#!/usr/bin/env python3
import os
import sys
import subprocess
import datetime
import sqlite3
from pathlib import Path
from io import BytesIO
from huggingface_hub import HfApi, HfFileSystem, hf_hub_download
import tempfile

# Set up path to include the application module
SCRIPT_DIR = Path(__file__).parent.resolve()
BACKEND_DIR = SCRIPT_DIR.parent
sys.path.append(str(BACKEND_DIR))

# Database path (actual application database)
DATA_DIR = os.environ.get("DATA_DIR", "/app/backend/data")
DB_FILE_PATH = os.path.join(DATA_DIR, "webui.db")

# Hugging Face repo paths (virtual paths in HF storage)
REPO_DB_GPG_FILE = "db_backup/webui.db.gpg"
REPO_TIMESTAMP_FILE = "db_backup/last_backup_time.txt"


def verify_database():
    """Verify database integrity."""
    if not os.path.exists(DB_FILE_PATH):
        print(f"Database file not found at: {DB_FILE_PATH}")
        return False
        
    try:
        with sqlite3.connect(DB_FILE_PATH) as conn:
            cursor = conn.cursor()
            cursor.execute("PRAGMA integrity_check;")
            result = cursor.fetchone()[0]
            cursor.execute("SELECT name FROM sqlite_master WHERE type='table';")
            tables = cursor.fetchall()
            
            if result.lower() == "ok" and len(tables) > 0:
                print(f"Database verified: {len(tables)} tables found")
                return True
            print("Database verification failed")
            return False
    except Exception as e:
        print(f"Database verification error: {e}")
        return False


def encrypt_database_to_memory(passphrase):
    """Encrypt database directly to a memory buffer."""
    try:
        # Create a secure temporary directory for GPG
        with tempfile.TemporaryDirectory(prefix='gpg_home_') as gpg_home:
            os.chmod(gpg_home, 0o700)
            
            encrypt_cmd = [
                "gpg",
                "--batch",
                "--yes",
                "--homedir", gpg_home,
                "--passphrase", passphrase,
                "--pinentry-mode", "loopback",
                "-c",
                "--cipher-algo", "AES256",
                "-o", "-",  # Output to stdout
                DB_FILE_PATH
            ]
            
            # Run GPG and capture output directly
            result = subprocess.run(
                encrypt_cmd,
                capture_output=True,
                check=True
            )
            
            if result.returncode != 0:
                print(f"GPG encryption failed: {result.stderr.decode()}")
                return None
                
            return result.stdout
    except subprocess.CalledProcessError as e:
        print(f"GPG process error: {e.stderr.decode()}")
        return None
    except Exception as e:
        print(f"Encryption error: {e}")
        return None


def get_last_backup_time(repo_id, hf_token):
    """Get timestamp of last backup from HuggingFace."""
    try:
        api = HfApi()
        files = api.list_repo_files(repo_id=repo_id, repo_type="space", token=hf_token)
        if REPO_TIMESTAMP_FILE not in files:
            return None
        
        tmp_file = hf_hub_download(
            repo_id=repo_id,
            repo_type="space",
            filename=REPO_TIMESTAMP_FILE,
            token=hf_token
        )
        with open(tmp_file, "r", encoding="utf-8") as f:
            stamp_str = f.read().strip()
        return datetime.datetime.fromisoformat(stamp_str)
    except Exception as e:
        print(f"Error getting last backup time: {e}")
        return None


def backup_db():
    """Main backup function using streaming approach."""
    # Validate environment
    passphrase = os.environ.get("BACKUP_PASSPHRASE")
    hf_token = os.environ.get("HF_TOKEN")
    space_id = os.environ.get("SPACE_ID")
    
    if not all([passphrase, hf_token, space_id]):
        print("Error: Missing required environment variables")
        return False

    # Check backup threshold
    threshold_minutes = int(os.environ.get("BACKUP_THRESHOLD_MINUTES", 120))
    if threshold_minutes > 0:
        last_backup_dt = get_last_backup_time(space_id, hf_token)
        if last_backup_dt is not None:
            now = datetime.datetime.now(datetime.timezone.utc)
            if not last_backup_dt.tzinfo:
                last_backup_dt = last_backup_dt.replace(tzinfo=datetime.timezone.utc)
            elapsed = now - last_backup_dt
            if elapsed.total_seconds() < threshold_minutes * 60:
                print(f"Last backup was {elapsed.total_seconds()/60:.1f} min ago (threshold: {threshold_minutes})")
                return True

    # Verify database before backup
    if not verify_database():
        return False

    # Encrypt database to memory
    print("Encrypting database...")
    encrypted_data = encrypt_database_to_memory(passphrase)
    if encrypted_data is None:
        return False
    print(f"Database encrypted successfully: {len(encrypted_data)} bytes")

    # Generate timestamp
    timestamp = datetime.datetime.now(datetime.timezone.utc).isoformat()
    timestamp_bytes = timestamp.encode('utf-8')

    # Upload both files to HuggingFace
    try:
        api = HfApi()
        api.upload_file(
            path_or_fileobj=BytesIO(encrypted_data),
            path_in_repo=REPO_DB_GPG_FILE,
            repo_id=space_id,
            repo_type="space",
            token=hf_token
        )
        api.upload_file(
            path_or_fileobj=BytesIO(timestamp_bytes),
            path_in_repo=REPO_TIMESTAMP_FILE,
            repo_id=space_id,
            repo_type="space",
            token=hf_token
        )
        print("Backup completed successfully!")
        return True
    except Exception as e:
        print(f"Error uploading to HuggingFace: {e}")
        return False


if __name__ == "__main__":
    success = backup_db()
    sys.exit(0 if success else 1)