"""FlowDeck — Notification service (v4.9.0 collaboration).

Creates in-app notifications (mentions, comments, page changes) and triggers
email delivery via :mod:`app.services.mailer` when the target user has opted in.
"""
from __future__ import annotations

import json
import re

from app.db import get_conn
from app.services import mailer


def create_notification(
    user_id: int,
    actor_id: int | None,
    ntype: str,
    title: str,
    message: str,
    resource_type: str = "page",
    resource_id: int = 0,
    url: str = "",
    conn=None,
    commit: bool = True,
) -> int | None:
    """Insert a notification row. Returns the new id (or None if skipped).

    ``conn`` may be supplied to join an existing transaction (caller controls
    commit). Otherwise a dedicated connection is opened and committed.
    """
    if not user_id:
        return None
    if conn is not None:
        cur = conn.execute(
            """INSERT INTO notifications
               (user_id, actor_id, ntype, title, message, resource_type, resource_id, url)
               VALUES (?,?,?,?,?,?,?,?)""",
            (user_id, actor_id, ntype, title, message, resource_type, resource_id, url),
        )
        if commit:
            conn.commit()
        return cur.lastrowid
    with get_conn() as conn:
        cur = conn.execute(
            """INSERT INTO notifications
               (user_id, actor_id, ntype, title, message, resource_type, resource_id, url)
               VALUES (?,?,?,?,?,?,?,?)""",
            (user_id, actor_id, ntype, title, message, resource_type, resource_id, url),
        )
        conn.commit()
        return cur.lastrowid


_MENTION_RE = re.compile(r"(?:^|\s)@([\w\-\.]+)")


def extract_mentions(text: str) -> list[str]:
    """Return the set of @login handles mentioned in ``text`` (lowercase)."""
    return list(dict.fromkeys(m.lower() for m in _MENTION_RE.findall(text or "")))


def process_mentions(
    text: str,
    actor_id: int,
    ntype: str,
    title: str,
    message: str,
    resource_type: str = "page",
    resource_id: int = 0,
    url: str = "",
    conn=None,
) -> list[int]:
    """Create notifications for every user @-mentioned in ``text``.

    Returns the list of mentioned user ids that were notified.
    """
    handles = extract_mentions(text)
    if not handles:
        return []
    notified = []
    if conn is not None:
        _do_mentions(conn, handles, actor_id, ntype, title, message,
                     resource_type, resource_id, url, notified)
        return notified
    with get_conn() as conn:
        _do_mentions(conn, handles, actor_id, ntype, title, message,
                     resource_type, resource_id, url, notified)
        conn.commit()
    return notified


def _do_mentions(conn, handles, actor_id, ntype, title, message,
                 resource_type, resource_id, url, notified):
    placeholders = ",".join("?" * len(handles))
    rows = conn.execute(
        "SELECT id, login, email FROM users WHERE lower(login) IN (%s)" % placeholders,
        handles,
    ).fetchall()
    for row in rows:
        if row["id"] == actor_id:
            continue
        create_notification(
            row["id"], actor_id, ntype, title, message,
            resource_type, resource_id, url, conn=conn, commit=False,
        )
        notified.append(row["id"])
        mailer.notify_user(
            row["id"], subject=title, body_text=message, cta_url=url or "",
        )


def get_user_prefs(user_id: int, conn=None) -> dict:
    if conn is not None:
        row = conn.execute(
            "SELECT notification_prefs FROM users WHERE id=?", (user_id,)
        ).fetchone()
    else:
        with get_conn() as conn:
            row = conn.execute(
                "SELECT notification_prefs FROM users WHERE id=?", (user_id,)
            ).fetchone()
    if not row or not row["notification_prefs"]:
        return {"comments": True, "mentions": True}
    try:
        prefs = json.loads(row["notification_prefs"])
    except (TypeError, json.JSONDecodeError):
        prefs = {}
    return {"comments": bool(prefs.get("comments", True)),
            "mentions": bool(prefs.get("mentions", True))}


def set_user_prefs(user_id: int, prefs: dict, conn=None) -> dict:
    if conn is not None:
        conn.execute(
            "UPDATE users SET notification_prefs=? WHERE id=?",
            (json.dumps(prefs), user_id),
        )
        conn.commit()
    else:
        with get_conn() as conn:
            conn.execute(
                "UPDATE users SET notification_prefs=? WHERE id=?",
                (json.dumps(prefs), user_id),
            )
            conn.commit()
    return prefs