#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
app/core/derive_edges.py
Mindnet V2 — Edge-Ableitung (real + defaults), idempotent

Erzeugt Kanten für eine Note aus:
1) Sequenzkanten pro Chunk: belongs_to, next, prev
2) Reale Referenzen aus Chunk-Text (Markdown-Links, Wikilinks) + optional Frontmatter-Refs
3) Abgeleitete Kanten je Typ-Regel (types.yaml.edge_defaults), z. B. additional relations wie "depends_on", "related_to"
   - Regel-Tagging via rule_id="edge_defaults:<type>:<relation>"
   - De-Dupe via Key: (source_id, target_id, relation, rule_id)

Edge-Payload-Minimum:
- relation (alias: kind)
- note_id (Quelle; also die ID der Note, zu der die Chunks gehören)
- source_id (Chunk-ID oder Note-ID, je nach scope)
- target_id (Note-/Slug-/URL-ID; deterministisch normalisiert)
- chunk_id (falls scope='chunk')
- scope: 'chunk'|'note'
- confidence: float (bei abgeleitet z. B. 0.7)
- rule_id: str | None
"""

from __future__ import annotations
from typing import Any, Dict, Iterable, List, Optional, Tuple
import os, re, yaml, hashlib

# ---------------- Registry Laden ----------------

def _env(n: str, d: Optional[str]=None) -> str:
    v = os.getenv(n)
    return v if v is not None else (d or "")

def _load_types() -> dict:
    p = _env("MINDNET_TYPES_FILE", "./config/types.yaml")
    try:
        with open(p, "r", encoding="utf-8") as f:
            return yaml.safe_load(f) or {}
    except Exception:
        return {}

def _get_types_map(reg: dict) -> dict:
    if isinstance(reg, dict) and isinstance(reg.get("types"), dict):
        return reg["types"]
    return reg if isinstance(reg, dict) else {}

def _edge_defaults_for(note_type: str, reg: dict) -> List[str]:
    m = _get_types_map(reg)
    if isinstance(m, dict):
        t = m.get(note_type) or {}
        if isinstance(t, dict):
            vals = t.get("edge_defaults")
            if isinstance(vals, list):
                return [str(x) for x in vals if isinstance(x, (str,))]
    return []

# ---------------- Utils ----------------

SYM_REL = {"related_to", "similar_to"}  # symmetrische Relationen

def _slug_id(s: str) -> str:
    s = (s or "").strip().lower()
    s = re.sub(r"\s+", "-", s)
    s = re.sub(r"[^\w\-:/#\.]", "", s)  # lasse urls, hashes rudimentär zu
    if not s:
        s = "ref"
    return s

def _mk_edge_id(source_id: str, relation: str, target_id: str, rule_id: Optional[str]) -> str:
    base = f"{source_id}|{relation}|{target_id}|{rule_id or ''}"
    h = hashlib.sha1(base.encode("utf-8")).hexdigest()[:16]
    return f"e_{h}"

def _add(edge_list: List[Dict[str, Any]],
         dedupe: set,
         note_id: str,
         source_id: str,
         relation: str,
         target_id: str,
         *,
         chunk_id: Optional[str] = None,
         scope: str = "chunk",
         confidence: Optional[float] = None,
         rule_id: Optional[str] = None) -> None:
    key = (source_id, target_id, relation, rule_id or "")
    if key in dedupe:
        return
    dedupe.add(key)
    payload = {
        "edge_id": _mk_edge_id(source_id, relation, target_id, rule_id),
        "note_id": note_id,
        "kind": relation,         # alias
        "relation": relation,
        "scope": scope,
        "source_id": source_id,
        "target_id": target_id,
    }
    if chunk_id:
        payload["chunk_id"] = chunk_id
    if confidence is not None:
        payload["confidence"] = float(confidence)
    if rule_id is not None:
        payload["rule_id"] = rule_id
    edge_list.append(payload)

# ---------------- Refs Parsen ----------------

MD_LINK = re.compile(r"\[([^\]]+)\]\(([^)]+)\)")            # [text](target)
WIKI_LINK = re.compile(r"\[\[([^|\]]+)(?:\|[^]]+)?\]\]")    # [[Title]] oder [[Title|alias]]

def _extract_refs(text: str) -> List[Tuple[str, str]]:
    """liefert Liste (label, target) – target kann URL, Title, etc. sein"""
    out: List[Tuple[str,str]] = []
    if not text:
        return out
    for m in MD_LINK.finditer(text):
        label = (m.group(1) or "").strip()
        tgt = (m.group(2) or "").strip()
        out.append((label, tgt))
    for m in WIKI_LINK.finditer(text):
        title = (m.group(1) or "").strip()
        out.append((title, title))
    return out

# ---------------- Haupt-API ----------------

def build_edges_for_note(*,
                         note_id: str,
                         chunk_payloads: List[Dict[str, Any]],
                         note_level_refs: Optional[List[Dict[str, Any]]] = None,
                         include_note_scope_refs: bool = False) -> List[Dict[str, Any]]:
    """
    Baut alle Kanten für eine Note.
    - Sequenzkanten (belongs_to, next, prev)
    - Referenzen aus Chunk-Text (scope=chunk)
    - Abgeleitete Kanten gemäß edge_defaults aus types.yaml (für jede gefundene Referenz)
    """
    note_type = None
    if chunk_payloads:
        note_type = chunk_payloads[0].get("type")
    reg = _load_types()
    defaults = _edge_defaults_for(note_type or "concept", reg)

    edges: List[Dict[str, Any]] = []
    seen = set()

    # 1) Sequenzkanten
    for ch in chunk_payloads:
        cid = ch.get("chunk_id") or ch.get("id")
        nid = ch.get("note_id") or note_id
        idx = ch.get("index")
        # belongs_to
        _add(edges, seen, note_id=nid, source_id=cid, relation="belongs_to",
             target_id=nid, chunk_id=cid, scope="chunk")
        # next/prev
        for nb, rel in ((ch.get("neighbors_next"), "next"), (ch.get("neighbors_prev"), "prev")):
            if not nb:
                continue
            # neighbors sind Listen
            items = nb if isinstance(nb, list) else [nb]
            for tid in items:
                _add(edges, seen, note_id=nid, source_id=cid, relation=rel,
                     target_id=tid, chunk_id=cid, scope="chunk")

    # 2) Refs aus Chunk-Text (+ derived edges je ref)
    for ch in chunk_payloads:
        cid = ch.get("chunk_id") or ch.get("id")
        nid = ch.get("note_id") or note_id
        text = ch.get("text") or ""
        for (label, tgt) in _extract_refs(text):
            target_id = _slug_id(tgt)
            # real reference
            _add(edges, seen, note_id=nid, source_id=cid, relation="references",
                 target_id=target_id, chunk_id=cid, scope="chunk")
            # defaults amplification
            for rel in defaults:
                if rel == "references":
                    continue
                rule = f"edge_defaults:{note_type}:{rel}"
                _add(edges, seen, note_id=nid, source_id=cid, relation=rel,
                     target_id=target_id, chunk_id=cid, scope="chunk",
                     confidence=0.7, rule_id=rule)
                # symmetrisch?
                if rel in SYM_REL:
                    _add(edges, seen, note_id=nid, source_id=target_id, relation=rel,
                         target_id=cid, chunk_id=cid, scope="chunk",
                         confidence=0.7, rule_id=rule)

    # 3) optionale Note-Scope-Refs aus Frontmatter (falls geliefert)
    note_level_refs = note_level_refs or []
    if include_note_scope_refs and note_level_refs:
        nid = note_id
        for r in note_level_refs:
            tgt = (r or {}).get("target_id") or (r or {}).get("target") or ""
            if not tgt:
                continue
            target_id = _slug_id(str(tgt))
            _add(edges, seen, note_id=nid, source_id=nid, relation="references",
                 target_id=target_id, chunk_id=None, scope="note")
            for rel in defaults:
                if rel == "references":
                    continue
                rule = f"edge_defaults:{note_type}:{rel}"
                _add(edges, seen, note_id=nid, source_id=nid, relation=rel,
                     target_id=target_id, chunk_id=None, scope="note",
                     confidence=0.7, rule_id=rule)

    return edges