package k8s

import (
	"context"
	"fmt"
	"sort"
	"strings"

	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
	"k8s.io/apimachinery/pkg/runtime/schema"
)

const longhornSystemNamespace = "longhorn-system"

var longhornBackupGVR = schema.GroupVersionResource{
	Group:    "longhorn.io",
	Version:  "v1beta2",
	Resource: "backups",
}

// LonghornBackupSummary is the subset of the Longhorn Backup CRD that Soteria
// needs while waiting for an async backup to reach a terminal state.
type LonghornBackupSummary struct {
	Name         string
	SnapshotName string
	Namespace    string
	PVC          string
	State        string
	Error        string
	Progress     int64
	CreatedAt    string
}

// ListLonghornBackups returns Soteria-owned Longhorn Backup CRDs.
func (c *Client) ListLonghornBackups(ctx context.Context) ([]LonghornBackupSummary, error) {
	if c.Dynamic == nil {
		return nil, fmt.Errorf("dynamic Kubernetes client is unavailable")
	}

	list, err := c.Dynamic.Resource(longhornBackupGVR).Namespace(longhornSystemNamespace).List(ctx, metav1.ListOptions{})
	if err != nil {
		return nil, fmt.Errorf("list Longhorn backups: %w", err)
	}

	items := make([]LonghornBackupSummary, 0, len(list.Items))
	for _, item := range list.Items {
		summary := summarizeLonghornBackup(item)
		if summary.Namespace != "" && summary.PVC != "" {
			items = append(items, summary)
		}
	}
	sortLonghornBackupsNewestFirst(items)
	return items, nil
}

// GetLonghornBackupBySnapshot returns the newest Longhorn Backup CRD for a snapshot.
func (c *Client) GetLonghornBackupBySnapshot(ctx context.Context, snapshotName string) (LonghornBackupSummary, bool, error) {
	snapshotName = strings.TrimSpace(snapshotName)
	if snapshotName == "" {
		return LonghornBackupSummary{}, false, fmt.Errorf("snapshot name is required")
	}
	if c.Dynamic == nil {
		return LonghornBackupSummary{}, false, fmt.Errorf("dynamic Kubernetes client is unavailable")
	}

	list, err := c.Dynamic.Resource(longhornBackupGVR).Namespace(longhornSystemNamespace).List(ctx, metav1.ListOptions{})
	if err != nil {
		return LonghornBackupSummary{}, false, fmt.Errorf("list Longhorn backups: %w", err)
	}

	matches := make([]LonghornBackupSummary, 0, len(list.Items))
	for _, item := range list.Items {
		summary := summarizeLonghornBackup(item)
		if summary.SnapshotName == snapshotName {
			matches = append(matches, summary)
		}
	}
	if len(matches) == 0 {
		return LonghornBackupSummary{}, false, nil
	}

	sortLonghornBackupsNewestFirst(matches)
	return matches[0], true, nil
}

func summarizeLonghornBackup(item unstructured.Unstructured) LonghornBackupSummary {
	snapshotName, _, _ := unstructured.NestedString(item.Object, "spec", "snapshotName")
	state, _, _ := unstructured.NestedString(item.Object, "status", "state")
	errorMessage, _, _ := unstructured.NestedString(item.Object, "status", "error")
	progress, _, _ := unstructured.NestedInt64(item.Object, "status", "progress")
	specLabels, _, _ := unstructured.NestedStringMap(item.Object, "spec", "labels")
	createdAt, _, _ := unstructured.NestedString(item.Object, "status", "backupCreatedAt")
	if strings.TrimSpace(createdAt) == "" {
		createdAt, _, _ = unstructured.NestedString(item.Object, "status", "snapshotCreatedAt")
	}
	if strings.TrimSpace(createdAt) == "" {
		createdAt = item.GetCreationTimestamp().UTC().Format("2006-01-02T15:04:05Z")
	}

	return LonghornBackupSummary{
		Name:         item.GetName(),
		SnapshotName: strings.TrimSpace(snapshotName),
		Namespace:    strings.TrimSpace(specLabels["soteria.bstein.dev/namespace"]),
		PVC:          strings.TrimSpace(specLabels["soteria.bstein.dev/pvc"]),
		State:        strings.TrimSpace(state),
		Error:        strings.TrimSpace(errorMessage),
		Progress:     progress,
		CreatedAt:    strings.TrimSpace(createdAt),
	}
}

func sortLonghornBackupsNewestFirst(items []LonghornBackupSummary) {
	sort.Slice(items, func(i, j int) bool {
		if items[i].CreatedAt == items[j].CreatedAt {
			return items[i].Name > items[j].Name
		}
		return items[i].CreatedAt > items[j].CreatedAt
	})
}