Support editing sail Dockerfile inside code-server

Closes #98

Only thing left to do is switch to using a output pane instead of
a terminal and blocking the save on the dockerfile while the reload
is in progress.

proxycmd.go

@@ -239,9 +239,7 @@ func (c *proxycmd) proxy(cntName string) (addr string, err error) {
 	go func() {
 		m := http.NewServeMux()
 		m.HandleFunc("/sail.js", func(w http.ResponseWriter, r *http.Request) {
-			w.Write([]byte(`
-console.log("injected")
-`))
+			w.Write([]byte(sailJS))
 		})
 		m.HandleFunc("/sail/api/v1/healthz", func(w http.ResponseWriter, r *http.Request) {
 			w.Write([]byte("ok\n"))

sail.js

@@ -0,0 +1,43 @@
+let reloadInProgress = false
+let tty
+window.addEventListener("ide-ready", (ev) => {
+    window.ide.workbench.onFileSaved((ev) => {
+        if (!ev.endsWith(".sail/Dockerfile")) {
+            return
+        }
+
+        if (reloadInProgress) {
+            alert("reload is still in progress")
+            return
+        }
+        reloadInProgress = true
+
+        const srv = window.ide.workbench.terminalService
+
+        if (tty == null) {
+            tty = srv.createTerminal({
+                name: "sail",
+                isRendererOnly: true,
+            }, false)
+        } else {
+            tty.clear()
+        }
+        let oldTTY = srv.getActiveInstance()
+        srv.setActiveInstance(tty)
+
+        const ws = new WebSocket("ws://" + location.host + "/sail/api/v1/reload")
+        ws.onmessage = (ev) => {
+            const msg = JSON.parse(ev.data)
+            const out = atob(msg.v).replace(/\n/g, "\n\r")
+            tty.write(out)
+        }
+        ws.onclose = (ev) => {
+            if (ev.code === 1000) {
+                srv.setActiveInstance(oldTTY)
+            } else {
+                alert("reload failed; please see logs in sail terminal")
+            }
+            reloadInProgress = false
+        }
+    })
+})

sail.js.go

@@ -0,0 +1,4 @@
+package main
+
+//go:generate go run sail.js_gen.go
+const sailJS = "let reloadInProgress = false\nlet tty\nwindow.addEventListener(\"ide-ready\", (ev) => {\n    window.ide.workbench.onFileSaved((ev) => {\n        if (!ev.endsWith(\".sail/Dockerfile\")) {\n            return\n        }\n\n        if (reloadInProgress) {\n            alert(\"reload is still in progress\")\n            return\n        }\n        reloadInProgress = true\n\n        const srv = window.ide.workbench.terminalService\n\n        if (tty == null) {\n            tty = srv.createTerminal({\n                name: \"sail\",\n                isRendererOnly: true,\n            }, false)\n        } else {\n            tty.clear()\n        }\n        let oldTTY = srv.getActiveInstance()\n        srv.setActiveInstance(tty)\n\n        const ws = new WebSocket(\"ws://\" + location.host + \"/sail/api/v1/reload\")\n        ws.onmessage = (ev) => {\n            const msg = JSON.parse(ev.data)\n            const out = atob(msg.v).replace(/\\n/g, \"\\n\\r\")\n            tty.write(out)\n        }\n        ws.onclose = (ev) => {\n            if (ev.code == 1000) {\n                srv.setActiveInstance(oldTTY)\n                alert(\"success\")\n            } else {\n                alert(\"reload failed; please see logs in sail terminal\")\n            }\n            reloadInProgress = false\n        }\n    })\n})\n"

sail.js_gen.go

@@ -0,0 +1,31 @@
+// +build ignore
+
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"log"
+)
+
+func main() {
+	sailJS, err := ioutil.ReadFile("sail.js")
+	if err != nil {
+		log.Fatalf("failed to read sail.js: %v", err)
+	}
+
+	err = ioutil.WriteFile("sail.js.go", genFile(sailJS), 0644)
+	if err != nil {
+		log.Fatalf("failed to write sail.js: %v", err)
+	}
+}
+
+func genFile(sailJS []byte) []byte {
+	tmpl := `package main
+
+//go:generate go run sail.js_gen.go
+const sailJS = %q
+`
+
+	return []byte(fmt.Sprintf(tmpl, sailJS))
+}