ceresdb-sql/src/main/java/io/ceresdb/sql/JSqlParser.java

/*
 * Copyright 2023 CeresDB Project Authors. Licensed under Apache-2.0.
 */
package io.ceresdb.sql;

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

import io.ceresdb.common.parser.SqlParser;
import io.ceresdb.common.util.internal.ThrowUtil;

import net.sf.jsqlparser.JSQLParserException;
import net.sf.jsqlparser.parser.CCJSqlParserUtil;
import net.sf.jsqlparser.statement.DescribeStatement;
import net.sf.jsqlparser.statement.ShowStatement;
import net.sf.jsqlparser.statement.Statement;
import net.sf.jsqlparser.statement.alter.Alter;
import net.sf.jsqlparser.statement.create.table.CreateTable;
import net.sf.jsqlparser.statement.drop.Drop;
import net.sf.jsqlparser.statement.insert.Insert;
import net.sf.jsqlparser.statement.select.Select;

/**
 * Parse SQL use JSqlParser.
 *
 */
public class JSqlParser implements SqlParser {

    private final String sql;

    private boolean       parsed;
    private StatementType statementType = StatementType.Unknown;
    private Statement     stmt;

    public JSqlParser(String sql) {
        this.sql = sql;
    }

    public String getSql() {
        return sql;
    }

    @Override
    public StatementType statementType() {
        parse();

        return this.statementType;
    }

    @Override
    public List<String> tableNames() {
        parse();

        switch (this.statementType) {
            case Create:
            case Select:
            case Describe:
                return SqlParserUtil.extractTableNames(this.stmt);
            case Alter:
                return Collections.singletonList(((Alter) (this.stmt)).getTable().getName());
            case Show:
                return Collections.singletonList(((ShowStatement) this.stmt).getName());
            case Drop:
                return Collections.singletonList(((Drop) this.stmt).getName().getName());
            case Insert:
                return Collections.singletonList(((Insert) this.stmt).getTable().getName());
            case Unknown:
            default:
                return reject("Invalid.statement: " + this.statementType);
        }
    }

    @Override
    public List<Column> createColumns() {
        parse();

        if (this.statementType == StatementType.Create) {
            return SqlParserUtil.extractCreateColumns((CreateTable) this.stmt);
        }

        return reject("Must be " + StatementType.Create);
    }

    private void parse() {
        if (this.parsed) {
            return;
        }

        this.parsed = true;

        try {
            final Statement stmt = CCJSqlParserUtil.parse(SqlParserUtil.amendSql(this.sql));

            if (stmt instanceof Select) {
                this.statementType = StatementType.Select;
            } else if (stmt instanceof CreateTable) {
                this.statementType = StatementType.Create;
            } else if (stmt instanceof Alter) {
                this.statementType = StatementType.Alter;
            } else if (stmt instanceof DescribeStatement) {
                this.statementType = StatementType.Describe;
            } else if (stmt instanceof ShowStatement) {
                this.statementType = StatementType.Show;
            } else if (stmt instanceof Drop) {
                this.statementType = StatementType.Drop;
            } else if (stmt instanceof Insert) {
                this.statementType = StatementType.Insert;
            } else {
                this.statementType = StatementType.Unknown;
            }

            this.stmt = stmt;
        } catch (final JSQLParserException e) {
            ThrowUtil.throwException(e);
        }
    }

    private static <T> T reject(final String msg) {
        throw new IllegalArgumentException(msg);
    }
}