feat: port stacks command from influxdb (#168)

pkg/template/out.go

@@ -0,0 +1,63 @@
+package template
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+
+	"github.com/influxdata/influx-cli/v2/api"
+	"gopkg.in/yaml.v3"
+)
+
+type OutEncoding int
+
+const (
+	YamlEncoding OutEncoding = iota
+	JsonEncoding
+)
+
+type OutParams struct {
+	Out      io.Writer
+	Encoding OutEncoding
+}
+
+func ParseOutParams(path string, fallback io.Writer) (OutParams, func(), error) {
+	if path == "" {
+		return OutParams{Out: fallback, Encoding: YamlEncoding}, nil, nil
+	}
+
+	f, err := os.OpenFile(path, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
+	if err != nil {
+		return OutParams{}, nil, fmt.Errorf("failed to open output path %q: %w", path, err)
+	}
+	params := OutParams{Out: f}
+	switch filepath.Ext(path) {
+	case ".json":
+		params.Encoding = JsonEncoding
+	default:
+		params.Encoding = YamlEncoding
+	}
+
+	return params, func() { _ = f.Close() }, nil
+}
+
+func (o OutParams) WriteTemplate(template []api.TemplateEntry) error {
+	switch o.Encoding {
+	case JsonEncoding:
+		enc := json.NewEncoder(o.Out)
+		enc.SetIndent("", "\t")
+		return enc.Encode(template)
+	case YamlEncoding:
+		enc := yaml.NewEncoder(o.Out)
+		for _, entry := range template {
+			if err := enc.Encode(entry); err != nil {
+				return err
+			}
+		}
+	default:
+		return fmt.Errorf("encoding %q is not recognized", o.Encoding)
+	}
+	return nil
+}

pkg/template/out_test.go

@@ -0,0 +1,124 @@
+package template_test
+
+import (
+	"bytes"
+	"encoding/json"
+	"io"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/influxdata/influx-cli/v2/api"
+	"github.com/influxdata/influx-cli/v2/pkg/template"
+	"github.com/stretchr/testify/require"
+	"gopkg.in/yaml.v3"
+)
+
+var tmpls = []api.TemplateEntry{
+	{
+		ApiVersion: "api1",
+		Kind:       "Foo",
+		Metadata: api.TemplateEntryMetadata{
+			Name: "foo",
+		},
+		Spec: map[string]interface{}{
+			"hello":   "world",
+			"1 + 1 =": "2",
+		},
+	},
+	{
+		ApiVersion: "api1",
+		Kind:       "Bar",
+		Metadata: api.TemplateEntryMetadata{
+			Name: "bar",
+		},
+		Spec: map[string]interface{}{
+			"success?": "true",
+		},
+	},
+}
+
+func TestOutParams(t *testing.T) {
+	t.Parallel()
+
+	t.Run("json to file", func(t *testing.T) {
+		t.Parallel()
+
+		tmp, err := os.MkdirTemp("", "")
+		require.NoError(t, err)
+		defer os.RemoveAll(tmp)
+
+		out := filepath.Join(tmp, "test.json")
+		params, closer, err := template.ParseOutParams(out, nil)
+		require.NoError(t, err)
+		require.NotNil(t, closer)
+		defer closer()
+
+		require.NoError(t, params.WriteTemplate(tmpls))
+		contents, err := os.ReadFile(out)
+		require.NoError(t, err)
+
+		var written []api.TemplateEntry
+		dec := json.NewDecoder(bytes.NewReader(contents))
+		require.NoError(t, dec.Decode(&written))
+
+		require.Equal(t, tmpls, written)
+	})
+
+	t.Run("yaml to file", func(t *testing.T) {
+		t.Parallel()
+
+		tmp, err := os.MkdirTemp("", "")
+		require.NoError(t, err)
+		defer os.RemoveAll(tmp)
+
+		out := filepath.Join(tmp, "test.yaml")
+		params, closer, err := template.ParseOutParams(out, nil)
+		require.NoError(t, err)
+		require.NotNil(t, closer)
+		defer closer()
+
+		require.NoError(t, params.WriteTemplate(tmpls))
+		contents, err := os.ReadFile(out)
+		require.NoError(t, err)
+
+		var written []api.TemplateEntry
+		dec := yaml.NewDecoder(bytes.NewReader(contents))
+		for {
+			var e api.TemplateEntry
+			err := dec.Decode(&e)
+			if err == io.EOF {
+				break
+			}
+			require.NoError(t, err)
+			written = append(written, e)
+		}
+
+		require.Equal(t, tmpls, written)
+	})
+
+	t.Run("yaml to buffer", func(t *testing.T) {
+		t.Parallel()
+
+		out := bytes.Buffer{}
+		params, closer, err := template.ParseOutParams("", &out)
+		require.NoError(t, err)
+		require.Nil(t, closer)
+
+		require.NoError(t, params.WriteTemplate(tmpls))
+
+		var written []api.TemplateEntry
+		dec := yaml.NewDecoder(&out)
+		for {
+			var e api.TemplateEntry
+			err := dec.Decode(&e)
+			if err == io.EOF {
+				break
+			}
+			require.NoError(t, err)
+			written = append(written, e)
+		}
+
+		require.Equal(t, tmpls, written)
+	})
+}