"""Notification backend abstraction. ntfy is the only implementation today,
but call sites always go through get_notifier() / notify_flight_staged() so
a second backend could be added later (a new class + registry entry) without
touching the pipeline code that triggers notifications.
"""

import json
import urllib.error
import urllib.request
from abc import ABC, abstractmethod

import config
import models
import tokens


class Notifier(ABC):
    @abstractmethod
    def send(self, title: str, body: str, url: str | None = None, actions: list[dict] | None = None) -> None:
        ...


class NtfyNotifier(Notifier):
    def __init__(self, server_url: str, topic: str, auth_token: str | None = None):
        self.server_url = server_url.rstrip("/")
        self.topic = topic
        self.auth_token = auth_token

    def send(self, title: str, body: str, url: str | None = None, actions: list[dict] | None = None) -> None:
        if not self.topic:
            return  # not configured yet - silently skip rather than crash the pipeline

        payload = {"topic": self.topic, "title": title, "message": body}
        if url:
            payload["click"] = url
        if actions:
            payload["actions"] = actions

        req = urllib.request.Request(
            self.server_url,
            data=json.dumps(payload).encode("utf-8"),
            headers={"Content-Type": "application/json"},
        )
        if self.auth_token:
            req.add_header("Authorization", f"Bearer {self.auth_token}")

        try:
            with urllib.request.urlopen(req, timeout=15):
                pass
        except (urllib.error.HTTPError, urllib.error.URLError):
            pass  # best-effort; a failed push shouldn't crash the pipeline run


def get_notifier() -> Notifier:
    settings = models.get_all_settings()
    # Only one backend exists today; settings.notify_backend is read here so
    # a second implementation can be switched in later without changing
    # call sites.
    return NtfyNotifier(
        server_url=settings["ntfy_server_url"],
        topic=settings["ntfy_topic"],
        auth_token=settings["ntfy_auth_token"] or None,
    )


def flight_url(flight_id: int) -> str | None:
    if not config.PUBLIC_BASE_URL:
        return None
    return f"{config.PUBLIC_BASE_URL}/flights/{flight_id}"


def notify_flight_staged(row: dict) -> None:
    flight_id = row["id"]
    route = f"{row.get('from_iata') or '?'}→{row.get('to_iata') or '?'}"
    flight_number = f"{row.get('operating_carrier_iata') or ''}{row.get('flight_number') or ''}"
    title = f"{flight_number or 'Flight'} staged for review"

    if row["status"] == "track_unavailable":
        summary = "no track found"
    else:
        count = row.get("track_point_count") or 0
        summary = f"track found, {count} points"

    body = f"{route} · {row.get('flight_date') or '?'} · {summary}"

    review_url = flight_url(flight_id)
    actions = []
    if review_url:
        actions.append({"action": "view", "label": "Investigate", "url": review_url})

    base = config.PUBLIC_BASE_URL
    if base:
        approve_token = tokens.sign_token(flight_id, "approve")
        reject_token = tokens.sign_token(flight_id, "reject")
        actions.append({
            "action": "http", "label": "Approve", "method": "POST", "clear": True,
            "url": f"{base}/flights/{flight_id}/approve?token={approve_token}",
        })
        actions.append({
            "action": "http", "label": "Deny", "method": "POST", "clear": True,
            "url": f"{base}/flights/{flight_id}/reject?token={reject_token}",
        })

    get_notifier().send(title=title, body=body, url=review_url, actions=actions or None)