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/**
 * Copyright (c) 1997-2013, www.tinygroup.org ([email protected]).
 * 
 * Licensed under the GPL, Version 3.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 

 * http://www.gnu.org/licenses/gpl.html
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.tinygroup.tinysqldsl.base;

import org.tinygroup.commons.tools.StringUtil;
import org.tinygroup.tinysqldsl.expression.Expression;
import org.tinygroup.tinysqldsl.expression.FragmentExpressionSql;
import org.tinygroup.tinysqldsl.operator.ColumnOperator;
import org.tinygroup.tinysqldsl.selectitem.Distinct;
import org.tinygroup.tinysqldsl.selectitem.SelectItem;

/**
 * 列
 */
public class Column extends ColumnOperator implements Expression,
        MultiPartName, SelectItem, Cloneable {
    /**
     * 表名
     */
    private Table table;
    /**
     * 列名
     */
    private String columnName;
    /**
     * 别名
     */
    private Alias alias;

    public Column() {
    }

    public Column(Table table, String columnName) {
        this.table = table;
        this.columnName = columnName;
    }

    public Column(Table table, String columnName, String alias) {
        this(table, columnName);
        this.alias = new Alias(alias);
    }

    public Column(String columnName) {
        this(null, columnName);
    }

    public Column as(String aliasName) {
        return as(aliasName, false);
    }

    public Column as(String aliasName, boolean withAs) {
        try {
            Column column = (Column) this.clone();
            column.setAlias(new Alias(aliasName, withAs));
            return column;
        } catch (CloneNotSupportedException e) {
            throw new RuntimeException(e);
        }
    }

    public Distinct distinct() {
        return new Distinct(this);
    }

    public Value value(Object value) {
        return new Value(this, value);
    }

    public Value value(Expression expression) {
        return new Value(this, expression);
    }

    public Value fragmentValue(String fragmentSql) {
        return new Value(this, new FragmentExpressionSql(fragmentSql));
    }

    public Table getTable() {
        return table;
    }

    public void setTable(Table table) {
        this.table = table;
    }

    public String getColumnName() {
        return columnName;
    }

    public void setColumnName(String string) {
        columnName = string;
    }

    public Alias getAlias() {
        return alias;
    }

    public void setAlias(Alias alias) {
        this.alias = alias;
    }

    public String getFullyQualifiedName() {
        StringBuilder fqn = new StringBuilder();

        if (table != null) {
            fqn.append(table.getReferenceName());
        }
        if (fqn.length() > 0) {
            fqn.append('.');
        }
        if (columnName != null) {
            fqn.append(columnName);
        }
        return fqn.toString();
    }

    public String toString() {
        return getFullyQualifiedName()
                + ((alias != null) ? alias.toString() : "");
    }

    public void builderExpression(StatementSqlBuilder builder) {
        internalBuilder(builder);
    }

    private void internalBuilder(StatementSqlBuilder builder) {
        String tableName = getTableName();
        String result = "";
        if (!StringUtil.isBlank(tableName)) {
            result += tableName + ".";
        }
        result += columnName;
        builder.appendSql(result);
    }

    private String getTableName() {
        String tableName = null;
        if (table != null) {
            if (table.getAlias() != null) {
                tableName = table.getAlias().getName();
            } else {
                tableName = table.getFullyQualifiedName();
            }
        }
        return tableName;
    }

    public void builderSelectItem(StatementSqlBuilder builder) {
        internalBuilder(builder);
        if (alias != null) {
            builder.appendSql(alias.toString());
        }
    }

}