import json
import warnings

import numpy as np

from keras_core.api_export import keras_core_export
from keras_core.callbacks.callback import Callback

try:
    import requests
except ImportError:
    requests = None


@keras_core_export("keras_core.callbacks.RemoteMonitor")
class RemoteMonitor(Callback):
    """Callback used to stream events to a server.

    Requires the `requests` library.
    Events are sent to `root + '/publish/epoch/end/'` by default. Calls are
    HTTP POST, with a `data` argument which is a
    JSON-encoded dictionary of event data.
    If `send_as_json=True`, the content type of the request will be
    `"application/json"`.
    Otherwise the serialized JSON will be sent within a form.

    Args:
        root: String; root url of the target server.
        path: String; path relative to `root` to which the events will be sent.
        field: String; JSON field under which the data will be stored.
            The field is used only if the payload is sent within a form
            (i.e. send_as_json is set to False).
        headers: Dictionary; optional custom HTTP headers.
        send_as_json: Boolean; whether the request should be
            sent as `"application/json"`.
    """

    def __init__(
        self,
        root="http://localhost:9000",
        path="/publish/epoch/end/",
        field="data",
        headers=None,
        send_as_json=False,
    ):
        super().__init__()

        self.root = root
        self.path = path
        self.field = field
        self.headers = headers
        self.send_as_json = send_as_json

    def on_epoch_end(self, epoch, logs=None):
        if requests is None:
            raise ImportError("RemoteMonitor requires the `requests` library.")
        logs = logs or {}
        send = {}
        send["epoch"] = epoch
        for k, v in logs.items():
            # np.ndarray and np.generic are not scalar types
            # therefore we must unwrap their scalar values and
            # pass to the json-serializable dict 'send'
            if isinstance(v, (np.ndarray, np.generic)):
                send[k] = v.item()
            else:
                send[k] = v
        try:
            if self.send_as_json:
                requests.post(
                    self.root + self.path, json=send, headers=self.headers
                )
            else:
                requests.post(
                    self.root + self.path,
                    {self.field: json.dumps(send)},
                    headers=self.headers,
                )
        except requests.exceptions.RequestException:
            warnings.warn(
                f"Could not reach RemoteMonitor root server at {self.root}",
                stacklevel=2,
            )