gwoe-antragspruefer/app/embeddings.py

"""Semantic search for Wahlprogramme and Parteiprogramme using Qwen embeddings."""

import json
import sqlite3
from pathlib import Path
from typing import Optional

import fitz  # PyMuPDF
from openai import OpenAI

from .config import settings

# Embedding model
EMBEDDING_MODEL = "text-embedding-v3"
EMBEDDING_DIMENSIONS = 1024

# Database path
EMBEDDINGS_DB = settings.data_dir / "embeddings.db"

# Programme definitions
PROGRAMME = {
    # Wahlprogramme NRW 2022
    "spd-nrw-2022": {
        "name": "SPD NRW Wahlprogramm 2022",
        "typ": "wahlprogramm",
        "partei": "SPD",
        "bundesland": "NRW",
        "pdf": "spd-nrw-2022.pdf",
    },
    "cdu-nrw-2022": {
        "name": "CDU NRW Wahlprogramm 2022", 
        "typ": "wahlprogramm",
        "partei": "CDU",
        "bundesland": "NRW",
        "pdf": "cdu-nrw-2022.pdf",
    },
    "gruene-nrw-2022": {
        "name": "Grüne NRW Wahlprogramm 2022",
        "typ": "wahlprogramm",
        "partei": "GRÜNE",
        "bundesland": "NRW",
        "pdf": "gruene-nrw-2022.pdf",
    },
    "fdp-nrw-2022": {
        "name": "FDP NRW Wahlprogramm 2022",
        "typ": "wahlprogramm",
        "partei": "FDP",
        "bundesland": "NRW",
        "pdf": "fdp-nrw-2022.pdf",
    },
    "afd-nrw-2022": {
        "name": "AfD NRW Wahlprogramm 2022",
        "typ": "wahlprogramm",
        "partei": "AfD",
        "bundesland": "NRW",
        "pdf": "afd-nrw-2022.pdf",
    },
    # Grundsatzprogramme (Bund)
    "spd-grundsatz": {
        "name": "SPD Grundsatzprogramm 2007",
        "typ": "parteiprogramm",
        "partei": "SPD",
        "pdf": "spd-grundsatzprogramm.pdf",
    },
    "cdu-grundsatz": {
        "name": "CDU Grundsatzprogramm 2007",
        "typ": "parteiprogramm", 
        "partei": "CDU",
        "pdf": "cdu-grundsatzprogramm.pdf",
    },
    "gruene-grundsatz": {
        "name": "Grüne Grundsatzprogramm 2020",
        "typ": "parteiprogramm",
        "partei": "GRÜNE",
        "pdf": "gruene-grundsatzprogramm.pdf",
    },
    "fdp-grundsatz": {
        "name": "FDP Grundsatzprogramm 2012",
        "typ": "parteiprogramm",
        "partei": "FDP",
        "pdf": "fdp-grundsatzprogramm.pdf",
    },
}


def init_embeddings_db():
    """Initialize the embeddings database.

    Includes a forward-only migration step (Issue #5): adds the
    ``bundesland`` column if missing and backfills existing rows from the
    ``PROGRAMME`` registry. Grundsatzprogramme (federal level) keep
    ``bundesland = NULL``; the ``find_relevant_chunks`` query treats NULL
    as "matches any state".
    """
    conn = sqlite3.connect(EMBEDDINGS_DB)
    conn.execute("""
        CREATE TABLE IF NOT EXISTS chunks (
            id INTEGER PRIMARY KEY,
            programm_id TEXT NOT NULL,
            partei TEXT NOT NULL,
            typ TEXT NOT NULL,
            seite INTEGER,
            text TEXT NOT NULL,
            embedding BLOB NOT NULL,
            created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
        )
    """)
    conn.execute("CREATE INDEX IF NOT EXISTS idx_chunks_partei ON chunks(partei)")
    conn.execute("CREATE INDEX IF NOT EXISTS idx_chunks_typ ON chunks(typ)")

    # Migration: bundesland-Spalte ergänzen, falls Tabelle aus Pre-#5-Zeit
    cols = {row[1] for row in conn.execute("PRAGMA table_info(chunks)").fetchall()}
    if "bundesland" not in cols:
        conn.execute("ALTER TABLE chunks ADD COLUMN bundesland TEXT")
        conn.execute("CREATE INDEX IF NOT EXISTS idx_chunks_bundesland ON chunks(bundesland)")

    # Backfill: Bundesland aus PROGRAMME-Registry für bestehende Zeilen
    # nachtragen. Grundsatzprogramme bleiben NULL.
    for prog_id, info in PROGRAMME.items():
        bl = info.get("bundesland")
        if bl is not None:
            conn.execute(
                "UPDATE chunks SET bundesland = ? WHERE programm_id = ? AND bundesland IS NULL",
                (bl, prog_id),
            )

    conn.commit()
    conn.close()


def get_client() -> OpenAI:
    """Get DashScope client."""
    return OpenAI(
        api_key=settings.dashscope_api_key,
        base_url=settings.dashscope_base_url,
    )


def create_embedding(text: str) -> list[float]:
    """Create embedding for text using Qwen."""
    client = get_client()
    response = client.embeddings.create(
        model=EMBEDDING_MODEL,
        input=text,
        dimensions=EMBEDDING_DIMENSIONS,
    )
    return response.data[0].embedding


def chunk_text(text: str, chunk_size: int = 500, overlap: int = 50) -> list[str]:
    """Split text into overlapping chunks by words."""
    words = text.split()
    chunks = []
    
    i = 0
    while i < len(words):
        chunk_words = words[i:i + chunk_size]
        chunk = " ".join(chunk_words)
        if chunk.strip():
            chunks.append(chunk)
        i += chunk_size - overlap
    
    return chunks


def extract_text_with_pages(pdf_path: Path) -> list[tuple[int, str]]:
    """Extract text from PDF with page numbers."""
    doc = fitz.open(pdf_path)
    pages = []
    
    for page_num in range(len(doc)):
        page = doc[page_num]
        text = page.get_text()
        if text.strip():
            pages.append((page_num + 1, text))
    
    doc.close()
    return pages


def index_programm(programm_id: str, pdf_dir: Path) -> int:
    """Index a single program PDF into embeddings database."""
    if programm_id not in PROGRAMME:
        raise ValueError(f"Unknown program: {programm_id}")
    
    info = PROGRAMME[programm_id]
    pdf_path = pdf_dir / info["pdf"]
    
    if not pdf_path.exists():
        print(f"PDF not found: {pdf_path}")
        return 0
    
    conn = sqlite3.connect(EMBEDDINGS_DB)
    
    # Remove existing chunks for this program
    conn.execute("DELETE FROM chunks WHERE programm_id = ?", (programm_id,))
    
    # Extract and chunk
    pages = extract_text_with_pages(pdf_path)
    total_chunks = 0
    
    for page_num, page_text in pages:
        chunks = chunk_text(page_text, chunk_size=400, overlap=50)
        
        for chunk_text_content in chunks:
            if len(chunk_text_content.split()) < 20:  # Skip tiny chunks
                continue
                
            try:
                embedding = create_embedding(chunk_text_content)
                embedding_blob = json.dumps(embedding).encode()
                
                conn.execute("""
                    INSERT INTO chunks (programm_id, partei, typ, seite, text, embedding, bundesland)
                    VALUES (?, ?, ?, ?, ?, ?, ?)
                """, (
                    programm_id,
                    info["partei"],
                    info["typ"],
                    page_num,
                    chunk_text_content,
                    embedding_blob,
                    info.get("bundesland"),  # NULL für Grundsatzprogramme
                ))
                total_chunks += 1
            except Exception as e:
                print(f"Error embedding chunk: {e}")
                continue
    
    conn.commit()
    conn.close()
    
    print(f"Indexed {total_chunks} chunks from {programm_id}")
    return total_chunks


def cosine_similarity(a: list[float], b: list[float]) -> float:
    """Calculate cosine similarity between two vectors."""
    dot = sum(x * y for x, y in zip(a, b))
    norm_a = sum(x * x for x in a) ** 0.5
    norm_b = sum(x * x for x in b) ** 0.5
    if norm_a == 0 or norm_b == 0:
        return 0.0
    return dot / (norm_a * norm_b)


def find_relevant_chunks(
    query: str,
    parteien: list[str] = None,
    typ: str = None,
    bundesland: str = None,
    top_k: int = 3,
    min_similarity: float = 0.5,
) -> list[dict]:
    """Find most relevant chunks for a query.

    Args:
        bundesland: Wenn gesetzt, werden nur Chunks dieses Bundeslands ODER
            globale Chunks (bundesland IS NULL, z.B. Grundsatzprogramme)
            berücksichtigt. Wenn None, kein Filter.
    """

    query_embedding = create_embedding(query)

    conn = sqlite3.connect(EMBEDDINGS_DB)
    conn.row_factory = sqlite3.Row

    # Build query
    sql = "SELECT * FROM chunks WHERE 1=1"
    params = []

    if parteien:
        placeholders = ",".join("?" * len(parteien))
        sql += f" AND partei IN ({placeholders})"
        params.extend(parteien)

    if typ:
        sql += " AND typ = ?"
        params.append(typ)

    if bundesland:
        # Bundesland-spezifische ODER globale Chunks (Grundsatzprogramme).
        sql += " AND (bundesland = ? OR bundesland IS NULL)"
        params.append(bundesland)

    rows = conn.execute(sql, params).fetchall()
    conn.close()
    
    # Calculate similarities
    results = []
    for row in rows:
        chunk_embedding = json.loads(row["embedding"])
        similarity = cosine_similarity(query_embedding, chunk_embedding)
        
        if similarity >= min_similarity:
            results.append({
                "programm_id": row["programm_id"],
                "partei": row["partei"],
                "typ": row["typ"],
                "seite": row["seite"],
                "text": row["text"],
                "similarity": similarity,
            })
    
    # Sort by similarity and return top_k
    results.sort(key=lambda x: x["similarity"], reverse=True)
    return results[:top_k]


def get_relevant_quotes_for_antrag(
    antrag_text: str,
    fraktionen: list[str],
    bundesland: str,
    top_k_per_partei: int = 2,
) -> dict[str, list[dict]]:
    """Get relevant quotes from Wahl- and Parteiprogramme for an Antrag.

    Args:
        bundesland: Pflicht. Bestimmt, welche Wahlprogramme durchsucht werden
            und welche Regierungsfraktionen zusätzlich zu den Antragstellern
            einbezogen werden.
    """
    # Lokaler Import vermeidet Zirkularität: bundeslaender.py importiert nichts
    # aus diesem Modul, aber der saubere Trennstrich bleibt erhalten.
    from .bundeslaender import BUNDESLAENDER

    if bundesland not in BUNDESLAENDER:
        raise ValueError(f"Unbekanntes Bundesland: {bundesland}")

    regierungsfraktionen = BUNDESLAENDER[bundesland].regierungsfraktionen
    parteien_to_search = list(dict.fromkeys(fraktionen + regierungsfraktionen))  # dedupe, Reihenfolge stabil

    results = {}

    for partei in parteien_to_search:
        partei_upper = partei.upper() if partei != "GRÜNE" else "GRÜNE"

        # Wahlprogramm — bundesland-gefiltert
        wahl_chunks = find_relevant_chunks(
            antrag_text,
            parteien=[partei_upper],
            typ="wahlprogramm",
            bundesland=bundesland,
            top_k=top_k_per_partei,
            min_similarity=0.45,
        )

        # Parteiprogramm (Grundsatz, federal — bundesland=NULL matched implizit)
        partei_chunks = find_relevant_chunks(
            antrag_text,
            parteien=[partei_upper],
            typ="parteiprogramm",
            bundesland=bundesland,
            top_k=top_k_per_partei,
            min_similarity=0.45,
        )

        if wahl_chunks or partei_chunks:
            results[partei_upper] = {
                "wahlprogramm": wahl_chunks,
                "parteiprogramm": partei_chunks,
            }

    return results


def format_quotes_for_prompt(quotes: dict) -> str:
    """Format quotes for inclusion in LLM prompt."""
    if not quotes:
        return ""
    
    lines = ["\n## Relevante Passagen aus Wahl- und Parteiprogrammen\n"]
    
    for partei, data in quotes.items():
        lines.append(f"\n### {partei}\n")
        
        if data.get("wahlprogramm"):
            lines.append("**Wahlprogramm:**")
            for chunk in data["wahlprogramm"]:
                text = chunk["text"][:500] + "..." if len(chunk["text"]) > 500 else chunk["text"]
                lines.append(f'- S. {chunk["seite"]}: "{text}"')
        
        if data.get("parteiprogramm"):
            lines.append("\n**Grundsatzprogramm:**")
            for chunk in data["parteiprogramm"]:
                text = chunk["text"][:500] + "..." if len(chunk["text"]) > 500 else chunk["text"]
                lines.append(f'- S. {chunk["seite"]}: "{text}"')
    
    return "\n".join(lines)


def get_programme_info() -> list[dict]:
    """Get list of all indexed programmes with metadata."""
    info_list = []
    
    for prog_id, info in PROGRAMME.items():
        info_list.append({
            "id": prog_id,
            "name": info["name"],
            "typ": info["typ"],
            "partei": info["partei"],
            "bundesland": info.get("bundesland"),
            "pdf": info["pdf"],
            "pdf_url": f"/static/referenzen/{info['pdf']}",
        })
    
    return info_list


def get_indexing_status() -> dict:
    """Get status of indexed programmes."""
    if not EMBEDDINGS_DB.exists():
        return {"indexed": 0, "programmes": []}
    
    conn = sqlite3.connect(EMBEDDINGS_DB)
    
    # Count chunks per program
    rows = conn.execute("""
        SELECT programm_id, COUNT(*) as chunks 
        FROM chunks 
        GROUP BY programm_id
    """).fetchall()
    
    conn.close()
    
    indexed = {row[0]: row[1] for row in rows}
    
    programmes = []
    for prog_id, info in PROGRAMME.items():
        programmes.append({
            "id": prog_id,
            "name": info["name"],
            "partei": info["partei"],
            "chunks": indexed.get(prog_id, 0),
            "indexed": prog_id in indexed,
        })
    
    return {
        "indexed": len(indexed),
        "total": len(PROGRAMME),
        "programmes": programmes,
    }