Extract reading of input i/o to input

And add the ability of other modules to listen to either
the final result (a `Key`) or tap into the input as it is read

src/input/input.gleam

@@ -0,0 +1,59 @@
+import gleam/erlang/process.{type Name, type Subject}
+import gleam/list
+import gleam/option.{type Option, None, Some}
+
+import input/key.{type Key}
+
+pub type Listener {
+  InputListener(final: Subject(Key), tap: Option(Subject(List(String))))
+}
+
+/// `new` accepts a list of listeners that are composed of two subjects;
+///   - one to get the final `Key` and
+///   - one to tap the input as it is read from i/o
+/// and
+///   - a subject name that is used to create a `Subject` that other processes
+///     know they can inject a `Key` into the input with
+pub fn new(listeners: List(Listener), inject_input_name: Name(Key)) -> Nil {
+  let _ =
+    process.spawn(fn() {
+      let inject_input: Subject(Key) = process.named_subject(inject_input_name)
+      let assert Ok(_) = process.register(process.self(), inject_input_name)
+
+      // Extract all finals and taps (that are defined)
+      let #(finals, taps) =
+        list.fold(listeners, #([], []), fn(acc, listener) {
+          let #(finals, taps) = acc
+
+          let finals = [listener.final, ..finals]
+
+          let taps = case listener.tap {
+            Some(t) -> [t, ..taps]
+            None -> taps
+          }
+
+          #(finals, taps)
+        })
+
+      read_input(finals, taps, inject_input)
+    })
+
+  Nil
+}
+
+fn read_input(
+  finals: List(Subject(Key)),
+  taps: List(Subject(List(String))),
+  inject_input: Subject(Key),
+) -> Nil {
+  let buffer = case process.receive(inject_input, 1) {
+    Ok(key.Continue(buffer)) -> buffer
+    Ok(_) | Error(_) -> []
+  }
+
+  let _ =
+    key.read_input_until_key(buffer, taps)
+    |> fn(k) { list.each(finals, process.send(_, k)) }
+
+  read_input(finals, taps, inject_input)
+}

src/input/key.gleam

@@ -62,7 +62,7 @@ pub fn start_raw_shell() {
 
 pub fn read_input_until_key(
   l: List(String),
-  tap_input: Subject(List(String)),
+  taps: List(Subject(List(String))),
 ) -> Key {
   case
     internal_input.read_input()
@@ -71,8 +71,8 @@ pub fn read_input_until_key(
     |> from_list
   {
     Continue(l) -> {
-      process.send(tap_input, l)
-      read_input_until_key(l, tap_input)
+      list.each(taps, process.send(_, l))
+      read_input_until_key(l, taps)
     }
     k -> k
   }

src/mpv/mpv.gleam

@@ -1,41 +1,32 @@
 import gleam/erlang/process.{type Subject}
 import gleam/float
+import gleam/option.{None}
 import gleam/otp/actor
 import gleam/result
 import gleam/string
 
+import input/input.{type Listener, InputListener}
 import input/key.{type Key}
 import mpv/control.{type Control}
 import tcp/reason
 import tcp/tcp.{type Socket}
 
-type State(socket, inject_input, tap_input, exit) {
-  State(
-    socket: Socket,
-    inject_input: Subject(Key),
-    tap_input: Subject(List(String)),
-    exit: Subject(Nil),
-  )
+type State(socket, exit) {
+  State(socket: Socket, exit: Subject(Nil))
 }
 
-pub fn new(exit: Subject(Nil)) -> Result(Nil, String) {
+pub fn new(exit: Subject(Nil)) -> Result(Listener, String) {
   // TODO start up mvp here, currently hi-jacking `naviterm`s socket
   let socket_path = "/tmp/naviterm_mpv"
 
   case tcp.connect(socket_path) {
     Error(r) -> Error("Could not connect to mpv: " <> reason.to_string(r))
     Ok(socket) -> {
-      // `inject_input` is created by name to allow the process that
-      // owns `read_input` to be able to register it, while the agent
-      // also have a reference to it to be able to inject input
-      let inject_input_name = process.new_name("inject_input")
-      let inject_input = process.named_subject(inject_input_name)
-
-      let tap_input_name = process.new_name("tap_input")
-      let tap_input = process.named_subject(tap_input_name)
+      let final_input_name = process.new_name("mpv_final_input")
+      let final_input: Subject(Key) = process.named_subject(final_input_name)
 
       case
-        actor.new(State(socket, inject_input, tap_input, exit))
+        actor.new(State(socket, exit))
         |> actor.on_message(handle_message)
         |> actor.start
       {
@@ -47,12 +38,12 @@ pub fn new(exit: Subject(Nil)) -> Result(Nil, String) {
 
           process.spawn(fn() {
             let assert Ok(_) =
-              process.register(process.self(), inject_input_name)
+              process.register(process.self(), final_input_name)
 
-            read_input(data, inject_input, tap_input)
+            handle_key(final_input, data)
           })
 
-          Ok(Nil)
+          Ok(InputListener(final: final_input, tap: None))
         }
       }
     }
@@ -60,9 +51,9 @@ pub fn new(exit: Subject(Nil)) -> Result(Nil, String) {
 }
 
 fn handle_message(
-  state: State(socket, inject, input_output, exit),
+  state: State(socket, exit),
   control: Control,
-) -> actor.Next(State(socket, inject, input_output, exit), Control) {
+) -> actor.Next(State(socket, exit), Control) {
   case control {
     control.TogglePlayPause -> {
       echo "toggling play/pause"
@@ -86,25 +77,13 @@ fn handle_message(
   }
 }
 
-/// `read_input` operates by reading from input until a `Key` can be created.
-/// It is possible to create a `Key` without the users input by sending
-/// messages to `inject_input` which will initialize the "input to key" sequence.
-/// This is useful to ultimately create a `Control` without the user having to
-/// input all of the character(s) needed.
-fn read_input(
-  subject: Subject(Control),
-  inject_input: Subject(Key),
-  tap_input: Subject(List(String)),
-) -> Nil {
-  let buffer = case process.receive(inject_input, 1) {
-    Ok(key.Continue(buffer)) -> buffer
-    Ok(_) | Error(_) -> []
-  }
-
+/// `handle_key` listens to a subject onto which `input` will send messages with
+/// parsed `Key`s which will be mapped to `Control`s (if possible)
+fn handle_key(final_input: Subject(Key), subject: Subject(Control)) -> Nil {
   let _ =
-    key.read_input_until_key(buffer, tap_input)
+    process.receive_forever(final_input)
     |> control.from_key
     |> result.map(process.send(subject, _))
 
-  read_input(subject, inject_input, tap_input)
+  handle_key(final_input, subject)
 }

src/musicplayer.gleam

@@ -1,8 +1,22 @@
-import gleam/erlang/process
+import gleam/erlang/process.{type Name}
+
+import input/input.{type Listener}
+import input/key.{type Key}
 import mpv/mpv
 
 pub fn main() -> Nil {
   let exit = process.new_subject()
-  let assert Ok(_) = mpv.new(exit)
+
+  // `inject_input` is created by name to allow the `input` process that
+  // owns `read_input` to be able to register and receive from it,
+  //  while the any other processes can use the name reference to
+  // inject input
+  let inject_input_name: Name(Key) = process.new_name("inject_input")
+
+  let assert Ok(mpv_listener) = mpv.new(exit)
+
+  let listeners: List(Listener) = [mpv_listener]
+
+  input.new(listeners, inject_input_name)
   process.receive_forever(exit)
 }