#!/usr/bin/env python3
"""Read-only MySQL query helper used by local verification."""

import os
import sys

if sys.stdout.encoding and sys.stdout.encoding.lower() != "utf-8":
    sys.stdout.reconfigure(encoding="utf-8", errors="replace")

try:
    import pymysql
    import pymysql.cursors
except ImportError:
    print("缺少依赖，请先执行: pip install pymysql")
    sys.exit(1)


def required_env(name: str) -> str:
    value = os.getenv(name)
    if value is None or not value.strip():
        print(f"缺少必需环境变量: {name}")
        sys.exit(2)
    return value.strip()


DB_CONFIG = {
    "host": required_env("SUPERBIZ_MYSQL_HOST"),
    "port": int(required_env("SUPERBIZ_MYSQL_PORT")),
    "user": required_env("SUPERBIZ_MYSQL_USERNAME"),
    "password": required_env("SUPERBIZ_MYSQL_PASSWORD"),
    "database": required_env("SUPERBIZ_MYSQL_DATABASE"),
    "charset": "utf8mb4",
    "cursorclass": pymysql.cursors.DictCursor,
    "read_timeout": 10,
    "write_timeout": 10,
}


def validate_read_only_sql(sql: str) -> str:
    normalized = sql.strip()
    if not normalized:
        raise ValueError("SQL 不能为空")
    statements = [part.strip() for part in normalized.split(";") if part.strip()]
    if len(statements) != 1:
        raise ValueError("只允许单条 SELECT")
    statement = statements[0]
    upper = statement.upper()
    if upper != "SELECT" and not upper.startswith("SELECT "):
        raise ValueError("只允许 SELECT 查询")
    padded = f" {upper} "
    forbidden = (
        " INTO ",
        " FOR UPDATE",
        " SHOW ",
        " DESCRIBE ",
        " INFORMATION_SCHEMA",
        " WITH ",
        " UNION ",
        " CALL ",
    )
    if any(token in padded for token in forbidden):
        raise ValueError("查询包含禁止的只读或元数据语法")
    return statement


def run_query(sql: str) -> None:
    statement = validate_read_only_sql(sql)
    connection = pymysql.connect(**DB_CONFIG)
    try:
        with connection.cursor() as cursor:
            cursor.execute("START TRANSACTION READ ONLY")
            cursor.execute(statement)
            rows = cursor.fetchall()
            if not rows:
                print("(空结果)")
                return
            columns = list(rows[0].keys())
            widths = {
                column: max(len(column), max(len(str(row[column])) for row in rows))
                for column in columns
            }
            header = " | ".join(column.ljust(widths[column]) for column in columns)
            print(header)
            print("-" * len(header))
            for row in rows:
                print(" | ".join(str(row[column]).ljust(widths[column]) for column in columns))
            print(f"\n({len(rows)} 行)")
    finally:
        connection.rollback()
        connection.close()


if __name__ == "__main__":
    if len(sys.argv) > 1:
        try:
            run_query(" ".join(sys.argv[1:]))
        except ValueError as exc:
            print(f"拒绝执行: {exc}")
            sys.exit(3)
    else:
        print("MySQL 只读交互模式（输入 exit 退出）")
        print(
            f"连接: {DB_CONFIG['user']}@{DB_CONFIG['host']}:"
            f"{DB_CONFIG['port']}/{DB_CONFIG['database']}"
        )
        print("-" * 50)
        while True:
            try:
                sql = input("sql> ").strip()
                if sql.lower() in ("exit", "quit", "q"):
                    break
                if sql:
                    run_query(sql)
            except KeyboardInterrupt:
                break
            except Exception as exc:
                print(f"错误: {exc}")