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";
      }
  }