package link_test

import (
	"context"
	"crypto/ed25519"
	"encoding/base64"
	"encoding/json"
	"os"
	"strings"
	"testing"

	"golang.org/x/crypto/nacl/box"

	"github.com/novox/mesh-control/internal/catalogue"
	"github.com/novox/mesh-control/internal/inventory"
	"github.com/novox/mesh-control/internal/link"
)

// What a node says when it joins, as that node's own code writes it.
//
// The two ends are separate structs in separate repositories, and a field renamed on one side
// fails silently: enrolment succeeds, a key is simply absent, and the node looks joined until the
// first thing sealed to it cannot be opened — by which time nobody is looking at enrolment.
//
// Skipped unless MESH_ENROL names the file the host's suite wrote:
//
//	mesh-host:    MESH_ENROL_OUT=/tmp/enrol.json go test ./internal/link/
//	mesh-control: MESH_ENROL=/tmp/enrol.json make check
//
// **What this does not cover**, said so nobody reads more into a pass than is there: the full
// enrolment path also issues a broker account, and that needs a broker. What is checked here is
// the shape the two sides agree on and that a key which arrives this way can actually be sealed
// to — which is the part that was newly wired and the part that fails quietly.
func TestWhatANodeSaysWhenItJoinsIsWhatThisMeshReads(t *testing.T) {
	path := os.Getenv("MESH_ENROL")
	if path == "" {
		t.Skip("set MESH_ENROL to an enrolment request written by the host's suite")
	}
	raw, err := os.ReadFile(path)
	if err != nil {
		t.Fatal(err)
	}

	var request link.EnrolRequest
	if err := json.Unmarshal(raw, &request); err != nil {
		t.Fatalf("this mesh cannot read what a node sends:\n%v", err)
	}
	for what, got := range map[string]string{
		"node":        request.Node,
		"secret":      request.Secret,
		"overlay key": request.OverlayKey,
		"sealing key": request.SealingKey,
	} {
		if got == "" {
			t.Fatalf("the %s did not survive the crossing — a field name differs", what)
		}
	}
	if len(request.PublicKey) != ed25519.PublicKeySize {
		t.Fatalf("the identity arrived as %d bytes", len(request.PublicKey))
	}

	// And that a key arriving this way is one the mesh can actually seal to. Recording it is not
	// the same as it being usable, and "recorded" is what a shape check on its own would prove.
	inv := liveInventory(t)
	ctx := context.Background()
	node, err := inv.AddNode(ctx, request.Node)
	if err != nil {
		t.Fatal(err)
	}
	other, err := inv.AddNode(ctx, "the-other-end")
	if err != nil {
		t.Fatal(err)
	}
	if err := inv.RecordSealingKey(ctx, node.ID, request.SealingKey); err != nil {
		t.Fatal(err)
	}
	if err := inv.RecordSealingKey(ctx, other.ID, request.SealingKey); err != nil {
		t.Fatal(err)
	}

	// A credential belongs to a module on a machine (novox/hq 04-ISSUES/022), so the module
	// holding it has to exist before it can.
	if err := inv.RegisterModule(ctx, catalogue.Manifest{Module: "gitea", Version: "1"},
		inventory.Source{}); err != nil {
		t.Fatal(err)
	}

	secret, err := inv.SecretFor(ctx, "postgres-database", request.Node, "gitea", "the-other-end")
	if err != nil {
		t.Fatalf("nothing could be sealed to a key that arrived from a real node: %v", err)
	}

	// Opened with the private half the host's suite kept, so this asserts the node could read it
	// rather than that a blob exists.
	privateRaw, err := os.ReadFile(path + ".sealing-private")
	if err != nil {
		t.Skipf("no private half beside %s, so this can only check the shape", path)
	}
	private, err := base64.StdEncoding.DecodeString(strings.TrimSpace(string(privateRaw)))
	if err != nil || len(private) != 32 {
		t.Fatal("the private half beside the request is not a key")
	}
	public, err := base64.StdEncoding.DecodeString(request.SealingKey)
	if err != nil {
		t.Fatal(err)
	}
	var pub, priv [32]byte
	copy(pub[:], public)
	copy(priv[:], private)
	blob, err := base64.StdEncoding.DecodeString(secret.ForConsumer)
	if err != nil {
		t.Fatal(err)
	}
	if _, ok := box.OpenAnonymous(nil, blob, &pub, &priv); !ok {
		t.Fatal("the node could not open what this mesh sealed to the key it sent")
	}
}

// liveInventory is a database of its own for this test, skipping where there is none.
func liveInventory(t *testing.T) *inventory.Inventory {
	t.Helper()
	if os.Getenv("MESH_TEST_POSTGRES") == "" {
		t.Skip("no MESH_TEST_POSTGRES; run `make check` to raise one")
	}
	return inventory.ForTest(t)
}