import signal

from django.db.backends.base.client import BaseDatabaseClient


class DatabaseClient(BaseDatabaseClient):
    executable_name = "mysql"

    @classmethod
    def settings_to_cmd_args_env(cls, settings_dict, parameters):
        args = [cls.executable_name]
        env = None
        database = settings_dict["OPTIONS"].get(
            "database",
            settings_dict["OPTIONS"].get("db", settings_dict["NAME"]),
        )
        user = settings_dict["OPTIONS"].get("user", settings_dict["USER"])
        password = settings_dict["OPTIONS"].get(
            "password",
            settings_dict["OPTIONS"].get("passwd", settings_dict["PASSWORD"]),
        )
        host = settings_dict["OPTIONS"].get("host", settings_dict["HOST"])
        port = settings_dict["OPTIONS"].get("port", settings_dict["PORT"])
        server_ca = settings_dict["OPTIONS"].get("ssl", {}).get("ca")
        client_cert = settings_dict["OPTIONS"].get("ssl", {}).get("cert")
        client_key = settings_dict["OPTIONS"].get("ssl", {}).get("key")
        defaults_file = settings_dict["OPTIONS"].get("read_default_file")
        charset = settings_dict["OPTIONS"].get("charset")
        # Seems to be no good way to set sql_mode with CLI.

        if defaults_file:
            args += ["--defaults-file=%s" % defaults_file]
        if user:
            args += ["--user=%s" % user]
        if password:
            # The MYSQL_PWD environment variable usage is discouraged per
            # MySQL's documentation due to the possibility of exposure through
            # `ps` on old Unix flavors but --password suffers from the same
            # flaw on even more systems. Usage of an environment variable also
            # prevents password exposure if the subprocess.run(check=True) call
            # raises a CalledProcessError since the string representation of
            # the latter includes all of the provided `args`.
            env = {"MYSQL_PWD": password}
        if host:
            if "/" in host:
                args += ["--socket=%s" % host]
            else:
                args += ["--host=%s" % host]
        if port:
            args += ["--port=%s" % port]
        if server_ca:
            args += ["--ssl-ca=%s" % server_ca]
        if client_cert:
            args += ["--ssl-cert=%s" % client_cert]
        if client_key:
            args += ["--ssl-key=%s" % client_key]
        if charset:
            args += ["--default-character-set=%s" % charset]
        if database:
            args += [database]
        args.extend(parameters)
        return args, env

    def runshell(self, parameters):
        sigint_handler = signal.getsignal(signal.SIGINT)
        try:
            # Allow SIGINT to pass to mysql to abort queries.
            signal.signal(signal.SIGINT, signal.SIG_IGN)
            super().runshell(parameters)
        finally:
            # Restore the original SIGINT handler.
            signal.signal(signal.SIGINT, sigint_handler)