pretty print json output

go.mod

@@ -49,6 +49,7 @@ require (
 	github.com/hashicorp/go-version v1.2.1 // indirect
 	github.com/hashicorp/hcl v0.0.0-20170504190234-a4b07c25de5f // indirect
 	github.com/hashicorp/terraform-svchost v0.0.0-20200729002733-f050f53b9734 // indirect
+	github.com/hokaccha/go-prettyjson v0.0.0-20211117102719-0474bc63780f // indirect
 	github.com/lucasb-eyer/go-colorful v1.2.0 // indirect
 	github.com/mattn/go-colorable v0.1.4 // indirect
 	github.com/mattn/go-isatty v0.0.19 // indirect

go.sum

@@ -316,6 +316,8 @@ github.com/hashicorp/terraform-svchost v0.0.0-20200729002733-f050f53b9734 h1:HKL
 github.com/hashicorp/terraform-svchost v0.0.0-20200729002733-f050f53b9734/go.mod h1:kNDNcF7sN4DocDLBkQYz73HGKwN1ANB1blq4lIYLYvg=
 github.com/hashicorp/yamux v0.0.0-20180604194846-3520598351bb/go.mod h1:+NfK9FKeTrX5uv1uIXGdwYDTeHna2qgaIlx54MXqjAM=
 github.com/hashicorp/yamux v0.0.0-20181012175058-2f1d1f20f75d/go.mod h1:+NfK9FKeTrX5uv1uIXGdwYDTeHna2qgaIlx54MXqjAM=
+github.com/hokaccha/go-prettyjson v0.0.0-20211117102719-0474bc63780f h1:7LYC+Yfkj3CTRcShK0KOL/w6iTiKyqqBA9a41Wnggw8=
+github.com/hokaccha/go-prettyjson v0.0.0-20211117102719-0474bc63780f/go.mod h1:pFlLw2CfqZiIBOx6BuCeRLCrfxBJipTY0nIOF/VbGcI=
 github.com/hpcloud/tail v1.0.0/go.mod h1:ab1qPbhIpdTxEkNHXyeSf5vhxWSCs/tWer42PpOxQnU=
 github.com/huandu/xstrings v1.3.2/go.mod h1:y5/lhBue+AyNmUVz9RLU9xbLR0o4KIIExikq4ovT0aE=
 github.com/ianlancetaylor/demangle v0.0.0-20181102032728-5e5cf60278f6/go.mod h1:aSSvb/t6k1mPoxDqO4vJh6VOCGPwU4O0C2/Eqndh1Sc=

internal/state/service.go

@@ -88,6 +88,7 @@ func (s *Service) Reload(workspaceID resource.ID) (*task.Task, error) {
 
 	task, err := s.createTask(workspaceID, task.CreateOptions{
 		Command: []string{"show", "-json"},
+		JSON:    true,
 		AfterError: func(t *task.Task) {
 			s.logger.Error("reloading state", "error", t.Err, "workspace", ws)
 		},

internal/task/task.go

@@ -27,6 +27,7 @@ type Task struct {
 	Blocking bool
 	State    Status
 	Env      []string
+	JSON     bool
 
 	program   string
 	exclusive bool
@@ -94,6 +95,8 @@ type CreateOptions struct {
 	Blocking bool
 	// Globally exclusive task - at most only one such task can be running
 	Exclusive bool
+	// Set to true to indicate that the task produces JSON output
+	JSON bool
 	// Call this function after the task has successfully finished
 	AfterExited func(*Task)
 	// Call this function after the task is enqueued.
@@ -123,6 +126,7 @@ func (f *factory) newTask(opts CreateOptions) (*Task, error) {
 		Path:          opts.Path,
 		Args:          opts.Args,
 		Env:           opts.Env,
+		JSON:          opts.JSON,
 		Blocking:      opts.Blocking,
 		exclusive:     opts.Exclusive,
 		AfterExited:   opts.AfterExited,

internal/tui/task/model.go

@@ -10,6 +10,7 @@ import (
 	"github.com/charmbracelet/bubbles/viewport"
 	tea "github.com/charmbracelet/bubbletea"
 	"github.com/charmbracelet/lipgloss"
+	"github.com/hokaccha/go-prettyjson"
 	"github.com/leg100/pug/internal/resource"
 	"github.com/leg100/pug/internal/task"
 	"github.com/leg100/pug/internal/tui"
@@ -112,7 +113,28 @@ func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		m.content = wordwrap.String(m.content, m.width)
 		m.viewport.SetContent(m.content)
 		m.viewport.GotoBottom()
-		if !msg.eof {
+		if msg.eof {
+			if m.task.JSON {
+				// Prettify JSON output from task. This can only be done once
+				// the task has finished and has produced complete and
+				// syntactically valid json object(s).
+				//
+				// Note: terraform commands such as `state -json` can produce
+				// json strings with embedded newlines, which is invalid json
+				// and breaks the pretty printer. So we escape the newlines.
+				//
+				// TODO: avoid casting to string and back, thereby avoiding
+				// unnecessary allocations.
+				m.content = strings.ReplaceAll(m.content, "\n", "\\n")
+				if b, err := prettyjson.Format([]byte(m.content)); err != nil {
+					cmds = append(cmds, tui.ReportError(err, "pretty printing task json output"))
+				} else {
+					m.content = string(b)
+					m.viewport.SetContent(string(b))
+					m.viewport.GotoBottom()
+				}
+			}
+		} else {
 			cmds = append(cmds, m.getOutput)
 		}
 	case resource.Event[*task.Task]: