[MM-55268] Implement ServeMetrics plugins hook (#24249)

* Implement ServeMetrics plugins hook

* Update error id

* Simplify

* Revert "Simplify"

This reverts commit c9dc5d5eac6c933ff69e158cf3e34d0973bd3bcd.

* Add comment and error handler

* Wrap error

* Update translation file

---------

Co-authored-by: Mattermost Build <build@mattermost.com>

server/public/plugin/product_hooks_generated.go

@@ -9,6 +9,7 @@ package plugin
 import (
 	"errors"
 	"io"
+	"net/http"
 	"reflect"
 
 	"github.com/mattermost/mattermost/server/public/model"
@@ -134,6 +135,10 @@ type UserHasBeenDeactivatedIFace interface {
 	UserHasBeenDeactivated(c *Context, user *model.User)
 }
 
+type ServeMetricsIFace interface {
+	ServeMetrics(c *Context, w http.ResponseWriter, r *http.Request)
+}
+
 type HooksAdapter struct {
 	implemented  map[int]struct{}
 	productHooks any
@@ -417,6 +422,15 @@ func NewAdapter(productHooks any) (*HooksAdapter, error) {
 		return nil, errors.New("hook has UserHasBeenDeactivated method but does not implement plugin.UserHasBeenDeactivated interface")
 	}
 
+	// Assessing the type of the productHooks if it individually implements ServeMetrics interface.
+	tt = reflect.TypeOf((*ServeMetricsIFace)(nil)).Elem()
+
+	if ft.Implements(tt) {
+		a.implemented[ServeMetricsID] = struct{}{}
+	} else if _, ok := ft.MethodByName("ServeMetrics"); ok {
+		return nil, errors.New("hook has ServeMetrics method but does not implement plugin.ServeMetrics interface")
+	}
+
 	return a, nil
 }
 
@@ -689,3 +703,12 @@ func (a *HooksAdapter) UserHasBeenDeactivated(c *Context, user *model.User) {
 	a.productHooks.(UserHasBeenDeactivatedIFace).UserHasBeenDeactivated(c, user)
 
 }
+
+func (a *HooksAdapter) ServeMetrics(c *Context, w http.ResponseWriter, r *http.Request) {
+	if _, ok := a.implemented[ServeMetricsID]; !ok {
+		panic("product hooks must implement ServeMetrics")
+	}
+
+	a.productHooks.(ServeMetricsIFace).ServeMetrics(c, w, r)
+
+}