package main

import (
	"context"
	"io"
	"os"
	"path/filepath"
	"strings"
	"testing"
	"time"

	"github.com/novox/mesh-host/internal/identity"
)

// `key` makes the tunnel key once and prints its public half; asked again it prints the same one,
// because a token may already have been issued for it (novox/hq ADR 0169).
func TestKeyMakesTheTunnelKeyOnceAndKeepsIt(t *testing.T) {
	dir := t.TempDir()
	opts := options{state: filepath.Join(dir, "state.json")}
	first := captureStdout(t, func() {
		if err := keyCommand(opts); err != nil {
			t.Fatal(err)
		}
	})
	second := captureStdout(t, func() {
		if err := keyCommand(opts); err != nil {
			t.Fatal(err)
		}
	})
	if strings.TrimSpace(first) == "" || strings.TrimSpace(first) != strings.TrimSpace(second) {
		t.Fatalf("the key changed between two asks: %q then %q", first, second)
	}
	info, err := os.Stat(identity.OverlayKeyPath(opts.state))
	if err != nil {
		t.Fatal(err)
	}
	if info.Mode().Perm() != 0o600 {
		t.Errorf("the private half is readable beyond root: %v", info.Mode().Perm())
	}
}

// A token through the tunnel takes the key it was issued for, and says so when this machine has none
// or another.
func TestATokenThroughTheTunnelTakesItsOwnKey(t *testing.T) {
	dir := t.TempDir()
	state := filepath.Join(dir, "state.json")
	tt := &identity.TokenTunnel{Key: "x", Address: "10.42.0.9/32", Range: "10.42.0.0/16", HubKey: "h", HubEndpoint: "198.51.100.1:51820"}
	if _, err := tunnelKeyFor(tt, state); err == nil || !strings.Contains(err.Error(), "nox-mesh-host key") {
		t.Fatalf("a machine with no key was not told to make one: %v", err)
	}
	captureStdout(t, func() { _ = keyCommand(options{state: state}) })
	if _, err := tunnelKeyFor(tt, state); err == nil || !strings.Contains(err.Error(), "issued for the tunnel key x") {
		t.Fatalf("another machine's token was taken: %v", err)
	}
	mine, _ := identity.LoadOverlayKey(identity.OverlayKeyPath(state))
	tt.Key = mine.Public
	if got, err := tunnelKeyFor(tt, state); err != nil || got.Public != mine.Public {
		t.Fatalf("this machine's own token was refused: %v", err)
	}
}

// The first tunnel is the mesh's interface and unit, with the hub as its one peer and no secret in
// the file — the same shape the mesh's declaration replaces it with.
func TestTheFirstTunnelIsTheMeshsInterfaceWithTheHubAsItsPeer(t *testing.T) {
	dir := t.TempDir()
	tunnelConfigPath = filepath.Join(dir, "wireguard", "mesh0.conf")
	lookPath = func(string) (string, error) { return "/usr/bin/wg-quick", nil }
	t.Cleanup(func() { tunnelConfigPath = "/etc/wireguard/mesh0.conf" })
	var ran []string
	run := func(_ context.Context, name string, args ...string) (string, error) {
		if name == "wg" {
			return "HUBKEY\t1759400000\n", nil
		}
		ran = append(ran, name+" "+strings.Join(args, " "))
		return "", nil
	}
	tt := &identity.TokenTunnel{Key: "k", Address: "10.42.0.9/32", Range: "10.42.0.0/16", HubKey: "HUBKEY", HubEndpoint: "198.51.100.1:51820"}
	captureStdout(t, func() {
		if err := bringTheTunnelUp(context.Background(), tt, "/var/lib/mesh-host/overlay.key", run); err != nil {
			t.Fatal(err)
		}
	})
	raw, err := os.ReadFile(tunnelConfigPath)
	if err != nil {
		t.Fatal(err)
	}
	conf := string(raw)
	for _, want := range []string{"Address = 10.42.0.9/32", "PostUp = wg set %i private-key /var/lib/mesh-host/overlay.key",
		"PublicKey = HUBKEY", "Endpoint = 198.51.100.1:51820", "AllowedIPs = 10.42.0.0/16", "PersistentKeepalive = 25"} {
		if !strings.Contains(conf, want) {
			t.Errorf("the first tunnel lacks %q:\n%s", want, conf)
		}
	}
	if strings.Contains(conf, "PrivateKey") {
		t.Error("the first tunnel's file holds the private key")
	}
	if len(ran) != 1 || ran[0] != "systemctl restart wg-quick@mesh0" {
		t.Errorf("the tunnel was started as %v", ran)
	}
}

// captureStdout is what fn printed to standard output.
func captureStdout(t *testing.T, fn func()) string {
	t.Helper()
	r, w, err := os.Pipe()
	if err != nil {
		t.Fatal(err)
	}
	was := os.Stdout
	os.Stdout = w
	fn()
	os.Stdout = was
	w.Close()
	out, _ := io.ReadAll(r)
	return string(out)
}

// The bus is dialled only once the hub has answered the tunnel, and a hub that never does is said
// as the tunnel's fault rather than the bus's.
func TestTheBusWaitsForTheHubToAnswer(t *testing.T) {
	asked := 0
	answersOnThird := func(_ context.Context, name string, args ...string) (string, error) {
		asked++
		if asked < 3 {
			return "HUBKEY\t0\n", nil
		}
		return "HUBKEY\t1759400000\n", nil
	}
	captureStdout(t, func() {
		if err := waitForTheHub(context.Background(), answersOnThird, time.Minute); err != nil {
			t.Fatal(err)
		}
	})
	never := func(context.Context, string, ...string) (string, error) { return "HUBKEY\t0\n", nil }
	err := waitForTheHub(context.Background(), never, 0)
	if err == nil || !strings.Contains(err.Error(), "has not answered the tunnel") {
		t.Fatalf("a hub that never answered was not said: %v", err)
	}
}