PyWebIO/pywebio/io_ctrl.py

"""
输入输出的底层实现函数
"""
import inspect
import json
import logging
from functools import partial, wraps

from .session import chose_impl, next_client_event, get_current_task_id, get_current_session

logger = logging.getLogger(__name__)


class OutputReturn:
    """ ``put_xxx()`` 类函数的返回值

    若 ``put_xxx()`` 调用的返回值没有被变量接收，则直接将消息发送到会话；
    否则消息则作为其他消息的一部分
    """

    @staticmethod
    def safely_destruct(obj):
        """安全销毁 OutputReturn 对象, 使 OutputReturn.__del__ 不进行任何操作"""
        try:
            json.dumps(obj, default=partial(output_json_encoder, ignore_error=True))
        except Exception:
            pass

    def __init__(self, spec, on_embed=None):
        self.processed = False
        self.on_embed = on_embed or (lambda d: d)
        try:
            # todo 使用其他方式来转换spec
            self.spec = json.loads(json.dumps(spec, default=output_json_encoder))  # this may raise TypeError
        except TypeError:
            self.processed = True  #
            type(self).safely_destruct(spec)
            raise

    def embed_data(self):
        """返回供嵌入到其他消息中的数据，可以设置一些默认值"""
        self.processed = True
        return self.on_embed(self.spec)

    def __del__(self):
        """返回值没有被变量接收时的操作：直接输出消息"""
        if not self.processed:
            send_msg('output', self.spec)


def output_json_encoder(obj, ignore_error=False):
    """json序列化与输出相关消息的Encoder函数 """
    if isinstance(obj, OutputReturn):
        return obj.embed_data()
    if not ignore_error:
        raise TypeError('Object of type  %s is not JSON serializable' % obj.__class__.__name__)


def safely_destruct_output_when_exp(content_param):
    """装饰器生成: 异常时安全释放 OutputReturn 对象

    :param content_param: 含有OutputReturn实例的参数名或参数名列表
    :type content_param: list/str
    :return: 装饰器
    """

    def decorator(func):
        sig = inspect.signature(func)

        @wraps(func)
        def inner(*args, **kwargs):
            try:
                return func(*args, **kwargs)
            except Exception:
                # 发生异常，安全地释放 OutputReturn 对象
                params = [content_param] if isinstance(content_param, str) else content_param
                bound = sig.bind(*args, **kwargs).arguments
                for param in params:
                    if bound.get(param):
                        OutputReturn.safely_destruct(bound.get(param))

                raise

        return inner

    return decorator


def send_msg(cmd, spec=None):
    msg = dict(command=cmd, spec=spec, task_id=get_current_task_id())
    get_current_session().send_task_command(msg)


@chose_impl
def single_input(item_spec, valid_func, preprocess_func):
    """
    Note: 鲁棒性在上层完成
    将单个input构造成input_group，并获取返回值
    :param item_spec: 单个输入项的参数 'name' must in item_spec， 参数一定已经验证通过
    :param valid_func: Not None
    :param preprocess_func: Not None
    """
    if item_spec.get('name') is None:  # single input
        item_spec['name'] = 'data'
    else:  # as input_group item
        return dict(item_spec=item_spec, valid_func=valid_func, preprocess_func=preprocess_func)

    label = item_spec['label']
    name = item_spec['name']
    # todo 是否可以原地修改spec
    item_spec['label'] = ''

    item_spec.setdefault('auto_focus', True)  # 如果没有设置autofocus参数，则开启参数  todo CHECKBOX, RADIO 特殊处理

    spec = dict(label=label, inputs=[item_spec])
    data = yield input_control(spec, {name: preprocess_func}, {name: valid_func})
    return data[name]


@chose_impl
def input_control(spec, preprocess_funcs, item_valid_funcs, form_valid_funcs=None):
    """
    发送input命令，监听事件，验证输入项，返回结果
    :param spec:
    :param preprocess_funcs: keys 严格等于 spec中的name集合
    :param item_valid_funcs: keys 严格等于 spec中的name集合
    :param form_valid_funcs:
    :return:
    """
    send_msg('input_group', spec)

    data = yield input_event_handle(item_valid_funcs, form_valid_funcs, preprocess_funcs)

    send_msg('destroy_form')
    return data


def check_item(name, data, valid_func, preprocess_func):
    try:
        data = preprocess_func(data)
        error_msg = valid_func(data)
    except Exception as e:
        logger.warning('Get %r in valid_func for name:"%s"', e, name)
        error_msg = '字段内容不合法'
    if error_msg is not None:
        send_msg('update_input', dict(target_name=name, attributes={
            'valid_status': False,
            'invalid_feedback': error_msg
        }))
        return False
    return True


@chose_impl
def input_event_handle(item_valid_funcs, form_valid_funcs, preprocess_funcs):
    """
    根据提供的校验函数处理表单事件
    :param item_valid_funcs: map(name -> valid_func)  valid_func 为 None 时，不进行验证
                        valid_func: callback(data) -> error_msg or None
    :param form_valid_funcs: callback(data) -> (name, error_msg) or None
    :param preprocess_funcs:
    :return:
    """
    while True:
        event = yield next_client_event()
        event_name, event_data = event['event'], event['data']
        if event_name == 'input_event':
            input_event = event_data['event_name']
            if input_event == 'blur':
                onblur_name = event_data['name']
                check_item(onblur_name, event_data['value'], item_valid_funcs[onblur_name],
                           preprocess_funcs[onblur_name])

        elif event_name == 'from_submit':
            all_valid = True

            # 调用输入项验证函数进行校验
            for name, valid_func in item_valid_funcs.items():
                if not check_item(name, event_data[name], valid_func, preprocess_funcs[name]):
                    all_valid = False

            if all_valid:  # todo 减少preprocess_funcs[name]调用次数
                data = {name: preprocess_funcs[name](val) for name, val in event_data.items()}
                # 调用表单验证函数进行校验
                if form_valid_funcs:
                    v_res = form_valid_funcs(data)
                    if v_res is not None:
                        all_valid = False
                        onblur_name, error_msg = v_res
                        send_msg('update_input', dict(target_name=onblur_name, attributes={
                            'valid_status': False,
                            'invalid_feedback': error_msg
                        }))

            if all_valid:
                break
        elif event_name == 'from_cancel':
            data = None
            break
        else:
            logger.warning("Unhandled Event: %s", event)

    return data


def output_register_callback(callback, **options):
    task_id = get_current_session().register_callback(callback, **options)
    return task_id