/*
 * Copyright 1999-2011 Alibaba Group Holding Ltd.
 *
 * 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.alibaba.druid.sql.parser;

import java.util.ArrayList;
import java.util.List;

import com.alibaba.druid.sql.ast.SQLExpr;
import com.alibaba.druid.sql.ast.SQLName;
import com.alibaba.druid.sql.ast.SQLStatement;
import com.alibaba.druid.sql.ast.expr.SQLQueryExpr;
import com.alibaba.druid.sql.ast.statement.SQLAssignItem;
import com.alibaba.druid.sql.ast.statement.SQLCallStatement;
import com.alibaba.druid.sql.ast.statement.SQLCommentStatement;
import com.alibaba.druid.sql.ast.statement.SQLCreateTableStatement;
import com.alibaba.druid.sql.ast.statement.SQLCreateViewStatement;
import com.alibaba.druid.sql.ast.statement.SQLDeleteStatement;
import com.alibaba.druid.sql.ast.statement.SQLDropTableStatement;
import com.alibaba.druid.sql.ast.statement.SQLInsertInto;
import com.alibaba.druid.sql.ast.statement.SQLInsertStatement;
import com.alibaba.druid.sql.ast.statement.SQLSelectStatement;
import com.alibaba.druid.sql.ast.statement.SQLSetStatement;
import com.alibaba.druid.sql.ast.statement.SQLTableSource;
import com.alibaba.druid.sql.ast.statement.SQLTruncateStatement;
import com.alibaba.druid.sql.ast.statement.SQLUpdateSetItem;
import com.alibaba.druid.sql.ast.statement.SQLUpdateStatement;

public class SQLStatementParser extends SQLParser {

    protected SQLExprParser exprParser;

    public SQLStatementParser(String sql){
        super(sql);

        this.exprParser = createExprParser();
    }

    public SQLStatementParser(Lexer lexer){
        super(lexer);
        this.exprParser = createExprParser();
    }

    protected SQLExprParser createExprParser() {
        return new SQLExprParser(lexer);
    }

    public List<SQLStatement> parseStatementList() throws ParserException {
        List<SQLStatement> statementList = new ArrayList<SQLStatement>();
        parseStatementList(statementList);
        return statementList;
    }

    public void parseStatementList(List<SQLStatement> statementList) throws ParserException {
        for (;;) {
            if (lexer.token() == Token.EOF) {
                return;
            }

            if (lexer.token() == (Token.SEMI)) {
                lexer.nextToken();
                continue;
            }

            if (lexer.token() == (Token.SELECT)) {
                statementList.add(parseSelect());
                continue;
            }

            if (lexer.token() == (Token.UPDATE)) {
                statementList.add(parseUpdateStatement());
                continue;
            }

            if (lexer.token() == (Token.CREATE)) {
                statementList.add(parseCreate());
                continue;
            }

            if (lexer.token() == (Token.INSERT)) {
                SQLStatement insertStatement = parseInsert();
                statementList.add(insertStatement);

                continue;
            }

            if (lexer.token() == (Token.DELETE)) {
                statementList.add(parseDeleteStatement());
                continue;
            }

            if (lexer.token() == Token.SET) {
                statementList.add(parseSet());
                continue;
            }

            if (lexer.token() == Token.ALTER) {
                throw new ParserException("TODO");
            }

            if (lexer.token() == Token.DROP) {
                lexer.nextToken();

                if (lexer.token() == Token.TABLE) {
                    lexer.nextToken();

                    SQLDropTableStatement stmt = new SQLDropTableStatement();

                    for (;;) {
                        SQLName name = this.exprParser.name();
                        stmt.getTableNames().add(name);
                        if (lexer.token() == Token.COMMA) {
                            lexer.nextToken();
                            continue;
                        }
                        break;
                    }

                    statementList.add(stmt);
                    continue;
                } else if (lexer.token() == Token.USER) {
                    SQLStatement stmt = parseDropUser();
                    statementList.add(stmt);
                    continue;
                } else {
                    throw new ParserException("TODO " + lexer.token());
                }
            }

            if (lexer.token() == Token.TRUNCATE) {
                SQLStatement stmt = parseTruncate();
                statementList.add(stmt);
                continue;
            }

            if (identifierEquals("CALL")) {
                SQLCallStatement stmt = parseCall();
                statementList.add(stmt);
                continue;
            }

            if (parseStatementListDialect(statementList)) {
                continue;
            }

            throw new ParserException("TODO " + lexer.token());
        }
    }

    public SQLStatement parseTruncate() {
        accept(Token.TRUNCATE);
        accept(Token.TABLE);
        SQLTruncateStatement stmt = new SQLTruncateStatement();
        
        for (;;) {
            SQLName name = this.exprParser.name();
            stmt.getTableNames().add(name);

            if (lexer.token() == Token.COMMA) {
                lexer.nextToken();
                continue;
            }

            break;
        }

        return stmt;
    }

    public SQLStatement parseInsert() {
        accept(Token.INSERT);

        SQLInsertStatement insertStatement = new SQLInsertStatement();

        parseInsert0(insertStatement);
        return insertStatement;
    }
    
    protected void parseInsert0(SQLInsertInto insertStatement) {
        parseInsert0(insertStatement, true);
    }

    protected void parseInsert0_hinits(SQLInsertInto insertStatement) {
        
    }
                                
    protected void parseInsert0(SQLInsertInto insertStatement, boolean acceptSubQuery) {
        accept(Token.INTO);
        
        SQLName tableName = this.exprParser.name();
        insertStatement.setTableName(tableName);
        
        if (lexer.token() == Token.LITERAL_ALIAS) {
            insertStatement.setAlias(as());
        }
        
        parseInsert0_hinits(insertStatement);
        
        if (lexer.token() == Token.IDENTIFIER) {
            insertStatement.setAlias(lexer.stringVal());
            lexer.nextToken();
        }

        if (lexer.token() == (Token.LPAREN)) {
            lexer.nextToken();
            this.exprParser.exprList(insertStatement.getColumns());
            accept(Token.RPAREN);
        }

        if (lexer.token() == Token.VALUES) {
            lexer.nextToken();
            accept(Token.LPAREN);
            SQLInsertStatement.ValuesClause values = new SQLInsertStatement.ValuesClause();
            this.exprParser.exprList(values.getValues());
            insertStatement.setValues(values);
            accept(Token.RPAREN);
        } else if (acceptSubQuery && (lexer.token() == Token.SELECT || lexer.token() == Token.LPAREN)) {
            SQLQueryExpr queryExpr = (SQLQueryExpr) this.createExprParser().expr();
            insertStatement.setQuery(queryExpr.getSubQuery());
        }
    }

    public boolean parseStatementListDialect(List<SQLStatement> statementList) {
        return false;
    }

    public SQLStatement parseDropUser() throws ParserException {
        throw new ParserException("TODO " + lexer.token());
    }

    public SQLCallStatement parseCall() throws ParserException {
        acceptIdentifier("CALL");

        SQLCallStatement stmt = new SQLCallStatement();
        stmt.setProcedureName(exprParser.name());

        if (lexer.token() == Token.LPAREN) {
            lexer.nextToken();
            exprParser.exprList(stmt.getParameters());
            accept(Token.RPAREN);
        }

        return stmt;
    }

    public SQLStatement parseSet() throws ParserException {
        accept(Token.SET);
        SQLSetStatement stmt = new SQLSetStatement();

        parseAssignItems(stmt.getItems());

        return stmt;
    }

    public void parseAssignItems(List<SQLAssignItem> items) {
        for (;;) {
            SQLAssignItem item = new SQLAssignItem();
            item.setTarget(exprParser.primary());
            accept(Token.EQ);
            item.setValue(exprParser.expr());

            items.add(item);

            if (lexer.token() == Token.COMMA) {
                lexer.nextToken();
                continue;
            } else {
                break;
            }
        }
    }

    public SQLStatement parseCreate() throws ParserException {
        accept(Token.CREATE);

        Token token = lexer.token();

        if (token == Token.TABLE || identifierEquals("GLOBAL")) {
            SQLCreateTableParser createTableParser = getSQLCreateTableParser();
            return createTableParser.parseCrateTable(false);
        } else if (token == Token.INDEX || token == Token.UNIQUE) {
            return parseCreateIndex(false);
        } else if (identifierEquals("SEQUENCE")) {
            return parseCreateSequence(false);
        }

        throw new ParserException("TODO " + lexer.token());
    }
    
    public SQLStatement parseCreateSequence(boolean acceptCreate) {
        throw new ParserException("TODO " + lexer.token());
    }
    
    public SQLStatement parseCreateIndex(boolean acceptCreate) {
        throw new ParserException("TODO " + lexer.token());
    }

    public SQLCreateTableParser getSQLCreateTableParser() {
        return new SQLCreateTableParser(lexer);
    }

    public SQLSelectStatement parseSelect() throws ParserException {
        return new SQLSelectStatement(createSQLSelectParser().select());
    }

    public SQLSelectParser createSQLSelectParser() {
        return new SQLSelectParser(this.lexer);
    }

    public SQLUpdateStatement parseUpdateStatement() throws ParserException {
        accept(Token.UPDATE);

        SQLUpdateStatement udpateStatement = new SQLUpdateStatement();

        SQLTableSource tableSource = this.exprParser.createSelectParser().parseTableSource();
        udpateStatement.setTableSource(tableSource);

        accept(Token.SET);

        for (;;) {
            SQLUpdateSetItem item = new SQLUpdateSetItem();
            item.setColumn(this.exprParser.name());
            accept(Token.EQ);
            item.setValue(this.exprParser.expr());

            udpateStatement.getItems().add(item);

            if (lexer.token() == (Token.COMMA)) {
                lexer.nextToken();
                continue;
            }

            break;
        }

        if (lexer.token() == (Token.WHERE)) {
            lexer.nextToken();
            udpateStatement.setWhere(this.exprParser.expr());
        }

        return udpateStatement;
    }

    public SQLDeleteStatement parseDeleteStatement() throws ParserException {
        lexer.nextToken();
        if (lexer.token() == (Token.FROM)) {
            lexer.nextToken();
        }

        SQLName tableName = exprParser.name();

        SQLDeleteStatement deleteStatement = new SQLDeleteStatement();
        deleteStatement.setTableName(tableName);

        if (lexer.token() == (Token.WHERE)) {
            lexer.nextToken();
            SQLExpr where = this.exprParser.expr();
            deleteStatement.setWhere(where);
        }

        return deleteStatement;
    }

    public SQLCreateTableStatement parseCreateTable() throws ParserException {
        // SQLCreateTableParser parser = new SQLCreateTableParser(this.lexer);
        // return parser.parseCrateTable();
        throw new ParserException("TODO");
    }

    public SQLCreateViewStatement parseCreateView() throws ParserException {
        SQLCreateViewStatement createView = new SQLCreateViewStatement();

        this.accept(Token.CREATE);

        this.accept(Token.VIEW);

        createView.setName(exprParser.name());

        if (lexer.token() == Token.LPAREN) {
            lexer.nextToken();
            this.exprParser.exprList(createView.getColumns());
            accept(Token.RPAREN);
        }

        this.accept(Token.AS);

        createView.setSubQuery(new SQLSelectParser(this.lexer).select());
        return createView;
    }

    public SQLCommentStatement parseComment() {
        accept(Token.COMMENT);
        SQLCommentStatement stmt = new SQLCommentStatement();
        
        accept(Token.ON);
        
        if (lexer.token() == Token.TABLE) {
            stmt.setType(SQLCommentStatement.Type.TABLE);
            lexer.nextToken();
        } else if (lexer.token() == Token.COLUMN) {
            stmt.setType(SQLCommentStatement.Type.COLUMN);
            lexer.nextToken();
        }
        
        stmt.setOn(this.exprParser.name());
        
        accept(Token.IS);
        stmt.setComment(this.exprParser.expr());
        
        return stmt;
    }
}