"""
app/models/dto.py — Pydantic-Modelle (DTOs) für WP-04 Endpunkte

Zweck:
    Laufzeit-Modelle für FastAPI (Requests/Responses), getrennt von JSON-Schemas.
    Deckt die Graph-/Retriever-Endpunkte ab.
    Enthält Erweiterungen für WP-04b (Explanation Layer) und WP-04c (Feedback).

Kompatibilität:
    Python 3.12+, Pydantic 2.x, FastAPI 0.110+
Version:
    0.3.0  (Update für WP-04c Feedback)
Stand:
    2025-12-07
"""

from __future__ import annotations
from pydantic import BaseModel, Field
from typing import List, Literal, Optional, Dict, Any
import uuid

EdgeKind = Literal["references", "references_at", "backlink", "next", "prev", "belongs_to", "depends_on", "related_to", "similar_to"]


# --- Basis-DTOs ---

class NodeDTO(BaseModel):
    """Darstellung eines Knotens (Note oder Chunk) im API-Graph."""
    id: str
    type: Literal["note", "chunk"]
    title: Optional[str] = None
    note_id: Optional[str] = None
    tags: Optional[List[str]] = None
    in_degree: Optional[int] = None
    out_degree: Optional[int] = None
    score: Optional[float] = None
    section_title: Optional[str] = None
    section_path: Optional[str] = None
    path: Optional[str] = None


class EdgeDTO(BaseModel):
    """Darstellung einer Kante im API-Graph."""
    id: str
    kind: str  # String statt Literal, um flexibel für Custom-Types zu bleiben
    source: str
    target: str
    weight: float
    direction: Literal["out", "in", "undirected"] = "out"


# --- Request Models ---

class QueryRequest(BaseModel):
    """
    Request für /query:
    - mode: 'semantic' | 'edge' | 'hybrid'
    - query: (optional) Freitext
    - query_vector: (optional) direkter Vektor
    - explain: (optional) Fordert detaillierte Erklärungen an (WP-04b)
    """
    mode: Literal["semantic", "edge", "hybrid"] = "hybrid"
    query: Optional[str] = None
    query_vector: Optional[List[float]] = None
    top_k: int = 10
    expand: Dict = {"depth": 1, "edge_types": ["references", "belongs_to", "prev", "next", "depends_on", "related_to"]}
    filters: Optional[Dict] = None
    ret: Dict = {"with_paths": True, "with_notes": True, "with_chunks": True}
    explain: bool = False


class FeedbackRequest(BaseModel):
    """
    User-Feedback zu einem spezifischen Treffer (WP-04c).
    """
    query_id: str = Field(..., description="ID der ursprünglichen Suche")
    node_id: str = Field(..., description="ID des bewerteten Treffers")
    score: int = Field(..., ge=0, le=1, description="1 (Positiv) oder 0 (Negativ/Irrelevant)")
    comment: Optional[str] = None


# --- WP-04b Explanation Models ---

class ScoreBreakdown(BaseModel):
    """Aufschlüsselung der Score-Komponenten."""
    semantic_contribution: float = Field(..., description="W_sem * semantic_score * weight")
    edge_contribution: float = Field(..., description="W_edge * edge_bonus")
    centrality_contribution: float = Field(..., description="W_cent * centrality_bonus")
    
    # Rohwerte
    raw_semantic: float
    raw_edge_bonus: float
    raw_centrality: float
    node_weight: float = Field(..., description="Typ-Gewicht (retriever_weight)")


class Reason(BaseModel):
    """Ein semantischer Grund für das Ranking."""
    kind: Literal["semantic", "edge", "type", "centrality"]
    message: str
    score_impact: Optional[float] = None
    details: Optional[Dict[str, Any]] = None


class Explanation(BaseModel):
    """Container für alle Erklärungsdaten eines Treffers."""
    breakdown: ScoreBreakdown
    reasons: List[Reason]
    related_edges: Optional[List[EdgeDTO]] = None


# --- Response Models ---

class QueryHit(BaseModel):
    """Einzelnes Trefferobjekt für /query."""
    node_id: str
    note_id: Optional[str]
    
    # Flache Scores
    semantic_score: float
    edge_bonus: float
    centrality_bonus: float
    total_score: float
    
    paths: Optional[List[List[Dict]]] = None
    source: Optional[Dict] = None
    
    # WP-04b: Erklärungsobjekt
    explanation: Optional[Explanation] = None


class QueryResponse(BaseModel):
    """
    Antwortstruktur für /query (Liste von Treffern + Telemetrie).
    Enthält query_id für Traceability (WP-04c).
    """
    query_id: str = Field(default_factory=lambda: str(uuid.uuid4()))
    results: List[QueryHit]
    used_mode: str
    latency_ms: int


class GraphResponse(BaseModel):
    """Antwortstruktur für /graph/{note_id}."""
    center_note_id: str
    nodes: List[NodeDTO]
    edges: List[EdgeDTO]
    stats: Dict[str, int]