from app import db
from datetime import datetime, timedelta
from enum import Enum

class ReservationStatus(Enum):
    PENDING = 'PENDING'
    CONFIRMED = 'CONFIRMED'
    CANCELLED = 'CANCELLED'
    COMPLETED = 'COMPLETED'
    NO_SHOW = 'NO_SHOW'

class Reservation(db.Model):
    __tablename__ = 'reservations'
    
    id = db.Column(db.Integer, primary_key=True)
    classroom_id = db.Column(db.Integer, db.ForeignKey('classrooms.id'), nullable=False)
    commission_id = db.Column(db.Integer, db.ForeignKey('commissions.id'), nullable=False)
    user_id = db.Column(db.Integer, db.ForeignKey('users.id'), nullable=False)
    
    start_time = db.Column(db.DateTime, nullable=False)
    end_time = db.Column(db.DateTime, nullable=False)
    purpose = db.Column(db.String(500), nullable=False)
    status = db.Column(db.Enum(ReservationStatus), default=ReservationStatus.PENDING, nullable=False)
    expected_attendees = db.Column(db.Integer, nullable=False)
    notes = db.Column(db.Text)
    
    created_at = db.Column(db.DateTime, default=datetime.utcnow)
    updated_at = db.Column(db.DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
    
# Relationships
    classroom = db.relationship('Classroom', backref=db.backref('reservation_list', lazy=True, cascade='all, delete-orphan'))
    commission = db.relationship('Commission', backref=db.backref('reservation_list', lazy=True, cascade='all, delete-orphan'))
    # User already defines the relationship back to reservation
    
    def to_dict(self):
        """Convert reservation to dictionary"""
        return {
            'id': self.id,
            'classroom_id': self.classroom_id,
            'commission_id': self.commission_id,
            'user_id': self.user_id,
            'start_time': self.start_time.isoformat() if self.start_time else None,
            'end_time': self.end_time.isoformat() if self.end_time else None,
            'purpose': self.purpose,
            'status': self.status.value if self.status else None,
            'expected_attendees': self.expected_attendees,
            'notes': self.notes,
            'created_at': self.created_at.isoformat() if self.created_at else None,
            'updated_at': self.updated_at.isoformat() if self.updated_at else None,
            'classroom': self.classroom.to_dict() if self.classroom else None,
            'commission': self.commission.to_dict() if self.commission else None,
            'user': self.user.to_dict() if self.user else None
        }
    
    def is_confirmed(self):
        """Check if reservation is confirmed"""
        return self.status == ReservationStatus.CONFIRMED
    
    def can_be_cancelled(self):
        """Check if reservation can be cancelled (24 hours before start)"""
        from datetime import timedelta
        return self.start_time > datetime.utcnow() + timedelta(hours=24)
    
    def check_conflict(self, other_reservation):
        """Check if this reservation conflicts with another"""
        if self.classroom_id != other_reservation.classroom_id:
            return False
        if self.status != ReservationStatus.CONFIRMED:
            return False
        if other_reservation.status != ReservationStatus.CONFIRMED:
            return False
        
        # Check time overlap
        return (self.start_time < other_reservation.end_time and 
                self.end_time > other_reservation.start_time)
    
    @staticmethod
    def find_conflicts(classroom_id, start_time, end_time, exclude_reservation_id=None):
        """Find conflicting reservations for a specific classroom and time slot"""
        query = Reservation.query.filter(
            Reservation.classroom_id == classroom_id,
            Reservation.status == ReservationStatus.CONFIRMED,
            Reservation.start_time < end_time,
            Reservation.end_time > start_time
        )
        
        if exclude_reservation_id:
            query = query.filter(Reservation.id != exclude_reservation_id)
        
        return query.all()
    
    def __repr__(self):
        return f'<Reservation {self.id}>'