//go:build !android && !ios && !freebsd && !js

package main

import (
	"context"
	"net/netip"
	"sort"
	"strings"
	"time"

	log "github.com/sirupsen/logrus"
	"github.com/wailsapp/wails/v3/pkg/application"

	"github.com/netbirdio/netbird/client/ui/services"
)

// exitNodeEntry is one selectable row in the Exit Node submenu. ID is the
// network's NetID — both the row label and the argument the Select/Deselect
// RPCs take; Selected drives the ✓ prefix.
type exitNodeEntry struct {
	ID       string
	Selected bool
}

// rebuildExitNodes paints one clickable row per exit-node candidate into the
// Exit Node submenu. Each row carries the network's NetID and its selected
// state from ListNetworks; clicking toggles it via toggleExitNode. The active
// node is marked with a "✓ " prefix using a plain Add rather than AddCheckbox
// for the same reason as loadProfiles — Wails auto-toggles a checkbox's state
// on click before the OnClick handler runs, so the deselect/select round-trip
// would briefly show two checked rows. Rebuilds via Clear + Add so the row set
// stays in sync; SetMenu on the root menu is required because Wails v3 alpha
// menu Update() builds a detached NSMenu on darwin that never replaces the
// empty submenu attached at initial setup (same workaround as loadProfiles).
// Callers must hold exitNodesRebuildMu so concurrent rebuilds can't race the
// submenu's item slice.
func (t *Tray) rebuildExitNodes(nodes []exitNodeEntry) {
	if t.exitNodeSubmenu == nil {
		return
	}
	t.exitNodeSubmenu.Clear()
	for _, n := range nodes {
		id := n.ID
		selected := n.Selected
		label := id
		if selected {
			label = "✓ " + id
		}
		t.exitNodeSubmenu.Add(label).OnClick(func(*application.Context) {
			t.toggleExitNode(id, selected)
		})
	}
	if t.menu != nil {
		t.tray.SetMenu(t.menu)
	}
}

// refreshExitNodes re-fetches the routed-network list from the daemon and
// repaints the Exit Node submenu. Sourcing the rows from Networks.List() (not
// the Status stream) is what makes them selectable: the stream only ships peer
// FQDNs, whereas ListNetworks returns the NetID + selected state the
// Select/Deselect RPCs need. Serialized by exitNodesRebuildMu so overlapping
// Status pushes can't race the submenu rebuild. Owns the parent item's
// enablement: greyed unless the tunnel is up and at least one candidate exists.
func (t *Tray) refreshExitNodes() {
	t.exitNodesRebuildMu.Lock()
	defer t.exitNodesRebuildMu.Unlock()

	t.statusMu.Lock()
	connected := t.connected
	t.statusMu.Unlock()

	var nodes []exitNodeEntry
	if connected {
		ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
		list, err := t.svc.Networks.List(ctx)
		cancel()
		if err != nil {
			log.Debugf("tray list networks: %v", err)
			return
		}
		nodes = exitNodesFromNetworks(list)
	}

	log.Infof("tray refreshExitNodes: %d exit node(s)", len(nodes))
	for _, n := range nodes {
		log.Infof("tray exit node: id=%q selected=%v", n.ID, n.Selected)
	}

	t.exitNodesMu.Lock()
	changed := !equalExitNodes(nodes, t.exitNodes)
	t.exitNodes = nodes
	t.exitNodesMu.Unlock()

	// Set enablement before rebuildExitNodes' SetMenu so the rebuild reads the
	// updated state at NSMenuItem construction time (Wails v3 alpha reads
	// item.disabled at build time, not lazily).
	if t.exitNodeItem != nil {
		t.exitNodeItem.SetEnabled(connected && len(nodes) > 0)
	}
	if changed {
		t.rebuildExitNodes(nodes)
	}
}

// toggleExitNode activates or deactivates one exit node by NetID. Exit nodes
// are mutually exclusive, so Select uses append=false to clear any other
// active node before turning this one on; deselecting an active node turns
// routing off entirely. Mirrors the frontend's toggleExitNode semantics. Runs
// the RPC off the menu-click goroutine and re-fetches so the ✓ moves to the
// new selection.
func (t *Tray) toggleExitNode(id string, selected bool) {
	go func() {
		ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
		defer cancel()

		params := services.SelectNetworksParams{NetworkIDs: []string{id}, Append: false, All: false}
		var err error
		if selected {
			err = t.svc.Networks.Deselect(ctx, params)
		} else {
			err = t.svc.Networks.Select(ctx, params)
		}
		if err != nil {
			log.Errorf("tray toggle exit node %q: %v", id, err)
			t.notifyError(t.loc.T("notify.error.exitNode", "name", id))
			return
		}
		t.refreshExitNodes()
	}()
}

// exitNodesFromNetworks filters the daemon's routed-network list down to
// exit-node candidates (a default-route range) and maps them to selectable
// rows. Sorted case-insensitively by ID so the submenu reads alphabetically.
func exitNodesFromNetworks(networks []services.Network) []exitNodeEntry {
	out := []exitNodeEntry{}
	for _, n := range networks {
		if !rangeIsDefaultRoute(n.Range) {
			continue
		}
		out = append(out, exitNodeEntry{ID: n.ID, Selected: n.Selected})
	}
	sort.Slice(out, func(i, j int) bool {
		return strings.ToLower(out[i].ID) < strings.ToLower(out[j].ID)
	})
	return out
}

// rangeIsDefaultRoute reports whether a Network.Range string contains an IPv4
// or IPv6 default route. The daemon may merge a v4+v6 exit pair into a single
// comma-joined range ("0.0.0.0/0, ::/0"), so we split and check each part,
// matching by Bits()==0 && unspecified rather than a literal string compare.
func rangeIsDefaultRoute(r string) bool {
	for _, part := range strings.Split(r, ",") {
		pref, err := netip.ParsePrefix(strings.TrimSpace(part))
		if err != nil {
			continue
		}
		if pref.Bits() == 0 && pref.Addr().IsUnspecified() {
			return true
		}
	}
	return false
}

func equalExitNodes(a, b []exitNodeEntry) bool {
	if len(a) != len(b) {
		return false
	}
	for i := range a {
		if a[i] != b[i] {
			return false
		}
	}
	return true
}