package broker

import (
	"os"
	"path/filepath"
	"strings"
	"testing"

	"github.com/nats-io/nats-server/v2/server"
)

// 1147/AC1: the composed accounts file declares $SYS with no user, exporting only the connect and disconnect events of
// MESH and the request listing MESH's connections, and MESH imports exactly those three as mesh.bus.connect,
// mesh.bus.disconnect and mesh.bus.connz (novox/hq ADR 0431 §1); the server's own grammar takes it with $SYS as its
// system account; the golden file shows it (TestTheComposedConfigMatchesTheGolden).
func TestTheComposedAccountsExportMeshsConnectionEventsFromTheSystemAccount(t *testing.T) { // 1147/AC1
	text, err := ComposeAccounts([]Principal{{Kind: KindNode, Node: "one", PasswordHash: "x"}})
	if err != nil {
		t.Fatal(err)
	}
	sys := between(text, `"$SYS" {`, "\n  }\n")
	if sys == "" {
		t.Fatalf("no account $SYS in the composed accounts:\n%s", text)
	}
	if strings.Contains(sys, "users") || strings.Contains(sys, "user:") {
		t.Errorf("$SYS holds a user:\n%s", sys)
	}
	for _, want := range []string{
		`{ stream: "$SYS.ACCOUNT.MESH.CONNECT", accounts: ["MESH"] }`,
		`{ stream: "$SYS.ACCOUNT.MESH.DISCONNECT", accounts: ["MESH"] }`,
		`{ service: "$SYS.REQ.ACCOUNT.MESH.CONNZ", accounts: ["MESH"] }`,
	} {
		if !strings.Contains(sys, want) {
			t.Errorf("$SYS does not export %s:\n%s", want, sys)
		}
	}
	if n := strings.Count(sys, "{ stream:") + strings.Count(sys, "{ service:"); n != 3 {
		t.Errorf("$SYS exports %d things, want exactly 3:\n%s", n, sys)
	}
	mesh := between(text, "  MESH {", "    users = [")
	for _, want := range []string{
		`{ stream: { account: "$SYS", subject: "$SYS.ACCOUNT.MESH.CONNECT" }, to: "mesh.bus.connect" }`,
		`{ stream: { account: "$SYS", subject: "$SYS.ACCOUNT.MESH.DISCONNECT" }, to: "mesh.bus.disconnect" }`,
		`{ service: { account: "$SYS", subject: "$SYS.REQ.ACCOUNT.MESH.CONNZ" }, to: "mesh.bus.connz" }`,
	} {
		if !strings.Contains(mesh, want) {
			t.Errorf("MESH does not import %s:\n%s", want, mesh)
		}
	}
	if n := strings.Count(mesh, "{ stream:") + strings.Count(mesh, "{ service:"); n != 3 {
		t.Errorf("MESH imports %d things, want exactly 3:\n%s", n, mesh)
	}

	// The pinned server's grammar takes it, and makes $SYS its system account.
	path := filepath.Join(t.TempDir(), "accounts.conf")
	if err := os.WriteFile(path, []byte(text), 0o600); err != nil {
		t.Fatal(err)
	}
	opts, err := server.ProcessConfigFile(path)
	if err != nil {
		t.Fatalf("the server refuses the composed accounts: %v", err)
	}
	var found bool
	for _, a := range opts.Accounts {
		if a.Name != "$SYS" {
			continue
		}
		found = true
		if !a.IsExportService("$SYS.REQ.ACCOUNT.MESH.CONNZ") {
			t.Error("$SYS does not export the connections request as a service")
		}
	}
	if !found {
		t.Error("the server read no account $SYS")
	}
	for _, u := range opts.Users {
		if u.Account != nil && u.Account.Name == "$SYS" {
			t.Errorf("user %s is in $SYS", u.Username)
		}
	}
}

// between is the text from the first start to the first end after it, or empty.
func between(s, start, end string) string {
	i := strings.Index(s, start)
	if i < 0 {
		return ""
	}
	rest := s[i:]
	j := strings.Index(rest[len(start):], end)
	if j < 0 {
		return rest
	}
	return rest[:len(start)+j]
}

// 1147/AC2: only mesh-delivery-watchman's principal may subscribe to mesh.bus.connect and mesh.bus.disconnect and
// publish to mesh.bus.connz; no other principal's grant covers them by a wildcard (ADR 0431 §2).
func TestOnlyTheWatchmanHearsTheBusConnectionEvents(t *testing.T) { // 1147/AC2
	builder := Seat{Name: "node-build-agent", Scope: "node", Accepts: []string{"build"}, Emits: []string{"built"}}
	watchman := Principal{Kind: KindModule, Node: "one", Module: "mesh-delivery-watchman", PasswordHash: "x"}
	others := []Principal{
		{Kind: KindController, PasswordHash: "x"},
		{Kind: KindNode, Node: "one", PasswordHash: "x"},
		{Kind: KindEnrolment, Node: "two", PasswordHash: "x"},
		{Kind: KindPerson, Module: "jochen", Invokes: []string{"*"}, PasswordHash: "x"},
		{Kind: KindProvisioner, Node: "one", PasswordHash: "x"},
		{Kind: KindModule, Node: "one", Module: "gitea", Emits: []string{"pull.merged"}, PasswordHash: "x"},
		{Kind: KindModule, Node: "one", Module: "mesh-delivery-view", PasswordHash: "x",
			Reads: []string{"node-engine.have"}, Consumes: []string{"mesh-delivery-watchman.presence"}},
		{Kind: KindModule, Node: "one", Module: "build-agent", Holds: []Seat{builder}, PasswordHash: "x"},
		{Kind: KindModule, Node: "one", Module: "nats", SnapshotsTheBus: true, PasswordHash: "x"},
		{Kind: KindNodeTools, Node: "one", Module: RuntimeModule, PasswordHash: "x", Carries: []Declared{
			{Module: "mesh-delivery-watchman"}, {Module: "build-agent", Holds: []Seat{builder}}}},
	}
	heard := []string{"mesh.bus.connect", "mesh.bus.disconnect"}
	perms, err := PermissionsFor(watchman)
	if err != nil {
		t.Fatal(err)
	}
	for _, s := range heard {
		has(t, perms.Subscribe, s)
	}
	has(t, perms.Publish, "mesh.bus.connz")
	for _, s := range append(heard, "mesh.bus.connz") {
		for _, p := range perms.Subscribe {
			if p != s && SubjectsOverlap(p, s) && !strings.HasPrefix(p, "_INBOX.") {
				t.Errorf("the watchman's subscription %q reaches %s beyond naming it", p, s)
			}
		}
	}
	for _, p := range others {
		perms, err := PermissionsFor(p)
		if err != nil {
			t.Fatalf("%s: %v", p.Username(), err)
		}
		for _, s := range append(heard, "mesh.bus.connz") {
			for _, g := range append(append([]string(nil), perms.Publish...), perms.Subscribe...) {
				if SubjectsOverlap(g, s) {
					t.Errorf("%s is granted %q, which covers %s", p.Username(), g, s)
				}
			}
		}
	}
}