#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
Modul: app/graph/service.py
Version: 0.1.0
Datum: 2025-09-10

Zweck
-----
Leichtgewichtiger Graph-Layer über Qdrant:
  - get_note(note_id)
  - get_chunks(note_id)
  - neighbors(source_id, kinds=[...], scope=['note','chunk'], depth=1)
  - walk_bfs(source_id, kinds, max_depth)
  - context_for_note(note_id, max_neighbors): heuristische Kontextsammlung

Hinweise
--------
- Nutzt die bestehenden Collections <prefix>_notes/_chunks/_edges.
- Edges werden über Payload-Felder (`kind`, `source_id`, `target_id`) abgefragt.
"""
from __future__ import annotations
from typing import List, Dict, Any, Optional, Iterable, Set, Tuple
from qdrant_client.http import models as rest
from app.core.qdrant import QdrantConfig, get_client

def _cols(prefix: str):
    return f"{prefix}_notes", f"{prefix}_chunks", f"{prefix}_edges"

class GraphService:
    def __init__(self, cfg: Optional[QdrantConfig] = None, prefix: Optional[str] = None):
        self.cfg = cfg or QdrantConfig.from_env()
        if prefix:
            self.cfg.prefix = prefix
        self.client = get_client(self.cfg)
        self.notes_col, self.chunks_col, self.edges_col = _cols(self.cfg.prefix)

    # ------------------------ fetch helpers ------------------------
    def _scroll(self, col: str, flt: Optional[rest.Filter] = None, limit: int = 256):
        out = []
        nextp = None
        while True:
            pts, nextp = self.client.scroll(
                collection_name=col,
                with_payload=True,
                with_vectors=False,
                limit=limit,
                offset=nextp,
                scroll_filter=flt,
            )
            if not pts:
                break
            out.extend(pts)
            if nextp is None:
                break
        return out

    # ------------------------ public API ---------------------------
    def get_note(self, note_id: str) -> Optional[Dict[str, Any]]:
        f = rest.Filter(must=[rest.FieldCondition(key="note_id", match=rest.MatchValue(value=note_id))])
        pts, _ = self.client.scroll(self.notes_col, with_payload=True, with_vectors=False, limit=1, scroll_filter=f)
        return (pts[0].payload or None) if pts else None

    def get_chunks(self, note_id: str) -> List[Dict[str, Any]]:
        f = rest.Filter(must=[rest.FieldCondition(key="note_id", match=rest.MatchValue(value=note_id))])
        pts = self._scroll(self.chunks_col, f)
        # Sortierung analog Export
        def key(pl):
            p = pl.payload or {}
            s = p.get("seq") or 0
            ci = p.get("chunk_index") or 0
            n = 0
            cid = p.get("chunk_id") or ""
            if isinstance(cid, str) and "#" in cid:
                try:
                    n = int(cid.rsplit("#", 1)[-1])
                except Exception:
                    n = 0
            return (int(s), int(ci), n)
        pts_sorted = sorted(pts, key=key)
        return [p.payload or {} for p in pts_sorted]

    def neighbors(self, source_id: str, kinds: Optional[Iterable[str]] = None,
                  scope: Optional[Iterable[str]] = None, depth: int = 1) -> Dict[str, List[Dict[str, Any]]]:
        """
        Liefert eingehende & ausgehende Nachbarn (nur nach kind gefiltert).
        depth==1: direkte Kanten.
        """
        kinds = list(kinds) if kinds else None
        must = [rest.FieldCondition(key="source_id", match=rest.MatchValue(value=source_id))]
        if kinds:
            must.append(rest.FieldCondition(key="kind", match=rest.MatchAny(any=kinds)))
        f = rest.Filter(must=must)
        edges = self._scroll(self.edges_col, f)
        out = {"out": [], "in": []}
        for e in edges:
            out["out"].append(e.payload or {})
        # Inverse Richtung (eingehend)
        must_in = [rest.FieldCondition(key="target_id", match=rest.MatchValue(value=source_id))]
        if kinds:
            must_in.append(rest.FieldCondition(key="kind", match=rest.MatchAny(any=kinds)))
        f_in = rest.Filter(must=must_in)
        edges_in = self._scroll(self.edges_col, f_in)
        for e in edges_in:
            out["in"].append(e.payload or {})
        return out

    def walk_bfs(self, source_id: str, kinds: Iterable[str], max_depth: int = 2) -> Set[str]:
        visited: Set[str] = {source_id}
        frontier: Set[str] = {source_id}
        kinds = list(kinds)
        for _ in range(max_depth):
            nxt: Set[str] = set()
            for s in frontier:
                neigh = self.neighbors(s, kinds=kinds)
                for e in neigh["out"]:
                    t = e.get("target_id")
                    if isinstance(t, str) and t not in visited:
                        visited.add(t)
                        nxt.add(t)
            frontier = nxt
            if not frontier:
                break
        return visited

    def context_for_note(self, note_id: str, kinds: Iterable[str] = ("references","backlink"), max_neighbors: int = 12) -> Dict[str, Any]:
        """
        Heuristischer Kontext: eigene Chunks + Nachbarn nach Kantenarten, dedupliziert.
        """
        note = self.get_note(note_id) or {}
        chunks = self.get_chunks(note_id)
        neigh = self.neighbors(note_id, kinds=list(kinds))
        targets = []
        for e in neigh["out"]:
            t = e.get("target_id")
            if isinstance(t, str):
                targets.append(t)
        for e in neigh["in"]:
            s = e.get("source_id")
            if isinstance(s, str):
                targets.append(s)
        # de-dupe
        seen = set()
        uniq = []
        for t in targets:
            if t not in seen:
                seen.add(t)
                uniq.append(t)
        uniq = uniq[:max_neighbors]
        neighbor_notes = [self.get_note(t) for t in uniq]
        return {
            "note": note,
            "chunks": chunks,
            "neighbors": [n for n in neighbor_notes if n],
            "edges_out": neigh["out"],
            "edges_in": neigh["in"],
        }

# Optional: Mini-CLI
if __name__ == "__main__":  # pragma: no cover
    import argparse, json
    ap = argparse.ArgumentParser()
    ap.add_argument("--prefix", help="Collection-Prefix (überschreibt ENV)")
    ap.add_argument("--note-id", required=True)
    ap.add_argument("--neighbors", action="store_true", help="Nur Nachbarn anzeigen")
    args = ap.parse_args()
    svc = GraphService(prefix=args.prefix)
    if args.neighbors:
        out = svc.neighbors(args.note_id, kinds=["references","backlink","prev","next","belongs_to"])
    else:
        out = svc.context_for_note(args.note_id)
    print(json.dumps(out, ensure_ascii=False, indent=2))