feat: add core.json snapshot generation from manifest

Co-Authored-By: Virgil <virgil@lethean.io>

snapshot/snapshot.go

@@ -0,0 +1,62 @@
+// Package snapshot generates frozen core.json release manifests.
+package snapshot
+
+import (
+	"encoding/json"
+	"errors"
+	"time"
+
+	"forge.lthn.ai/core/go-scm/manifest"
+)
+
+// Snapshot is the frozen release manifest written as core.json.
+type Snapshot struct {
+	Schema      int                            `json:"schema"`
+	Code        string                         `json:"code"`
+	Name        string                         `json:"name"`
+	Version     string                         `json:"version"`
+	Description string                         `json:"description,omitempty"`
+	Commit      string                         `json:"commit"`
+	Tag         string                         `json:"tag"`
+	Built       string                         `json:"built"`
+	Daemons     map[string]manifest.DaemonSpec `json:"daemons,omitempty"`
+	Layout      string                         `json:"layout,omitempty"`
+	Slots       map[string]string              `json:"slots,omitempty"`
+	Permissions *manifest.Permissions          `json:"permissions,omitempty"`
+	Modules     []string                       `json:"modules,omitempty"`
+}
+
+// Generate creates a core.json snapshot from a manifest.
+// The built timestamp is set to the current time.
+func Generate(m *manifest.Manifest, commit, tag string) ([]byte, error) {
+	return GenerateAt(m, commit, tag, time.Now().UTC())
+}
+
+// GenerateAt creates a core.json snapshot with an explicit build timestamp.
+func GenerateAt(m *manifest.Manifest, commit, tag string, built time.Time) ([]byte, error) {
+	if m == nil {
+		return nil, errors.New("snapshot: manifest is nil")
+	}
+
+	snap := Snapshot{
+		Schema:      1,
+		Code:        m.Code,
+		Name:        m.Name,
+		Version:     m.Version,
+		Description: m.Description,
+		Commit:      commit,
+		Tag:         tag,
+		Built:       built.Format(time.RFC3339),
+		Daemons:     m.Daemons,
+		Layout:      m.Layout,
+		Slots:       m.Slots,
+		Modules:     m.Modules,
+	}
+
+	if m.Permissions.Read != nil || m.Permissions.Write != nil ||
+		m.Permissions.Net != nil || m.Permissions.Run != nil {
+		snap.Permissions = &m.Permissions
+	}
+
+	return json.MarshalIndent(snap, "", "  ")
+}

snapshot/snapshot_test.go

@@ -0,0 +1,55 @@
+package snapshot
+
+import (
+	"encoding/json"
+	"testing"
+
+	"forge.lthn.ai/core/go-scm/manifest"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestGenerate_Good(t *testing.T) {
+	m := &manifest.Manifest{
+		Code:        "test-app",
+		Name:        "Test App",
+		Version:     "1.0.0",
+		Description: "A test application",
+		Daemons: map[string]manifest.DaemonSpec{
+			"serve": {Binary: "core-php", Args: []string{"php", "serve"}, Default: true},
+		},
+		Modules: []string{"core/media"},
+	}
+
+	data, err := Generate(m, "abc123def456", "v1.0.0")
+	require.NoError(t, err)
+
+	var snap Snapshot
+	require.NoError(t, json.Unmarshal(data, &snap))
+
+	assert.Equal(t, 1, snap.Schema)
+	assert.Equal(t, "test-app", snap.Code)
+	assert.Equal(t, "1.0.0", snap.Version)
+	assert.Equal(t, "abc123def456", snap.Commit)
+	assert.Equal(t, "v1.0.0", snap.Tag)
+	assert.NotEmpty(t, snap.Built)
+	assert.Len(t, snap.Daemons, 1)
+	assert.Equal(t, "core-php", snap.Daemons["serve"].Binary)
+}
+
+func TestGenerate_Good_NoDaemons(t *testing.T) {
+	m := &manifest.Manifest{
+		Code:    "simple",
+		Name:    "Simple",
+		Version: "0.1.0",
+	}
+
+	data, err := Generate(m, "abc123", "v0.1.0")
+	require.NoError(t, err)
+
+	var snap Snapshot
+	require.NoError(t, json.Unmarshal(data, &snap))
+
+	assert.Equal(t, "simple", snap.Code)
+	assert.Nil(t, snap.Daemons)
+}