#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
Modul: app/core/derive_edges.py
Version: 1.4.0
Datum: 2025-10-01

Zweck
-----
Robuste Kantenbildung für mindnet (Notes/Chunks):
- belongs_to (chunk -> note)
- next / prev (chunk-Kette)
- references (chunk-scope) aus Chunk.window/text
- optional references/backlink (note-scope)

Wichtig: Wikilinks werden mit der Parser-Funktion `extract_wikilinks` extrahiert,
damit Varianten wie [[id#anchor]] oder [[id|label]] korrekt auf 'id' reduziert werden.

Erwartete Chunk-Payload-Felder:
  {
    "note_id": "...",
    "chunk_id": "...",   # Alias "id" ist zulässig
    "id": "...",
    "chunk_index": int,
    "seq": int,
    "window": str,
    "text": str,
    "path": "rel/path.md",
    ...
  }
"""
from __future__ import annotations

from typing import Dict, List, Optional, Iterable

# WICHTIG: benutze die Parser-Extraktion für saubere Wikilinks
from app.core.parser import extract_wikilinks

def _get(d: dict, *keys, default=None):
    for k in keys:
        if k in d and d[k] is not None:
            return d[k]
    return default

def _chunk_text_for_refs(chunk: dict) -> str:
    # bevorzugt 'window' → dann 'text' → 'content' → 'raw'
    return (
        _get(chunk, "window")
        or _get(chunk, "text")
        or _get(chunk, "content")
        or _get(chunk, "raw")
        or ""
    )

def _dedupe(seq: Iterable[str]) -> List[str]:
    seen = set()
    out: List[str] = []
    for s in seq:
        if s not in seen:
            seen.add(s)
            out.append(s)
    return out

def _edge(kind: str, scope: str, source_id: str, target_id: str, note_id: str, extra: Optional[dict] = None) -> dict:
    pl = {
        "kind": kind,
        "scope": scope,         # "chunk" | "note"
        "source_id": source_id,
        "target_id": target_id,
        "note_id": note_id,     # Träger/Quelle der Kante (aktuelle Note)
    }
    if extra:
        pl.update(extra)
    return pl

def build_edges_for_note(
    note_id: str,
    chunks: List[dict],
    note_level_references: Optional[List[str]] = None,
    include_note_scope_refs: bool = False,
) -> List[dict]:
    """
    Erzeugt Kanten für eine Note.

    - belongs_to:   für jeden Chunk   (chunk -> note)
    - next / prev:  zwischen aufeinanderfolgenden Chunks
    - references:   pro Chunk aus window/text
    - optional note-scope references/backlinks: dedupliziert über alle Chunk-Funde + note_level_references
    """
    edges: List[dict] = []

    # belongs_to
    for ch in chunks:
        cid = _get(ch, "chunk_id", "id")
        if not cid:
            continue
        edges.append(_edge("belongs_to", "chunk", cid, note_id, note_id, {"chunk_id": cid}))

    # next/prev
    for i in range(len(chunks) - 1):
        a, b = chunks[i], chunks[i + 1]
        a_id = _get(a, "chunk_id", "id")
        b_id = _get(b, "chunk_id", "id")
        if not a_id or not b_id:
            continue
        edges.append(_edge("next", "chunk", a_id, b_id, note_id, {"chunk_id": a_id}))
        edges.append(_edge("prev", "chunk", b_id, a_id, note_id, {"chunk_id": b_id}))

    # references (chunk-scope) – Links aus window bevorzugen (Overlap-fest)
    refs_all: List[str] = []
    for ch in chunks:
        cid = _get(ch, "chunk_id", "id")
        if not cid:
            continue
        txt = _chunk_text_for_refs(ch)
        refs = extract_wikilinks(txt)  # <— Parser-Logik, kompatibel zu deinem System
        for r in refs:
            edges.append(_edge("references", "chunk", cid, r, note_id, {"chunk_id": cid, "ref_text": r}))
        refs_all.extend(refs)

    # optional: note-scope references/backlinks
    if include_note_scope_refs:
        refs_note = refs_all[:]
        if note_level_references:
            refs_note.extend([r for r in note_level_references if isinstance(r, str) and r])
        refs_note = _dedupe(refs_note)
        for r in refs_note:
            edges.append(_edge("references", "note", note_id, r, note_id))
            edges.append(_edge("backlink", "note", r, note_id, note_id))

    return edges