package liquibase.sqlgenerator.core;

 import liquibase.database.Database;

 import liquibase.database.core.OracleDatabase;

 import liquibase.exception.DatabaseException;

 import liquibase.exception.UnexpectedLiquibaseException;

 import liquibase.exception.ValidationErrors;

 import liquibase.sql.Sql;

 import liquibase.sql.UnparsedSql;

 import liquibase.sqlgenerator.SqlGenerator;

 import liquibase.sqlgenerator.SqlGeneratorChain;

 import liquibase.statement.core.FindForeignKeyConstraintsStatement;

 public class FindForeignKeyConstraintsGeneratorOracle extends AbstractSqlGenerator<FindForeignKeyConstraintsStatement> {

     @Override

     public int getPriority() {

         return PRIORITY_DATABASE;

     }

     @Override

     public boolean supports(FindForeignKeyConstraintsStatement statement, Database database) {

         return database instanceof OracleDatabase;

     }

     public ValidationErrors validate(FindForeignKeyConstraintsStatement findForeignKeyConstraintsStatement,

             Database database, SqlGeneratorChain sqlGeneratorChain) {

         ValidationErrors validationErrors = new ValidationErrors();

         validationErrors.checkRequiredField("baseTableName", findForeignKeyConstraintsStatement.getBaseTableName());

         return validationErrors;

     }

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

             SqlGeneratorChain sqlGeneratorChain) {

         StringBuilder sb = new StringBuilder();

         sb.append("SELECT ");

         sb.append("BASE.TABLE_NAME as ").append(FindForeignKeyConstraintsStatement.RESULT_COLUMN_BASE_TABLE_NAME)

                 .append(", ");

         sb.append("BCOLS.COLUMN_NAME as ")

                 .append(FindForeignKeyConstraintsStatement.RESULT_COLUMN_BASE_TABLE_COLUMN_NAME).append(", ");

         sb.append("FRGN.TABLE_NAME ").append(FindForeignKeyConstraintsStatement.RESULT_COLUMN_FOREIGN_TABLE_NAME)

                 .append(", ");

         sb.append("FCOLS.COLUMN_NAME as ").append(FindForeignKeyConstraintsStatement.RESULT_COLUMN_FOREIGN_COLUMN_NAME)

                 .append(", ");

         sb.append("BASE.CONSTRAINT_NAME as ").append(FindForeignKeyConstraintsStatement.RESULT_COLUMN_CONSTRAINT_NAME)

                 .append(" ");

         sb.append("FROM ALL_CONSTRAINTS BASE,");

         sb.append("     ALL_CONSTRAINTS FRGN,");

         sb.append("     ALL_CONS_COLUMNS BCOLS,");

         sb.append("     ALL_CONS_COLUMNS FCOLS ");

         sb.append("WHERE BASE.R_OWNER = FRGN.OWNER ");

         sb.append("AND BASE.R_CONSTRAINT_NAME = FRGN.CONSTRAINT_NAME ");

         sb.append("AND BASE.OWNER = BCOLS.OWNER ");

         sb.append("AND BASE.CONSTRAINT_NAME = BCOLS.CONSTRAINT_NAME ");

         sb.append("AND FRGN.OWNER = FCOLS.OWNER ");

         sb.append("AND FRGN.CONSTRAINT_NAME = FCOLS.CONSTRAINT_NAME ");

         sb.append("AND BASE.TABLE_NAME =  '").append(statement.getBaseTableName().toUpperCase()).append("' ");

         sb.append("AND BASE.CONSTRAINT_TYPE = 'R' ");

         try {

             sb.append("AND BASE.OWNER = '")

                     .append(database.convertRequestedSchemaToSchema(statement.getBaseTableSchemaName())).append("'");

         } catch (DatabaseException e) {

             throw new UnexpectedLiquibaseException(e);

         }

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

     }

 }