"""Notification channels: LogChannel + WebhookChannel.

Protocol-based: NotificationChannel defines send(kind, text, data) -> bool.
LogChannel writes to notification_log (delivered=true always).
WebhookChannel POSTs to NOTIFY_WEBHOOK_URL (2xx=delivered, else error row).

send_notification(kind, text, data) is the public entry point used by
the scheduler and email watch modules.
"""

from __future__ import annotations

import json
import logging
import os
from typing import Any, Protocol

from app.db import execute, fetch_all

logger = logging.getLogger(__name__)


class NotificationChannel(Protocol):
    """Protocol for notification delivery channels."""

    def send(self, kind: str, text: str, data: dict[str, Any]) -> bool:
        """Send a notification. Returns True if delivered, False otherwise."""
        ...


def _normalize_log_row(row: dict[str, Any]) -> dict[str, Any]:
    payload = row.get("payload")
    if payload is not None and not isinstance(payload, dict):
        payload = json.loads(payload) if isinstance(payload, str) else payload
    return {
        "id": str(row["id"]),
        "channel": row["channel"],
        "kind": row["kind"],
        "payload": payload or {},
        "delivered": row["delivered"],
        "error": row.get("error"),
        "created_at": row["created_at"].isoformat() if row.get("created_at") else None,
    }


class LogChannel:
    """Writes notification entries to notification_log with delivered=true."""

    channel_name: str = "log"

    def send(self, kind: str, text: str, data: dict[str, Any]) -> bool:
        row = execute(
            """
            INSERT INTO notification_log (channel, kind, payload, delivered, error)
            VALUES (%s, %s, %s, true, NULL)
            RETURNING *
            """,
            (self.channel_name, kind, json.dumps({"text": text, **data})),
        )
        if row is None:
            logger.error("LogChannel: insert notification_log failed")
            return False
        logger.info("LogChannel: delivered kind=%s", kind)
        return True


class WebhookChannel:
    """POSTs notification payload to NOTIFY_WEBHOOK_URL.

    On 2xx response: writes notification_log with delivered=true.
    On non-2xx or exception: writes notification_log with delivered=false and error.
    """

    channel_name: str = "webhook"

    def __init__(self, url: str | None = None) -> None:
        self.url = url or os.environ.get("NOTIFY_WEBHOOK_URL", "")

    def send(self, kind: str, text: str, data: dict[str, Any]) -> bool:
        payload: dict[str, Any] = {"kind": kind, "text": text, "data": data}
        error: str | None = None
        delivered = False

        if not self.url:
            error = "NOTIFY_WEBHOOK_URL not configured"
            logger.warning("WebhookChannel: %s", error)
        else:
            try:
                import httpx

                resp = httpx.post(self.url, json=payload, timeout=10)
                if 200 <= resp.status_code < 300:
                    delivered = True
                else:
                    error = f"HTTP {resp.status_code}: {resp.text[:200]}"
                    logger.warning("WebhookChannel: %s", error)
            except Exception as exc:
                error = str(exc)
                logger.warning("WebhookChannel: exception: %s", error)

        row = execute(
            """
            INSERT INTO notification_log (channel, kind, payload, delivered, error)
            VALUES (%s, %s, %s, %s, %s)
            RETURNING *
            """,
            (
                self.channel_name,
                kind,
                json.dumps(payload),
                delivered,
                error,
            ),
        )
        if row is None:
            logger.error("WebhookChannel: insert notification_log failed")
        return delivered


# --- Channel registry ---

_channels: list[NotificationChannel] | None = None


def get_channels() -> list[NotificationChannel]:
    """Return the list of active notification channels.

    LogChannel is always included.
    WebhookChannel is included when NOTIFY_WEBHOOK_URL is set.
    """
    global _channels
    if _channels is not None:
        return _channels

    channels: list[NotificationChannel] = [LogChannel()]
    webhook_url = os.environ.get("NOTIFY_WEBHOOK_URL", "").strip()
    if webhook_url:
        channels.append(WebhookChannel())
    _channels = channels
    return channels


def set_channels(channels: list[NotificationChannel] | None) -> None:
    """Override channel list (for testing)."""
    global _channels
    _channels = channels


def reset_channels() -> None:
    """Reset to default (for testing)."""
    global _channels
    _channels = None


def send_notification(kind: str, text: str, data: dict[str, Any] | None = None) -> None:
    """Send a notification via all active channels.

    kind: e.g. 'daily_digest', 'email_suggestion'
    text: human-readable notification text
    data: structured payload dict
    """
    chs = get_channels()
    payload = data or {}
    for ch in chs:
        try:
            ch.send(kind, text, payload)
        except Exception:
            logger.exception("send_notification: channel %s failed", type(ch).__name__)


# --- Repository helpers ---

def list_notification_log(limit: int = 50) -> list[dict[str, Any]]:
    """Return recent notification_log rows, newest first."""
    rows = fetch_all(
        """
        SELECT * FROM notification_log
        ORDER BY created_at DESC
        LIMIT %s
        """,
        (limit,),
    )
    return [_normalize_log_row(r) for r in rows]