package controller

import (
	"context"
	"fmt"
	"strings"

	appsv1 "k8s.io/api/apps/v1"
	corev1 "k8s.io/api/core/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/util/intstr"
	"sigs.k8s.io/controller-runtime/pkg/client"
	"sigs.k8s.io/controller-runtime/pkg/controller/controllerutil"

	terdutv1alpha1 "git.ryuvia.com/niklas/terdut-operator/api/v1alpha1"
)

// labelsFor returns the selector labels for srv's Deployment/Service —
// fixed once a Deployment exists (its selector is immutable), so this must
// never depend on anything in srv.Spec that could change later.
func labelsFor(srv *terdutv1alpha1.TerdutServer) map[string]string {
	return map[string]string{
		"app.kubernetes.io/name":     "terdut-server",
		"app.kubernetes.io/instance": srv.Name,
	}
}

// reconcileDeployment creates or updates the Deployment running
// terdut-server, owned by srv (DESIGN.md §7: same-namespace generated
// objects carry a plain OwnerReference, no finalizer). Returns the live
// object (not just the desired one) so the caller can check
// status.readyReplicas.
func (r *TerdutServerReconciler) reconcileDeployment(
	ctx context.Context, srv *terdutv1alpha1.TerdutServer, dbEnv []corev1.EnvVar,
) (*appsv1.Deployment, error) {
	deploy := &appsv1.Deployment{ObjectMeta: metav1.ObjectMeta{Name: srv.Name, Namespace: srv.Namespace}}
	_, err := controllerutil.CreateOrUpdate(ctx, r.Client, deploy, func() error {
		replicas := srv.Spec.Replicas
		if replicas == 0 {
			replicas = 1
		}
		labels := labelsFor(srv)

		deploy.Spec.Replicas = &replicas
		deploy.Spec.Selector = &metav1.LabelSelector{MatchLabels: labels}
		// Recreate, not RollingUpdate: the sweeper and the notifier are
		// unsynchronised singletons inside terdut-server, and two replicas
		// overlapping during a rollout would both page for the same
		// incident (matches the chart's own deployment.yaml comment).
		deploy.Spec.Strategy = appsv1.DeploymentStrategy{Type: appsv1.RecreateDeploymentStrategyType}
		pod := srv.Spec.Pod
		deploy.Spec.Template = corev1.PodTemplateSpec{
			// pod.Annotations is assigned directly, not merged -- nothing
			// else sets pod-template annotations today. If a future change
			// needs the controller to set one of its own (e.g. a
			// Prometheus-scrape annotation), this needs to become a real
			// map merge with a stated precedence rather than silently
			// clobbering one side.
			ObjectMeta: metav1.ObjectMeta{Labels: labels, Annotations: pod.Annotations},
			Spec: corev1.PodSpec{
				EnableServiceLinks:        new(false),
				NodeSelector:              pod.NodeSelector,
				Tolerations:               pod.Tolerations,
				Affinity:                  pod.Affinity,
				TopologySpreadConstraints: pod.TopologySpreadConstraints,
				SecurityContext:           pod.SecurityContext,
				ServiceAccountName:        pod.ServiceAccountName,
				ImagePullSecrets:          pod.ImagePullSecrets,
				InitContainers:            []corev1.Container{waitForPostgresContainer(dbEnv)},
				Volumes:                   pod.ExtraVolumes,
				Containers: []corev1.Container{{
					Name:  "terdut-server",
					Image: fmt.Sprintf("%s:%s", srv.Spec.Image.Repository, srv.Spec.Image.Tag),
					Ports: []corev1.ContainerPort{{
						Name:          "http",
						ContainerPort: servicePort(srv),
						Protocol:      corev1.ProtocolTCP,
					}},
					Env:             buildEnv(srv, dbEnv),
					EnvFrom:         pod.ExtraEnvFrom,
					VolumeMounts:    pod.ExtraVolumeMounts,
					Resources:       pod.Resources,
					SecurityContext: pod.ContainerSecurityContext,
					LivenessProbe:   healthzProbe(),
					ReadinessProbe:  healthzProbe(),
				}},
			},
		}
		return controllerutil.SetControllerReference(srv, deploy, r.Scheme)
	})
	if err != nil {
		return nil, err
	}
	// CreateOrUpdate's own object is desired-state-only on a fresh create
	// (no .status yet); re-fetch so the ready-replica check the caller does
	// next sees the real, live object.
	if err := r.Get(ctx, client.ObjectKeyFromObject(deploy), deploy); err != nil {
		return nil, err
	}
	return deploy, nil
}

// reconcileService creates or updates the ClusterIP Service in front of the
// Deployment, owned by srv.
func (r *TerdutServerReconciler) reconcileService(ctx context.Context, srv *terdutv1alpha1.TerdutServer) error {
	svc := &corev1.Service{ObjectMeta: metav1.ObjectMeta{Name: srv.Name, Namespace: srv.Namespace}}
	_, err := controllerutil.CreateOrUpdate(ctx, r.Client, svc, func() error {
		svc.Spec.Selector = labelsFor(srv)
		svc.Spec.Ports = []corev1.ServicePort{{
			Name:       "http",
			Port:       servicePort(srv),
			TargetPort: intstr.FromString("http"),
			Protocol:   corev1.ProtocolTCP,
		}}
		return controllerutil.SetControllerReference(srv, svc, r.Scheme)
	})
	return err
}

func servicePort(srv *terdutv1alpha1.TerdutServer) int32 {
	if srv.Spec.Networking.ServicePort == 0 {
		return 8080
	}
	return srv.Spec.Networking.ServicePort
}

// waitForPostgresContainer blocks the main container from starting until
// Postgres accepts connections, matching charts/terdut-server's own
// deployment.yaml template as of v0.33.2 (that repo's CLAUDE.md/release
// notes) -- that chart grew this the moment this exact Deployment, created
// by this controller, crash-looped a few times against a from-scratch
// postgres-operator cluster still doing initdb and Patroni leader election:
// terdut-server's own ping-retry budget on startup (internal/db/db.go) is
// sized for a much shorter, different race (NetworkPolicy propagation, a
// few seconds), not for genuine first-time cluster creation, so it
// exhausted and the process exited before ever binding its HTTP port -- a
// startupProbe cannot help there, since the crash happens before there is
// anything to probe.
//
// Reuses dbEnv unchanged: both of resolveDatabaseEnv's paths put
// TERDUT_DB_DSN first (terdutserver_database.go), so it's already exactly
// what pg_isready needs, and pg_isready needs no credentials -- it reports
// PQPING_OK on anything that amounts to a Postgres backend answering,
// including an auth challenge -- so including dbEnv's optional PGPASSWORD
// here too is harmless rather than load-bearing.
func waitForPostgresContainer(dbEnv []corev1.EnvVar) corev1.Container {
	return corev1.Container{
		Name:  "wait-for-postgres",
		Image: "postgres:17-alpine",
		Env:   dbEnv,
		Command: []string{"sh", "-c",
			`until pg_isready -d "$TERDUT_DB_DSN"; do echo "wait-for-postgres: not ready yet, retrying in 2s"; sleep 2; done`,
		},
	}
}

func healthzProbe() *corev1.Probe {
	return &corev1.Probe{
		ProbeHandler: corev1.ProbeHandler{
			HTTPGet: &corev1.HTTPGetAction{
				Path: "/healthz",
				Port: intstr.FromString("http"),
			},
		},
		InitialDelaySeconds: 5,
	}
}

// buildEnv mirrors charts/terdut-server's own deployment.yaml env block
// field-for-field (confirmed against that source, not reconstructed from
// DESIGN.md's illustrative YAML alone) — dbEnv (TERDUT_DB_DSN, optionally
// PGPASSWORD) comes from resolveDatabaseEnv, since which of §8's two paths
// produced it doesn't matter past this point. spec.pod.extraEnv is appended
// last, after every fixed var -- this is the one place that owns "what env
// this container gets," so the escape hatch lives here rather than being
// appended separately in reconcileDeployment.
func buildEnv(srv *terdutv1alpha1.TerdutServer, dbEnv []corev1.EnvVar) []corev1.EnvVar {
	env := []corev1.EnvVar{{Name: "TERDUT_ADDR", Value: fmt.Sprintf(":%d", servicePort(srv))}}
	env = append(env, dbEnv...)

	sweeper := srv.Spec.Sweeper
	env = append(env,
		corev1.EnvVar{Name: "TERDUT_STALE_AFTER", Value: sweeper.StaleAfter},
		corev1.EnvVar{Name: "TERDUT_ARCHIVE_AFTER", Value: sweeper.ArchiveAfter},
	)

	deadman := srv.Spec.Deadman
	env = append(env,
		corev1.EnvVar{Name: "TERDUT_DEADMAN_MATCHERS", Value: deadman.Matchers},
		corev1.EnvVar{Name: "TERDUT_DEADMAN_TIMEOUT", Value: deadman.Timeout},
		corev1.EnvVar{Name: "TERDUT_DEADMAN_SEVERITY", Value: deadman.Severity},
	)

	notify := srv.Spec.Notify
	if notify.NtfyURL != "" {
		env = append(env,
			corev1.EnvVar{Name: "TERDUT_NTFY_URL", Value: notify.NtfyURL},
			corev1.EnvVar{Name: "TERDUT_NTFY_FALLBACK_TOPIC", Value: notify.FallbackTopic},
			corev1.EnvVar{Name: "TERDUT_NOTIFY_REPEAT", Value: notify.RepeatEvery},
		)
		if notify.TokenSecretRef != nil {
			env = append(env, corev1.EnvVar{
				Name:      "TERDUT_NTFY_TOKEN",
				ValueFrom: secretEnvSource(notify.TokenSecretRef),
			})
		}
	}

	publicURL := fmt.Sprintf("https://%s", srv.Spec.Networking.Hostname)
	env = append(env,
		corev1.EnvVar{Name: "TERDUT_PUBLIC_URL", Value: publicURL},
		corev1.EnvVar{Name: "TERDUT_PASSWORD_LOGIN", Value: boolString(srv.Spec.PasswordLogin)},
		// Always on, unlike the chart's own default-off operatorMode: every
		// write this operator's own TerdutTeam/EscalationRule/etc.
		// controllers make goes through a service account already, and the
		// whole reason to run this operator is gitops-managed config, not a
		// human editing an operator-managed install's teams/policies by
		// hand (chart's values.yaml comment: "a statement that something
		// like terdut-operator... owns this install's configuration from
		// here on" -- which is unconditionally true for anything this
		// operator creates).
		corev1.EnvVar{Name: "TERDUT_OPERATOR_MODE", Value: "true"},
	)

	if oidc := srv.Spec.OIDC; oidc.Enabled {
		env = append(env,
			corev1.EnvVar{Name: "TERDUT_OIDC_ISSUER", Value: oidc.Issuer},
			corev1.EnvVar{Name: "TERDUT_OIDC_CLIENT_ID", Value: oidc.ClientID},
			corev1.EnvVar{Name: "TERDUT_OIDC_NAME", Value: oidc.Name},
			corev1.EnvVar{Name: "TERDUT_OIDC_SCOPES", Value: oidc.Scopes},
			// terdut-server's own defaults for the claims/trust-email knobs
			// the chart exposes but DESIGN.md's spec doesn't (§4.1's doc
			// comment on OIDCSpec) -- not configurable here, not an
			// oversight.
			corev1.EnvVar{Name: "TERDUT_OIDC_USERNAME_CLAIM", Value: "preferred_username"},
			corev1.EnvVar{Name: "TERDUT_OIDC_EMAIL_CLAIM", Value: "email"},
			corev1.EnvVar{Name: "TERDUT_OIDC_GROUPS_CLAIM", Value: "groups"},
			corev1.EnvVar{Name: "TERDUT_OIDC_TRUST_EMAIL", Value: "false"},
			corev1.EnvVar{Name: "TERDUT_OIDC_SESSION_MAX_AGE", Value: oidc.SessionMaxAge},
		)
		if oidc.ClientSecretRef != nil {
			env = append(env, corev1.EnvVar{
				Name:      "TERDUT_OIDC_CLIENT_SECRET",
				ValueFrom: secretEnvSource(oidc.ClientSecretRef),
			})
		}
		if len(oidc.AllowedGroups) > 0 {
			env = append(env, corev1.EnvVar{Name: "TERDUT_OIDC_ALLOWED_GROUPS", Value: strings.Join(oidc.AllowedGroups, ",")})
		}
		if oidc.AdminGroup != "" {
			env = append(env, corev1.EnvVar{Name: "TERDUT_OIDC_ADMIN_GROUP", Value: oidc.AdminGroup})
		}
	}

	return append(env, srv.Spec.Pod.ExtraEnv...)
}

func secretEnvSource(ref *terdutv1alpha1.SecretKeyRef) *corev1.EnvVarSource {
	return &corev1.EnvVarSource{
		SecretKeyRef: &corev1.SecretKeySelector{
			LocalObjectReference: corev1.LocalObjectReference{Name: ref.Name},
			Key:                  ref.Key,
		},
	}
}

func boolString(b bool) string {
	if b {
		return "true"
	}
	return "false"
}