package k8s

import (
	"fmt"
	"strconv"
	"time"

	appsv1 "k8s.io/api/apps/v1"

	"tower/internal/model"
)

// WorkloadGrace tracks how long a workload must be NotReady before we emit an issue.
const defaultWorkloadNotReadyGrace = 180 * time.Second

// IssuesFromDeployments applies the PLAN.md workload rules for Deployments.
func IssuesFromDeployments(deploys []*appsv1.Deployment, now time.Time, grace time.Duration) []model.Issue {
	if grace <= 0 {
		grace = defaultWorkloadNotReadyGrace
	}
	out := make([]model.Issue, 0, 16)

	for _, d := range deploys {
		if d == nil {
			continue
		}
		desired := int32(1)
		if d.Spec.Replicas != nil {
			desired = *d.Spec.Replicas
		}
		ready := d.Status.ReadyReplicas
		if desired > 0 && ready < desired {
			// Prefer LastUpdateTime / LastTransitionTime when available; fallback to creation time.
			since := d.CreationTimestamp.Time
			if cond := findDeploymentProgressingCondition(d); cond != nil {
				if !cond.LastUpdateTime.IsZero() {
					since = cond.LastUpdateTime.Time
				} else if !cond.LastTransitionTime.IsZero() {
					since = cond.LastTransitionTime.Time
				}
			}
			if !since.IsZero() && now.Sub(since) < grace {
				continue
			}

			ns := d.Namespace
			name := d.Name
			out = append(out, model.Issue{
				ID:       fmt.Sprintf("k8s:deploy:%s/%s:NotReady", ns, name),
				Category: model.CategoryKubernetes,
				Priority: model.PriorityP1,
				Title:    fmt.Sprintf("Deployment not ready: %s/%s", ns, name),
				Details:  "Ready replicas below desired.",
				Evidence: map[string]string{
					"kind":          "Deployment",
					"reason":        "NotReady",
					"namespace":     ns,
					"name":          name,
					"desired":       strconv.Itoa(int(desired)),
					"ready":         strconv.Itoa(int(ready)),
					"observed_gen":  strconv.FormatInt(d.Status.ObservedGeneration, 10),
					"resource_gen":  strconv.FormatInt(d.Generation, 10),
					"min_grace_sec": strconv.Itoa(int(grace.Seconds())),
				},
				SuggestedFix: fmt.Sprintf("kubectl -n %s describe deployment %s", ns, name),
			})
		}
	}

	return out
}

// IssuesFromStatefulSets applies the PLAN.md workload rules for StatefulSets.
func IssuesFromStatefulSets(sts []*appsv1.StatefulSet, now time.Time, grace time.Duration) []model.Issue {
	if grace <= 0 {
		grace = defaultWorkloadNotReadyGrace
	}
	out := make([]model.Issue, 0, 16)

	for _, s := range sts {
		if s == nil {
			continue
		}
		desired := int32(1)
		if s.Spec.Replicas != nil {
			desired = *s.Spec.Replicas
		}
		ready := s.Status.ReadyReplicas
		if desired > 0 && ready < desired {
			since := s.CreationTimestamp.Time
			if !since.IsZero() && now.Sub(since) < grace {
				continue
			}

			ns, name := s.Namespace, s.Name
			out = append(out, model.Issue{
				ID:       fmt.Sprintf("k8s:sts:%s/%s:NotReady", ns, name),
				Category: model.CategoryKubernetes,
				Priority: model.PriorityP1,
				Title:    fmt.Sprintf("StatefulSet not ready: %s/%s", ns, name),
				Details:  "Ready replicas below desired.",
				Evidence: map[string]string{
					"kind":          "StatefulSet",
					"reason":        "NotReady",
					"namespace":     ns,
					"name":          name,
					"desired":       strconv.Itoa(int(desired)),
					"ready":         strconv.Itoa(int(ready)),
					"observed_gen":  strconv.FormatInt(s.Status.ObservedGeneration, 10),
					"resource_gen":  strconv.FormatInt(s.Generation, 10),
					"min_grace_sec": strconv.Itoa(int(grace.Seconds())),
				},
				SuggestedFix: fmt.Sprintf("kubectl -n %s describe statefulset %s", ns, name),
			})
		}
	}

	return out
}

// IssuesFromDaemonSets applies the PLAN.md workload rules for DaemonSets.
func IssuesFromDaemonSets(dss []*appsv1.DaemonSet, now time.Time, grace time.Duration) []model.Issue {
	if grace <= 0 {
		grace = defaultWorkloadNotReadyGrace
	}
	out := make([]model.Issue, 0, 16)

	for _, ds := range dss {
		if ds == nil {
			continue
		}
		unavailable := ds.Status.NumberUnavailable
		if unavailable > 0 {
			since := ds.CreationTimestamp.Time
			if !since.IsZero() && now.Sub(since) < grace {
				continue
			}
			ns, name := ds.Namespace, ds.Name
			out = append(out, model.Issue{
				ID:       fmt.Sprintf("k8s:ds:%s/%s:Unavailable", ns, name),
				Category: model.CategoryKubernetes,
				Priority: model.PriorityP1,
				Title:    fmt.Sprintf("DaemonSet unavailable: %s/%s", ns, name),
				Details:  "DaemonSet has unavailable pods.",
				Evidence: map[string]string{
					"kind":          "DaemonSet",
					"reason":        "Unavailable",
					"namespace":     ns,
					"name":          name,
					"unavailable":   strconv.Itoa(int(unavailable)),
					"desired":       strconv.Itoa(int(ds.Status.DesiredNumberScheduled)),
					"available":     strconv.Itoa(int(ds.Status.NumberAvailable)),
					"min_grace_sec": strconv.Itoa(int(grace.Seconds())),
				},
				SuggestedFix: fmt.Sprintf("kubectl -n %s describe daemonset %s", ns, name),
			})
		}
	}

	return out
}

func findDeploymentProgressingCondition(d *appsv1.Deployment) *appsv1.DeploymentCondition {
	if d == nil {
		return nil
	}
	for i := range d.Status.Conditions {
		c := &d.Status.Conditions[i]
		if c.Type == appsv1.DeploymentProgressing {
			return c
		}
	}
	return nil
}