package checkout

import (
	"encoding/json"
	"fmt"

	messages "git.k6n.net/go-cart-actor/proto/checkout"
)

// mutation_initialize_checkout.go
//
// Registers the InitializeCheckout mutation.
// This mutation is invoked AFTER an external checkout session
// has been successfully created or updated. It persists the
// order reference / status and marks the checkout as having a payment in progress.
//
// Behavior:
//   - Sets OrderId to the order ID.
//   - Sets Status to the current status.
//   - Sets PaymentInProgress flag.
//   - Assumes inventory is already reserved.
//
// Validation:
//   - Returns an error if payload is nil.
//   - Returns an error if orderId is empty.

func HandleInitializeCheckout(g *CheckoutGrain, m *messages.InitializeCheckout) error {
	if m == nil {
		return fmt.Errorf("InitializeCheckout: nil payload")
	}
	if m.OrderId == "" {
		return fmt.Errorf("InitializeCheckout: missing orderId")
	}
	if m.CartState != nil {
		return fmt.Errorf("InitializeCheckout: checkout already initialized")
	}

	err := json.Unmarshal(m.CartState.Value, &g.CartState)
	if err != nil {
		return fmt.Errorf("InitializeCheckout: failed to unmarshal cart state: %w", err)
	}

	return nil
}