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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.expression;

import org.tinygroup.tinysqldsl.base.Alias;
import org.tinygroup.tinysqldsl.base.Column;
import org.tinygroup.tinysqldsl.base.StatementSqlBuilder;
import org.tinygroup.tinysqldsl.expression.relational.ExpressionList;
import org.tinygroup.tinysqldsl.operator.SimpleBinaryOperator;
import org.tinygroup.tinysqldsl.selectitem.SelectItem;

/**
 * A function as MAX,COUNT...
 */
public class Function extends SimpleBinaryOperator implements Expression,
        SelectItem, Cloneable {

    private String name;
    private ExpressionList parameters;
    private boolean allColumns = false;
    private boolean distinct = false;
    private boolean isEscaped = false;

    /**
     * 别名
     */
    private Alias alias;

    public Function() {
        super();
    }

    public Function(String name, boolean allColumns) {
        this.name = name;
        this.allColumns = allColumns;
    }

    public Function(String name, ExpressionList parameters) {
        super();
        this.name = name;
        this.parameters = parameters;
    }

    public Function(String name, ExpressionList parameters, boolean allColumns,
                    boolean distinct, boolean isEscaped) {
        super();
        this.name = name;
        this.parameters = parameters;
        this.allColumns = allColumns;
        this.distinct = distinct;
        this.isEscaped = isEscaped;
    }

    public static Function sum() {
        return new Function("sum", true);
    }

    public static Function count() {
        return new Function("count", true);
    }

    public static Function avg() {
        return new Function("avg", true);
    }

    public static Function max() {
        return new Function("max", true);
    }

    public static Function min() {
        return new Function("min", true);
    }

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

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

    public Function sum(String columnName) {
        return new Function("sum", ExpressionList.expressionList(new Column(
                columnName)));
    }

    public Function count(String columnName) {
        return new Function("count", ExpressionList.expressionList(new Column(
                columnName)));
    }

    public Function avg(String columnName) {
        return new Function("avg", ExpressionList.expressionList(new Column(
                columnName)));
    }

    public Function max(String columnName) {
        return new Function("max", ExpressionList.expressionList(new Column(
                columnName)));
    }

    public Function min(String columnName) {
        return new Function("min", ExpressionList.expressionList(new Column(
                columnName)));
    }

    /**
     * The name of he function, i.e. "MAX"
     *
     * @return the name of he function
     */
    public String getName() {
        return name;
    }

    public void setName(String string) {
        name = string;
    }

    /**
     * true if the parameter to the function is "*"
     *
     * @return true if the parameter to the function is "*"
     */
    public boolean isAllColumns() {
        return allColumns;
    }

    public void setAllColumns(boolean b) {
        allColumns = b;
    }

    public Alias getAlias() {
        return alias;
    }

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

    /**
     * true if the function is "distinct"
     *
     * @return true if the function is "distinct"
     */
    public boolean isDistinct() {
        return distinct;
    }

    public void setDistinct(boolean b) {
        distinct = b;
    }

    /**
     * The list of parameters of the function (if any, else null) If the
     * parameter is "*", allColumns is set to true
     *
     * @return the list of parameters of the function (if any, else null)
     */
    public ExpressionList getParameters() {
        return parameters;
    }

    public void setParameters(ExpressionList list) {
        parameters = list;
    }

    /**
     * Return true if it's in the form "{fn function_body() }"
     *
     * @return true if it's java-escaped
     */
    public boolean isEscaped() {
        return isEscaped;
    }

    public void setEscaped(boolean isEscaped) {
        this.isEscaped = isEscaped;
    }

    public String toString() {
        String params;

        if (parameters != null) {
            params = parameters.toString();
            if (isDistinct()) {
                params = params.replaceFirst("\\(", "(DISTINCT ");
            } else if (isAllColumns()) {
                params = params.replaceFirst("\\(", "(ALL ");
            }
        } else if (isAllColumns()) {
            params = "(*)";
        } else {
            params = "()";
        }

        String ans = name + "" + params + "";

        if (isEscaped) {
            ans = "{fn " + ans + "}";
        }

        return ans;
    }

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

    private void internalBuilder(StatementSqlBuilder builder) {
        StringBuilder buffer = builder.getStringBuilder();
        if (isEscaped()) {
            buffer.append("{fn ");
        }
        buffer.append(name);
        if (isAllColumns() && getParameters() == null) {
            buffer.append("(*)");
        } else if (getParameters() == null) {
            buffer.append("()");
        } else {
            boolean oldUseBracketsInExprList = builder
                    .isUseBracketsInExprList();
            if (isDistinct()) {
                buffer.append("(DISTINCT ");
                builder.setUseBracketsInExprList(false);
            } else if (isAllColumns()) {
                buffer.append("(ALL ");
                builder.setUseBracketsInExprList(false);
            }
            getParameters().builderItemList(builder);
            builder.setUseBracketsInExprList(oldUseBracketsInExprList);
            if (isDistinct() || isAllColumns()) {
                buffer.append(")");
            }
        }
        if (isEscaped()) {
            buffer.append("}");
        }
    }

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