package liquibase.change.core;
   
   import liquibase.change.AbstractChange;
   import liquibase.change.Change;
   import liquibase.change.ChangeMetaData;
   import liquibase.change.ColumnConfig;
   import liquibase.database.Database;
   import liquibase.database.core.SQLiteDatabase;
   import liquibase.database.core.SQLiteDatabase.AlterTableVisitor;
  import liquibase.database.structure.Index;
  import liquibase.statement.SqlStatement;
  import liquibase.statement.core.AddUniqueConstraintStatement;
  import liquibase.util.StringUtils;
  
  import java.util.ArrayList;
  import java.util.List;
  
  /**
   * Adds a unique constraint to an existing column.
   */
  public class AddUniqueConstraintChange extends AbstractChange {
  
      private String schemaName;
      private String tableName;
      private String columnNames;
      private String constraintName;
      private String tablespace;
  
      private Boolean deferrable;
      private Boolean initiallyDeferred;
      private Boolean disabled;
  
      public AddUniqueConstraintChange() {
          super("addUniqueConstraint", "Add Unique 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 getColumnNames() {
          return columnNames;
      }
  
      public void setColumnNames(String columnNames) {
          this.columnNames = columnNames;
      }
  
      public String getConstraintName() {
          return constraintName;
      }
  
      public void setConstraintName(String constraintName) {
          this.constraintName = constraintName;
      }
  
      public String getTablespace() {
          return tablespace;
      }
  
      public void setTablespace(String tablespace) {
          this.tablespace = tablespace;
      }
  
      public Boolean getDeferrable() {
          return deferrable;
      }
  
      public void setDeferrable(Boolean deferrable) {
          this.deferrable = deferrable;
      }
  
      public Boolean getInitiallyDeferred() {
          return initiallyDeferred;
      }
  
      public void setInitiallyDeferred(Boolean initiallyDeferred) {
          this.initiallyDeferred = initiallyDeferred;
      }
  
      public Boolean getDisabled() {
          return disabled;
      }
  
      public void setDisabled(Boolean disabled) {
          this.disabled = disabled;
      }
 
     public SqlStatement[] generateStatements(Database database) {
 
         // todo if (database instanceof SQLiteDatabase) {
         // // return special statements for SQLite databases
         // return generateStatementsForSQLiteDatabase(database);
         // }
 
         boolean deferrable = false;
         if (getDeferrable() != null) {
             deferrable = getDeferrable();
         }
 
         boolean initiallyDeferred = false;
         if (getInitiallyDeferred() != null) {
             initiallyDeferred = getInitiallyDeferred();
         }
         boolean disabled = false;
         if (getDisabled() != null) {
             disabled = getDisabled();
         }
 
         AddUniqueConstraintStatement statement = new AddUniqueConstraintStatement(
                 getSchemaName() == null ? database.getDefaultSchemaName() : getSchemaName(), getTableName(),
                 getColumnNames(), getConstraintName());
         statement.setTablespace(getTablespace()).setDeferrable(deferrable).setInitiallyDeferred(initiallyDeferred)
                 .setDisabled(disabled);
 
         return new SqlStatement[] { statement };
     }
 
     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>();
 
         // define alter table logic
         AlterTableVisitor rename_alter_visitor = new AlterTableVisitor() {
             public ColumnConfig[] getColumnsToAdd() {
                 return new ColumnConfig[0];
             }
 
             public boolean copyThisColumn(ColumnConfig column) {
                 return true;
             }
 
             public boolean createThisColumn(ColumnConfig column) {
                 String[] split_columns = getColumnNames().split("[ ]*,[ ]*");
                 for (String split_column : split_columns) {
                     if (column.getName().equals(split_column)) {
                         column.getConstraints().setUnique(true);
                     }
                 }
                 return true;
             }
 
             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()]);
     }
 
     public String getConfirmationMessage() {
         return "Unique constraint added to " + getTableName() + "(" + getColumnNames() + ")";
     }
 
     @Override
     protected Change[] createInverses() {
         DropUniqueConstraintChange inverse = new DropUniqueConstraintChange();
         inverse.setSchemaName(getSchemaName());
         inverse.setTableName(getTableName());
         inverse.setConstraintName(getConstraintName());
 
         return new Change[] { inverse, };
     }
 }