package com.tesora.dve.sql.infoschema.direct;

/*
 * #%L
 * Tesora Inc.
 * Database Virtualization Engine
 * %%
 * Copyright (C) 2011 - 2014 Tesora Inc.
 * %%
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License, version 3,
 * as published by the Free Software Foundation.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Affero General Public License for more details.
 * 
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 * #L%
 */

import java.util.Collections;
import java.util.List;

import com.tesora.dve.sql.infoschema.InfoView;
import com.tesora.dve.sql.infoschema.direct.ViewShowSchemaTable.TemporaryTableHandler;
import com.tesora.dve.sql.parser.InvokeParser;
import com.tesora.dve.sql.parser.ParserOptions;
import com.tesora.dve.sql.schema.SchemaContext;
import com.tesora.dve.sql.schema.UnqualifiedName;
import com.tesora.dve.sql.statement.Statement;
import com.tesora.dve.sql.statement.ddl.PECreateViewStatement;

public class ViewTableGenerator extends DirectTableGenerator {

	private final String viewName; 
	private final String viewDef;
	private TemporaryTableHandler tempTableHandler = null;
	
	public ViewTableGenerator(InfoView view, String tableName, String pluralTableName,  String viewName, String viewDef,
			DirectColumnGenerator...colDefs) {
		super(view,tableName,pluralTableName,colDefs);
		this.viewDef = viewDef;
		this.viewName = viewName;
	}
	
	public ViewTableGenerator withTempHandler(TemporaryTableHandler tth) {
		this.tempTableHandler = tth;
		return this;
	}
	
	public DirectInformationSchemaTable generate(SchemaContext sc) {
		StringBuilder buf = new StringBuilder();
		String actualDef = viewDef;
		if (actualDef == null) {
			// empty - so we build a dumb query
			actualDef = buildEmptyQuery();
		}
		buf.append("create view ").append(viewName).append(" as ").append(actualDef).append(" TABLE ( ");
		boolean first = true;
		for(DirectColumnGenerator dcg : columns) {
			if (first) first = false;
			else buf.append(", ");
			buf.append("`").append(dcg.getName()).append("` ").append(dcg.getType());
		}
		buf.append(" )");
		String vc = buf.toString();
		// I need a parser option here that defangs the view mode computation - so maybe just
		// an override
		ParserOptions opts = sc.getOptions();
		try {
			ParserOptions topts = ParserOptions.TEST.setResolve().setIgnoreMissingUser().setInfoSchemaView();
			List<Statement> stmts = InvokeParser.parse(vc, sc, Collections.emptyList(), topts);
			PECreateViewStatement pecs = (PECreateViewStatement) stmts.get(0);
			if (view == InfoView.SHOW) {
				return new ViewShowSchemaTable(sc,view,pecs.getViewTable(),
						new UnqualifiedName(tableName),
						(pluralTableName == null ? null : new UnqualifiedName(pluralTableName)),
						isPrivilege(),isExtension(), columns,
						tempTableHandler);
			} else {
				return new ViewInformationSchemaTable(sc,view,pecs.getViewTable(),
					new UnqualifiedName(tableName),
					(pluralTableName == null ? null : new UnqualifiedName(pluralTableName)),
					isPrivilege(),isExtension(), columns);
			}
		} finally {
			sc.setOptions(opts);
		}
	}
		
	private String buildEmptyQuery() {
		StringBuilder buf = new StringBuilder();
		buf.append("select ");
		boolean first = true;
		for(DirectColumnGenerator dcg : columns) {
			if (first) first = false;
			else buf.append(", ");
			buf.append("null as `").append(dcg.getName()).append("`");
		}
		buf.append(" from pe_version where 1 = 0");
		return buf.toString();
	}
	
}