"""Relations app fragment endpoints.

Generic container-nav fragment that renders navigation items for all
related entities, driven by the relation registry.
"""

from __future__ import annotations

from quart import Blueprint, Response, g, request

from shared.infrastructure.fragments import FRAGMENT_HEADER


def register():
    bp = Blueprint("fragments", __name__, url_prefix="/internal/fragments")

    _handlers: dict[str, object] = {}

    @bp.before_request
    async def _require_fragment_header():
        if not request.headers.get(FRAGMENT_HEADER):
            return Response("", status=403)

    @bp.get("/<fragment_type>")
    async def get_fragment(fragment_type: str):
        handler = _handlers.get(fragment_type)
        if handler is None:
            return Response("", status=200, content_type="text/html")
        html = await handler()
        return Response(html, status=200, content_type="text/html")

    # --- generic container-nav fragment ----------------------------------------

    async def _container_nav_handler():
        """Render nav items for all visible relations of a container entity.

        Query params:
            container_type: entity type (e.g. "page")
            container_id:   entity id
            post_slug:      used for URL construction
            exclude:        comma-separated relation types to skip
        """
        from shared.sexp.jinja_bridge import sexp as render_sexp
        from shared.sexp.relations import relations_from
        from shared.services.relationships import get_children
        from shared.infrastructure.urls import events_url, market_url

        _SERVICE_URL = {
            "calendar": events_url,
            "market": market_url,
        }

        container_type = request.args.get("container_type", "page")
        container_id = int(request.args.get("container_id", 0))
        post_slug = request.args.get("post_slug", "")
        nav_class = request.args.get("nav_class", "")
        exclude_raw = request.args.get("exclude", "")
        exclude = set(exclude_raw.split(",")) if exclude_raw else set()

        nav_defs = [
            d for d in relations_from(container_type)
            if d.nav != "hidden" and d.name not in exclude
        ]

        if not nav_defs:
            return ""

        parts = []
        for defn in nav_defs:
            children = await get_children(
                g.s,
                parent_type=container_type,
                parent_id=container_id,
                child_type=defn.to_type,
                relation_type=defn.name,
            )
            for child in children:
                slug = (child.metadata_ or {}).get("slug", "")
                if not slug:
                    continue
                nav_label = defn.nav_label or ""
                if post_slug and nav_label:
                    path = f"/{post_slug}/{nav_label}/{slug}/"
                elif post_slug:
                    path = f"/{post_slug}/{slug}/"
                else:
                    path = f"/{slug}/"
                url_fn = _SERVICE_URL.get(defn.to_type)
                href = url_fn(path) if url_fn else path
                parts.append(render_sexp(
                    '(~relation-nav :href href :name name :icon icon :nav-class nav-class :relation-type relation-type)',
                    href=href,
                    name=child.label or "",
                    icon=defn.nav_icon or "",
                    **{
                        "nav-class": nav_class,
                        "relation-type": defn.name,
                    },
                ))

        return "\n".join(parts)

    _handlers["container-nav"] = _container_nav_handler

    return bp