mindnet/app/core/retriever.py

"""
app/core/retriever.py — Hybrider Such-Algorithmus

Version:
    0.5.3 (WP-06 Fix: Populate 'payload' in QueryHit for meta-data access)
"""
from __future__ import annotations

import os
import time
from functools import lru_cache
from typing import Any, Dict, List, Tuple, Iterable, Optional

from app.config import get_settings
from app.models.dto import (
    QueryRequest, 
    QueryResponse, 
    QueryHit, 
    Explanation, 
    ScoreBreakdown, 
    Reason, 
    EdgeDTO
)
import app.core.qdrant as qdr
import app.core.qdrant_points as qp
import app.services.embeddings_client as ec
import app.core.graph_adapter as ga

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


@lru_cache
def _get_scoring_weights() -> Tuple[float, float, float]:
    """Liefert (semantic_weight, edge_weight, centrality_weight) für den Retriever."""
    settings = get_settings()
    sem = float(getattr(settings, "RETRIEVER_W_SEM", 1.0))
    edge = float(getattr(settings, "RETRIEVER_W_EDGE", 0.0))
    cent = float(getattr(settings, "RETRIEVER_W_CENT", 0.0))

    config_path = os.getenv("MINDNET_RETRIEVER_CONFIG", "config/retriever.yaml")
    if yaml is None:
        return sem, edge, cent
    try:
        if os.path.exists(config_path):
            with open(config_path, "r", encoding="utf-8") as f:
                data = yaml.safe_load(f) or {}
            scoring = data.get("scoring", {}) or {}
            sem = float(scoring.get("semantic_weight", sem))
            edge = float(scoring.get("edge_weight", edge))
            cent = float(scoring.get("centrality_weight", cent))
    except Exception:
        return sem, edge, cent
    return sem, edge, cent


def _get_client_and_prefix() -> Tuple[Any, str]:
    """Liefert (QdrantClient, prefix)."""
    cfg = qdr.QdrantConfig.from_env()
    client = qdr.get_client(cfg)
    return client, cfg.prefix


def _get_query_vector(req: QueryRequest) -> List[float]:
    """Liefert den Query-Vektor aus dem Request."""
    if req.query_vector:
        return list(req.query_vector)

    if not req.query:
        raise ValueError("QueryRequest benötigt entweder query oder query_vector")

    settings = get_settings()
    model_name = settings.MODEL_NAME

    try:
        return ec.embed_text(req.query, model_name=model_name)
    except TypeError:
        return ec.embed_text(req.query)


def _semantic_hits(
    client: Any,
    prefix: str,
    vector: List[float],
    top_k: int,
    filters: Dict[str, Any] | None = None,
) -> List[Tuple[str, float, Dict[str, Any]]]:
    """Führt eine semantische Suche aus."""
    flt = filters or None
    raw_hits = qp.search_chunks_by_vector(client, prefix, vector, top=top_k, filters=flt)
    results: List[Tuple[str, float, Dict[str, Any]]] = []
    for pid, score, payload in raw_hits:
        results.append((str(pid), float(score), dict(payload or {})))
    return results


def _compute_total_score(
    semantic_score: float,
    payload: Dict[str, Any],
    edge_bonus: float = 0.0,
    cent_bonus: float = 0.0,
) -> Tuple[float, float, float]:
    """Berechnet total_score."""
    raw_weight = payload.get("retriever_weight", 1.0)
    try:
        weight = float(raw_weight)
    except (TypeError, ValueError):
        weight = 1.0
    if weight < 0.0:
        weight = 0.0

    sem_w, edge_w, cent_w = _get_scoring_weights()
    total = (sem_w * float(semantic_score) * weight) + (edge_w * edge_bonus) + (cent_w * cent_bonus)
    return float(total), float(edge_bonus), float(cent_bonus)


# --- WP-04b Explanation Logic ---

def _build_explanation(
    semantic_score: float,
    payload: Dict[str, Any],
    edge_bonus: float,
    cent_bonus: float,
    subgraph: Optional[ga.Subgraph],
    node_key: Optional[str]
) -> Explanation:
    """Erstellt ein Explanation-Objekt."""
    sem_w, _edge_w, _cent_w = _get_scoring_weights()
    # Scoring weights erneut laden für Reason-Details
    _, edge_w_cfg, cent_w_cfg = _get_scoring_weights()
    
    try:
        type_weight = float(payload.get("retriever_weight", 1.0))
    except (TypeError, ValueError):
        type_weight = 1.0
    
    note_type = payload.get("type", "unknown")

    breakdown = ScoreBreakdown(
        semantic_contribution=(sem_w * semantic_score * type_weight),
        edge_contribution=(edge_w_cfg * edge_bonus),
        centrality_contribution=(cent_w_cfg * cent_bonus),
        raw_semantic=semantic_score,
        raw_edge_bonus=edge_bonus,
        raw_centrality=cent_bonus,
        node_weight=type_weight
    )

    reasons: List[Reason] = []
    edges_dto: List[EdgeDTO] = []

    if semantic_score > 0.85:
        reasons.append(Reason(kind="semantic", message="Sehr hohe textuelle Übereinstimmung.", score_impact=breakdown.semantic_contribution))
    elif semantic_score > 0.70:
        reasons.append(Reason(kind="semantic", message="Gute textuelle Übereinstimmung.", score_impact=breakdown.semantic_contribution))

    if type_weight != 1.0:
        msg = "Bevorzugt" if type_weight > 1.0 else "Leicht abgewertet"
        reasons.append(Reason(kind="type", message=f"{msg} aufgrund des Typs '{note_type}'.", score_impact=(sem_w * semantic_score * (type_weight - 1.0))))

    if subgraph and node_key and edge_bonus > 0:
        if hasattr(subgraph, "get_outgoing_edges"):
            outgoing = subgraph.get_outgoing_edges(node_key)
            for edge in outgoing:
                target = edge.get("target", "Unknown")
                kind = edge.get("kind", "edge")
                weight = edge.get("weight", 0.0)
                if weight > 0.05:
                    edges_dto.append(EdgeDTO(id=f"{node_key}->{target}:{kind}", kind=kind, source=node_key, target=target, weight=weight, direction="out"))

        if hasattr(subgraph, "get_incoming_edges"):
            incoming = subgraph.get_incoming_edges(node_key)
            for edge in incoming:
                src = edge.get("source", "Unknown")
                kind = edge.get("kind", "edge")
                weight = edge.get("weight", 0.0)
                if weight > 0.05:
                    edges_dto.append(EdgeDTO(id=f"{src}->{node_key}:{kind}", kind=kind, source=src, target=node_key, weight=weight, direction="in"))

        all_edges = sorted(edges_dto, key=lambda e: e.weight, reverse=True)
        for top_edge in all_edges[:3]:
            impact = edge_w_cfg * top_edge.weight
            dir_txt = "Verweist auf" if top_edge.direction == "out" else "Referenziert von"
            tgt_txt = top_edge.target if top_edge.direction == "out" else top_edge.source
            reasons.append(Reason(kind="edge", message=f"{dir_txt} '{tgt_txt}' via '{top_edge.kind}'", score_impact=impact, details={"kind": top_edge.kind}))

    if cent_bonus > 0.01:
        reasons.append(Reason(kind="centrality", message="Knoten liegt zentral im Kontext.", score_impact=breakdown.centrality_contribution))

    return Explanation(breakdown=breakdown, reasons=reasons, related_edges=edges_dto if edges_dto else None)


def _extract_expand_options(req: QueryRequest) -> Tuple[int, List[str] | None]:
    """Extrahiert depth und edge_types."""
    expand = getattr(req, "expand", None)
    if not expand:
        return 0, None

    depth = 1
    edge_types: List[str] | None = None

    if hasattr(expand, "depth") or hasattr(expand, "edge_types"):
        depth = int(getattr(expand, "depth", 1) or 1)
        types_val = getattr(expand, "edge_types", None)
        if types_val:
            edge_types = list(types_val)
        return depth, edge_types

    if isinstance(expand, dict):
        if "depth" in expand:
            depth = int(expand.get("depth") or 1)
        if "edge_types" in expand and expand["edge_types"] is not None:
            edge_types = list(expand["edge_types"])
        return depth, edge_types

    return 0, None


def _build_hits_from_semantic(
    hits: Iterable[Tuple[str, float, Dict[str, Any]]],
    top_k: int,
    used_mode: str,
    subgraph: ga.Subgraph | None = None,
    explain: bool = False,
) -> QueryResponse:
    """Baut strukturierte QueryHits."""
    t0 = time.time()
    enriched: List[Tuple[str, float, Dict[str, Any], float, float, float]] = []

    for pid, semantic_score, payload in hits:
        edge_bonus = 0.0
        cent_bonus = 0.0
        node_key = payload.get("chunk_id") or payload.get("note_id")
        
        if subgraph is not None and node_key:
            try:
                edge_bonus = float(subgraph.edge_bonus(node_key))
            except Exception:
                edge_bonus = 0.0
            try:
                cent_bonus = float(subgraph.centrality_bonus(node_key))
            except Exception:
                cent_bonus = 0.0

        total, edge_bonus, cent_bonus = _compute_total_score(semantic_score, payload, edge_bonus=edge_bonus, cent_bonus=cent_bonus)
        enriched.append((pid, float(semantic_score), payload, total, edge_bonus, cent_bonus))

    enriched_sorted = sorted(enriched, key=lambda h: h[3], reverse=True)
    limited = enriched_sorted[: max(1, top_k)]

    results: List[QueryHit] = []
    for pid, semantic_score, payload, total, edge_bonus, cent_bonus in limited:
        explanation_obj = None
        if explain:
            explanation_obj = _build_explanation(
                semantic_score=float(semantic_score),
                payload=payload,
                edge_bonus=edge_bonus,
                cent_bonus=cent_bonus,
                subgraph=subgraph,
                node_key=payload.get("chunk_id") or payload.get("note_id")
            )

        text_content = payload.get("page_content") or payload.get("text") or payload.get("content")

        results.append(QueryHit(
            node_id=str(pid),
            note_id=payload.get("note_id"),
            semantic_score=float(semantic_score),
            edge_bonus=edge_bonus,
            centrality_bonus=cent_bonus,
            total_score=total,
            paths=None,
            source={
                "path": payload.get("path"),
                "section": payload.get("section") or payload.get("section_title"),
                "text": text_content
            },
            # --- FIX: Wir füllen das payload-Feld explizit ---
            payload=payload, 
            explanation=explanation_obj
        ))

    dt = int((time.time() - t0) * 1000)
    return QueryResponse(results=results, used_mode=used_mode, latency_ms=dt)


def semantic_retrieve(req: QueryRequest) -> QueryResponse:
    """Reiner semantischer Retriever."""
    client, prefix = _get_client_and_prefix()
    vector = _get_query_vector(req)
    top_k = req.top_k or get_settings().RETRIEVER_TOP_K

    hits = _semantic_hits(client, prefix, vector, top_k=top_k, filters=req.filters)
    return _build_hits_from_semantic(hits, top_k=top_k, used_mode="semantic", subgraph=None, explain=req.explain)


def hybrid_retrieve(req: QueryRequest) -> QueryResponse:
    """Hybrid-Retriever: semantische Suche + optionale Edge-Expansion."""
    client, prefix = _get_client_and_prefix()
    if req.query_vector:
        vector = list(req.query_vector)
    else:
        vector = _get_query_vector(req)

    top_k = req.top_k or get_settings().RETRIEVER_TOP_K
    hits = _semantic_hits(client, prefix, vector, top_k=top_k, filters=req.filters)

    depth, edge_types = _extract_expand_options(req)
    subgraph: ga.Subgraph | None = None
    if depth and depth > 0:
        seed_ids: List[str] = []
        for _pid, _score, payload in hits:
            key = payload.get("chunk_id") or payload.get("note_id")
            if key and key not in seed_ids:
                seed_ids.append(key)
        if seed_ids:
            try:
                subgraph = ga.expand(client, prefix, seed_ids, depth=depth, edge_types=edge_types)
            except Exception:
                subgraph = None

    return _build_hits_from_semantic(hits, top_k=top_k, used_mode="hybrid", subgraph=subgraph, explain=req.explain)


class Retriever:
    """
    Wrapper-Klasse für WP-05 (Chat).
    """
    def __init__(self):
        pass

    async def search(self, request: QueryRequest) -> QueryResponse:
        return hybrid_retrieve(request)