package web

import (
	"encoding/json"
	"fmt"
	"net/http"
	"net/url"
	"strconv"
	"strings"
)

// handleOSAdmin serves the operator's OS-update controls (behind the operator login, like every route here):
//
//	POST /os/ring/<host_id>     ring=0|1
//	POST /os/enabled/<host_id>  on=1|0
//	POST /os/approve-now        approve the current ring-0 set at once (an operator event)
//	POST /os/approve-docker     approve the Docker engine set ring 0 ran 2 healthy nights (`11` §5.8)
//	(a form field return=/system makes any POST answer with a redirect to the System page)
//	GET  /os/fleet              one line per box (JSON)
func (s *Server) handleOSAdmin(w http.ResponseWriter, r *http.Request, path string) {
	if s.osUpdates == nil {
		http.Error(w, "os updates not configured", http.StatusServiceUnavailable)
		return
	}
	// A button on the System page posts return=/system: answer with a redirect and a flash, never JSON.
	fromPage := r.Method == http.MethodPost && r.FormValue("return") == "/system"
	reply := func(v any, err error) {
		if fromPage {
			q := "flash=done"
			if err != nil {
				q = "err=" + url.QueryEscape(err.Error())
			} else if m, ok := v.(map[string]string); ok && m["release_id"] != "" {
				q = "flash=" + url.QueryEscape("approved "+m["release_id"])
			}
			http.Redirect(w, r, "/system?"+q, http.StatusSeeOther)
			return
		}
		if err != nil {
			http.Error(w, err.Error(), http.StatusBadRequest)
			return
		}
		w.Header().Set("Content-Type", "application/json")
		_ = json.NewEncoder(w).Encode(v)
	}
	switch {
	case r.Method == http.MethodGet && path == "/os/fleet":
		reply(s.osUpdates.FleetJSON())
	case r.Method == http.MethodPost && strings.HasPrefix(path, "/os/ring/"):
		n, err := strconv.Atoi(r.FormValue("ring"))
		if err != nil {
			http.Error(w, "ring must be 0 or 1", http.StatusBadRequest)
			return
		}
		reply(map[string]bool{"ok": true}, s.osUpdates.SetRing(strings.TrimPrefix(path, "/os/ring/"), n))
	case r.Method == http.MethodPost && strings.HasPrefix(path, "/os/enabled/"):
		on := r.FormValue("on")
		if on != "0" && on != "1" {
			http.Error(w, "on must be 0 or 1", http.StatusBadRequest)
			return
		}
		reply(map[string]bool{"ok": true}, s.osUpdates.SetEnabled(strings.TrimPrefix(path, "/os/enabled/"), on == "1"))
	case r.Method == http.MethodPost && path == "/os/approve-now":
		id, err := s.osUpdates.ApproveNow()
		reply(map[string]string{"release_id": id}, err)
	case r.Method == http.MethodPost && path == "/os/approve-docker":
		view, ok := s.osUpdates.(OSSystemView)
		if !ok {
			reply(nil, fmt.Errorf("docker approval not available"))
			return
		}
		id, err := view.ApproveDocker()
		reply(map[string]string{"release_id": id}, err)
	default:
		http.Error(w, "not found", http.StatusNotFound)
	}
}