From d69544f9ab0393e4aa5d5160518a3255bd0b1cb5 Mon Sep 17 00:00:00 2001
From: Yichuan Shen <shen.yichuan@gmail.com>
Date: Thu, 20 Feb 2020 17:44:54 +0100
Subject: [PATCH] Add stateTracker.queueCommand()

---
 README.md                            |  6 ++++++
 src/ControllerStateTracker.js        | 11 +++++++++++
 tests/ControllerStateTracker.test.js | 25 +++++++++++++++++++++++++
 3 files changed, 42 insertions(+)

diff --git a/README.md b/README.md
index 080e3b1..6982f0a 100644
--- a/README.md
+++ b/README.md
@@ -331,6 +331,12 @@ controller of the engine that we're tracking the state of.
 
 Returns a boolean whether the engine supports the given command.
 
+#### `async stateTracker.queueCommand(command)`
+
+- `command` [`<Command>`](#command)
+
+Sends the given command to the engine after all ongoing syncs have finished.
+
 #### `async stateTracker.sync(state)`
 
 - `state` [`<EngineState>`](#enginestate)
diff --git a/src/ControllerStateTracker.js b/src/ControllerStateTracker.js
index 75cc050..56118fd 100644
--- a/src/ControllerStateTracker.js
+++ b/src/ControllerStateTracker.js
@@ -125,6 +125,16 @@ class ControllerStateTracker {
     return this._commands.includes(commandName)
   }
 
+  async queueCommand(...args) {
+    if (this.syncing) {
+      await new Promise(r =>
+        this._syncFinishedEmitter.once('syncs-finished', r)
+      )
+    }
+
+    return this.controller.sendCommand(...args)
+  }
+
   async _startProcessingSyncs() {
     if (this.syncing) return
 
@@ -143,6 +153,7 @@ class ControllerStateTracker {
     }
 
     this.syncing = false
+    this._syncFinishedEmitter.emit('syncs-finished')
   }
 
   async _sync(state) {
diff --git a/tests/ControllerStateTracker.test.js b/tests/ControllerStateTracker.test.js
index c9e66c1..03a2c8c 100644
--- a/tests/ControllerStateTracker.test.js
+++ b/tests/ControllerStateTracker.test.js
@@ -130,6 +130,31 @@ t.test('sync history state', async t => {
     t.strictDeepEquals(stateTracker.state.history, commands)
   })
 
+  t.test('queueCommand will send command after syncs are done', async t => {
+    let {stateTracker} = t.context
+    let commands = [
+      {name: 'set_free_handicap', args: ['F4', 'G4', 'H4']},
+      {name: 'play', args: ['B', 'D4']},
+      {name: 'play', args: ['W', 'E4']}
+    ]
+
+    let sentCommands = []
+
+    stateTracker.controller.on('command-sent', ({command}) => {
+      sentCommands.push(command)
+    })
+
+    let queuedCommand = {name: 'genmove', args: ['B']}
+
+    await Promise.all([
+      stateTracker.sync({history: commands}),
+      stateTracker.sync({history: commands}),
+      stateTracker.queueCommand(queuedCommand)
+    ])
+
+    t.strictDeepEquals(sentCommands.slice(-1)[0], queuedCommand)
+  })
+
   t.test('sync genmove commands', async t => {
     let {stateTracker} = t.context
     let history = []