🔀 Add logging to `lustre/try` (#30)

* :heavy_plus_sign: Add `gleam_community_ansi` dependency

* :sparkles: Add log message when server is started

* :sparkles: Add retry policy and logging if port is taken

3 files changed, 70 insertions, 8 deletions

diff --git a/src/http.ffi.mjs b/src/http.ffi.mjs
index 06d5b31..3f59933 100644
--- a/src/http.ffi.mjs
+++ b/src/http.ffi.mjs
@@ -85,6 +85,17 @@ const server = Http.createServer((req, res) => {
   }
 });
 
-export const serve = (port) => {
-  server.listen(port, "localhost");
+export const serve = (host, port, on_start, on_port_taken) => {
+  let tries = 1;
+  server.on("error", (error) => {
+    if (error.code === "EADDRINUSE") {
+      let is_first_try = tries === 1;
+      if (is_first_try) {
+        on_port_taken(port);
+      }
+      tries++;
+      port++;
+      server.listen(port, host);
+    }
+  }).listen(port, host, () => { on_start(port) });
 };
diff --git a/src/http_ffi.erl b/src/http_ffi.erl
index 507ee06..5304ee4 100644
--- a/src/http_ffi.erl
+++ b/src/http_ffi.erl
@@ -1,7 +1,7 @@
 -module(http_ffi).
--export([serve/1]).
+-export([serve/4]).
 
-serve(Port) ->
+serve(Host, Port, OnStart, OnPortTaken) ->
     {ok, Pattern} = re:compile("name *= *\"(?<Name>.+)\""),
     {ok, Toml} = file:read_file("gleam.toml"),
     {match, [Name]} = re:run(Toml, Pattern, [{capture, all_names, binary}]),
@@ -43,25 +43,51 @@ serve(Port) ->
     inets:start(),
     Address = {127, 0, 0, 1},
 
+    ActualPort =
+        case port_available(Port) of
+            true ->
+                Port;
+            false ->
+                OnPortTaken(Port),
+                first_available_port(Port + 1)
+        end,
+
     {ok, Pid} =
         httpd:start_service([
             {bind_address, Address},
             {document_root, AbsPath},
             {server_root, AbsPath},
             {directory_index, ["index.html"]},
-            {server_name, "localhost"},
-            {port, Port},
+            {server_name, binary_to_list(Host)},
+            {port, ActualPort},
             {default_type, "text/html"},
             {mime_types, mime_types()},
             {modules, [mod_alias, mod_dir, mod_get]}
         ]),
 
+    OnStart(ActualPort),
+
     receive
         {From, shutdown} ->
             ok = httpd:stop_service(Pid),
             From ! done
     end.
 
+port_available(Port) ->
+    case gen_tcp:listen(Port, []) of
+        {ok, Sock} ->
+            ok = gen_tcp:close(Sock),
+            true;
+        _ ->
+            false
+    end.
+
+first_available_port(Port) ->
+    case port_available(Port) of
+        true -> Port;
+        false -> first_available_port(Port + 1)
+    end.
+
 mime_types() ->
     [
         {"html", "text/html"},
diff --git a/src/lustre/try.gleam b/src/lustre/try.gleam
index 5984f30..83d6e5a 100644
--- a/src/lustre/try.gleam
+++ b/src/lustre/try.gleam
@@ -1,7 +1,32 @@
+import gleam/int
+import gleam/io
+import gleam_community/ansi
+
 pub fn main() {
-  serve(1234)
+  let host = "localhost"
+  let port = 1234
+
+  let on_start = fn(actual_port) {
+    let address = "http://" <> host <> ":" <> int.to_string(actual_port)
+    io.println("✨ Server has been started at " <> ansi.bold(address))
+  }
+
+  let on_port_taken = fn(taken_port) {
+    io.println(
+      "🚨 Port "
+      <> ansi.bold(int.to_string(taken_port))
+      <> " already in use, using next available port",
+    )
+  }
+
+  serve(host, port, on_start, on_port_taken)
 }
 
 @external(erlang, "http_ffi", "serve")
 @external(javascript, "../http.ffi.mjs", "serve")
-fn serve(port: Int) -> Nil
+fn serve(
+  host: String,
+  port: Int,
+  on_start: fn(Int) -> Nil,
+  on_port_taken: fn(Int) -> Nil,
+) -> Nil