# Copyright (c) 2025 Patrick Motsch
# All rights reserved.
"""
Stripe Checkout service for billing credit top-ups.
Creates Checkout Sessions for redirect-based payment flow.
"""

import logging
from typing import Optional

from modules.shared.configuration import APP_CONFIG

logger = logging.getLogger(__name__)

# Server-side allowed amounts in CHF - never trust client
ALLOWED_AMOUNTS_CHF = [10, 25, 50, 100, 250, 500]


def create_checkout_session(
    mandate_id: str,
    user_id: Optional[str],
    amount_chf: float
) -> str:
    """
    Create a Stripe Checkout Session for credit top-up.
    
    Amount and currency are validated server-side. The client-provided amount
    must match an allowed preset.
    
    Args:
        mandate_id: Target mandate ID
        user_id: Target user ID (for PREPAY_USER) or None (for mandate pool)
        amount_chf: Amount in CHF (must be in ALLOWED_AMOUNTS_CHF)
        
    Returns:
        Stripe Checkout Session URL for redirect
        
    Raises:
        ValueError: If amount is invalid
    """
    import stripe
    
    # Validate amount server-side
    if amount_chf not in ALLOWED_AMOUNTS_CHF:
        raise ValueError(
            f"Invalid amount {amount_chf} CHF. Allowed: {ALLOWED_AMOUNTS_CHF}"
        )
    
    # Pin API version from config (match Stripe Dashboard)
    api_version = APP_CONFIG.get("STRIPE_API_VERSION")
    if api_version:
        stripe.api_version = api_version
    
    # Get secrets
    secret_key = APP_CONFIG.get("STRIPE_SECRET_KEY_SECRET") or APP_CONFIG.get("STRIPE_SECRET_KEY")
    if not secret_key:
        raise ValueError("STRIPE_SECRET_KEY_SECRET not configured")
    
    stripe.api_key = secret_key
    
    frontend_url = APP_CONFIG.get("APP_FRONTEND_URL", "https://nyla-int.poweron-center.net")
    base_path = "/admin/billing"
    success_url = f"{frontend_url.rstrip('/')}{base_path}?success=true&session_id={{CHECKOUT_SESSION_ID}}"
    cancel_url = f"{frontend_url.rstrip('/')}{base_path}?canceled=true"
    
    # Amount in cents for Stripe (CHF uses 2 decimal places)
    amount_cents = int(round(amount_chf * 100))
    
    metadata = {
        "mandateId": mandate_id,
        "amountChf": str(amount_chf),
    }
    if user_id:
        metadata["userId"] = user_id
    
    session = stripe.checkout.Session.create(
        mode="payment",
        line_items=[
            {
                "price_data": {
                    "currency": "chf",
                    "unit_amount": amount_cents,
                    "product_data": {
                        "name": "Guthaben aufladen",
                        "description": "AI Service Guthaben (CHF)",
                    },
                },
                "quantity": 1,
            }
        ],
        success_url=success_url,
        cancel_url=cancel_url,
        metadata=metadata,
    )
    
    if not session or not session.url:
        raise ValueError("Stripe Checkout Session creation failed")
    
    logger.info(
        f"Created Stripe Checkout Session {session.id} for mandate {mandate_id}, "
        f"amount {amount_chf} CHF"
    )
    
    return session.url