CIA/e-voting-system/backend/init_blockchain.py

"""
Initialize blockchain with existing elections from database.

This module ensures that when the backend starts, all elections in the database
are recorded to the blockchain if they aren't already.
"""

from sqlalchemy.orm import Session
from . import models
from .blockchain_elections import elections_blockchain, record_election_to_blockchain
from datetime import datetime
import json


def initialize_elections_blockchain(db: Session) -> None:
    """
    Initialize the elections blockchain with all elections from database.

    Called on backend startup to ensure all elections are immutably recorded.
    Uses the elections_blockchain.blocks to check if an election is already recorded.

    Args:
        db: Database session
    """
    # Get all elections from database
    elections = db.query(models.Election).all()

    if not elections:
        print("No elections to record to blockchain")
        return

    # Check which elections are already on blockchain
    existing_election_ids = {block.election_id for block in elections_blockchain.blocks}

    # Record each election that isn't already on blockchain
    for election in elections:
        if election.id in existing_election_ids:
            print(f"Election {election.id} already on blockchain, skipping")
            continue

        try:
            # Get candidates for this election
            candidates = db.query(models.Candidate).filter(
                models.Candidate.election_id == election.id
            ).all()

            candidates_data = [
                {
                    "id": c.id,
                    "name": c.name,
                    "description": c.description or "",
                    "order": c.order or 0
                }
                for c in candidates
            ]

            # Record to blockchain
            record_election_to_blockchain(
                election_id=election.id,
                election_name=election.name,
                election_description=election.description or "",
                candidates=candidates_data,
                start_date=election.start_date.isoformat(),
                end_date=election.end_date.isoformat(),
                is_active=election.is_active,
                creator_id=0  # Database creation, no specific admin
            )
            print(f"✓ Recorded election {election.id} ({election.name}) to blockchain")
        except Exception as e:
            print(f"✗ Failed to record election {election.id} to blockchain: {e}")

    # Verify blockchain integrity
    if elections_blockchain.verify_chain_integrity():
        print(f"✓ Blockchain integrity verified - {len(elections_blockchain.blocks)} blocks")
    else:
        print("✗ Blockchain integrity check failed!")