from datetime import datetime, timedelta

from flask import Blueprint, abort, jsonify, request, url_for

from ..extensions import db
from ..models import Display, DisplaySession

bp = Blueprint("api", __name__, url_prefix="/api")


MAX_ACTIVE_SESSIONS_PER_DISPLAY = 2
SESSION_TTL_SECONDS = 90


@bp.get("/display/<token>/playlist")
def display_playlist(token: str):
    display = Display.query.filter_by(token=token).first()
    if not display:
        abort(404)

    # Enforce: a display URL/token can be opened by max 2 concurrently active sessions.
    # Player sends a stable `sid` via querystring.
    sid = (request.args.get("sid") or "").strip()
    if sid:
        cutoff = datetime.utcnow() - timedelta(seconds=SESSION_TTL_SECONDS)
        DisplaySession.query.filter(
            DisplaySession.display_id == display.id,
            DisplaySession.last_seen_at < cutoff,
        ).delete(synchronize_session=False)
        db.session.commit()

        existing = DisplaySession.query.filter_by(display_id=display.id, sid=sid).first()
        if existing:
            existing.last_seen_at = datetime.utcnow()
            db.session.commit()
        else:
            active_count = (
                DisplaySession.query.filter(
                    DisplaySession.display_id == display.id,
                    DisplaySession.last_seen_at >= cutoff,
                ).count()
            )
            if active_count >= MAX_ACTIVE_SESSIONS_PER_DISPLAY:
                return (
                    jsonify(
                        {
                            "error": "display_limit_reached",
                            "message": f"This display URL is already open on {MAX_ACTIVE_SESSIONS_PER_DISPLAY} displays.",
                        }
                    ),
                    429,
                )

            s = DisplaySession(
                display_id=display.id,
                sid=sid,
                last_seen_at=datetime.utcnow(),
                ip=request.headers.get("X-Forwarded-For", request.remote_addr),
                user_agent=(request.headers.get("User-Agent") or "")[:300],
            )
            db.session.add(s)
            db.session.commit()

    playlist = display.assigned_playlist
    if not playlist:
        return jsonify({"display": display.name, "playlist": None, "items": []})

    items = []
    for item in playlist.items:
        payload = {
            "id": item.id,
            "type": item.item_type,
            "title": item.title,
            "duration": item.duration_seconds,
        }
        if item.item_type in ("image", "video") and item.file_path:
            payload["src"] = url_for("static", filename=item.file_path)
        if item.item_type == "webpage":
            payload["url"] = item.url
        items.append(payload)

    return jsonify(
        {
            "display": display.name,
            "playlist": {"id": playlist.id, "name": playlist.name},
            "items": items,
        }
    )