com.nesscomputing.migratory.mojo.database.util.TemplatingStatementLocator Maven / Gradle / Ivy

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/**
 * Copyright (C) 2012 Ness Computing, Inc.
 *
 * 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.nesscomputing.migratory.mojo.database.util;

import java.io.StringReader;
import java.net.URL;

import com.google.common.io.Resources;

import org.antlr.stringtemplate.StringTemplate;
import org.antlr.stringtemplate.StringTemplateGroup;
import org.antlr.stringtemplate.language.AngleBracketTemplateLexer;
import org.apache.commons.lang3.StringUtils;
import org.skife.jdbi.v2.StatementContext;
import org.skife.jdbi.v2.tweak.StatementLocator;

import com.nesscomputing.logging.Log;
import com.nesscomputing.migratory.loader.LoaderManager;

public class TemplatingStatementLocator implements StatementLocator
{
    private static final Log LOG = Log.findLog();

    private final LoaderManager loaderManager;
    private final String prefix;

    public TemplatingStatementLocator(final String prefix, final LoaderManager loaderManager)
    {
        this.prefix = prefix;
        this.loaderManager = loaderManager;
    }

    @Override
    public String locate(final String statementName, final StatementContext context) throws Exception
    {
        if (StringUtils.isEmpty(statementName)) {
            throw new IllegalStateException("Statement Name can not be empty/null!");
        }

        if (statementName.charAt(0) == '#') {
            // Multiple templates can be in a string template group. In that case, the name is #
            final String [] statementNames = StringUtils.split(statementName.substring(1), ":");

            final String location = prefix + statementNames[0] + ".st";

            LOG.trace("Loading SQL: %s", location);
            final URL locationUrl = Resources.getResource(this.getClass(), location);

            if (locationUrl == null) {
                throw new IllegalArgumentException("Location '" + location + "' does not exist!");
            }
            final String contents = loaderManager.loadFile(locationUrl.toURI());

            if (statementNames.length == 1) {
                final StringTemplate template = new StringTemplate(contents, AngleBracketTemplateLexer.class);
                template.setAttributes(context.getAttributes());
                final String sql = template.toString();

                LOG.trace("SQL: %s", sql);
                return sql;
            }
            else {
                final StringTemplateGroup group = new StringTemplateGroup(new StringReader(contents), AngleBracketTemplateLexer.class);
                LOG.trace("Found %s in %s", group.getTemplateNames(), locationUrl);

                final StringTemplate template = group.getInstanceOf(statementNames[1]);
                template.setAttributes(context.getAttributes());
                final String sql = template.toString();

                LOG.trace("SQL: %s", sql);
                return sql;
            }
        }
        else {
            return statementName;
        }
    }
}