mesh-host/cmd/mesh-host/file_references_test.go

package main

import (
	"context"
	"encoding/json"
	"fmt"
	engcomp "github.com/novox/mesh-host/internal/compositions"
	"os"
	"path/filepath"
	"strconv"
	"strings"
	"testing"

	"git.novox.be/novox/mesh-sdk/go/declaration"
	"github.com/nats-io/nats.go"
	"github.com/novox/mesh-host/internal/link"
)

// aFilesLink is a link that serves objects by name, or fails every read with err.
type aFilesLink struct {
	objects map[string][]byte
	err     error
}

func (a aFilesLink) FileObject(_ context.Context, name string, _ int64) ([]byte, error) {
	if a.err != nil {
		return nil, a.err
	}
	if b, ok := a.objects[name]; ok {
		return b, nil
	}
	return nil, os.ErrNotExist
}

func referenceDeclaration(path string, body []byte) []byte {
	return []byte(`{"declaration":1,"resources":[{"id":"m.big","type":"file","path":"` + path + `","digest":"` +
		declaration.DigestOf(body) + `","size":` + strconv.Itoa(len(body)) + `}]}`)
}

// 1695/AC1 and AC2, through the whole apply: a reference is fetched, verified and written; a differing object
// refuses the declaration whole and writes nothing.
func TestADeclarationWithAFileByDigestAppliesFromTheObject(t *testing.T) {
	unansweringPacman(t)
	body := []byte(strings.Repeat("a line of a big file\n", 4000))
	name, _ := declaration.ObjectName(declaration.DigestOf(body))
	dir := t.TempDir()
	target := filepath.Join(dir, "big")
	opts := options{state: filepath.Join(dir, "state.json"), out: &strings.Builder{}}
	raw := referenceDeclaration(target, body)

	bad := append([]byte(nil), body...)
	bad[10] ^= 1
	ctx := link.WithFiles(context.Background(), aFilesLink{objects: map[string][]byte{name: bad}})
	report := applyAndKeep(ctx, opts, raw, nil, nil, nil)
	if report.Refused == "" || !strings.Contains(report.Refused, "m.big") {
		t.Errorf("1695/AC2: a differing object did not refuse the declaration: %+v", report)
	}
	if _, err := os.Stat(target); err == nil {
		t.Error("1695/AC2: a file was written from an object that differs")
	}
	if failedWith(report.Refused).Transient {
		t.Errorf("an object that differs is a real failure, and was taken as the bus not answering: %s", report.Refused)
	}

	// The bus answers no JetStream request while it reloads its accounts (2026-10-25 23:04:24, mesh-vault on the bus
	// node): the failure is transient, so the agent tries it again, and the detail kept is its cause, the tail.
	noResponders := fmt.Errorf("fetching the object 2bd98ebd of this node's own object bucket: reading the chunks of "+
		"object %s: %w", strings.Repeat("x", 300), nats.ErrNoResponders)
	ctx = link.WithFiles(context.Background(), aFilesLink{err: noResponders})
	report = applyAndKeep(ctx, opts, raw, nil, nil, nil)
	failed := failedWith("a file of this composition could not be had by its digest: file mesh-vault.kept: " + report.Refused)
	if !failed.Transient || !strings.HasSuffix(failed.Detail, nats.ErrNoResponders.Error()) || len(failed.Detail) > 310 ||
		!strings.HasPrefix(failed.Detail, "a file of this composition") {
		t.Errorf("a fetch that met no responders: transient %v, detail %q (%d bytes); want transient, its head and its cause",
			failed.Transient, failed.Detail, len(failed.Detail))
	}

	ctx = link.WithFiles(context.Background(), aFilesLink{objects: map[string][]byte{name: body}})
	report = applyAndKeep(ctx, opts, raw, nil, nil, nil)
	if report.Refused != "" {
		t.Fatalf("1695/AC1: refused: %s", report.Refused)
	}
	got, err := os.ReadFile(target)
	if err != nil || string(got) != string(body) {
		t.Errorf("1695/AC1: the file holds %d bytes (%v), want %d", len(got), err, len(body))
	}

	// Issue 924 (novox, 2026-10-29 01:16): the controller's sweep removed an object a composition the node ran still named,
	// and the module's apply failed while it ran. Content the node once had is its own keep's, and the bus is not asked.
	gone := aFilesLink{err: fmt.Errorf("the object %s was deleted from the bucket declaration-files-novox", name)}
	never := []byte(strings.Repeat("never had here\n", 6000))
	for _, row := range []struct {
		name    string
		raw     []byte
		onDisk  []byte // nil removes the file
		refused string // "" applies
	}{
		{"the file here drifted, its object deleted", raw, []byte("the module wrote it since"), ""},
		{"the file here is gone, its object deleted", raw, nil, ""},
		{"never had here, its object deleted", referenceDeclaration(target, never), nil, "never held it"},
	} {
		if row.onDisk == nil {
			_ = os.Remove(target)
		} else if err := os.WriteFile(target, row.onDisk, 0o600); err != nil {
			t.Fatal(err)
		}
		report = applyAndKeep(link.WithFiles(context.Background(), gone), opts, row.raw, nil, nil, nil)
		if row.refused == "" {
			got, _ := os.ReadFile(target)
			if report.Refused != "" || string(got) != string(body) {
				t.Errorf("924: %s: refused %q, the file holds %d bytes; want it applied from the node's own keep",
					row.name, report.Refused, len(got))
			}
		} else if !strings.Contains(report.Refused, row.refused) || !strings.Contains(report.Refused, "was deleted") {
			t.Errorf("924: %s: refused %q; want a refusal saying the bucket and the keep both lack it", row.name, report.Refused)
		}
	}

	// Issue 924, the live case: what runs came from the kept declaration, whose export names a digest swept long ago,
	// while the node wrote a newer export since. Composed as it runs, the file names what the node wrote, and applies with
	// no object; a file someone else changed since is left as named.
	newer := []byte(strings.Repeat("the export the node wrote since\n", 3000))
	newerName, _ := declaration.ObjectName(declaration.DigestOf(newer))
	ctx = link.WithFiles(context.Background(), aFilesLink{objects: map[string][]byte{newerName: newer}})
	if report = applyAndKeep(ctx, opts, referenceDeclaration(target, newer), nil, nil, nil); report.Refused != "" {
		t.Fatalf("924: the newer export: %s", report.Refused)
	}
	stale := json.RawMessage(`{"id":"m.big","type":"file","path":"` + target + `","digest":"` + declaration.DigestOf(body) +
		`","size":` + strconv.Itoa(len(body)) + `}`)
	for _, row := range []struct {
		name   string
		edit   []byte // what someone else wrote there since; nil for nobody
		digest string
	}{
		{"the file is what the node wrote", nil, declaration.DigestOf(newer)},
		{"someone changed the file since", []byte("a hand edit"), declaration.DigestOf(body)},
	} {
		if row.edit != nil {
			if err := os.WriteFile(target, row.edit, 0o600); err != nil {
				t.Fatal(err)
			}
		}
		runs := runsAsWritten([]engcomp.Composed{{Node: "n", Module: "m", Resources: []json.RawMessage{stale}}}, opts.state)
		var got struct {
			Digest string `json:"digest"`
		}
		_ = json.Unmarshal(runs[0].Resources[0], &got)
		if got.Digest != row.digest {
			t.Errorf("924: %s: what runs names %s, want %s", row.name, got.Digest, row.digest)
		}
		if row.edit == nil {
			raw := []byte(`{"declaration":1,"resources":[` + string(runs[0].Resources[0]) + `]}`)
			if report = applyAndKeep(link.WithFiles(context.Background(), gone), opts, raw, nil, nil, nil); report.Refused != "" {
				t.Errorf("924: %s: composed as it runs, refused %q; want applied with no object", row.name, report.Refused)
			}
		}
	}
}

// 1695/AC8: the hand-run `apply <file>` and `reconcile` have no bus: a reference whose file here verifies is applied
// as it is, any other refuses and writes nothing — never an empty file.
func TestTheHandApplyNeverWritesAReferenceEmpty(t *testing.T) {
	unansweringPacman(t)
	body := []byte(strings.Repeat("a line of a big file\n", 4000))
	dir := t.TempDir()
	target := filepath.Join(dir, "big")
	opts := options{state: filepath.Join(dir, "state.json"), out: &strings.Builder{}}
	raw := referenceDeclaration(target, body)
	d, err := declaration.ParseFileTrusted(raw)
	if err != nil {
		t.Fatal(err)
	}
	if err := runApply(context.Background(), opts, d, raw, fromFile); err == nil || !strings.Contains(err.Error(), "digest") {
		t.Errorf("1695/AC8: a reference with no file and no bus was not refused: %v", err)
	}
	if _, err := os.Stat(target); err == nil {
		t.Error("1695/AC8: a file was written for a reference that could not be had")
	}
	if err := os.WriteFile(target, body, 0o644); err != nil {
		t.Fatal(err)
	}
	d, _ = declaration.ParseFileTrusted(raw)
	if err := runApply(context.Background(), opts, d, raw, fromFile); err != nil && !strings.Contains(err.Error(), "applied only in part") {
		t.Fatalf("1695/AC8: %v", err)
	}
	if got, _ := os.ReadFile(target); string(got) != string(body) {
		t.Errorf("1695/AC8: the file holds %d bytes, want %d", len(got), len(body))
	}
}