validationErrors = new ValidationErrors();

         if (getIndexName() == null && getTableName() == null && getColumnNames() == null) {

             validationErrors.addError("indexName OR tableName and columnNames is required");

         }

         return validationErrors;

     }

     @Override

     public void check(Database database, DatabaseChangeLog changeLog, ChangeSet changeSet)

             throws PreconditionFailedException, PreconditionErrorException {

         try {

             if (!DatabaseSnapshotGeneratorFactory.getInstance().getGenerator(database)

                     .hasIndex(getSchemaName(), getTableName(), getIndexName(), database, getColumnNames())) {

                 String name = "";

                 if (getIndexName() != null) {

                     name += database.escapeStringForDatabase(getIndexName());

                 }

                 if (StringUtils.trimToNull(getTableName()) != null) {

                     name += " on " + database.escapeStringForDatabase(getTableName());

                     if (StringUtils.trimToNull(getColumnNames()) != null) {

                         name += " columns " + getColumnNames();

                     }

                 }

                 throw new PreconditionFailedException("Index " + name + " does not exist", changeLog, this);

             }

         } catch (DatabaseException e) {

             throw new PreconditionErrorException(e, changeLog, this);

         }

     }

     @Override

     public String getName() {

         return "indexExists";

     }

 }