"""
Subscription model - Tracks therapist billing and student limits
"""
from sqlalchemy import Column, Integer, String, Float, DateTime, ForeignKey, Boolean, Enum
from sqlalchemy.orm import relationship
from sqlalchemy.sql import func
from config.database import Base
import enum

class PlanType(enum.Enum):
    FREE = "free"
    BASIC = "basic"         # e.g., $29/month - up to 5 students
    PROFESSIONAL = "professional"  # e.g., $79/month - up to 20 students  
    ENTERPRISE = "enterprise"      # Custom pricing - unlimited students

class BillingPeriod(enum.Enum):
    MONTHLY = "monthly"
    YEARLY = "yearly"

class Subscription(Base):
    __tablename__ = "subscriptions"
    
    id = Column(Integer, primary_key=True, index=True)
    therapist_id = Column(Integer, ForeignKey("therapists.id"), unique=True, nullable=False)
    
    # Plan details
    plan_type = Column(Enum(PlanType), nullable=False, default=PlanType.FREE)
    billing_period = Column(Enum(BillingPeriod), nullable=True)
    
    # Pricing
    base_price = Column(Float, default=0.0)  # Base monthly price
    per_student_price = Column(Float, default=0.0)  # Additional cost per student over limit
    
    # Limits
    included_students = Column(Integer, default=1)  # Students included in base price
    max_students = Column(Integer, nullable=True)  # Hard limit (null = unlimited)
    current_student_count = Column(Integer, default=0)  # Active students
    
    # Billing
    stripe_customer_id = Column(String, nullable=True)
    stripe_subscription_id = Column(String, nullable=True)
    
    # Status
    is_active = Column(Boolean, default=True)
    trial_ends_at = Column(DateTime(timezone=True), nullable=True)
    current_period_start = Column(DateTime(timezone=True), nullable=True)
    current_period_end = Column(DateTime(timezone=True), nullable=True)
    
    # Timestamps
    created_at = Column(DateTime(timezone=True), server_default=func.now())
    updated_at = Column(DateTime(timezone=True), onupdate=func.now())
    canceled_at = Column(DateTime(timezone=True), nullable=True)
    
    # Relationships
    therapist = relationship("Therapist", backref="subscription")
    
    def calculate_monthly_cost(self):
        """Calculate total monthly cost based on current student count"""
        base = self.base_price
        
        # If yearly billing, calculate monthly equivalent
        if self.billing_period == BillingPeriod.YEARLY:
            base = base / 12
            
        # Calculate overage if exceeding included students
        if self.current_student_count > self.included_students:
            overage = self.current_student_count - self.included_students
            additional = overage * self.per_student_price
            return base + additional
            
        return base
    
    def can_add_student(self):
        """Check if therapist can add another student"""
        if self.max_students is None:
            return True
        return self.current_student_count < self.max_students
    
    def __repr__(self):
        return f"<Subscription {self.plan_type.value} for therapist {self.therapist_id}>"