import re

from django.core.management.base import BaseCommand, CommandError
from django.db import connection


MINIMUM_VERSION = (8, 0, 35)


class Command(BaseCommand):
    help = "检查生产 MySQL 的版本、字符集、引擎、严格模式和事务隔离级别"

    def handle(self, *args, **options):
        if connection.vendor != "mysql":
            raise CommandError(f"数据库必须是 MySQL，当前为 {connection.vendor}")

        with connection.cursor() as cursor:
            cursor.execute(
                """
                SELECT VERSION(),
                       @@character_set_server,
                       @@collation_server,
                       @@sql_mode,
                       @@transaction_isolation,
                       @@default_storage_engine
                """
            )
            (
                version_text,
                charset,
                collation,
                sql_mode,
                isolation,
                storage_engine,
            ) = cursor.fetchone()

        match = re.match(r"^(\d+)\.(\d+)\.(\d+)", version_text)
        if match is None:
            raise CommandError(f"无法解析 MySQL 版本: {version_text}")
        version = tuple(int(part) for part in match.groups())
        if version < MINIMUM_VERSION:
            minimum = ".".join(str(part) for part in MINIMUM_VERSION)
            raise CommandError(f"MySQL 版本过低: {version_text}，最低要求 {minimum}")
        if charset.lower() != "utf8mb4":
            raise CommandError(f"character_set_server 必须是 utf8mb4，当前为 {charset}")
        if not collation.lower().startswith("utf8mb4_"):
            raise CommandError(f"collation_server 必须属于 utf8mb4，当前为 {collation}")

        modes = {mode.strip().upper() for mode in sql_mode.split(",")}
        if not {"STRICT_TRANS_TABLES", "STRICT_ALL_TABLES"} & modes:
            raise CommandError(f"MySQL 未启用严格模式: {sql_mode}")
        if isolation.upper().replace("_", "-") != "READ-COMMITTED":
            raise CommandError(f"事务隔离级别必须是 READ-COMMITTED，当前为 {isolation}")
        if storage_engine.lower() != "innodb":
            raise CommandError(f"默认存储引擎必须是 InnoDB，当前为 {storage_engine}")

        self.stdout.write(
            self.style.SUCCESS(
                "MySQL 检查通过: "
                f"version={version_text}, charset={charset}, "
                f"collation={collation}, isolation={isolation}, engine={storage_engine}"
            )
        )