package broker

import (
	"encoding/json"
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"testing"
	"time"

	"github.com/nats-io/nats.go"
	"golang.org/x/crypto/bcrypt"
)

// The bus's own module's composed authority, against the bus's release in a throwaway container
// (novox/hq ADR 0235): it can take a whole snapshot of a stream through the server's chunked
// protocol, and every write — to a stream's definition, its messages, a bucket — is refused.
//
//	MESH_TEST_DOCKER=1 go test ./internal/broker/ -run TestTheComposedSnapshotUser
//
// The program that takes the night's snapshot lives in the nats module (mesh-catalog
// modules/nats/snapshot) and is tested there against these same grants; this proves the grants are
// what the controller composes, by composing them.
func TestTheComposedSnapshotUserCanSnapshotAndCannotWrite(t *testing.T) {
	if os.Getenv("MESH_TEST_DOCKER") != "1" {
		t.Skip("MESH_TEST_DOCKER is not 1: this starts a throwaway nats container")
	}
	hash := func(pw string) string {
		h, err := bcrypt.GenerateFromPassword([]byte(pw), bcrypt.MinCost)
		if err != nil {
			t.Fatal(err)
		}
		return string(h)
	}
	accounts, err := ComposeAccounts([]Principal{
		{Kind: KindController, PasswordHash: hash("controller")},
		{Kind: KindModule, Node: "anchor", Module: "nats", SnapshotsTheBus: true, PasswordHash: hash("snap")},
	})
	if err != nil {
		t.Fatal(err)
	}
	conf, data := t.TempDir(), t.TempDir()
	_ = os.WriteFile(filepath.Join(conf, "accounts.conf"), []byte(accounts), 0o644)
	_ = os.WriteFile(filepath.Join(conf, "nats.conf"), []byte("port: 4222\njetstream { store_dir: \"/data\" }\ninclude accounts.conf\n"), 0o644)
	name := fmt.Sprintf("mesh-controller-snapshot-test-%d", time.Now().UnixNano())
	run := exec.Command("docker", "run", "-d", "--rm", "--name", name, "--user", fmt.Sprintf("%d:%d", os.Getuid(), os.Getgid()),
		"-p", "127.0.0.1::4222", "-v", conf+":/etc/nats:ro", "-v", data+":/data", "nats:2.11-alpine", "-c", "/etc/nats/nats.conf")
	if out, err := run.CombinedOutput(); err != nil {
		t.Fatalf("%v\n%s", err, out)
	}
	t.Cleanup(func() { _ = exec.Command("docker", "rm", "-f", name).Run() })
	out, err := exec.Command("docker", "port", name, "4222/tcp").Output()
	if err != nil {
		t.Fatal(err)
	}
	_, port, _ := strings.Cut(strings.TrimSpace(strings.Split(string(out), "\n")[0]), ":")
	url := "nats://127.0.0.1:" + port

	dial := func(user, pw string, errs chan error) *nats.Conn {
		var nc *nats.Conn
		var err error
		for deadline := time.Now().Add(15 * time.Second); ; time.Sleep(200 * time.Millisecond) {
			nc, err = nats.Connect(url, nats.UserInfo(user, pw), nats.CustomInboxPrefix("_INBOX."+user),
				nats.ErrorHandler(func(_ *nats.Conn, _ *nats.Subscription, err error) {
					if errs != nil {
						select {
						case errs <- err:
						default:
						}
					}
				}))
			if err == nil || time.Now().After(deadline) {
				break
			}
		}
		if err != nil {
			t.Fatal(err)
		}
		t.Cleanup(nc.Close)
		return nc
	}

	// The controller defines the streams and fills them, as it does.
	controller := dial("controller", "controller", nil)
	js, _ := controller.JetStream()
	if _, err := js.AddStream(&nats.StreamConfig{Name: "EVENTS", Subjects: []string{"mesh.mod.*.event.>"}}); err != nil {
		t.Fatal(err)
	}
	kv, err := js.CreateKeyValue(&nats.KeyValueConfig{Bucket: HandActsBucket})
	if err != nil {
		t.Fatal(err)
	}
	if _, err := kv.Put("act", []byte("done by hand")); err != nil {
		t.Fatal(err)
	}

	errs := make(chan error, 32)
	snap := dial("anchor.nats", "snap", errs)

	// What it may do: list, read a stream's information, and take a whole snapshot.
	names, err := snap.Request("$JS.API.STREAM.NAMES", nil, 5*time.Second)
	if err != nil || !strings.Contains(string(names.Data), "KV_"+HandActsBucket) {
		t.Fatalf("it cannot list the streams: %v", err)
	}
	deliver := snap.NewRespInbox()
	done := make(chan string, 1)
	var bytes int
	sub, err := snap.Subscribe(deliver, func(m *nats.Msg) {
		if len(m.Data) == 0 {
			done <- m.Header.Get("Status")
			return
		}
		bytes += len(m.Data)
		if m.Reply != "" {
			_ = snap.Publish(m.Reply, nil)
		}
	})
	if err != nil {
		t.Fatal(err)
	}
	defer sub.Unsubscribe()
	req, _ := json.Marshal(map[string]any{"deliver_subject": deliver})
	answer, err := snap.Request("$JS.API.STREAM.SNAPSHOT.KV_"+HandActsBucket, req, 5*time.Second)
	if err != nil || strings.Contains(string(answer.Data), `"error"`) {
		t.Fatalf("the snapshot was not granted: %v", err)
	}
	select {
	case status := <-done:
		if status != "" && status != "204" {
			t.Fatalf("the snapshot ended with %s", status)
		}
	case <-time.After(10 * time.Second):
		t.Fatal("the snapshot never finished")
	}
	if bytes == 0 {
		t.Fatal("the snapshot delivered nothing")
	}
	select {
	case e := <-errs:
		t.Fatalf("taking a snapshot met a refusal: %v", e)
	default:
	}

	// What it may not: every write, and every subscription beyond its own inbox.
	for _, subject := range []string{"$JS.API.STREAM.CREATE.NEW", "$JS.API.STREAM.UPDATE.EVENTS",
		"$JS.API.STREAM.DELETE.EVENTS", "$JS.API.STREAM.PURGE.EVENTS", "$JS.API.STREAM.MSG.DELETE.EVENTS",
		"$JS.API.STREAM.RESTORE.NEW", "$JS.API.CONSUMER.CREATE.EVENTS", "$KV." + HandActsBucket + ".act",
		"mesh.mod.nats.event.anything", "mesh.node.anchor.declare"} {
		if _, err := snap.Request(subject, []byte(`{}`), 300*time.Millisecond); err == nil {
			t.Errorf("%s was answered", subject)
		}
		select {
		case e := <-errs:
			if !strings.Contains(strings.ToLower(e.Error()), "permissions violation") {
				t.Errorf("%s: %v", subject, e)
			}
		case <-time.After(2 * time.Second):
			t.Errorf("the bus did not refuse %s", subject)
		}
	}
	for _, subject := range []string{"mesh.>", "_INBOX.controller.>", "$KV.>"} {
		if _, err := snap.SubscribeSync(subject); err != nil {
			t.Fatal(err)
		}
		_ = snap.Flush()
		select {
		case e := <-errs:
			if !strings.Contains(strings.ToLower(e.Error()), "permissions violation") {
				t.Errorf("subscribing %s: %v", subject, e)
			}
		case <-time.After(2 * time.Second):
			t.Errorf("the bus let it subscribe %s", subject)
		}
	}
	if info, err := js.StreamInfo("EVENTS"); err != nil || info == nil {
		t.Fatalf("the stream is gone: %v", err)
	}
	if e, err := kv.Get("act"); err != nil || string(e.Value()) != "done by hand" {
		t.Fatalf("the bucket changed: %v", err)
	}
}