Get rid of switch statements in favor of an EventEmitter-based router for message handling.

lib/roles/device.js

@@ -13,6 +13,7 @@ var split = require('split')
 var logger = require('../util/logger')
 var wire = require('../wire')
 var wireutil = require('../util/wireutil')(wire)
+var wirerouter = require('../wire/router')
 var devutil = require('../util/devutil')
 var pathutil = require('../util/pathutil')
 var promiseutil = require('../util/promiseutil')
@@ -326,90 +327,86 @@ module.exports = function(options) {
       selfDestruct()
     })
 
-  sub.on('message', function(channel, data) {
-    var wrapper = wire.Envelope.decode(data)
-    channels.keepalive(channel)
-    switch (wrapper.type) {
-      case wire.MessageType.PROBE:
-        var message = wire.ProbeMessage.decode(wrapper.message)
-        push.send([channel,
-          wireutil.makeDeviceIdentityMessage(options.serial, identity)])
-        break
-      case wire.MessageType.GROUP:
-        var message = wire.GroupMessage.decode(wrapper.message)
-          , groupChannel = message.channel
-        if (devutil.matchesRequirements(identity, message.requirements)) {
-          channels.register(groupChannel, message.timeout)
-          log.info('Subscribing to group channel "%s"', groupChannel)
-          sub.subscribe(groupChannel)
-          push.send([groupChannel,
-            wireutil.makeJoinGroupMessage(options.serial)])
-        }
-        break
-      case wire.MessageType.UNGROUP:
-        var message = wire.UngroupMessage.decode(wrapper.message)
-          , groupChannel = message.channel
-        if (devutil.matchesRequirements(identity, message.requirements)) {
-          channels.unregister(groupChannel)
-          log.info('Unsubscribing from group channel "%s"', groupChannel)
-          sub.unsubscribe(groupChannel)
-          push.send([groupChannel,
-            wireutil.makeLeaveGroupMessage(options.serial)])
-        }
-        break
-      case wire.MessageType.SHELL_COMMAND:
-        var message = wire.ShellCommandMessage.decode(wrapper.message)
-        log.info('Running shell command "%s"', message.command.join(' '))
-        adb.shellAsync(options.serial, message.command)
-          .then(function(stream) {
-            var resolver = Promise.defer()
-              , seq = 0
+  sub.on('message', wirerouter()
+    .on(wire.MessageType.ProbeMessage, function(channel, message) {
+      push.send([channel,
+        wireutil.makeDeviceIdentityMessage(options.serial, identity)])
+      channels.keepalive(channel)
+    })
+    .on(wire.MessageType.GroupMessage, function(channel, message) {
+      var groupChannel = message.channel
+      if (devutil.matchesRequirements(identity, message.requirements)) {
+        channels.register(groupChannel, message.timeout)
+        log.info('Subscribing to group channel "%s"', groupChannel)
+        sub.subscribe(groupChannel)
+        push.send([groupChannel,
+          wireutil.makeJoinGroupMessage(options.serial)])
+      }
+      channels.keepalive(channel)
+    })
+    .on(wire.MessageType.UngroupMessage, function(channel, message) {
+      var groupChannel = message.channel
+      if (devutil.matchesRequirements(identity, message.requirements)) {
+        channels.unregister(groupChannel)
+        log.info('Unsubscribing from group channel "%s"', groupChannel)
+        sub.unsubscribe(groupChannel)
+        push.send([groupChannel,
+          wireutil.makeLeaveGroupMessage(options.serial)])
+      }
+      channels.keepalive(channel)
+    })
+    .on(wire.MessageType.ShellCommandMessage, function(channel, message) {
+      log.info('Running shell command "%s"', message.command.join(' '))
+      adb.shellAsync(options.serial, message.command)
+        .then(function(stream) {
+          var resolver = Promise.defer()
+            , seq = 0
 
-            function dataListener(chunk) {
-              push.send([message.channel,
-                wireutil.makeDeviceDataMessage(
-                  options.serial
-                , seq++
-                , chunk
-                )])
-            }
-
-            function endListener() {
-              push.send([message.channel,
-                wireutil.makeDeviceDoneMessage(options.serial)])
-              resolver.resolve()
-            }
-
-            function errorListener(err) {
-              log.error('Shell command "%s" failed due to "%s"'
-                , message.command.join(' '), err.message)
-              resolver.reject(err)
-              push.send([message.channel,
-                wireutil.makeDeviceFailMessage(
-                  options.serial
-                , err.message
-                )])
-            }
-
-            stream.on('data', dataListener)
-            stream.on('end', endListener)
-            stream.on('error', errorListener)
-
-            return resolver.promise.finally(function() {
-              stream.removeListener('data', dataListener)
-              stream.removeListener('end', endListener)
-              stream.removeListener('error', errorListener)
-            })
-          })
-          .error(function(err) {
-            log.error('Shell command "%s" failed due to "%s"'
-                , message.command.join(' '), err.message)
+          function dataListener(chunk) {
             push.send([message.channel,
-              wire.makeDeviceFailMessage(options.serial, err.message)])
+              wireutil.makeShellCommandDataMessage(
+                options.serial
+              , seq++
+              , chunk
+              )])
+          }
+
+          function endListener() {
+            push.send([message.channel,
+              wireutil.makeShellCommandDoneMessage(options.serial)])
+            resolver.resolve()
+          }
+
+          function errorListener(err) {
+            log.error('Shell command "%s" failed due to "%s"'
+              , message.command.join(' '), err.message)
+            resolver.reject(err)
+            push.send([message.channel,
+              wireutil.makeShellCommandFailMessage(
+                options.serial
+              , err.message
+              )])
+          }
+
+          stream.on('data', dataListener)
+          stream.on('end', endListener)
+          stream.on('error', errorListener)
+
+          return resolver.promise.finally(function() {
+            stream.removeListener('data', dataListener)
+            stream.removeListener('end', endListener)
+            stream.removeListener('error', errorListener)
           })
-        break
-    }
-  })
+        })
+        .error(function(err) {
+          log.error('Shell command "%s" failed due to "%s"'
+              , message.command.join(' '), err.message)
+          push.send([message.channel,
+            wire.makeShellCommandFailMessage(options.serial, err.message)])
+        })
+      channels.keepalive(channel)
+    })
+    .handler())
 
   function poke() {
     push.send([wireutil.global,