Added file watching (#164)

* Added file watching

If the server supports it, we will now receive watched file
notifications for files that have been added / updated or deleted in
the project directories.

This will help determining whether we should recompile the whole
project if a dependency has changed, or if we should remove a module
from our compiled module cache.

* Started supervisor after init is sent

apps/protocol/lib/generated/lexical/protocol/types/did_change_watched_files/registration/options.ex

@@ -0,0 +1,7 @@
+# This file's contents are auto-generated. Do not edit.
+defmodule Lexical.Protocol.Types.DidChangeWatchedFiles.Registration.Options do
+  alias Lexical.Proto
+  alias Lexical.Protocol.Types
+  use Proto
+  deftype watchers: list_of(Types.FileSystemWatcher)
+end

apps/protocol/lib/generated/lexical/protocol/types/file_system_watcher.ex

@@ -0,0 +1,7 @@
+# This file's contents are auto-generated. Do not edit.
+defmodule Lexical.Protocol.Types.FileSystemWatcher do
+  alias Lexical.Proto
+  alias Lexical.Protocol.Types
+  use Proto
+  deftype glob_pattern: Types.GlobPattern, kind: optional(Types.Watch.Kind)
+end

apps/protocol/lib/generated/lexical/protocol/types/glob_pattern.ex

@@ -0,0 +1,7 @@
+# This file's contents are auto-generated. Do not edit.
+defmodule Lexical.Protocol.Types.GlobPattern do
+  alias Lexical.Proto
+  alias Lexical.Protocol.Types
+  use Proto
+  defalias one_of([Types.Pattern, Types.RelativePattern])
+end

apps/protocol/lib/generated/lexical/protocol/types/relative_pattern.ex

@@ -0,0 +1,7 @@
+# This file's contents are auto-generated. Do not edit.
+defmodule Lexical.Protocol.Types.RelativePattern do
+  alias Lexical.Proto
+  alias Lexical.Protocol.Types
+  use Proto
+  deftype base_uri: one_of([Types.Workspace.Folder, string()]), pattern: Types.Pattern
+end

apps/protocol/lib/generated/lexical/protocol/types/watch/kind.ex

@@ -0,0 +1,6 @@
+# This file's contents are auto-generated. Do not edit.
+defmodule Lexical.Protocol.Types.Watch.Kind do
+  alias Lexical.Proto
+  use Proto
+  defenum create: 1, change: 2, delete: 4
+end

apps/protocol/lib/lexical/protocol/json_rpc.ex

@@ -2,6 +2,8 @@ defmodule Lexical.Protocol.JsonRpc do
   alias Lexical.Protocol.Notifications
   alias Lexical.Protocol.Requests
 
+  require Logger
+
   @crlf "\r\n"
 
   def decode(message_string) do
@@ -30,6 +32,11 @@ defmodule Lexical.Protocol.JsonRpc do
     {:ok, json_rpc}
   end
 
+  defp do_decode(%{"id" => id, "result" => nil}) do
+    Logger.info("Reply for id #{id} had no body")
+    :error
+  end
+
   defp do_decode(%{"method" => method, "id" => _id} = request) do
     Requests.decode(method, request)
   end

apps/server/lib/lexical/server/state.ex

@@ -1,26 +1,28 @@
 defmodule Lexical.Server.State do
   alias Lexical.Document
-
-  alias Lexical.Protocol.Notifications.{
-    DidChange,
-    DidChangeConfiguration,
-    DidClose,
-    DidOpen,
-    DidSave,
-    Initialized
-  }
-
+  alias Lexical.Protocol.Id
+  alias Lexical.Protocol.Notifications.DidChange
+  alias Lexical.Protocol.Notifications.DidChangeConfiguration
+  alias Lexical.Protocol.Notifications.DidClose
+  alias Lexical.Protocol.Notifications.DidOpen
+  alias Lexical.Protocol.Notifications.DidSave
   alias Lexical.Protocol.Notifications.Exit
+  alias Lexical.Protocol.Notifications.Initialized
   alias Lexical.Protocol.Requests.Initialize
+  alias Lexical.Protocol.Requests.RegisterCapability
   alias Lexical.Protocol.Requests.Shutdown
   alias Lexical.Protocol.Responses
   alias Lexical.Protocol.Types
   alias Lexical.Protocol.Types.CodeAction
   alias Lexical.Protocol.Types.Completion
+  alias Lexical.Protocol.Types.DidChangeWatchedFiles
+  alias Lexical.Protocol.Types.FileSystemWatcher
+  alias Lexical.Protocol.Types.Registration
   alias Lexical.Protocol.Types.TextDocument
   alias Lexical.RemoteControl.Api
   alias Lexical.Server.CodeIntelligence
   alias Lexical.Server.Configuration
+  alias Lexical.Server.Project
   alias Lexical.Server.Transport
 
   require CodeAction.Kind
@@ -43,12 +45,13 @@ defmodule Lexical.Server.State do
     new_state = %__MODULE__{state | configuration: config, initialized?: true}
     Logger.info("Starting project at uri #{config.project.root_uri}")
 
-    Lexical.Server.Project.Supervisor.start(config.project)
-
     event.id
     |> initialize_result()
     |> Transport.write()
 
+    Transport.write(registrations())
+
+    Project.Supervisor.start(config.project)
     {:ok, new_state}
   end
 
@@ -168,6 +171,27 @@ defmodule Lexical.Server.State do
     {:ok, state}
   end
 
+  defp registrations do
+    RegisterCapability.new(id: Id.next(), registrations: [file_watcher_registration()])
+  end
+
+  @did_changed_watched_files_id "-42"
+  @watched_extensions ~w(ex exs)
+  defp file_watcher_registration do
+    extension_glob = "{" <> Enum.join(@watched_extensions, ",") <> "}"
+
+    watchers = [
+      FileSystemWatcher.new(glob_pattern: "**/mix.lock"),
+      FileSystemWatcher.new(glob_pattern: "**/*.#{extension_glob}")
+    ]
+
+    Registration.new(
+      id: @did_changed_watched_files_id,
+      method: "workspace/didChangeWatchedFiles",
+      register_options: DidChangeWatchedFiles.Registration.Options.new(watchers: watchers)
+    )
+  end
+
   def initialize_result(event_id) do
     sync_options =
       TextDocument.Sync.Options.new(open_close: true, change: :incremental, save: true)