package liquibase.change.core;

 import java.util.ArrayList;

 import java.util.List;

 import liquibase.change.AbstractChange;

 import liquibase.change.Change;

 import liquibase.change.ChangeMetaData;

 import liquibase.change.ColumnConfig;

 import liquibase.database.Database;

 import liquibase.database.core.DB2Database;

 import liquibase.database.core.SQLiteDatabase;

 import liquibase.database.core.SQLiteDatabase.AlterTableVisitor;

 import liquibase.database.structure.Index;

 import liquibase.statement.SqlStatement;

 import liquibase.statement.core.ReorganizeTableStatement;

 import liquibase.statement.core.SetNullableStatement;

 import liquibase.statement.core.UpdateStatement;

 import liquibase.util.StringUtils;

 /**

  * Adds a not-null constraint to an existing column.

  */

 public class AddNotNullConstraintChange extends AbstractChange {

     private String schemaName;

     private String tableName;

     private String columnName;

     private String defaultNullValue;

     private String columnDataType;

     public AddNotNullConstraintChange() {

         super("addNotNullConstraint", "Add Not-Null Constraint", ChangeMetaData.PRIORITY_DEFAULT);

     }

     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 getColumnName() {

         return columnName;

     }

     public void setColumnName(String columnName) {

         this.columnName = columnName;

     }

     public String getDefaultNullValue() {

         return defaultNullValue;

     }

     public void setDefaultNullValue(String defaultNullValue) {

         this.defaultNullValue = defaultNullValue;

     }

     public String getColumnDataType() {

         return columnDataType;

     }

     public void setColumnDataType(String columnDataType) {

         this.columnDataType = columnDataType;

     }

     @Override

     public SqlStatement[] generateStatements(Database database) {

         // // if (database instanceof SQLiteDatabase) {

         // // return special statements for SQLite databases

         // return generateStatementsForSQLiteDatabase(database);

         // }

         List<SqlStatement> statements = new ArrayList<SqlStatement>();

         String schemaName = getSchemaName() == null ? database.getDefaultSchemaName() : getSchemaName();

         if (defaultNullValue != null) {

             statements.add(new UpdateStatement(schemaName, getTableName()).addNewColumnValue(getColumnName(),

                     getDefaultNullValue()).setWhereClause(getColumnName() + " IS NULL"));

         }

         statements

                 .add(new SetNullableStatement(schemaName, getTableName(), getColumnName(), getColumnDataType(), false));

         if (database instanceof DB2Database) {

             statements.add(new ReorganizeTableStatement(schemaName, getTableName()));

         }

         return statements.toArray(new SqlStatement[statements.size()]);

     }

     private SqlStatement[] generateStatementsForSQLiteDatabase(Database database) {

         // SQLite does not support this ALTER TABLE operation until now.

         // For more information see: http://www.sqlite.org/omitted.html.

         // This is a small work around...

         List<SqlStatement> statements = new ArrayList<SqlStatement>();

         String schemaName = getSchemaName() == null ? database.getDefaultSchemaName() : getSchemaName();

         if (defaultNullValue != null) {

             statements.add(new UpdateStatement(schemaName, getTableName()).addNewColumnValue(getColumnName(),

                     getDefaultNullValue()).setWhereClause(getColumnName() + " IS NULL"));

         }

         // // ... test if column contains NULL values

         // if (defaultNullValue == null) {

         // List<Map> null_rows = null;

         // try {

         // null_rows = database.getExecutor().

         // queryForList(new RawSqlStatement(

         // "SELECT * FROM `"+

         // database.escapeTableName(getSchemaName(), getTableName())+

         // "` WHERE `"+getColumnName()+"` IS NULL;"));

         // } catch (DatabaseException e) {

         // e.printStackTrace();

         // }

         // if (null_rows.size()>0) {

         // throw new UnsupportedChangeException(

         // "Failed to add a Not-Null-Constraint because " +

         // "some values are null. Use the " +

         // "defaultNullValue attribute to define default " +

         // "values for the existing null values.");

         // }

         // }

         // define alter table logic

         AlterTableVisitor rename_alter_visitor = new AlterTableVisitor() {

             @Override

             public ColumnConfig[] getColumnsToAdd() {

                 return new ColumnConfig[0];

             }

             @Override

             public boolean copyThisColumn(ColumnConfig column) {

                 return true;

             }

             @Override

             public boolean createThisColumn(ColumnConfig column) {

                 if (column.getName().equals(getColumnName())) {

                     column.getConstraints().setNullable(false);

                 }

                 return true;

             }

             @Override

             public boolean createThisIndex(Index index) {

                 return true;

             }

         };

         try {

             // alter table

             statements.addAll(SQLiteDatabase.getAlterTableStatements(rename_alter_visitor, database, getSchemaName(),

                     getTableName()));

         } catch (Exception e) {

             e.printStackTrace();

         }

         return statements.toArray(new SqlStatement[statements.size()]);

     }

     @Override

     protected Change[] createInverses() {

         DropNotNullConstraintChange inverse = new DropNotNullConstraintChange();

         inverse.setColumnName(getColumnName());

         inverse.setSchemaName(getSchemaName());

         inverse.setTableName(getTableName());

         inverse.setColumnDataType(getColumnDataType());

         return new Change[] { inverse };

     }

     @Override

     public String getConfirmationMessage() {

         return "Null constraint has been added to " + getTableName() + "." + getColumnName();

     }

 }