#!/usr/bin/env python3
"""
Lädt PDFs von URLs und extrahiert Text mit PyMuPDF.
Parallelisiert für Geschwindigkeit.
"""

import argparse
import sqlite3
import tempfile
import time
from concurrent.futures import ThreadPoolExecutor, as_completed
from pathlib import Path

import httpx
import pymupdf  # PyMuPDF

PROJECT_ROOT = Path(__file__).resolve().parent.parent
DB_PATH = PROJECT_ROOT / "data" / "tracker_remote.db"

# Rate limiting
REQUESTS_PER_SECOND = 5
MIN_DELAY = 1.0 / REQUESTS_PER_SECOND


def get_db():
    conn = sqlite3.connect(str(DB_PATH), check_same_thread=False)
    conn.row_factory = sqlite3.Row
    return conn


def download_and_extract(vorlage_id: int, url: str) -> tuple[int, str | None, str | None]:
    """
    Lädt PDF und extrahiert Text.
    Returns: (vorlage_id, text, error)
    """
    try:
        # Download
        resp = httpx.get(url, timeout=60, follow_redirects=True)
        resp.raise_for_status()
        
        if len(resp.content) < 100:
            return (vorlage_id, None, "PDF zu klein")
        
        # Text extrahieren
        with tempfile.NamedTemporaryFile(suffix=".pdf", delete=True) as tmp:
            tmp.write(resp.content)
            tmp.flush()
            
            doc = pymupdf.open(tmp.name)
            text_parts = []
            for page in doc:
                text_parts.append(page.get_text())
            doc.close()
            
            text = "\n".join(text_parts).strip()
            
            if len(text) < 50:
                return (vorlage_id, None, "Kein Text extrahiert")
            
            return (vorlage_id, text, None)
            
    except httpx.HTTPStatusError as e:
        return (vorlage_id, None, f"HTTP {e.response.status_code}")
    except Exception as e:
        return (vorlage_id, None, str(e)[:100])


def clean_text(text: str) -> str:
    """Bereinigt extrahierten Text."""
    import re
    # Mehrfache Leerzeilen reduzieren
    text = re.sub(r'\n{3,}', '\n\n', text)
    # Mehrfache Leerzeichen
    text = re.sub(r' {2,}', ' ', text)
    return text.strip()


def process_batch(vorlagen: list[dict], workers: int = 5) -> dict:
    """Verarbeitet einen Batch parallel."""
    results = {"success": 0, "failed": 0, "errors": []}
    conn = get_db()
    
    with ThreadPoolExecutor(max_workers=workers) as executor:
        futures = {}
        for v in vorlagen:
            time.sleep(MIN_DELAY)  # Rate limiting
            future = executor.submit(download_and_extract, v['vorlage_id'], v['url'])
            futures[future] = v
        
        for future in as_completed(futures):
            v = futures[future]
            vorlage_id, text, error = future.result()
            
            if text:
                clean = clean_text(text)
                conn.execute("""
                    UPDATE vorlagen SET volltext = ?, volltext_clean = ?
                    WHERE id = ?
                """, (text, clean, vorlage_id))
                conn.execute("""
                    UPDATE anlagen SET downloaded = 1 WHERE vorlage_id = ?
                """, (vorlage_id,))
                conn.commit()
                results["success"] += 1
                print(f"  ✓ #{vorlage_id}: {len(clean)} Zeichen")
            else:
                results["failed"] += 1
                results["errors"].append((vorlage_id, error))
                print(f"  ✗ #{vorlage_id}: {error}")
    
    conn.close()
    return results


def main():
    parser = argparse.ArgumentParser(description="PDF-Extraktion")
    parser.add_argument("--limit", type=int, default=100, help="Max. Anzahl")
    parser.add_argument("--workers", type=int, default=5, help="Parallele Downloads")
    parser.add_argument("--offset", type=int, default=0, help="Start-Offset")
    args = parser.parse_args()
    
    print(f"=== PDF-Extraktion ===")
    print(f"Limit: {args.limit}, Workers: {args.workers}\n")
    
    conn = get_db()
    
    # Vorlagen mit PDF-URL aber ohne Volltext
    vorlagen = conn.execute("""
        SELECT a.vorlage_id, a.url
        FROM anlagen a
        JOIN vorlagen v ON a.vorlage_id = v.id
        WHERE a.url IS NOT NULL
          AND a.downloaded = 0
          AND (v.volltext_clean IS NULL OR v.volltext_clean = '')
        ORDER BY v.datum_eingang DESC
        LIMIT ? OFFSET ?
    """, (args.limit, args.offset)).fetchall()
    
    conn.close()
    
    print(f"Zu verarbeiten: {len(vorlagen)}\n")
    
    if not vorlagen:
        print("Nichts zu tun!")
        return
    
    results = process_batch([dict(v) for v in vorlagen], args.workers)
    
    print(f"\n=== Fertig ===")
    print(f"Erfolgreich: {results['success']}")
    print(f"Fehlgeschlagen: {results['failed']}")


if __name__ == "__main__":
    main()