# app/core/derive_edges.py
# -*- coding: utf-8 -*-
"""
Edge-Builder v2 (explicit + type-default "rule" edges)
-----------------------------------------------------
- Extrahiert reale Kanten aus Chunks (Wikilinks) und aus Note-Frontmatter (note_level_refs)
- Ergänzt konfigurierbare Ableitungs-Kanten gemäß config/types.yaml.edge_defaults
- Liefert *idempotente* Edge-Payloads ohne Duplikate
- Payload enthält sowohl v1-Felder (kompatibel zu qdrant_points._normalize_edge_payload)
  als auch v2-Felder gem. Playbook (src_note_id, dst_note_id, relation, rule_id, provenance, confidence)

Konfiguration
- Pfad zu der Registry via ENV: MINDNET_TYPES_FILE (Default: ./config/types.yaml)
- Struktur (Beispiel):
    types:
      concept:
        retriever_weight: 1.0
        chunk_profile: medium
        edge_defaults: ["references","related_to"]
      journal:
        retriever_weight: 0.8
        chunk_profile: long
        edge_defaults: ["references"]

Siehe auch:
- mindnet_v2_implementation_playbook.md (edge.schema.json, default_edge.schema.json)
"""
from __future__ import annotations

import os
import re
import json
from typing import Dict, Iterable, List, Optional, Tuple, Set

try:
    import yaml  # type: ignore
except Exception:
    yaml = None  # pragma: no cover

# ---- Projekt-Utilities ----
try:
    from app.core.parser import extract_wikilinks
except Exception:
    # Fallback: Minimaler Wikilink-Parser [[some-id]] oder [[Title|some-id]]
    WIKILINK_RE = re.compile(r"\[\[(?:[^\|\]]+\|)?([a-zA-Z0-9_\-#:.]+)\]\]")
    def extract_wikilinks(text: str) -> List[Tuple[str, str]]:  # (link_text, target_id)
        links = []
        for m in WIKILINK_RE.finditer(text or ""):
            raw = m.group(0)
            target = m.group(1)
            links.append((raw, target))
        return links

# ---------------------------------------------------------------------------
# Registry-Lader
# ---------------------------------------------------------------------------

def _types_path() -> str:
    p = os.getenv("MINDNET_TYPES_FILE") or "./config/types.yaml"
    return p

def _load_types() -> Dict[str, dict]:
    path = _types_path()
    if not path or not os.path.isfile(path):
        return {}
    if yaml is None:
        return {}
    try:
        with open(path, "r", encoding="utf-8") as f:
            data = yaml.safe_load(f) or {}
        if isinstance(data, dict) and "types" in data and isinstance(data["types"], dict):
            return data["types"]
        return data if isinstance(data, dict) else {}
    except Exception:
        return {}

def _edge_defaults_for(note_type: Optional[str]) -> List[str]:
    types = _load_types()
    t = (note_type or "").strip().lower()
    cfg = types.get(t) or types.get("concept") or {}
    defaults = cfg.get("edge_defaults") or []
    if isinstance(defaults, str):
        defaults = [defaults]
    return [str(x) for x in defaults if isinstance(x, (str, int, float))]

# ---------------------------------------------------------------------------
# Edge-Erzeugung
# ---------------------------------------------------------------------------

def _dedupe(edges: List[Dict]) -> List[Dict]:
    """De-dupliziere anhand (source_id, target_id, relation, rule_id)."""
    seen: Set[Tuple[str, str, str, str]] = set()
    out: List[Dict] = []
    for e in edges:
        s = str(e.get("source_id") or e.get("src_note_id") or "")
        t = str(e.get("target_id") or e.get("dst_note_id") or "")
        rel = str(e.get("relation") or e.get("kind") or "edge")
        rule = str(e.get("rule_id") or "")
        key = (s, t, rel, rule)
        if key in seen:
            continue
        seen.add(key)
        out.append(e)
    return out

def _mk_edge_id(kind: str, s: str, t: str, scope: str, rule_id: Optional[str] = None) -> str:
    base = f"{kind}:{s}->{t}#{scope}"
    if rule_id:
        base += f"|{rule_id}"
    # kurze stabile ID (BLAKE2s 12 bytes hex) – qdrant_points macht ohnehin UUIDv5,
    # diese ID dient der Nachvollziehbarkeit im Payload
    try:
        import hashlib
        return hashlib.blake2s(base.encode("utf-8"), digest_size=12).hexdigest()
    except Exception:
        return base

def _structural_edges(note_id: str, chunks: List[Dict]) -> List[Dict]:
    """belongs_to + prev/next (scope=chunk)"""
    edges: List[Dict] = []
    # belongs_to
    for ch in chunks:
        cid = ch.get("chunk_id") or ch.get("id")
        if not cid:
            continue
        e = {
            "edge_id": _mk_edge_id("belongs_to", cid, note_id, "chunk", "structure:belongs_to:v1"),
            "kind": "belongs_to",
            "scope": "chunk",
            "source_id": cid,
            "target_id": note_id,
            # v2-Felder
            "src_note_id": note_id,
            "src_chunk_id": cid,
            "dst_note_id": note_id,
            "relation": "belongs_to",
            "provenance": "rule",
            "rule_id": "structure:belongs_to:v1",
            "confidence": 1.0,
        }
        edges.append(e)

    # prev/next
    ordered = sorted([c for c in chunks if c.get("chunk_id")], key=lambda c: c.get("ord") or c.get("chunk_index") or 0)
    for a, b in zip(ordered, ordered[1:]):
        a_id = a.get("chunk_id"); b_id = b.get("chunk_id")
        if not a_id or not b_id:
            continue
        # next
        e1 = {
            "edge_id": _mk_edge_id("next", a_id, b_id, "chunk", "structure:order:v1"),
            "kind": "next",
            "scope": "chunk",
            "source_id": a_id,
            "target_id": b_id,
            "src_note_id": note_id,
            "src_chunk_id": a_id,
            "dst_note_id": note_id,
            "dst_chunk_id": b_id,
            "relation": "next",
            "provenance": "rule",
            "rule_id": "structure:order:v1",
            "confidence": 0.95,
        }
        # prev (Gegenkante)
        e2 = {
            "edge_id": _mk_edge_id("prev", b_id, a_id, "chunk", "structure:order:v1"),
            "kind": "prev",
            "scope": "chunk",
            "source_id": b_id,
            "target_id": a_id,
            "src_note_id": note_id,
            "src_chunk_id": b_id,
            "dst_note_id": note_id,
            "dst_chunk_id": a_id,
            "relation": "prev",
            "provenance": "rule",
            "rule_id": "structure:order:v1",
            "confidence": 0.95,
        }
        edges.extend([e1, e2])
    return edges

def _explicit_edges_from_chunks(note_id: str, chunks: List[Dict]) -> List[Dict]:
    edges: List[Dict] = []
    for ch in chunks:
        cid = ch.get("chunk_id") or ch.get("id")
        window = ch.get("window") or ch.get("text") or ""
        for link_text, target_id in extract_wikilinks(window):
            # explizite Referenz (chunk-scope)
            e = {
                "edge_id": _mk_edge_id("references", cid, target_id, "chunk"),
                "kind": "references",
                "scope": "chunk",
                "source_id": cid,
                "target_id": target_id,
                "note_id": note_id,  # v1-Kompatibilität
                # v2
                "src_note_id": note_id,
                "src_chunk_id": cid,
                "dst_note_id": target_id,
                "relation": "references",
                "provenance": "explicit",
                "rule_id": "",
                "confidence": 1.0,
                "link_text": link_text,
            }
            edges.append(e)
    return edges

def _explicit_edges_from_note_level(note_id: str, refs: Iterable[str], include_note_scope_refs: bool) -> List[Dict]:
    edges: List[Dict] = []
    if not include_note_scope_refs:
        return edges
    for target_id in refs or []:
        e = {
            "edge_id": _mk_edge_id("references", note_id, target_id, "note"),
            "kind": "references",
            "scope": "note",
            "source_id": note_id,
            "target_id": target_id,
            # v2
            "src_note_id": note_id,
            "dst_note_id": target_id,
            "relation": "references",
            "provenance": "explicit",
            "rule_id": "",
            "confidence": 1.0,
        }
        edges.append(e)
    return edges

def _apply_type_defaults(note_type: Optional[str], base_edges: List[Dict]) -> List[Dict]:
    """
    Ergänzt pro vorhandener (expliziter) Referenz zusätzliche Kanten gemäß
    types.yaml.edge_defaults (relationen). Jede Relation wird als eigene Kante erzeugt.
    """
    rels = [r for r in _edge_defaults_for(note_type) if r and r != "references"]
    if not rels:
        return []
    out: List[Dict] = []
    for e in base_edges:
        if e.get("relation") != "references":
            continue
        s_note = e.get("src_note_id") or e.get("note_id")
        s_chunk = e.get("src_chunk_id")
        t_note = e.get("dst_note_id") or e.get("target_id")
        scope = e.get("scope") or "chunk"
        for rel in rels:
            rule_id = f"type_default:{(note_type or 'unknown')}:{rel}:v1"
            k = rel
            src = e.get("source_id")
            tgt = e.get("target_id")
            edge_id = _mk_edge_id(k, src, tgt, scope, rule_id)
            out.append({
                "edge_id": edge_id,
                "kind": k,
                "scope": scope,
                "source_id": src,
                "target_id": tgt,
                "note_id": s_note,
                # v2
                "src_note_id": s_note,
                "src_chunk_id": s_chunk,
                "dst_note_id": t_note,
                "relation": k,
                "provenance": "rule",
                "rule_id": rule_id,
                "confidence": 0.7,
            })
    return out

def build_edges_for_note(
    note_id: str,
    chunk_payloads: List[Dict],
    note_level_refs: Optional[List[str]] = None,
    include_note_scope_refs: bool = False,
) -> List[Dict]:
    """
    Liefert alle Kanten zu einer Note:
    - Struktur: belongs_to, prev/next (scope=chunk, provenance=rule)
    - Explizite Referenzen aus Chunks (scope=chunk, provenance=explicit)
    - Explizite Referenzen aus Frontmatter (scope=note, wenn aktiviert)
    - Type-Default-Regeln (pro expliziter Referenz zusätzliche Kanten, provenance=rule)
    - Backlinks auf Note-Ebene (pro Referenz eine Rückkante, provenance=rule)
    """
    chunks = list(chunk_payloads or [])
    note_type = None
    if chunks:
        note_type = chunks[0].get("type") or chunks[0].get("note_type")

    edges: List[Dict] = []
    edges.extend(_structural_edges(note_id, chunks))

    # Explizite Referenzen
    ref_chunk_edges = _explicit_edges_from_chunks(note_id, chunks)
    edges.extend(ref_chunk_edges)
    ref_note_edges = _explicit_edges_from_note_level(note_id, note_level_refs or [], include_note_scope_refs)
    edges.extend(ref_note_edges)

    # Type-Defaults (Regeln) – basierend auf expliziten Referenzen
    edges.extend(_apply_type_defaults(note_type, ref_chunk_edges + ref_note_edges))

    # Backlinks (nur Note-Ebene) – Gegenkanten für 'references'
    for e in ref_chunk_edges + ref_note_edges:
        t = e.get("target_id") or e.get("dst_note_id")
        if not t:
            continue
        scope = "note"
        rule_id = "derived:backlink:v1"
        back = {
            "edge_id": _mk_edge_id("backlink", t, note_id, scope, rule_id),
            "kind": "backlink",
            "scope": scope,
            "source_id": t,
            "target_id": note_id,
            "note_id": note_id,
            # v2
            "src_note_id": t,
            "dst_note_id": note_id,
            "relation": "backlink",
            "provenance": "rule",
            "rule_id": rule_id,
            "confidence": 0.9,
            "original_relation": e.get("relation"),
        }
        edges.append(back)

    # Final: de-dupe
    return _dedupe(edges)