Add 'GET /' endpoint for getting the program state (experimental)

Related #3372

CHANGELOG.md

@@ -14,6 +14,14 @@ CHANGELOG
   # Client
   curl localhost:6266 -H "x-api-key: $FZF_API_KEY" -d 'change-query(yo)'
   ```
+- `--listen` server can report program state in JSON format (`GET /`)
+  ```sh
+  # fzf server started in "headless" mode
+  fzf --listen 6266 2> /dev/null
+
+  # Get program state
+  curl localhost:6266 | jq .
+  ```
 - Added `toggle-header` action
 - Bug fixes
 

man/man1/fzf.1

@@ -795,6 +795,9 @@ e.g.
      \fB# Start HTTP server on port 6266
      fzf --listen 6266
 
+     # Get program state in JSON format (experimental)
+     curl localhost:6266
+
      # Send action to the server
      curl -XPOST localhost:6266 -d 'reload(seq 100)+change-prompt(hundred> )'
 

src/server.go

@@ -24,10 +24,11 @@ const (
 
 type httpServer struct {
 	apiKey          []byte
-	channel chan []*action
+	actionChannel   chan []*action
+	responseChannel chan string
 }
 
-func startHttpServer(port int, channel chan []*action) (error, int) {
+func startHttpServer(port int, actionChannel chan []*action, responseChannel chan string) (error, int) {
 	if port < 0 {
 		return nil, port
 	}
@@ -51,7 +52,8 @@ func startHttpServer(port int, channel chan []*action) (error, int) {
 
 	server := httpServer{
 		apiKey:          []byte(os.Getenv("FZF_API_KEY")),
-		channel: channel,
+		actionChannel:   actionChannel,
+		responseChannel: responseChannel,
 	}
 
 	go func() {
@@ -83,13 +85,18 @@ func (server *httpServer) handleHttpRequest(conn net.Conn) string {
 	contentLength := 0
 	apiKey := ""
 	body := ""
-	unauthorized := func(message string) string {
+	answer := func(code string, message string) string {
 		message += "\n"
-		return httpUnauthorized + fmt.Sprintf("Content-Length: %d%s", len(message), crlf+crlf+message)
+		return code + fmt.Sprintf("Content-Length: %d%s", len(message), crlf+crlf+message)
+	}
+	unauthorized := func(message string) string {
+		return answer(httpUnauthorized, message)
 	}
 	bad := func(message string) string {
-		message += "\n"
+		return answer(httpBadRequest, message)
-		return httpBadRequest + fmt.Sprintf("Content-Length: %d%s", len(message), crlf+crlf+message)
+	}
+	good := func(message string) string {
+		return answer(httpOk+"Content-Type: application/json"+crlf, message)
 	}
 	conn.SetReadDeadline(time.Now().Add(httpReadTimeout))
 	scanner := bufio.NewScanner(conn)
@@ -110,7 +117,12 @@ func (server *httpServer) handleHttpRequest(conn net.Conn) string {
 		text := scanner.Text()
 		switch section {
 		case 0:
-			if !strings.HasPrefix(text, "POST / HTTP") {
+			// TODO: Parameter support e.g. "GET /?limit=100 HTTP"
+			if strings.HasPrefix(text, "GET / HTTP") {
+				server.actionChannel <- []*action{{t: actResponse}}
+				response := <-server.responseChannel
+				return good(response)
+			} else if !strings.HasPrefix(text, "POST / HTTP") {
 				return bad("invalid request method")
 			}
 			section++
@@ -160,6 +172,6 @@ func (server *httpServer) handleHttpRequest(conn net.Conn) string {
 		return bad("no action specified")
 	}
 
-	server.channel <- actions
+	server.actionChannel <- actions
 	return httpOk
 }

src/terminal.go

@@ -2,6 +2,7 @@ package fzf
 
 import (
 	"bufio"
+	"encoding/json"
 	"fmt"
 	"io"
 	"math"
@@ -144,6 +145,23 @@ var emptyLine = itemLine{}
 
 type labelPrinter func(tui.Window, int)
 
+type StatusItem struct {
+	Index int    `json:"index"`
+	Text  string `json:"text"`
+}
+
+type Status struct {
+	Reading    bool         `json:"reading"`
+	Query      string       `json:"query"`
+	Position   int          `json:"position"`
+	Sort       bool         `json:"sort"`
+	TotalCount int          `json:"totalCount"`
+	MatchCount int          `json:"matchCount"`
+	Current    *StatusItem  `json:"current"`
+	Matches    []StatusItem `json:"matches"`
+	Selected   []StatusItem `json:"selected"`
+}
+
 // Terminal represents terminal input/output
 type Terminal struct {
 	initDelay          time.Duration
@@ -245,7 +263,8 @@ type Terminal struct {
 	sigstop            bool
 	startChan          chan fitpad
 	killChan           chan int
-	serverChan         chan []*action
+	serverInputChan    chan []*action
+	serverOutputChan   chan string
 	eventChan          chan tui.Event
 	slab               *util.Slab
 	theme              *tui.ColorTheme
@@ -398,6 +417,7 @@ const (
 	actUnbind
 	actRebind
 	actBecome
+	actResponse
 )
 
 type placeholderFlags struct {
@@ -657,7 +677,8 @@ func NewTerminal(opts *Options, eventBox *util.EventBox) *Terminal {
 		theme:              opts.Theme,
 		startChan:          make(chan fitpad, 1),
 		killChan:           make(chan int),
-		serverChan:         make(chan []*action, 10),
+		serverInputChan:    make(chan []*action, 10),
+		serverOutputChan:   make(chan string),
 		eventChan:          make(chan tui.Event, 1),
 		tui:                renderer,
 		initFunc:           func() { renderer.Init() },
@@ -703,7 +724,7 @@ func NewTerminal(opts *Options, eventBox *util.EventBox) *Terminal {
 	_, t.hasLoadActions = t.keymap[tui.Load.AsEvent()]
 
 	if t.listenPort != nil {
-		err, port := startHttpServer(*t.listenPort, t.serverChan)
+		err, port := startHttpServer(*t.listenPort, t.serverInputChan, t.serverOutputChan)
 		if err != nil {
 			errorExit(err.Error())
 		}
@@ -2813,7 +2834,7 @@ func (t *Terminal) Loop() {
 							t.printInfo()
 						}
 						if onFocus, prs := t.keymap[tui.Focus.AsEvent()]; prs && focusChanged {
-							t.serverChan <- onFocus
+							t.serverInputChan <- onFocus
 						}
 						if focusChanged || version != t.version {
 							version = t.version
@@ -2925,7 +2946,7 @@ func (t *Terminal) Loop() {
 			select {
 			case event = <-t.eventChan:
 				needBarrier = !event.Is(tui.Load, tui.One, tui.Zero)
-			case actions = <-t.serverChan:
+			case actions = <-t.serverInputChan:
 				event = tui.Invalid.AsEvent()
 				needBarrier = false
 			}
@@ -3000,6 +3021,8 @@ func (t *Terminal) Loop() {
 		doAction = func(a *action) bool {
 			switch a.t {
 			case actIgnore:
+			case actResponse:
+				t.serverOutputChan <- t.dumpStatus()
 			case actBecome:
 				valid, list := t.buildPlusList(a.a, false)
 				if valid {
@@ -3768,3 +3791,49 @@ func (t *Terminal) maxItems() int {
 	}
 	return util.Max(max, 0)
 }
+
+func (t *Terminal) dumpItem(i *Item) StatusItem {
+	if i == nil {
+		return StatusItem{}
+	}
+	return StatusItem{
+		Index: int(i.Index()),
+		Text:  i.AsString(t.ansi),
+	}
+}
+
+const dumpItemLimit = 100 // TODO: Make configurable via GET parameter
+
+func (t *Terminal) dumpStatus() string {
+	selectedItems := t.sortSelected()
+	selected := make([]StatusItem, util.Min(dumpItemLimit, len(selectedItems)))
+	for i, selectedItem := range selectedItems[:len(selected)] {
+		selected[i] = t.dumpItem(selectedItem.item)
+	}
+
+	matches := make([]StatusItem, util.Min(dumpItemLimit, t.merger.Length()))
+	for i := range matches {
+		matches[i] = t.dumpItem(t.merger.Get(i).item)
+	}
+
+	var current *StatusItem
+	currentItem := t.currentItem()
+	if currentItem != nil {
+		item := t.dumpItem(currentItem)
+		current = &item
+	}
+
+	dump := Status{
+		Reading:    t.reading,
+		Query:      string(t.input),
+		Position:   t.cy,
+		Sort:       t.sort,
+		TotalCount: t.count,
+		MatchCount: t.merger.Length(),
+		Current:    current,
+		Matches:    matches,
+		Selected:   selected,
+	}
+	bytes, _ := json.Marshal(&dump) // TODO: Errors?
+	return string(bytes)
+}

test/test_go.rb

@@ -8,6 +8,7 @@ require 'shellwords'
 require 'erb'
 require 'tempfile'
 require 'net/http'
+require 'json'
 
 TEMPLATE = DATA.read
 UNSETS = %w[
@@ -2776,9 +2777,21 @@ class TestGoFZF < TestBase
         -> { URI("http://localhost:#{File.read('/tmp/fzf-port').chomp}") } }.each do |opts, fn|
       tmux.send_keys "seq 10 | fzf #{opts}", :Enter
       tmux.until { |lines| assert_equal 10, lines.item_count }
+      state = JSON.parse(Net::HTTP.get(fn.call), symbolize_names: true)
+      assert_equal 10, state[:totalCount]
+      assert_equal 10, state[:matchCount]
+      assert_empty state[:query]
+      assert_equal({ index: 0, text: '1' }, state[:current])
+
       Net::HTTP.post(fn.call, 'change-query(yo)+reload(seq 100)+change-prompt:hundred> ')
       tmux.until { |lines| assert_equal 100, lines.item_count }
       tmux.until { |lines| assert_equal 'hundred> yo', lines[-1] }
+      state = JSON.parse(Net::HTTP.get(fn.call), symbolize_names: true)
+      assert_equal 100, state[:totalCount]
+      assert_equal 0, state[:matchCount]
+      assert_equal 'yo', state[:query]
+      assert_nil state[:current]
+
       teardown
       setup
     end