package inventory

import (
	"context"
	"strings"
	"testing"
	"time"

	"github.com/novox/mesh-controller/internal/broker"
	"github.com/novox/mesh-controller/internal/catalogue"
)

// Reading the bus's user list out of the mesh's records, against a real store.
//
// What each of these is about is a user that would be **missing or wrong in a way nothing reports**:
// the server reads whatever file it is given, and a module whose user is absent fails on its first
// publish with an authorisation error that says nothing about a missing assignment.

func aMeshWith(t *testing.T, manifests ...catalogue.Manifest) (*Inventory, context.Context) {
	t.Helper()
	inv := ForTest(t)
	ctx := context.Background()
	for _, m := range manifests {
		if err := inv.RegisterModule(ctx, m, Source{Repository: "/r"}); err != nil {
			t.Fatal(err)
		}
	}
	return inv, ctx
}

func theSeatDeclarer() catalogue.Manifest {
	return catalogue.Manifest{
		Module: "telegram", Version: "1",
		DefinesSeats: []catalogue.SeatDeclaration{{
			Name: "telegram-sender", Accepts: []string{"send"}, Emits: []string{"delivered"},
		}},
		Claims: []catalogue.Claim{{Name: "telegram-sender", Scope: catalogue.ScopeMesh}},
	}
}

// A module assigned to a machine becomes a user with the authority its manifest declared — and the
// protocol of a seat declared by a *different* module, which is the whole reason a seat exists.
func TestAnAssignedModuleBecomesAUserWithWhatItDeclared(t *testing.T) {
	shop := catalogue.Manifest{
		Module: "shop", Version: "1",
		Emits: []string{"order.placed"}, Tools: []string{"price"},
		Uses: []string{"telegram-sender"},
	}
	inv, ctx := aMeshWith(t, theSeatDeclarer(), shop)
	if _, err := inv.AddNode(ctx, "one"); err != nil {
		t.Fatal(err)
	}
	if _, err := inv.Assign(ctx, "one", "shop"); err != nil {
		t.Fatal(err)
	}

	records, err := inv.BusRecords(ctx)
	if err != nil {
		t.Fatal(err)
	}
	on := records.Assigned["one"]
	if len(on) != 1 || on[0].Module != "shop" {
		t.Fatalf("the machine's modules read as %+v", on)
	}
	if len(on[0].Uses) != 1 || on[0].Uses[0].Accepts[0] != "send" {
		t.Fatalf("the seat it uses carries no protocol: %+v — so it would be granted nothing on a "+
			"seat it was assigned to send to", on[0].Uses)
	}
	if len(on[0].Serves) != 1 || on[0].Serves[0] != "price" {
		t.Fatalf("its tools read as %v, and a module that cannot subscribe its own tool subject "+
			"serves nothing", on[0].Serves)
	}

	// And it derives into a user the server would accept.
	users, err := broker.Users(records)
	if err != nil {
		t.Fatal(err)
	}
	var found bool
	for _, u := range users {
		if u.Username() != "one.shop" {
			continue
		}
		found = true
		perms, err := broker.PermissionsFor(u)
		if err != nil {
			t.Fatal(err)
		}
		if !granted(perms.Publish, "mesh.mod.shop.event.order.placed") ||
			!granted(perms.Publish, "mesh.seat.telegram-sender.accept.send") ||
			!granted(perms.Subscribe, "mesh.mod.shop.tool.price") {
			t.Fatalf("one.shop's authority is not what it declared: %+v", perms)
		}
	}
	if !found {
		t.Fatal("no user was derived for the assigned module")
	}
}

// A machine holding a live token gets an enrolment user; one whose token is spent or expired does
// not. **An enrolment user outliving its token is a right to join that nobody issued.**
func TestOnlyAMachineWithALiveTokenHasAnEnrolmentUser(t *testing.T) {
	inv, ctx := aMeshWith(t)
	for _, name := range []string{"live", "expired", "none"} {
		if _, err := inv.AddNode(ctx, name); err != nil {
			t.Fatal(err)
		}
	}
	if _, err := inv.IssueToken(ctx, "live", time.Hour); err != nil {
		t.Fatal(err)
	}
	// Briefly, then waited out: a token with no lifetime is refused at issue, which is the right
	// refusal and leaves this as the way to have an expired one.
	if _, err := inv.IssueToken(ctx, "expired", 10*time.Millisecond); err != nil {
		t.Fatal(err)
	}
	time.Sleep(50 * time.Millisecond)

	records, err := inv.BusRecords(ctx)
	if err != nil {
		t.Fatal(err)
	}
	if strings.Join(records.Enrolling, ",") != "live" {
		t.Fatalf("machines with a live token read as %v", records.Enrolling)
	}
}

// A module assigned and absent from the catalogue is refused rather than composed with no authority.
//
// **The catalogue refuses to forget an assigned module, so this is the second line and not the
// first** — and it earns its place there: relying on another package's invariant is how a rule ends
// up enforced by nothing. Checked against the derivation directly, because the situation cannot be
// reached through the store.
func TestAnAssignmentWithNoManifestDerivesNoAuthority(t *testing.T) {
	// What BusRecords would have produced had it composed a ghost: a module with nothing declared.
	users, err := broker.Users(broker.Records{
		Nodes:    []string{"one"},
		Assigned: map[string][]broker.Declared{"one": {{Module: "ghost"}}},
	})
	if err != nil {
		t.Fatal(err)
	}
	perms, err := broker.PermissionsFor(users[len(users)-1])
	if err != nil {
		t.Fatal(err)
	}
	// Its inbox and its ack subject, and nothing it could say. That is a module which starts,
	// connects, and is refused by the server on its first publish — an authorisation error that
	// says nothing about a missing manifest, which is why BusRecords names it instead.
	for _, p := range perms.Publish {
		if strings.HasPrefix(p, "mesh.mod.ghost.event.") {
			t.Fatalf("a module with no manifest was granted %s", p)
		}
	}
}

func granted(all []string, one string) bool {
	for _, s := range all {
		if s == one {
			return true
		}
	}
	return false
}