// Copyright (c) 2023 Gitpod GmbH. All rights reserved.
// Licensed under the GNU Affero General Public License (AGPL).
// See License.AGPL.txt in the project root for license information.

package controllers

import (
	"context"
	"fmt"
	"strings"
	"time"

	wsk8s "github.com/gitpod-io/gitpod/common-go/kubernetes"
	"github.com/gitpod-io/gitpod/ws-manager-mk2/pkg/activity"
	"github.com/gitpod-io/gitpod/ws-manager-mk2/pkg/maintenance"
	workspacev1 "github.com/gitpod-io/gitpod/ws-manager/api/crd/v1"
	"github.com/go-logr/logr"
	lru "github.com/hashicorp/golang-lru"
	"github.com/prometheus/client_golang/prometheus"
	corev1 "k8s.io/api/core/v1"
	"sigs.k8s.io/controller-runtime/pkg/client"
	"sigs.k8s.io/controller-runtime/pkg/log"
)

const (
	maintenanceEnabled            string = "maintenance_enabled"
	workspaceStartupSeconds       string = "workspace_startup_seconds"
	workspacePendingSeconds       string = "workspace_pending_seconds"
	workspaceCreatingSeconds      string = "workspace_creating_seconds"
	workspaceStartFailuresTotal   string = "workspace_starts_failure_total"
	workspaceFailuresTotal        string = "workspace_failure_total"
	workspaceStopsTotal           string = "workspace_stops_total"
	workspaceRecreationsTotal     string = "workspace_recreations_total"
	workspaceBackupsTotal         string = "workspace_backups_total"
	workspaceBackupFailuresTotal  string = "workspace_backups_failure_total"
	workspaceRestoresTotal        string = "workspace_restores_total"
	workspaceRestoresFailureTotal string = "workspace_restores_failure_total"
	workspaceNodeUtilization      string = "workspace_node_utilization"
	workspaceActivityTotal        string = "workspace_activity_total"
)

type StopReason string

const (
	StopReasonFailed       = "failed"
	StopReasonStartFailure = "start-failure"
	StopReasonAborted      = "aborted"
	StopReasonOutOfSpace   = "out-of-space"
	StopReasonTimeout      = "timeout"
	StopReasonTabClosed    = "tab-closed"
	StopReasonRegular      = "regular-stop"
)

type controllerMetrics struct {
	startupTimeHistVec           *prometheus.HistogramVec
	pendingTimeHistVec           *prometheus.HistogramVec
	creatingTimeHistVec          *prometheus.HistogramVec
	totalStartsFailureCounterVec *prometheus.CounterVec
	totalFailuresCounterVec      *prometheus.CounterVec
	totalStopsCounterVec         *prometheus.CounterVec
	totalRecreationsCounterVec   *prometheus.CounterVec

	totalBackupCounterVec         *prometheus.CounterVec
	totalBackupFailureCounterVec  *prometheus.CounterVec
	totalRestoreCounterVec        *prometheus.CounterVec
	totalRestoreFailureCounterVec *prometheus.CounterVec

	workspacePhases *phaseTotalVec
	timeoutSettings *timeoutSettingsVec

	workspaceNodeUtilization *nodeUtilizationVec

	workspaceActivityTotal *workspaceActivityVec

	// used to prevent recording metrics multiple times
	cache *lru.Cache
}

func newControllerMetrics(r *WorkspaceReconciler) (*controllerMetrics, error) {
	cache, err := lru.New(6000)
	if err != nil {
		return nil, err
	}

	return &controllerMetrics{
		startupTimeHistVec: prometheus.NewHistogramVec(prometheus.HistogramOpts{
			Namespace: metricsNamespace,
			Subsystem: metricsWorkspaceSubsystem,
			Name:      workspaceStartupSeconds,
			Help:      "time it took for workspace pods to reach the running phase",
			Buckets:   prometheus.ExponentialBuckets(2, 2, 10),
		}, []string{"type", "class"}),
		pendingTimeHistVec: prometheus.NewHistogramVec(prometheus.HistogramOpts{
			Namespace: metricsNamespace,
			Subsystem: metricsWorkspaceSubsystem,
			Name:      workspacePendingSeconds,
			Help:      "time the workspace spent in pending",
			Buckets:   prometheus.ExponentialBuckets(2, 2, 10),
		}, []string{"type", "class"}),
		creatingTimeHistVec: prometheus.NewHistogramVec(prometheus.HistogramOpts{
			Namespace: metricsNamespace,
			Subsystem: metricsWorkspaceSubsystem,
			Name:      workspaceCreatingSeconds,
			Help:      "time the workspace spent in creation",
			Buckets:   prometheus.ExponentialBuckets(2, 2, 10),
		}, []string{"type", "class"}),
		totalStartsFailureCounterVec: prometheus.NewCounterVec(prometheus.CounterOpts{
			Namespace: metricsNamespace,
			Subsystem: metricsWorkspaceSubsystem,
			Name:      workspaceStartFailuresTotal,
			Help:      "total number of workspaces that failed to start",
		}, []string{"type", "class"}),
		totalFailuresCounterVec: prometheus.NewCounterVec(prometheus.CounterOpts{
			Namespace: metricsNamespace,
			Subsystem: metricsWorkspaceSubsystem,
			Name:      workspaceFailuresTotal,
			Help:      "total number of workspaces that had a failed condition",
		}, []string{"type", "class"}),
		totalStopsCounterVec: prometheus.NewCounterVec(prometheus.CounterOpts{
			Namespace: metricsNamespace,
			Subsystem: metricsWorkspaceSubsystem,
			Name:      workspaceStopsTotal,
			Help:      "total number of workspaces stopped",
		}, []string{"reason", "type", "class"}),
		totalRecreationsCounterVec: prometheus.NewCounterVec(prometheus.CounterOpts{
			Namespace: metricsNamespace,
			Subsystem: metricsWorkspaceSubsystem,
			Name:      workspaceRecreationsTotal,
			Help:      "total number of workspace recreations",
		}, []string{"type", "class", "attempt"}),

		totalBackupCounterVec: prometheus.NewCounterVec(prometheus.CounterOpts{
			Namespace: metricsNamespace,
			Subsystem: metricsWorkspaceSubsystem,
			Name:      workspaceBackupsTotal,
			Help:      "total number of workspace backups",
		}, []string{"type", "class"}),
		totalBackupFailureCounterVec: prometheus.NewCounterVec(prometheus.CounterOpts{
			Namespace: metricsNamespace,
			Subsystem: metricsWorkspaceSubsystem,
			Name:      workspaceBackupFailuresTotal,
			Help:      "total number of workspace backup failures",
		}, []string{"type", "class"}),
		totalRestoreCounterVec: prometheus.NewCounterVec(prometheus.CounterOpts{
			Namespace: metricsNamespace,
			Subsystem: metricsWorkspaceSubsystem,
			Name:      workspaceRestoresTotal,
			Help:      "total number of workspace restores",
		}, []string{"type", "class"}),
		totalRestoreFailureCounterVec: prometheus.NewCounterVec(prometheus.CounterOpts{
			Namespace: metricsNamespace,
			Subsystem: metricsWorkspaceSubsystem,
			Name:      workspaceRestoresFailureTotal,
			Help:      "total number of workspace restore failures",
		}, []string{"type", "class"}),

		workspacePhases:          newPhaseTotalVec(r),
		timeoutSettings:          newTimeoutSettingsVec(r),
		workspaceNodeUtilization: newNodeUtilizationVec(r),
		workspaceActivityTotal:   newWorkspaceActivityVec(r),
		cache:                    cache,
	}, nil
}

func (m *controllerMetrics) recordWorkspaceStartupTime(log *logr.Logger, ws *workspacev1.Workspace) {
	class := ws.Spec.Class
	tpe := string(ws.Spec.Type)

	hist, err := m.startupTimeHistVec.GetMetricWithLabelValues(tpe, class)
	if err != nil {
		log.Error(err, "could not record workspace startup time", "type", tpe, "class", class)
	}

	duration := time.Since(ws.CreationTimestamp.Time)
	hist.Observe(float64(duration.Seconds()))
}

func (m *controllerMetrics) recordWorkspacePendingTime(log *logr.Logger, ws *workspacev1.Workspace, pendingTs time.Time) {
	class := ws.Spec.Class
	tpe := string(ws.Spec.Type)

	hist, err := m.pendingTimeHistVec.GetMetricWithLabelValues(tpe, class)
	if err != nil {
		log.Error(err, "could not record workspace pending time", "type", tpe, "class", class)
	}

	hist.Observe(time.Since(pendingTs).Seconds())
}

func (m *controllerMetrics) recordWorkspaceCreatingTime(log *logr.Logger, ws *workspacev1.Workspace, creatingTs time.Time) {
	class := ws.Spec.Class
	tpe := string(ws.Spec.Type)

	hist, err := m.creatingTimeHistVec.GetMetricWithLabelValues(tpe, class)
	if err != nil {
		log.Error(err, "could not record workspace creating time", "type", tpe, "class", class)
	}

	hist.Observe(time.Since(creatingTs).Seconds())
}

func (m *controllerMetrics) countWorkspaceStartFailures(log *logr.Logger, ws *workspacev1.Workspace) {
	class := ws.Spec.Class
	tpe := string(ws.Spec.Type)

	m.totalStartsFailureCounterVec.WithLabelValues(tpe, class).Inc()
}

func (m *controllerMetrics) countWorkspaceFailure(log *logr.Logger, ws *workspacev1.Workspace) {
	class := ws.Spec.Class
	tpe := string(ws.Spec.Type)

	m.totalFailuresCounterVec.WithLabelValues(tpe, class).Inc()
}

func (m *controllerMetrics) countWorkspaceStop(log *logr.Logger, ws *workspacev1.Workspace) {
	var reason string
	if c := wsk8s.GetCondition(ws.Status.Conditions, string(workspacev1.WorkspaceConditionFailed)); c != nil {
		reason = StopReasonFailed
		if !ws.IsConditionTrue(workspacev1.WorkspaceConditionEverReady) {
			// Don't record 'failed' if there was a start failure.
			reason = StopReasonStartFailure
		} else if strings.Contains(c.Message, "Pod ephemeral local storage usage exceeds the total limit of containers") {
			reason = StopReasonOutOfSpace
		}
	} else if ws.IsConditionTrue(workspacev1.WorkspaceConditionAborted) {
		reason = StopReasonAborted
	} else if ws.IsConditionTrue(workspacev1.WorkspaceConditionTimeout) {
		reason = StopReasonTimeout
	} else if ws.IsConditionTrue(workspacev1.WorkspaceConditionClosed) {
		reason = StopReasonTabClosed
	} else {
		reason = StopReasonRegular
	}

	class := ws.Spec.Class
	tpe := string(ws.Spec.Type)

	log.Info("workspace stop reason", "type", tpe, "class", class, "reason", reason)

	m.totalStopsCounterVec.WithLabelValues(reason, tpe, class).Inc()
}

func (m *controllerMetrics) countWorkspaceRecreations(log *logr.Logger, ws *workspacev1.Workspace) {
	class := ws.Spec.Class
	tpe := string(ws.Spec.Type)
	attempt := fmt.Sprint(ws.Status.PodRecreated)

	m.totalRecreationsCounterVec.WithLabelValues(tpe, class, attempt).Inc()
}

func (m *controllerMetrics) countTotalBackups(log *logr.Logger, ws *workspacev1.Workspace) {
	class := ws.Spec.Class
	tpe := string(ws.Spec.Type)

	m.totalBackupCounterVec.WithLabelValues(tpe, class).Inc()
}

func (m *controllerMetrics) countTotalBackupFailures(log *logr.Logger, ws *workspacev1.Workspace) {
	class := ws.Spec.Class
	tpe := string(ws.Spec.Type)

	m.totalBackupFailureCounterVec.WithLabelValues(tpe, class).Inc()
}

func (m *controllerMetrics) countTotalRestores(log *logr.Logger, ws *workspacev1.Workspace) {
	class := ws.Spec.Class
	tpe := string(ws.Spec.Type)

	m.totalRestoreCounterVec.WithLabelValues(tpe, class).Inc()
}

func (m *controllerMetrics) countTotalRestoreFailures(log *logr.Logger, ws *workspacev1.Workspace) {
	class := ws.Spec.Class
	tpe := string(ws.Spec.Type)

	m.totalRestoreFailureCounterVec.WithLabelValues(tpe, class).Inc()
}

func (m *controllerMetrics) containsWorkspace(ws *workspacev1.Workspace) bool {
	return m.cache.Contains(ws.Name)
}

func (m *controllerMetrics) rememberWorkspace(ws *workspacev1.Workspace, state *metricState) {
	var s metricState
	if state != nil {
		s = *state
	} else {
		s = newMetricState(ws)
	}
	m.cache.Add(ws.Name, s)
}

func (m *controllerMetrics) forgetWorkspace(ws *workspacev1.Workspace) {
	m.cache.Remove(ws.Name)
}

// metricState is used to track which metrics have been recorded for a workspace.
type metricState struct {
	phase                   workspacev1.WorkspacePhase
	pendingStartTime        time.Time
	creatingStartTime       time.Time
	recordedStartTime       bool
	recordedInitFailure     bool
	recordedStartFailure    bool
	recordedFailure         bool
	recordedContentReady    bool
	recordedBackupFailed    bool
	recordedBackupCompleted bool
	recordedRecreations     int
}

func newMetricState(ws *workspacev1.Workspace) metricState {
	return metricState{
		phase: ws.Status.Phase,
		// Here we assume that we've recorded metrics for the following states already if their conditions already exist.
		// This is to prevent these from being re-recorded after the controller restarts and clears the metric state for
		// each workspace.
		recordedStartTime:       ws.Status.Phase == workspacev1.WorkspacePhaseRunning,
		recordedInitFailure:     wsk8s.ConditionWithStatusAndReason(ws.Status.Conditions, string(workspacev1.WorkspaceConditionContentReady), false, workspacev1.ReasonInitializationFailure),
		recordedStartFailure:    ws.Status.Phase == workspacev1.WorkspacePhaseStopped && isStartFailure(ws),
		recordedFailure:         ws.IsConditionTrue(workspacev1.WorkspaceConditionFailed),
		recordedContentReady:    ws.IsConditionTrue(workspacev1.WorkspaceConditionContentReady),
		recordedBackupFailed:    ws.IsConditionTrue(workspacev1.WorkspaceConditionBackupFailure),
		recordedBackupCompleted: ws.IsConditionTrue(workspacev1.WorkspaceConditionBackupComplete),
		recordedRecreations:     ws.Status.PodRecreated,
	}
}

// getWorkspace returns the last recorded metric state for that workspace.
func (m *controllerMetrics) getWorkspace(log *logr.Logger, ws *workspacev1.Workspace) (bool, metricState) {
	s, ok := m.cache.Get(ws.Name)
	if !ok {
		return false, metricState{}
	}

	return true, s.(metricState)
}

// Describe implements Collector. It will send exactly one Desc to the provided channel.
func (m *controllerMetrics) Describe(ch chan<- *prometheus.Desc) {
	m.startupTimeHistVec.Describe(ch)
	m.pendingTimeHistVec.Describe(ch)
	m.creatingTimeHistVec.Describe(ch)
	m.totalStopsCounterVec.Describe(ch)
	m.totalStartsFailureCounterVec.Describe(ch)
	m.totalFailuresCounterVec.Describe(ch)

	m.totalBackupCounterVec.Describe(ch)
	m.totalBackupFailureCounterVec.Describe(ch)
	m.totalRestoreCounterVec.Describe(ch)
	m.totalRestoreFailureCounterVec.Describe(ch)

	m.workspacePhases.Describe(ch)
	m.timeoutSettings.Describe(ch)
	m.workspaceNodeUtilization.Describe(ch)
	m.workspaceActivityTotal.Describe(ch)
}

// Collect implements Collector.
func (m *controllerMetrics) Collect(ch chan<- prometheus.Metric) {
	m.startupTimeHistVec.Collect(ch)
	m.pendingTimeHistVec.Collect(ch)
	m.creatingTimeHistVec.Collect(ch)
	m.totalStopsCounterVec.Collect(ch)
	m.totalStartsFailureCounterVec.Collect(ch)
	m.totalFailuresCounterVec.Collect(ch)

	m.totalBackupCounterVec.Collect(ch)
	m.totalBackupFailureCounterVec.Collect(ch)
	m.totalRestoreCounterVec.Collect(ch)
	m.totalRestoreFailureCounterVec.Collect(ch)

	m.workspacePhases.Collect(ch)
	m.timeoutSettings.Collect(ch)
	m.workspaceNodeUtilization.Collect(ch)
	m.workspaceActivityTotal.Collect(ch)
}

// phaseTotalVec returns a gauge vector counting the workspaces per phase
type phaseTotalVec struct {
	name       string
	desc       *prometheus.Desc
	reconciler *WorkspaceReconciler
}

func newPhaseTotalVec(r *WorkspaceReconciler) *phaseTotalVec {
	name := prometheus.BuildFQName(metricsNamespace, metricsWorkspaceSubsystem, "workspace_phase_total")
	return &phaseTotalVec{
		name:       name,
		desc:       prometheus.NewDesc(name, "Current number of workspaces per phase", []string{"phase", "type", "class"}, prometheus.Labels(map[string]string{})),
		reconciler: r,
	}
}

// Describe implements Collector. It will send exactly one Desc to the provided channel.
func (ptv *phaseTotalVec) Describe(ch chan<- *prometheus.Desc) {
	ch <- ptv.desc
}

// Collect implements Collector.
func (ptv *phaseTotalVec) Collect(ch chan<- prometheus.Metric) {
	ctx, cancel := context.WithTimeout(context.Background(), kubernetesOperationTimeout)
	defer cancel()

	var workspaces workspacev1.WorkspaceList
	err := ptv.reconciler.List(ctx, &workspaces, client.InNamespace(ptv.reconciler.Config.Namespace))
	if err != nil {
		return
	}

	counts := make(map[string]int)
	for _, ws := range workspaces.Items {
		counts[string(ws.Spec.Type)+"::"+string(ws.Status.Phase)+"::"+ws.Spec.Class]++
	}

	for key, count := range counts {
		segs := strings.Split(key, "::")
		tpe, phase, class := segs[0], segs[1], segs[2]

		metric, err := prometheus.NewConstMetric(ptv.desc, prometheus.GaugeValue, float64(count), phase, tpe, class)
		if err != nil {
			continue
		}

		ch <- metric
	}
}

// timeoutSettingsVec provides a gauge of the currently active/inactive workspaces.
// Adding both up returns the total number of workspaces.
type timeoutSettingsVec struct {
	name       string
	reconciler *WorkspaceReconciler
	desc       *prometheus.Desc
}

func newTimeoutSettingsVec(r *WorkspaceReconciler) *timeoutSettingsVec {
	name := prometheus.BuildFQName("wsman", "workspace", "timeout_settings_total")
	desc := prometheus.NewDesc(
		name,
		"Current number of workspaces per timeout setting",
		[]string{"timeout"},
		prometheus.Labels(map[string]string{}),
	)
	return &timeoutSettingsVec{
		name:       name,
		reconciler: r,
		desc:       desc,
	}
}

// Describe implements Collector. It will send exactly one Desc to the provided channel.
func (vec *timeoutSettingsVec) Describe(ch chan<- *prometheus.Desc) {
	ch <- vec.desc
}

// Collect implements Collector.
func (tsv *timeoutSettingsVec) Collect(ch chan<- prometheus.Metric) {
	ctx, cancel := context.WithTimeout(context.Background(), kubernetesOperationTimeout)
	defer cancel()

	var workspaces workspacev1.WorkspaceList
	err := tsv.reconciler.List(ctx, &workspaces, client.InNamespace(tsv.reconciler.Config.Namespace))
	if err != nil {
		return
	}

	timeouts := make(map[time.Duration]int)
	for _, ws := range workspaces.Items {
		if ws.Spec.Timeout.Time == nil {
			continue
		}

		timeouts[ws.Spec.Timeout.Time.Duration]++
	}

	for phase, cnt := range timeouts {
		// metrics cannot be re-used, we have to create them every single time
		metric, err := prometheus.NewConstMetric(tsv.desc, prometheus.GaugeValue, float64(cnt), phase.String())
		if err != nil {
			continue
		}

		ch <- metric
	}
}

type maintenanceEnabledGauge struct {
	name        string
	desc        *prometheus.Desc
	maintenance maintenance.Maintenance
}

func newMaintenanceEnabledGauge(m maintenance.Maintenance) *maintenanceEnabledGauge {
	name := prometheus.BuildFQName(metricsNamespace, metricsWorkspaceSubsystem, maintenanceEnabled)
	return &maintenanceEnabledGauge{
		name:        name,
		desc:        prometheus.NewDesc(name, "Whether the cluster is in maintenance mode", nil, prometheus.Labels(map[string]string{})),
		maintenance: m,
	}
}

func (m *maintenanceEnabledGauge) Describe(ch chan<- *prometheus.Desc) {
	ch <- m.desc
}

func (m *maintenanceEnabledGauge) Collect(ch chan<- prometheus.Metric) {
	var value float64
	if m.maintenance.IsEnabled(context.Background()) {
		value = 1
	}

	metric, err := prometheus.NewConstMetric(m.desc, prometheus.GaugeValue, value)
	if err != nil {
		return
	}

	ch <- metric
}

// nodeUtilizationVec provides metrics per workspace node on:
// - the amount of cpu/memory requested by workspaces on the node (size of the workspace class)
// CPU is measured in cores, memory in bytes.
// Differentiates between headless and regular workspace nodes using the type label.
// Useful to determine node utilization and capacity.
type nodeUtilizationVec struct {
	name       string
	desc       *prometheus.Desc
	reconciler *WorkspaceReconciler
}

func newNodeUtilizationVec(r *WorkspaceReconciler) *nodeUtilizationVec {
	name := prometheus.BuildFQName(metricsNamespace, metricsWorkspaceSubsystem, workspaceNodeUtilization)
	desc := prometheus.NewDesc(
		name,
		"Amount of resources requested by workspaces on the node (cpu/memory, workspace type)",
		[]string{"node", "resource", "type"},
		prometheus.Labels(map[string]string{}),
	)
	return &nodeUtilizationVec{
		name:       name,
		reconciler: r,
		desc:       desc,
	}
}

// Describe implements Collector. It will send exactly one Desc to the provided channel.
func (n *nodeUtilizationVec) Describe(ch chan<- *prometheus.Desc) {
	ch <- n.desc
}

// Collect implements Collector.
func (n *nodeUtilizationVec) Collect(ch chan<- prometheus.Metric) {
	ctx, cancel := context.WithTimeout(context.Background(), kubernetesOperationTimeout)
	defer cancel()

	var nodes corev1.NodeList
	err := n.reconciler.List(ctx, &nodes)
	if err != nil {
		log.FromContext(ctx).Error(err, "cannot list nodes for node utilization metric")
		return
	}

	var (
		nodeUtilization = make(map[string]map[corev1.ResourceName]float64)
		nodeTypes       = make(map[string]string)
	)
	for _, node := range nodes.Items {
		isRegular := node.Labels["gitpod.io/workload_workspace_regular"] == "true"
		isHeadless := node.Labels["gitpod.io/workload_workspace_headless"] == "true"
		if !isRegular && !isHeadless {
			// Ignore non-workspace nodes.
			continue
		}

		nodeUtilization[node.Name] = map[corev1.ResourceName]float64{
			corev1.ResourceCPU:    0,
			corev1.ResourceMemory: 0,
		}
		nodeTypes[node.Name] = "regular"
		if !isRegular && isHeadless {
			// In case a node is both regular and headless (e.g. a preview env), mark it as regular.
			nodeTypes[node.Name] = "headless"
		}
	}

	var workspaces workspacev1.WorkspaceList
	if err = n.reconciler.List(ctx, &workspaces, client.InNamespace(n.reconciler.Config.Namespace)); err != nil {
		log.FromContext(ctx).Error(err, "cannot list workspaces for node utilization metric")
		return
	}

	// Aggregate workspace pod resource requests per node.
	for _, ws := range workspaces.Items {
		// This list is indexed and reads from memory, so it's not that expensive to do this for every workspace.
		pods, err := n.reconciler.listWorkspacePods(ctx, &ws)
		if err != nil {
			log.FromContext(ctx).Error(err, "cannot list workspace pods for node utilization metric", "workspace", ws.Name)
			continue
		}

		if len(pods.Items) == 0 {
			// No pods (yet), not consuming resources on the node.
			continue
		}

		for _, pod := range pods.Items {
			nodeName := pod.Spec.NodeName
			if nodeName == "" {
				// Not yet scheduled.
				continue
			}

			if _, ok := nodeUtilization[nodeName]; !ok {
				nodeUtilization[nodeName] = map[corev1.ResourceName]float64{
					corev1.ResourceCPU:    0,
					corev1.ResourceMemory: 0,
				}
			}

			for _, container := range pod.Spec.Containers {
				requests := container.Resources.Requests
				nodeUtilization[nodeName][corev1.ResourceCPU] += float64(requests.Cpu().MilliValue()) / 1000.0
				nodeUtilization[nodeName][corev1.ResourceMemory] += float64(requests.Memory().Value())
			}
		}
	}

	for nodeName, metrics := range nodeUtilization {
		for resource, value := range metrics {
			nodeType := nodeTypes[nodeName]
			metric, err := prometheus.NewConstMetric(n.desc, prometheus.GaugeValue, value, nodeName, resource.String(), nodeType)
			if err != nil {
				log.FromContext(ctx).Error(err, "cannot create node utilization metric", "node", nodeName, "resource", resource.String(), "type", nodeType)
				continue
			}

			ch <- metric
		}
	}
}

type workspaceActivityVec struct {
	name       string
	desc       *prometheus.Desc
	reconciler *WorkspaceReconciler
}

func newWorkspaceActivityVec(r *WorkspaceReconciler) *workspaceActivityVec {
	name := prometheus.BuildFQName(metricsNamespace, metricsWorkspaceSubsystem, workspaceActivityTotal)
	desc := prometheus.NewDesc(
		name,
		"total number of active workspaces",
		[]string{"active"},
		prometheus.Labels(map[string]string{}),
	)
	return &workspaceActivityVec{
		name:       name,
		desc:       desc,
		reconciler: r,
	}
}

// Describe implements Collector. It will send exactly one Desc to the provided channel.
func (wav *workspaceActivityVec) Describe(ch chan<- *prometheus.Desc) {
	ch <- wav.desc
}

func (wav *workspaceActivityVec) Collect(ch chan<- prometheus.Metric) {
	ctx, cancel := context.WithTimeout(context.Background(), kubernetesOperationTimeout)
	defer cancel()

	active, notActive, err := wav.getWorkspaceActivityCounts()
	if err != nil {
		log.FromContext(ctx).Error(err, fmt.Sprintf("cannot determine active/inactive counts - %s will be inaccurate", wav.name))
		return
	}

	activeMetrics, err := prometheus.NewConstMetric(wav.desc, prometheus.GaugeValue, float64(active), "true")
	if err != nil {
		log.FromContext(ctx).Error(err, "cannot create wrokspace activity metric", "active", "true")
		return
	}
	notActiveMetrics, err := prometheus.NewConstMetric(wav.desc, prometheus.GaugeValue, float64(notActive), "false")
	if err != nil {
		log.FromContext(ctx).Error(err, "cannot create wrokspace activity metric", "active", "false")
		return
	}

	ch <- activeMetrics
	ch <- notActiveMetrics
}

func (wav *workspaceActivityVec) getWorkspaceActivityCounts() (active, notActive int, err error) {
	var workspaces workspacev1.WorkspaceList
	if err = wav.reconciler.List(context.Background(), &workspaces, client.InNamespace(wav.reconciler.Config.Namespace)); err != nil {
		return 0, 0, err
	}

	for _, ws := range workspaces.Items {
		if ws.Spec.Type != workspacev1.WorkspaceTypeRegular {
			continue
		}

		hasActivity := activity.Last(&ws) != nil
		if hasActivity {
			active++
		} else {
			notActive++
		}
	}

	return
}