package com.supervision.utils;
import com.alibaba.druid.sql.ast.SQLStatement;
import com.alibaba.druid.sql.ast.statement.*;
import com.alibaba.druid.sql.dialect.mysql.parser.MySqlStatementParser;
import com.alibaba.druid.sql.dialect.mysql.visitor.MySqlSchemaStatVisitor;
import com.alibaba.druid.sql.parser.SQLStatementParser;
import com.alibaba.druid.stat.TableStat;
import java.util.List;
import java.util.Set;

public class SqlParserUtil {


    /**
     * 解析 SQL
     * @param parser parser
     * @return null 表示解析失败
     */
    public static SQLStatement parseStatement(SQLStatementParser parser) {
        try {
            return parser.parseStatement();
        } catch (Exception e) {
            return null;
        }
    }

    /**
     *sql 类型
     * @param statement statement
     * @return
     */
    public static String detectSQLType(SQLStatement statement) {
        try {
            // 判断 SQL 类型
            if (statement instanceof SQLSelectStatement) {
                return "SELECT";
            } else if (statement instanceof SQLInsertStatement) {
                return "INSERT";
            } else if (statement instanceof SQLUpdateStatement) {
                return "UPDATE";
            } else if (statement instanceof SQLDeleteStatement) {
                return "DELETE";
            } else {
                return "UNKNOWN";
            }
        } catch (Exception e) {
            return "ERROR";
        }
    }

    /**
     * 提取 SQL 中的表名
     * @param statement statement
     * @return 表名
     */
    public static List<String> extractTableNames(SQLStatement statement) {
        MySqlSchemaStatVisitor visitor = new MySqlSchemaStatVisitor();
        statement.accept(visitor);

        Set<TableStat.Name> tableStatNames = visitor.getTables().keySet();

        return tableStatNames.stream().map(TableStat.Name::getName).toList();
    }

    public static void main(String[] args) {
        String sql = "select u.name, o.id FROM users u left JOIN orders o ON u.id = o.user_id left join dept d on u.id = d.id WHERE u.id = 1 and u.id in ( select id from people where name = 'dd' )";

        MySqlStatementParser parser = new MySqlStatementParser(sql);
        SQLStatement sqlStatement = parseStatement(parser);
        if (sqlStatement == null){
            System.out.println("SQL 是否合法: " + false);
            return;
        }

        String s = detectSQLType(sqlStatement);
        System.out.println("SQL 类型: " + s);

        List<String> tableNames = extractTableNames(sqlStatement);
        System.out.println("涉及到的表: " + tableNames);
    }
}