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.DatabaseSnapshot;

 import liquibase.snapshot.DatabaseSnapshotGeneratorFactory;

 import liquibase.util.StringUtils;

 public class PrimaryKeyExistsPrecondition implements Precondition {

     private String schemaName;

     private String primaryKeyName;

     private String tableName;

     public String getSchemaName() {

         return schemaName;

     }

     public void setSchemaName(String schemaName) {

         this.schemaName = StringUtils.trimToNull(schemaName);

     }

     public String getPrimaryKeyName() {

         return primaryKeyName;

     }

     public void setPrimaryKeyName(String primaryKeyName) {

         this.primaryKeyName = primaryKeyName;

     }

     public String getTableName() {

         return tableName;

     }

     public void setTableName(String tableName) {

         this.tableName = tableName;

     }

     @Override

     public Warnings warn(Database database) {

         return new Warnings();

     }

     @Override

     public ValidationErrors validate(Database database) {

         return new ValidationErrors();

     }

     @Override

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

             throws PreconditionFailedException, PreconditionErrorException {

         DatabaseSnapshot snapshot;

         try {

             snapshot = DatabaseSnapshotGeneratorFactory.getInstance().createSnapshot(database, getSchemaName(), null);

         } catch (DatabaseException e) {

             throw new PreconditionErrorException(e, changeLog, this);

         }

         if (tableName != null) {

             if (snapshot.getPrimaryKeyForTable(getTableName()) == null) {

                 throw new PreconditionFailedException("Primary Key does not exist on "

                         + database.escapeStringForDatabase(getTableName()), changeLog, this);

             }

         } else if (primaryKeyName != null) {

             if (snapshot.getPrimaryKey(getPrimaryKeyName()) == null) {

                 throw new PreconditionFailedException("Primary Key "

                         + database.escapeStringForDatabase(getPrimaryKeyName()) + " does not exist", changeLog, this);

             }

         } else {

             throw new RuntimeException("primaryKeyExists precondition requires a tableName or primaryKeyName");

         }

     }

     @Override

     public String getName() {

         return "primaryKeyExists";

     }

 }