package appconfig

import (
	"context"
	"crypto/ecdh"

	"github.com/carlosframework/platform/internal/instancekey"
	"github.com/carlosframework/platform/internal/registry"
	"github.com/carlosframework/platform/internal/release"
)

// ConfiguredKeyDigest is the SHA-256 of the CARLOS_INSTANCE_KEY rt's
// configuration in the bucket renders now, "" when it renders none: the
// same merge and renderer SyncExec writes <host>.config.env with
// (LoadMergedHostVersions, RenderEnv), read fresh rather than from the
// box's last sync. A replica launch whose configured key is not this
// digest is refused (instance-key plan ruling 27): a configuration change
// is in flight, and the home may already hold the new key. The value
// never leaves this function.
func ConfiguredKeyDigest(ctx context.Context, s release.Store, priv *ecdh.PrivateKey, rt registry.Route) (string, error) {
	m, _, err := LoadMergedHostVersions(ctx, s, release.RouteAccount(rt), rt.App, rt.Environment, rt.Host)
	if err != nil || m == nil {
		return "", err
	}
	rendered, err := RenderEnv(m, priv, routeBinding(rt))
	if err != nil {
		return "", err
	}
	key, _ := instancekey.Effective(instancekey.ParseEnv(rendered), nil)
	if key == "" {
		return "", nil
	}
	return instancekey.Digest(key), nil
}