Add support for compiling in umbrella projects

lib/caramel.ex

@@ -12,16 +12,32 @@ defmodule Caramel do
     IO.puts("🍬 Using Caramel #{version}")
   end
 
-  def compile([]), do: :ok
-  def compile(files) do
+  def compile(files, opts \\ [])
+  def compile([], _opts), do: :ok
+  def compile(files, opts) do
+    bin = Path.expand(@caramel_bin)
     Mix.Shell.cmd(
-      "#{@caramel_bin} compile " <> Enum.join(files, " "),
-      [],
+      "#{bin} compile " <> Enum.join(files, " "),
+      opts,
       fn res -> IO.puts(res) end
     )
 
+    target_dir = Path.join(opts[:cd] || ".", "src")
+
+    if not File.dir?(target_dir) do
+      Mix.raise "caramel: target dir `#{target_dir}` is not a diretory"
+    end
+
+
+    # move the given files to target directory
+    basedir = Path.dirname(target_dir)
+    erlfiles =
+      for file <- files do
+        Path.join(basedir, Path.basename(file, Path.extname(file)) <> ".erl")
+      end
+
     Mix.Shell.cmd(
-      "mv *.erl src",
+      "mv #{Enum.join(erlfiles, " ")} #{target_dir}",
       [],
       fn _ -> :ok end
     )

lib/caramel/installer.ex

@@ -18,6 +18,11 @@ defmodule Caramel.Installer do
   def download_caramel(version, tarball_name, release_url) do
     IO.puts("📦 Installing Caramel #{version}...")
     Mix.Shell.cmd("wget " <> release_url, [], fn _ -> :ok end)
+
+    if not File.exists?(tarball_name) do
+      Mix.raise("carmel: failed to download release tarball for #{version}.")
+    end
+
     Mix.Shell.cmd("tar -xzf " <> tarball_name, [], fn _ -> :ok end)
     Mix.Shell.cmd("rm " <> tarball_name, [], fn _ -> :ok end)
     Mix.Shell.cmd("mv caramel _build/", [], fn _ -> :ok end)

lib/mix/tasks/compiler/caramel.ex

@@ -1,13 +1,75 @@
 defmodule Mix.Tasks.Compile.Caramel do
   use Mix.Task.Compiler
 
+  require Logger
+
   def run(_) do
     project = Mix.Project.config()
-    source_paths = project[:caramel_paths]
-    version = project[:caramel_release]
-    :ok = Caramel.ensure_version(version)
+    version = project[:caramel_release] || current_version
+
+    # If we're running in an umbrella project we need to specify exactly
+    # where each source file it within apps path. This has the sideeffect
+    # of compiling all files accross all umbrella projects instead of
+    # compiling one by one
+    if Mix.Project.umbrella?(project) do
+      for {_app, path} <- Mix.Project.apps_paths(project) do
+        compile(version, sources: project[:caramel_paths], path: path)
+      end
+      :ok
+    else
+      :ok = compile(version, sources: project[:caramel_paths])
+    end
+  end
+
+  defp compile(version, opts \\ []) do
+    source_paths = opts[:source] || ["src"]
+
+    if nil == source_paths do
+      Mix.raise("Caramel configuration error: `caramel_paths` not set in mix.config")
+    end
+
+    if nil == version do
+      Mix.raise("Caramel configuration error: `caramel_release` not set in mix.config")
+    end
+
+
     Mix.Compilers.Erlang.assert_valid_erlc_paths(source_paths)
-    files = Mix.Utils.extract_files(source_paths, [:ml, :mli, :re, :rei])
-    :ok = Caramel.compile(files)
+
+    if opts[:path] do
+      len = byte_size(opts[:path])
+      source_paths = for s <- source_paths, do: Path.join(opts[:path], s)
+      files = Mix.Utils.extract_files(source_paths, [:ml, :mli, :re, :rei])
+
+      if files != source_paths do
+        files =
+          for f <- files do
+            <<_ :: binary-size(len), "/", file :: binary()>> = f
+            file
+          end
+
+        if files != [] do
+          :ok = Caramel.ensure_version(version)
+        end
+
+        Caramel.compile(files, cd: opts[:path])
+      end
+    else
+      files = Mix.Utils.extract_files(source_paths, [:ml, :mli, :re, :rei])
+
+      if files != [] do
+        :ok = Caramel.ensure_version(version)
+      end
+
+      Caramel.compile(files)
+    end
+
+
+  end
+
+  defp current_version() do
+    case System.shell("command -v caramel > /dev/null && caramel version") do
+      {"v" <> _ = buf, 0} -> List.last(String.split(buf))
+      _ -> nil
+    end
   end
 end