package handlers

import (
	"time"

	"github.com/gin-gonic/gin"

	"git.netcell-it.de/projekte/edgeguard-native/internal/cluster"
	"git.netcell-it.de/projekte/edgeguard-native/internal/handlers/response"
	"git.netcell-it.de/projekte/edgeguard-native/internal/models"
)

// ClusterHandler exposes cluster-state endpoints. v1 ist read-only;
// /status liefert eine strukturierte UI-Sicht (local + peers + health),
// /nodes bleibt als simpler list-endpoint für Tools/Scripts.
type ClusterHandler struct {
	Store   *cluster.Store
	LocalID string
}

func NewClusterHandler(store *cluster.Store, localID string) *ClusterHandler {
	return &ClusterHandler{Store: store, LocalID: localID}
}

func (h *ClusterHandler) Register(rg *gin.RouterGroup) {
	g := rg.Group("/cluster")
	g.GET("/nodes", h.ListNodes)
	g.GET("/status", h.Status)
}

func (h *ClusterHandler) ListNodes(c *gin.Context) {
	nodes, err := h.Store.List(c.Request.Context())
	if err != nil {
		response.Internal(c, err)
		return
	}
	response.OK(c, gin.H{"nodes": nodes, "local_id": h.LocalID})
}

// ClusterStatus ist die UI-zentrierte Sicht: local-Node hervorgehoben,
// peers separat, mode + health-flag.
type ClusterStatus struct {
	LocalID    string          `json:"local_id"`
	LocalNode  *models.HANode  `json:"local_node,omitempty"`
	Peers      []models.HANode `json:"peers"`
	Mode       string          `json:"mode"` // "single-node" | "cluster"
	Health     string          `json:"health"` // "ok" | "degraded" | "split-brain"
	DriftFound bool            `json:"drift_found"`
	UpdatedAt  time.Time       `json:"updated_at"`
}

// Status splittet alle Nodes in local + peers, berechnet mode + health.
func (h *ClusterHandler) Status(c *gin.Context) {
	all, err := h.Store.List(c.Request.Context())
	if err != nil {
		response.Internal(c, err)
		return
	}
	out := ClusterStatus{
		LocalID:   h.LocalID,
		Peers:     []models.HANode{},
		Mode:      "single-node",
		Health:    "ok",
		UpdatedAt: time.Now().UTC(),
	}
	var localHash *string
	for i := range all {
		n := all[i]
		if n.ID == h.LocalID {
			ln := n
			out.LocalNode = &ln
			localHash = ln.ConfigHash
			continue
		}
		out.Peers = append(out.Peers, n)
	}
	if len(out.Peers) > 0 {
		out.Mode = "cluster"
	}
	// Drift-Detection: jeder peer mit anderem config_hash als unser
	// lokaler → Banner-Trigger im UI.
	if localHash != nil && *localHash != "" {
		for _, p := range out.Peers {
			if p.ConfigHash == nil || *p.ConfigHash == "" {
				continue
			}
			if *p.ConfigHash != *localHash {
				out.DriftFound = true
				out.Health = "degraded"
				break
			}
		}
	}
	// Offline-Peers → degraded.
	if !out.DriftFound {
		for _, p := range out.Peers {
			if p.Status != "online" {
				out.Health = "degraded"
				break
			}
		}
	}
	response.OK(c, out)
}