package e2e

import (
	"bytes"
	"context"
	"encoding/json"
	"net"
	"net/url"
	"os"
	"path/filepath"
	"strings"
	"testing"
	"time"

	"git.veillax.com/Veillax/bamboo/sshd"
	"git.veillax.com/Veillax/blacktip"
	"golang.org/x/crypto/ssh"
	"golang.org/x/net/websocket"
)

type termMsg struct {
	Type, Message  string
	Code           int
	HostKeyChanged bool
}

// The dashboard's terminal: browser, Hammerhead (as the SSH client), the SSH port on the edge,
// the WireGuard tunnel, Bamboo, and Bamboo's SSH server.
func TestWebTerminalThroughTheEdgeToBamboosServer(t *testing.T) {
	w := setup(t, blacktip.TraefikConfig{})
	base := "/api/orgs/" + w.org
	u, _ := url.Parse(w.ts.URL)
	wsURL := "ws" + strings.TrimPrefix(w.ts.URL, "http") + base + "/sites/" + w.site + "/terminal?cols=100&rows=30"

	// dial opens the terminal's WebSocket as the administrator, or as nobody
	dial := func(origin string, signedIn bool) (*websocket.Conn, error) {
		cfg, err := websocket.NewConfig(wsURL, origin)
		if err != nil {
			t.Fatal(err)
		}
		if signedIn {
			var ck []string
			for _, c := range w.admin.c.Jar.Cookies(u) {
				ck = append(ck, c.Name+"="+c.Value)
			}
			cfg.Header.Set("Cookie", strings.Join(ck, "; "))
		}
		return websocket.DialConfig(cfg)
	}
	// control reads until the next text frame: the terminal's own messages ("ready", "error", "exit")
	control := func(ws *websocket.Conn) termMsg {
		t.Helper()
		for {
			ws.SetReadDeadline(time.Now().Add(15 * time.Second))
			var f []byte
			if err := websocket.Message.Receive(ws, &f); err != nil {
				t.Fatalf("waiting for the terminal: %v", err)
			}
			var m termMsg
			if json.Unmarshal(f, &m) == nil && m.Type != "" && f[0] == '{' {
				return m
			}
		}
	}
	// first says how a new terminal begins
	first := func() termMsg {
		t.Helper()
		ws, err := dial(w.ts.URL, true)
		if err != nil {
			t.Fatal(err)
		}
		defer ws.Close()
		return control(ws)
	}

	// nobody signed in, or a page on another site, cannot open it
	if ws, err := dial(w.ts.URL, false); err == nil {
		ws.Close()
		t.Error("the terminal opened for someone who is not signed in")
	}
	if ws, err := dial("https://evil.example", true); err == nil {
		ws.Close()
		t.Error("a page on another site opened the terminal with the administrator's cookie")
	}
	anon := newClient(t, w.ts.URL)
	anon.expect(401, "GET", base+"/terminal", nil)

	// this Bamboo has no SSH server of its own to call back to, so before a port exists the message says to start it
	if m := first(); m.Type != "error" || !strings.Contains(m.Message, "-ssh") {
		t.Errorf("before opening an SSH port: %+v", m)
	}

	// Hammerhead's public key, which goes in the site's authorized_keys
	var key struct{ PublicKey, Fingerprint string }
	w.admin.must("GET", base+"/terminal", nil, &key)
	if !strings.HasPrefix(key.PublicKey, "ssh-ed25519 ") || strings.Contains(key.PublicKey, "PRIVATE") {
		t.Fatalf("public key: %q", key.PublicKey)
	}
	var again struct{ PublicKey string }
	w.admin.must("GET", base+"/terminal", nil, &again)
	if again.PublicKey != key.PublicKey {
		t.Fatal("the key changed between requests")
	}
	dir := t.TempDir()
	keys := filepath.Join(dir, "authorized_keys")
	if err := os.WriteFile(keys, []byte(key.PublicKey+"\n"), 0o600); err != nil {
		t.Fatal(err)
	}
	srv, err := sshd.New(sshd.Config{AuthorizedKeys: keys, HostKey: filepath.Join(dir, "ssh_host_ed25519_key")})
	if err != nil {
		t.Fatal(err)
	}
	ln, err := net.Listen("tcp", "127.0.0.1:0")
	if err != nil {
		t.Fatal(err)
	}
	ctx, cancel := context.WithCancel(context.Background())
	t.Cleanup(cancel)
	go srv.Serve(ctx, ln)

	edgePort := freePort(t)
	w.admin.must("POST", base+"/mappings", map[string]any{"name": "ssh", "proto": "tcp", "edgeId": w.edge, "bindIp": "127.0.0.1", "port": edgePort,
		"enabled": true, "tags": []string{"ssh"}, "targets": tgt(w.site, ln.Addr().(*net.TCPAddr).Port)}, nil)

	// wait for the path through the tunnel to come up
	var m termMsg
	for i := 0; i < 60; i++ {
		if m = first(); !strings.Contains(m.Message, "reach the site") {
			break
		}
		time.Sleep(250 * time.Millisecond)
	}
	if sshd.Supported {
		if m.Type != "ready" {
			t.Fatalf("opening the terminal: %+v", m)
		}
	} else if m.Type != "error" || !strings.Contains(m.Message, "terminal") {
		// this platform can't run shells, but asking for one proves Hammerhead's key was accepted
		t.Fatalf("on a platform without shells: %+v", m)
	}

	if sshd.Supported {
		ws, err := dial(w.ts.URL, true)
		if err != nil {
			t.Fatal(err)
		}
		defer ws.Close()
		if m := control(ws); m.Type != "ready" {
			t.Fatalf("second terminal: %+v", m)
		}
		// $((40+2)) is expanded by the shell, so "terminal-42" can only come from the command running
		if err := websocket.Message.Send(ws, []byte("echo terminal-$((40+2))\n")); err != nil {
			t.Fatal(err)
		}
		var out strings.Builder
		for !strings.Contains(out.String(), "terminal-42\r\n") {
			ws.SetReadDeadline(time.Now().Add(10 * time.Second))
			var f []byte
			if err := websocket.Message.Receive(ws, &f); err != nil {
				t.Fatalf("waiting for the command's output (got %q): %v", out.String(), err)
			}
			out.Write(f)
		}
		websocket.Message.Send(ws, `{"type":"resize","cols":120,"rows":40}`)
		websocket.Message.Send(ws, []byte("exit\n"))
		var sawExit bool
		for !sawExit {
			ws.SetReadDeadline(time.Now().Add(10 * time.Second))
			var f []byte
			if err := websocket.Message.Receive(ws, &f); err != nil {
				break
			}
			sawExit = bytes.Contains(f, []byte(`"type":"exit"`))
		}
		if !sawExit {
			t.Error("the browser was not told the shell ended")
		}
	}

	// taking Hammerhead's key out of authorized_keys is refused with a message that says what to fix
	other := newSSHSigner(t)
	if err := os.WriteFile(keys, ssh.MarshalAuthorizedKey(other.PublicKey()), 0o600); err != nil {
		t.Fatal(err)
	}
	if m := first(); m.Type != "error" || !strings.Contains(m.Message, "authorized_keys") {
		t.Errorf("after removing the key: %+v", m)
	}

	// a site whose SSH server has stopped is reported, not left hanging
	cancel()
	ln.Close()
	time.Sleep(300 * time.Millisecond)
	if m := first(); m.Type != "error" || !strings.Contains(m.Message, "reach the site") {
		t.Errorf("with the SSH server stopped: %+v", m)
	}
}