package kvm

import (
	"encoding/xml"
	"fmt"
	"time"

	"gitea.home.hrajfrisbee.cz/kacerr/egress-proxies-operator/internal/provider"
)

// metadataURI namespaces the operator's element inside the domain's
// <metadata>. libvirt has no labels or tags, but it stores any namespaced XML
// there and hands it back through DomainGetMetadata, which is how the GC
// contract (managed flag + owning UID) and the creation time survive across
// operator restarts.
const metadataURI = "https://gitea.home.hrajfrisbee.cz/kacerr/egress-proxies-operator/kvm"

type instanceMetadata struct {
	XMLName   xml.Name `xml:"https://gitea.home.hrajfrisbee.cz/kacerr/egress-proxies-operator/kvm instance"`
	Managed   string   `xml:"managed"`
	UID       string   `xml:"uid"`
	CreatedAt string   `xml:"createdAt"`
}

func newInstanceMetadata(uid string, createdAt time.Time) instanceMetadata {
	return instanceMetadata{
		Managed:   provider.LabelManagedYes,
		UID:       uid,
		CreatedAt: createdAt.UTC().Format(time.RFC3339),
	}
}

// parseInstanceMetadata decodes the element as DomainGetMetadata returns it.
// libvirt selects the element by namespace URI but serialises it without the
// declaration (observed on libvirt 11.6: a bare <instance>), and other
// versions may keep a default or prefixed form. The URI is already checked
// by the lookup, so only the local name is matched here.
func parseInstanceMetadata(s string) (instanceMetadata, error) {
	var raw struct {
		XMLName xml.Name `xml:"instance"`
		instanceMetadata
	}
	if err := xml.Unmarshal([]byte(s), &raw); err != nil {
		return instanceMetadata{}, fmt.Errorf("parsing domain metadata: %w", err)
	}
	return raw.instanceMetadata, nil
}

func (m instanceMetadata) managed() bool {
	return m.Managed == provider.LabelManagedYes
}

// createdAt returns the zero time on a malformed timestamp: orphan GC treats
// zero as "old", so a corrupt value can never protect a domain forever.
func (m instanceMetadata) createdAt() time.Time {
	t, err := time.Parse(time.RFC3339, m.CreatedAt)
	if err != nil {
		return time.Time{}
	}
	return t
}