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/*
 * Copyright (C) 2004 - 2014 Brian McCallister
 *
 * 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.skife.jdbi.v2;

import org.antlr.runtime.ANTLRStringStream;
import org.antlr.runtime.Token;
import org.skife.jdbi.rewriter.colon.ColonStatementLexer;
import org.skife.jdbi.v2.exceptions.UnableToCreateStatementException;
import org.skife.jdbi.v2.exceptions.UnableToExecuteStatementException;
import org.skife.jdbi.v2.tweak.Argument;
import org.skife.jdbi.v2.tweak.RewrittenStatement;
import org.skife.jdbi.v2.tweak.StatementRewriter;

import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.WeakHashMap;

import static org.skife.jdbi.rewriter.colon.ColonStatementLexer.DOUBLE_QUOTED_TEXT;
import static org.skife.jdbi.rewriter.colon.ColonStatementLexer.ESCAPED_TEXT;
import static org.skife.jdbi.rewriter.colon.ColonStatementLexer.LITERAL;
import static org.skife.jdbi.rewriter.colon.ColonStatementLexer.NAMED_PARAM;
import static org.skife.jdbi.rewriter.colon.ColonStatementLexer.POSITIONAL_PARAM;
import static org.skife.jdbi.rewriter.colon.ColonStatementLexer.QUOTED_TEXT;

/**
 * Statement rewriter which replaces named parameter tokens of the form :tokenName
 * 
 * This is the default statement rewriter
 */
public class ColonPrefixNamedParamStatementRewriter implements StatementRewriter
{
    private final Map cache = Collections.synchronizedMap(new WeakHashMap());

    /**
     * Munge up the SQL as desired. Responsible for figuring out ow to bind any
     * arguments in to the resultant prepared statement.
     *
     * @param sql The SQL to rewrite
     * @param params contains the arguments which have been bound to this statement.
     * @param ctx The statement context for the statement being executed
     * @return something which can provide the actual SQL to prepare a statement from
     *         and which can bind the correct arguments to that prepared statement
     */
    @Override
    public RewrittenStatement rewrite(String sql, Binding params, StatementContext ctx)
    {
        ParsedStatement stmt = cache.get(sql);
        if (stmt == null) {
            try {
                stmt = parseString(sql);
                cache.put(sql, stmt);
            }
            catch (IllegalArgumentException e) {
                throw new UnableToCreateStatementException("Exception parsing for named parameter replacement", e, ctx);
            }
        }
        return new MyRewrittenStatement(stmt, ctx);
    }

    ParsedStatement parseString(final String sql) throws IllegalArgumentException
    {
        ParsedStatement stmt = new ParsedStatement();
        StringBuilder b = new StringBuilder(sql.length());
        ColonStatementLexer lexer = new ColonStatementLexer(new ANTLRStringStream(sql));
        Token t = lexer.nextToken();
        while (t.getType() != ColonStatementLexer.EOF) {
            switch (t.getType()) {
                case LITERAL:
                    b.append(t.getText());
                    break;
                case NAMED_PARAM:
                    stmt.addNamedParamAt(t.getText().substring(1, t.getText().length()));
                    b.append("?");
                    break;
                case QUOTED_TEXT:
                    b.append(t.getText());
                    break;
                case DOUBLE_QUOTED_TEXT:
                    b.append(t.getText());
                    break;
                case POSITIONAL_PARAM:
                    b.append("?");
                    stmt.addPositionalParamAt();
                    break;
                case ESCAPED_TEXT:
                    b.append(t.getText().substring(1));
                    break;
                default:
                    break;
            }
            t = lexer.nextToken();
        }
        stmt.sql = b.toString();
        return stmt;
    }

    private static class MyRewrittenStatement implements RewrittenStatement
    {
        private final ParsedStatement stmt;
        private final StatementContext context;

        MyRewrittenStatement(ParsedStatement stmt, StatementContext ctx)
        {
            this.context = ctx;
            this.stmt = stmt;
        }

        @Override
        public void bind(Binding params, PreparedStatement statement) throws SQLException
        {
            if (stmt.positionalOnly) {
                // no named params, is easy
                boolean finished = false;
                for (int i = 0; !finished; ++i) {
                    final Argument a = params.forPosition(i);
                    if (a != null) {
                        try {
                            a.apply(i + 1, statement, this.context);
                        }
                        catch (SQLException e) {
                            throw new UnableToExecuteStatementException(
                                    String.format("Exception while binding positional param at (0 based) position %d",
                                                  i), e, context);
                        }
                    }
                    else {
                        finished = true;
                    }
                }
            }
            else {
                //List named_params = stmt.params;
                int i = 0;
                for (String named_param : stmt.params) {
                    if ("*".equals(named_param)) {
                        continue;
                    }
                    Argument a = params.forName(named_param);
                    if (a == null) {
                        a = params.forPosition(i);
                    }

                    if (a == null) {
                        String msg = String.format("Unable to execute, no named parameter matches " +
                                                   "\"%s\" and no positional param for place %d (which is %d in " +
                                                   "the JDBC 'start at 1' scheme) has been set.",
                                                   named_param, i, i + 1);
                        throw new UnableToExecuteStatementException(msg, context);
                    }

                    try {
                        a.apply(i + 1, statement, this.context);
                    }
                    catch (SQLException e) {
                        throw new UnableToCreateStatementException(String.format("Exception while binding '%s'",
                                                                                 named_param), e, context);
                    }
                    i++;
                }
            }
        }

        @Override
        public String getSql()
        {
            return stmt.getParsedSql();
        }
    }

    static class ParsedStatement
    {
        private String sql;
        private boolean positionalOnly = true;
        private List params = new ArrayList();

        public void addNamedParamAt(String name)
        {
            positionalOnly = false;
            params.add(name);
        }

        public void addPositionalParamAt()
        {
            params.add("*");
        }

        public String getParsedSql()
        {
            return sql;
        }
    }
}