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, };

     }

 }