package controller

import (
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"

	crawlv1alpha1 "gitea.home.hrajfrisbee.cz/kacerr/egress-proxies-operator/api/v1alpha1"
)

// specHashInput is the explicit set of fields whose change requires
// replacing the instance. Deliberately not ProxySpec wholesale: adding a
// spec field that doesn't affect the VM (attributes, maxLeases, healthCheck)
// must not churn the fleet on operator upgrade.
type specHashInput struct {
	Placement *crawlv1alpha1.PlacementSpec `json:"placement,omitempty"`
	CloudInit string                       `json:"cloudInit,omitempty"`
	Port      int32                        `json:"port"`
}

// specHash returns the hex SHA-256 of the replacement-triggering spec
// fields. cloudInit is the already-resolved content, so rotating a
// referenced Secret changes the hash even though the spec is untouched.
func specHash(p *crawlv1alpha1.Proxy, cloudInit string) string {
	in := specHashInput{
		Placement: p.Spec.Placement,
		CloudInit: cloudInit,
		Port:      p.EffectivePort(),
	}
	// nil and empty placement mean the same thing; hash them identically.
	if in.Placement != nil && *in.Placement == (crawlv1alpha1.PlacementSpec{}) {
		in.Placement = nil
	}
	b, err := json.Marshal(in)
	if err != nil {
		// A struct of strings and an int32 cannot fail to marshal.
		panic(err)
	}
	sum := sha256.Sum256(b)
	return hex.EncodeToString(sum[:])
}