/*
 * Copyright 2004-2015 the Seasar Foundation and the Others.
 *
 * 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 org.seasar.extension.dataset.impl;

import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.util.ArrayList;
import java.util.List;

import javax.sql.DataSource;

import org.seasar.extension.dataset.DataColumn;
import org.seasar.extension.dataset.DataRow;
import org.seasar.extension.dataset.DataTable;
import org.seasar.extension.dataset.TableReader;
import org.seasar.extension.jdbc.SelectHandler;
import org.seasar.extension.jdbc.impl.BasicSelectHandler;
import org.seasar.extension.jdbc.util.ConnectionUtil;
import org.seasar.extension.jdbc.util.DataSourceUtil;

/**
 * SQLのreload用の {@link TableReader}です。
 * 
 * @author higa
 * 
 */
public class SqlReloadTableReader implements TableReader {

    private DataSource dataSource;

    private DataTable table;

    private String sql;

    private String[] primaryKeys;

    /**
     * {@link SqlReloadTableReader}を作成します。
     * 
     * @param dataSource
     *            データソース
     * @param table
     *            テーブル
     */
    public SqlReloadTableReader(DataSource dataSource, DataTable table) {

        this.dataSource = dataSource;
        this.table = table;
        Connection con = DataSourceUtil.getConnection(dataSource);
        try {
            DatabaseMetaData dbMetaData = ConnectionUtil.getMetaData(con);
            table.setupMetaData(dbMetaData);
        } finally {
            ConnectionUtil.close(con);
        }
        setup();
    }

    private void setup() {
        StringBuffer buf = new StringBuffer(100);
        buf.append("SELECT ");
        StringBuffer whereBuf = new StringBuffer(100);
        whereBuf.append(" WHERE");
        List primaryKeyList = new ArrayList();
        for (int i = 0; i < table.getColumnSize(); ++i) {
            DataColumn column = table.getColumn(i);
            buf.append(column.getColumnName());
            buf.append(", ");
            if (column.isPrimaryKey()) {
                whereBuf.append(" ");
                whereBuf.append(column.getColumnName());
                whereBuf.append(" = ? AND");
                primaryKeyList.add(column.getColumnName());
            }
        }
        buf.setLength(buf.length() - 2);
        whereBuf.setLength(whereBuf.length() - 4);
        buf.append(" FROM ");
        buf.append(table.getTableName());
        buf.append(whereBuf);
        sql = buf.toString();
        primaryKeys = (String[]) primaryKeyList
                .toArray(new String[primaryKeyList.size()]);
    }

    /**
     * データソースを返します。
     * 
     * @return データソース
     */
    public DataSource getDataSource() {
        return dataSource;
    }

    /**
     * テーブルを返します。
     * 
     * @return テーブル
     */
    public DataTable getTable() {
        return table;
    }

    public DataTable read() {
        DataTable newTable = new DataTableImpl(table.getTableName());
        for (int i = 0; i < table.getColumnSize(); ++i) {
            DataColumn column = table.getColumn(i);
            newTable.addColumn(column.getColumnName(), column.getColumnType());
        }
        for (int i = 0; i < table.getRowSize(); ++i) {
            DataRow row = table.getRow(i);
            DataRow newRow = newTable.addRow();
            reload(row, newRow);
        }
        return newTable;
    }

    /**
     * データを再読み込みします。
     * 
     * @param row
     *            元の行
     * @param newRow
     *            新しい行
     */
    protected void reload(DataRow row, DataRow newRow) {
        SelectHandler selectHandler = new BasicSelectHandler(dataSource, sql,
                new DataRowReloadResultSetHandler(newRow));
        Object[] args = new Object[primaryKeys.length];
        for (int i = 0; i < primaryKeys.length; ++i) {
            args[i] = row.getValue(primaryKeys[i]);
        }
        selectHandler.execute(args);
    }

}