/*
 * Copyright 2015, The Querydsl Team (http://www.querydsl.com/team)
 *
 * Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
 * 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 com.querydsl.jpa.support;

import java.util.Map;

import org.hibernate.dialect.function.SQLFunction;
import org.hibernate.dialect.function.SQLFunctionTemplate;
import org.hibernate.type.Type;

import com.google.common.collect.Maps;
import com.querydsl.core.types.Operator;
import com.querydsl.core.types.Ops;
import com.querydsl.core.types.Template;
import com.querydsl.jpa.hibernate.HibernateUtil;
import com.querydsl.sql.SQLTemplates;

final class DialectSupport {

    private DialectSupport() { }

    public static Map<String, SQLFunction> createFunctions(SQLTemplates templates) {
        Map<String, SQLFunction> functions = Maps.newHashMap();
        functions.put("second", createFunction(templates, Ops.DateTimeOps.SECOND));
        functions.put("minute", createFunction(templates, Ops.DateTimeOps.MINUTE));
        functions.put("hour", createFunction(templates, Ops.DateTimeOps.HOUR));
        functions.put("day", createFunction(templates, Ops.DateTimeOps.DAY_OF_MONTH));
        functions.put("week", createFunction(templates, Ops.DateTimeOps.WEEK));
        functions.put("month", createFunction(templates, Ops.DateTimeOps.MONTH));
        functions.put("year", createFunction(templates, Ops.DateTimeOps.YEAR));
        return functions;
    }

    public static SQLFunction createFunction(SQLTemplates templates, Operator operator) {
        Template template = templates.getTemplate(operator);
        Type type = HibernateUtil.getType(operator.getType());
        return new SQLFunctionTemplate(type, convert(template));
    }

    public static String convert(Template template) {
        StringBuilder builder = new StringBuilder();
        for (Template.Element element : template.getElements()) {
            if (element instanceof Template.AsString) {
                builder.append("?").append(((Template.AsString) element).getIndex() + 1);
            } else if (element instanceof Template.ByIndex) {
                builder.append("?").append(((Template.ByIndex) element).getIndex() + 1);
            } else if (element instanceof Template.Transformed) {
                builder.append("?").append(((Template.Transformed) element).getIndex() + 1);
            } else if (element instanceof Template.StaticText) {
                builder.append(((Template.StaticText) element).getText());
            } else {
                throw new IllegalStateException("Unsupported element " + element);
            }
        }
        return builder.toString();
    }

}