import json
import logging
from datetime import datetime

import pytz
import tornado

from core.prometheus_metrics_handler import api_requests_counter
from core.utils import serialize_everything


# API request handler for /api/v1/alerts
class APIAlertsHandler(tornado.web.RequestHandler):
    def initialize(self, alerts, web_server_metrics):
        self.alerts = alerts
        self.web_server_metrics = web_server_metrics

    def get(self):
        try:
            # Metrics
            self.web_server_metrics["last_api_access_time"] = datetime.now(pytz.UTC)
            self.web_server_metrics["api_access_counter"] += 1
            self.web_server_metrics["status"] = "OK"
            api_requests_counter.inc()

            # request.arguments contains lists for each param key because technically the client can supply multiple,
            # reduce that to just the first entry, and convert bytes to string
            query_params = {k: v[0].decode("utf-8") for k, v in self.request.arguments.items()}

            # Fetch all alerts matching the query
            data = get_alert_list_with_filters(self.alerts, query_params)
            self.write(json.dumps(data, default=serialize_everything))
            self.set_status(200)
        except ValueError as e:
            logging.error(e)
            self.write(json.dumps("Bad request - " + str(e), default=serialize_everything))
            self.set_status(400)
        except Exception as e:
            logging.error(e)
            self.write(json.dumps("Error - " + str(e), default=serialize_everything))
            self.set_status(500)
        self.set_header("Cache-Control", "no-store")
        self.set_header("Content-Type", "application/json")

# API request handler for /api/v1/alerts/stream
class APIAlertsStreamHandler(tornado.web.RequestHandler):
    def get(self):
        # todo
        # try:
        #     # Metrics
        #     api_requests_counter.inc()
        #
        #     response.content_type  = 'text/event-stream'
        #     response.cache_control = 'no-cache'
        #     yield 'retry: 1000\n\n'
        #
        #     alert_queue = Queue(maxsize=100)
        #     self.sse_alert_queues.append(alert_queue)
        #     while True:
        #         if alert_queue.empty():
        #             gevent.sleep(1)
        #         else:
        #             alert = alert_queue.get()
        #             yield 'data: ' + json.dumps(alert, default=serialize_everything) + '\n\n'
        # except Exception as e:
        #     logging.warn("Exception when serving SSE socket", e)
        pass




# Utility method to apply filters to the overall alert list and return only a subset. Enables query parameters in
# the main "alerts" GET call.
def get_alert_list_with_filters(all_alerts, query):
    # Create a shallow copy of the alert list ordered by start time, then filter the list to reduce it only to alerts
    # that match the filter parameters in the query string. Finally, apply a limit to the number of alerts returned.
    # The list of query string filters is defined in the API docs.
    alert_ids = list(all_alerts.iterkeys())
    alerts = []
    for k in alert_ids:
        a = all_alerts.get(k)
        if a is not None:
            alerts.append(a)
    alerts = sorted(alerts, key=lambda alert: (alert.start_time if alert and alert.start_time else 0))
    alerts = list(filter(lambda alert: alert_allowed_by_query(alert, query), alerts))
    if "limit" in query.keys():
        alerts = alerts[:int(query.get("limit"))]
    return alerts

# Given URL query params and an alert, figure out if the alert "passes" the requested filters or is rejected. The list
# of query parameters and their function is defined in the API docs.
def alert_allowed_by_query(alert, query):
    for k in query.keys():
        match k:
            case "received_since":
                since = datetime.fromtimestamp(int(query.get(k)), pytz.UTC)
                if not alert.received_time or alert.received_time <= since:
                    return False
            case "max_duration":
                max_duration = int(query.get(k))
                # Check the duration if end_time is provided. If end_time is not provided, assume the activation is
                # "short", i.e. it always passes this check. If dxpeditions_skip_max_duration_check is true and
                # the alert is a dxpedition, it also always passes the check.
                if alert.is_dxpedition and (bool(query.get(
                        "dxpeditions_skip_max_duration_check")) if "dxpeditions_skip_max_duration_check" in query.keys() else False):
                    continue
                if alert.end_time and alert.start_time and alert.end_time - alert.start_time > max_duration:
                    return False
            case "source":
                sources = query.get(k).split(",")
                if not alert.source or alert.source not in sources:
                    return False
            case "sig":
                # If a list of sigs is provided, the alert must have a sig and it must match one of them.
                # The special "sig" "NO_SIG", when supplied in the list, mathches alerts with no sig.
                sigs = query.get(k).split(",")
                include_no_sig = "NO_SIG" in sigs
                if not alert.sig and not include_no_sig:
                    return False
                if alert.sig and alert.sig not in sigs:
                    return False
            case "dx_continent":
                dxconts = query.get(k).split(",")
                if not alert.dx_continent or alert.dx_continent not in dxconts:
                    return False
            case "dx_call_includes":
                dx_call_includes = query.get(k).strip()
                if not alert.dx_call or dx_call_includes.upper() not in alert.dx_call.upper():
                    return False
    return True