package policies

import (
	"context"
	"fmt"

	acmapi "gitbucket.jerxie.com/yangyangxie/AnthosCertManager/pkg/apis/anthoscertmanager/v1"
	acmlisters "gitbucket.jerxie.com/yangyangxie/AnthosCertManager/pkg/client/listers/anthoscertmanager/v1"
	"gitbucket.jerxie.com/yangyangxie/AnthosCertManager/pkg/controller/certificates"
	logf "gitbucket.jerxie.com/yangyangxie/AnthosCertManager/pkg/logs"
	"gitbucket.jerxie.com/yangyangxie/AnthosCertManager/pkg/util/predicate"
	apierrors "k8s.io/apimachinery/pkg/api/errors"
	"k8s.io/apimachinery/pkg/labels"
	corelisters "k8s.io/client-go/listers/core/v1"
)

// Gatherer is used to gather data about a Certificate in order to evaluate
// its current readiness/state by applying policy functions to it.
type Gatherer struct {
	CertificateRequestLister acmlisters.CertificateRequestLister
	SecretLister             corelisters.SecretLister
}

// DataForCertificate returns the secret as well as the
// certificate request associated with the given certificate.
func (g *Gatherer) DataForCertificate(ctx context.Context, crt *acmapi.Certificate) (Input, error) {
	log := logf.FromContext(ctx)

	// attempts to fetch the secret being managed.
	secret, err := g.SecretLister.Secrets(crt.Namespace).Get(crt.Spec.SecretName)
	if err != nil && apierrors.IsNotFound(err) {
		return Input{}, err
	}

	// For the first time creation, the Status.Revision is nil, so we can skip the check.
	var curCr *acmapi.CertificateRequest
	if crt.Status.Revision != nil {
		reqs, err := certificates.ListCertificateRequestsMatchingPredicates(g.CertificateRequestLister.CertificateRequests(crt.Namespace),
			labels.Everything(),
			predicate.ResourceOwnedBy(crt),
			predicate.CertificateRequestRevision(*crt.Status.Revision))

		if err != nil {
			return Input{}, err
		}

		switch {
		case len(reqs) > 1:
			return Input{}, fmt.Errorf("multiple CertificateRequests were found for the 'current' revision %v, issuance is skipped until there are no more duplicates", *crt.Status.Revision)
		case len(reqs) == 1:
			curCr = reqs[0]
		case len(reqs) == 0:
			log.V(logf.DebugLevel).Info("Found no CertificateRequest resources owned by this Certificate for the current revision", "revision", *crt.Status.Revision)
		}
	}

	return Input{
		Certificate:            crt,
		Secret:                 secret,
		CurrentRevisionRequest: curCr,
	}, nil
}