import hashlib
import hmac
import logging

import httpx

logger = logging.getLogger(__name__)


def _compute_appsecret_proof(access_token: str, app_secret: str) -> str:
    return hmac.new(
        app_secret.encode("utf-8"),
        access_token.encode("utf-8"),
        hashlib.sha256,
    ).hexdigest()


async def list_subscriptions(
    app_id: str,
    app_token: str,
    api_version: str = "v24.0",
) -> list[dict]:
    url = f"https://graph.facebook.com/{api_version}/{app_id}/subscriptions"
    params = {"access_token": app_token}

    async with httpx.AsyncClient(timeout=15.0) as client:
        try:
            resp = await client.get(url, params=params)
            if resp.status_code == 200:
                data = resp.json()
                return data.get("data", [])
            logger.error("Failed to list subscriptions: %d %s", resp.status_code, resp.text[:200])
            return []
        except httpx.RequestError as exc:
            logger.error("Failed to list subscriptions: %s", exc)
            return []


async def subscribe_page(
    page_id: str,
    access_token: str,
    api_version: str = "v24.0",
    app_secret: str = "",
) -> dict:
    url = f"https://graph.facebook.com/{api_version}/{page_id}/subscribed_apps"
    params = {"access_token": access_token}
    if app_secret:
        params["appsecret_proof"] = _compute_appsecret_proof(access_token, app_secret)

    async with httpx.AsyncClient(timeout=15.0) as client:
        try:
            resp = await client.post(url, params=params)
            if resp.status_code == 200:
                logger.info("Page %s subscribed successfully", page_id)
                return {"success": True, "data": resp.json()}
            logger.error("Failed to subscribe page %s: %d %s", page_id, resp.status_code, resp.text[:200])
            return {"success": False, "error": resp.text[:200]}
        except httpx.RequestError as exc:
            logger.error("Failed to subscribe page %s: %s", page_id, exc)
            return {"success": False, "error": str(exc)}


async def unsubscribe_page(
    page_id: str,
    access_token: str,
    api_version: str = "v24.0",
    app_secret: str = "",
) -> dict:
    url = f"https://graph.facebook.com/{api_version}/{page_id}/subscribed_apps"
    params = {"access_token": access_token}
    if app_secret:
        params["appsecret_proof"] = _compute_appsecret_proof(access_token, app_secret)

    async with httpx.AsyncClient(timeout=15.0) as client:
        try:
            resp = await client.delete(url, params=params)
            if resp.status_code == 200:
                logger.info("Page %s unsubscribed successfully", page_id)
                return {"success": True, "data": resp.json()}
            logger.error("Failed to unsubscribe page %s: %d %s", page_id, resp.status_code, resp.text[:200])
            return {"success": False, "error": resp.text[:200]}
        except httpx.RequestError as exc:
            logger.error("Failed to unsubscribe page %s: %s", page_id, exc)
            return {"success": False, "error": str(exc)}