package api

// The VPN tab: this machine's WireGuard tunnels, who is on them, and — where the tunnel is
// one this machine configures — adding, renaming and removing the devices that dial in.
//
// Per machine like every other tab: the tunnels shown and edited are the ones on the machine
// in the switcher, which is the only honest way to show them, since the inbound server and an
// outbound tunnel are different machines here.

import (
	"context"
	"encoding/json"
	"errors"
	"io"
	"log"
	"net/http"
	"strings"

	"hamlab/internal/vpn"
)

func (s *Server) vpnReport(w http.ResponseWriter, r *http.Request) {
	jsonOK(w, 200, vpn.Look(r.Context()))
}

// tunnelOf finds the tunnel a request names, so every editing handler starts from the live
// state rather than from whatever the page last saw.
func (s *Server) tunnelOf(ctx context.Context, w http.ResponseWriter, name string) (vpn.Tunnel, bool) {
	for _, t := range vpn.Look(ctx).Tunnels {
		if t.Name == name {
			if !t.Managed {
				jsonErr(w, 400, vpn.ErrUnmanaged.Error())
				return t, false
			}
			return t, true
		}
	}
	jsonErr(w, 404, "no such tunnel on this machine")
	return vpn.Tunnel{}, false
}

// addVPNPeer makes a device and hands back its profile. The profile holds a private key that
// is generated for this call and stored nowhere, so it is the only time it can be read — the
// same bargain as any password this console generates.
func (s *Server) addVPNPeer(w http.ResponseWriter, r *http.Request) {
	t, ok := s.tunnelOf(r.Context(), w, r.PathValue("iface"))
	if !ok {
		return
	}
	var body vpn.NewPeer
	if err := json.NewDecoder(io.LimitReader(r.Body, 8<<10)).Decode(&body); err != nil {
		jsonErr(w, 400, "bad request")
		return
	}
	made, err := vpn.AddPeer(r.Context(), t, body)
	if err != nil {
		code := 400
		if errors.Is(err, vpn.ErrUnmanaged) {
			code = 409
		}
		jsonErr(w, code, err.Error())
		return
	}
	// The name and address are worth a log line; the profile is emphatically not.
	log.Printf("vpn: device %q added to %s as %s (by %s)", made.Name, t.Name, made.Address, clientIP(r))
	jsonOK(w, 200, made)
}

func (s *Server) editVPNPeer(w http.ResponseWriter, r *http.Request) {
	t, ok := s.tunnelOf(r.Context(), w, r.PathValue("iface"))
	if !ok {
		return
	}
	var body struct{ Name, Address string }
	if err := json.NewDecoder(io.LimitReader(r.Body, 4<<10)).Decode(&body); err != nil {
		jsonErr(w, 400, "bad request")
		return
	}
	section := r.PathValue("section")
	if err := vpn.EditPeer(r.Context(), t, section, body.Name, body.Address); err != nil {
		jsonErr(w, 400, err.Error())
		return
	}
	log.Printf("vpn: device %s on %s changed (by %s)", section, t.Name, clientIP(r))
	w.WriteHeader(204)
}

func (s *Server) removeVPNPeer(w http.ResponseWriter, r *http.Request) {
	t, ok := s.tunnelOf(r.Context(), w, r.PathValue("iface"))
	if !ok {
		return
	}
	section := r.PathValue("section")
	var body struct{ Confirm string }
	_ = json.NewDecoder(io.LimitReader(r.Body, 4<<10)).Decode(&body)
	// The name has to be typed back. Removing a device is the one action here that cannot be
	// undone — the key is gone and the profile on the device stops working — and it is one tap
	// away from a list of devices that all look alike.
	var want string
	for _, p := range t.Peers {
		if p.Section == section {
			want = p.Name
		}
	}
	if want != "" && !strings.EqualFold(strings.TrimSpace(body.Confirm), want) {
		jsonErr(w, 400, "type the device's name to remove it")
		return
	}
	if err := vpn.DeletePeer(r.Context(), t, section); err != nil {
		jsonErr(w, 400, err.Error())
		return
	}
	log.Printf("vpn: device %s (%s) removed from %s (by %s)", section, want, t.Name, clientIP(r))
	w.WriteHeader(204)
}