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

"""
Service de base de données - Opérations CRUD.
"""

from sqlalchemy.orm import Session
from sqlalchemy import func
from . import models, schemas
from .auth import hash_password, verify_password
from datetime import datetime
from .blockchain_elections import record_election_to_blockchain


class VoterService:
    """Service pour gérer les électeurs"""
    
    @staticmethod
    def create_voter(db: Session, voter: schemas.VoterRegister) -> models.Voter:
        """Créer un nouvel électeur"""
        db_voter = models.Voter(
            email=voter.email,
            first_name=voter.first_name,
            last_name=voter.last_name,
            citizen_id=voter.citizen_id,
            password_hash=hash_password(voter.password)
        )
        db.add(db_voter)
        db.commit()
        db.refresh(db_voter)
        return db_voter
    
    @staticmethod
    def get_voter_by_email(db: Session, email: str) -> models.Voter:
        """Récupérer un électeur par email"""
        return db.query(models.Voter).filter(
            models.Voter.email == email
        ).first()
    
    @staticmethod
    def verify_voter_credentials(
        db: Session,
        email: str,
        password: str
    ) -> models.Voter:
        """Vérifier les identifiants et retourner l'électeur"""
        voter = VoterService.get_voter_by_email(db, email)
        if not voter:
            return None
        if not verify_password(password, voter.password_hash):
            return None
        return voter
    
    @staticmethod
    def mark_as_voted(db: Session, voter_id: int) -> None:
        """Marquer l'électeur comme ayant voté"""
        voter = db.query(models.Voter).filter(
            models.Voter.id == voter_id
        ).first()
        if voter:
            voter.has_voted = True
            voter.updated_at = datetime.utcnow()
            db.commit()


class ElectionService:
    """Service pour gérer les élections"""

    @staticmethod
    def create_election(
        db: Session,
        name: str,
        description: str,
        start_date: datetime,
        end_date: datetime,
        elgamal_p: int = None,
        elgamal_g: int = None,
        is_active: bool = True,
        creator_id: int = 0
    ) -> models.Election:
        """
        Créer une nouvelle élection et l'enregistrer sur la blockchain.

        Args:
            db: Database session
            name: Election name
            description: Election description
            start_date: Election start date
            end_date: Election end date
            elgamal_p: ElGamal prime (optional)
            elgamal_g: ElGamal generator (optional)
            is_active: Whether election is active
            creator_id: ID of admin creating this election

        Returns:
            The created Election model
        """
        # Create election in database
        db_election = models.Election(
            name=name,
            description=description,
            start_date=start_date,
            end_date=end_date,
            elgamal_p=elgamal_p,
            elgamal_g=elgamal_g,
            is_active=is_active
        )
        db.add(db_election)
        db.commit()
        db.refresh(db_election)

        # Record to blockchain immediately after creation
        try:
            # Get candidates for this election to include in blockchain record
            candidates = db.query(models.Candidate).filter(
                models.Candidate.election_id == db_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 election to blockchain
            record_election_to_blockchain(
                election_id=db_election.id,
                election_name=name,
                election_description=description,
                candidates=candidates_data,
                start_date=start_date.isoformat(),
                end_date=end_date.isoformat(),
                is_active=is_active,
                creator_id=creator_id
            )
        except Exception as e:
            # Log error but don't fail election creation
            print(f"Warning: Could not record election {db_election.id} to blockchain: {e}")

        return db_election

    @staticmethod
    def get_active_election(db: Session) -> models.Election:
        """Récupérer l'élection active"""
        now = datetime.utcnow()
        return db.query(models.Election).filter(
            models.Election.is_active == True,
            models.Election.start_date <= now,
            models.Election.end_date > now
        ).first()

    @staticmethod
    def get_election(db: Session, election_id: int) -> models.Election:
        """Récupérer une élection par ID"""
        return db.query(models.Election).filter(
            models.Election.id == election_id
        ).first()


class VoteService:
    """Service pour gérer les votes"""
    
    @staticmethod
    def record_vote(
        db: Session,
        voter_id: int,
        election_id: int,
        candidate_id: int,
        encrypted_vote: bytes,
        ballot_hash: str,
        ip_address: str = None
    ) -> models.Vote:
        """Enregistrer un vote chiffré"""
        db_vote = models.Vote(
            voter_id=voter_id,
            election_id=election_id,
            candidate_id=candidate_id,
            encrypted_vote=encrypted_vote,
            ballot_hash=ballot_hash,
            ip_address=ip_address,
            timestamp=datetime.utcnow()
        )
        db.add(db_vote)
        db.commit()
        db.refresh(db_vote)
        return db_vote
    
    @staticmethod
    def has_voter_voted(
        db: Session,
        voter_id: int,
        election_id: int
    ) -> bool:
        """Vérifier si l'électeur a déjà voté"""
        vote = db.query(models.Vote).filter(
            models.Vote.voter_id == voter_id,
            models.Vote.election_id == election_id
        ).first()
        return vote is not None
    
    @staticmethod
    def get_election_results(
        db: Session,
        election_id: int
    ) -> list[schemas.ResultResponse]:
        """Calculer les résultats d'une élection"""
        results = db.query(
            models.Candidate.name,
            func.count(models.Vote.id).label("vote_count")
        ).join(
            models.Vote,
            models.Candidate.id == models.Vote.candidate_id
        ).filter(
            models.Vote.election_id == election_id
        ).group_by(
            models.Candidate.id,
            models.Candidate.name
        ).all()
        
        total_votes = sum(r.vote_count for r in results)
        
        return [
            schemas.ResultResponse(
                candidate_name=r.name,
                vote_count=r.vote_count,
                percentage=(r.vote_count / total_votes * 100) if total_votes > 0 else 0
            )
            for r in results
        ]