Move all code into musicplayer module

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/musicplayer.gleam

@@ -1,8 +1,22 @@
-import gleam/erlang/process
+import gleam/erlang/process.{type Name}
-import mpv/mpv
+
+import musicplayer/input/input.{type Listener}
+import musicplayer/input/key.{type Key}
+import musicplayer/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)
 }

src/musicplayer/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 musicplayer/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/musicplayer/input/key.gleam

@@ -1,6 +1,9 @@
 import gleam/erlang/atom
+import gleam/erlang/process.{type Subject}
 import gleam/list
-import mpv/internal/key as internal_key
+import gleam/string
+
+import musicplayer/input/internal as internal_input
 
 pub type Key {
   Char(String)
@@ -21,7 +24,7 @@ pub const esc = "\u{001B}"
 pub const csi = "["
 
 // input introducer
-const input_introducer = "$"
+pub const input_introducer = "::"
 
 pub fn from_list(l: List(String)) -> Key {
   case l {
@@ -34,9 +37,12 @@ pub fn from_list(l: List(String)) -> Key {
 
     [ci] | [ci, _] if ci == input_introducer -> Continue(l)
     [ii, cmd, tail] if ii == input_introducer -> {
-      case tail == "\r" {
+      case tail {
-        True -> Input(cmd)
+        // Return
-        False -> Continue([ii, cmd <> tail])
+        "\r" -> Input(cmd)
+        // Backspace
+        "\u{007F}" -> Continue([ii, string.drop_end(cmd, 1)])
+        _ -> Continue([ii, cmd <> tail])
       }
     }
 
@@ -51,17 +57,23 @@ pub fn from_list(l: List(String)) -> Key {
 pub fn start_raw_shell() {
   let no_shell = atom.create("noshell")
   let raw = atom.create("raw")
-  internal_key.shell_start_interactive(#(no_shell, raw))
+  internal_input.shell_start_interactive(#(no_shell, raw))
 }
 
-pub fn read_input_until_key(l: List(String)) -> Key {
+pub fn read_input_until_key(
+  l: List(String),
+  taps: List(Subject(List(String))),
+) -> Key {
   case
-    internal_key.read_input()
+    internal_input.read_input()
     |> list.wrap
     |> list.append(l, _)
     |> from_list
   {
-    Continue(l) -> read_input_until_key(l)
+    Continue(l) -> {
+      list.each(taps, process.send(_, l))
+      read_input_until_key(l, taps)
+    }
     k -> k
   }
 }

src/musicplayer/mpv/control.gleam

@@ -1,12 +1,11 @@
-import gleam/io
 import gleam/json
 import gleam/result
 import gleam/string
 
-import mpv/internal/control as internal_control
+import musicplayer/input/key.{type Key}
-import mpv/key.{type Key}
+import musicplayer/mpv/internal as internal_control
-import tcp/reason.{type Reason}
+import musicplayer/tcp/reason.{type Reason}
-import tcp/tcp.{type Socket}
+import musicplayer/tcp/tcp.{type Socket}
 
 pub type Control {
   TogglePlayPause
@@ -67,10 +66,6 @@ pub fn get_playback_time(socket: Socket) -> Result(PlaybackTime, ControlError) {
   }
 }
 
-pub fn clear_screen() -> Nil {
-  io.print("\u{001B}[2J\u{001B}[H")
-}
-
 fn send_command(socket: Socket, command: json.Json) -> Result(String, Reason) {
   result.try(tcp.send(socket, json.to_string(command) <> "\n"), fn(_) {
     let timeout_ms = 10_000

src/musicplayer/mpv/mpv.gleam

@@ -1,25 +1,30 @@
 import gleam/erlang/process.{type Subject}
 import gleam/float
+import gleam/option.{None}
 import gleam/otp/actor
 import gleam/result
 import gleam/string
 
-import mpv/control.{type Control}
+import musicplayer/input/input.{type Listener, InputListener}
-import mpv/key
+import musicplayer/input/key.{type Key}
-import tcp/reason
+import musicplayer/mpv/control.{type Control}
-import tcp/tcp.{type Socket}
+import musicplayer/tcp/reason
+import musicplayer/tcp/tcp.{type Socket}
 
 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) -> {
+      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, exit))
         |> actor.on_message(handle_message)
@@ -30,8 +35,15 @@ pub fn new(exit: Subject(Nil)) -> Result(Nil, String) {
         Ok(actor.Started(data:, ..)) -> {
           echo "waiting for input"
           key.start_raw_shell()
-          process.spawn(fn() { read_input(data) })
+
-          Ok(Nil)
+          process.spawn(fn() {
+            let assert Ok(_) =
+              process.register(process.self(), final_input_name)
+
+            handle_key(final_input, data)
+          })
+
+          Ok(InputListener(final: final_input, tap: None))
         }
       }
     }
@@ -65,14 +77,13 @@ fn handle_message(
   }
 }
 
-fn read_input(subject: Subject(Control)) -> Nil {
+/// `handle_key` listens to a subject onto which `input` will send messages with
-  case
+/// parsed `Key`s which will be mapped to `Control`s (if possible)
-    key.read_input_until_key([])
+fn handle_key(final_input: Subject(Key), subject: Subject(Control)) -> Nil {
+  let _ =
+    process.receive_forever(final_input)
     |> control.from_key
-  {
+    |> result.map(process.send(subject, _))
-    Error(_) -> Nil
-    Ok(control) -> process.send(subject, control)
-  }
 
-  read_input(subject)
+  handle_key(final_input, subject)
 }

src/musicplayer/tcp/tcp.gleam

@@ -2,7 +2,7 @@ import gleam/bit_array
 import gleam/erlang/atom
 import gleam/result
 
-import tcp/reason.{type Reason}
+import musicplayer/tcp/reason.{type Reason}
 
 pub type Socket
 

test/echo_server.gleam

@@ -4,8 +4,8 @@ import gleam/otp/actor
 import gleam/result
 import gleam/string
 
-import tcp/reason.{type Reason}
+import musicplayer/tcp/reason.{type Reason}
-import tcp/tcp
+import musicplayer/tcp/tcp
 
 pub type Message {
   Shutdown

test/mpv/key_test.gleam

@@ -1,33 +0,0 @@
-import gleam/list
-import gleeunit
-
-import mpv/key.{type Key, Char, csi, esc}
-
-pub fn main() -> Nil {
-  gleeunit.main()
-}
-
-type TestCase {
-  TestCase(input: List(String), expected: Key)
-}
-
-pub fn key_from_list_test() {
-  let test_cases = [
-    TestCase(["c"], Char("c")),
-    TestCase([esc, csi, "D"], key.Left),
-    TestCase([esc, csi, "C"], key.Right),
-    TestCase([esc, csi, "A"], key.Up),
-    TestCase([esc, csi, "B"], key.Down),
-    TestCase([esc, csi], key.Continue([esc, csi])),
-    TestCase([esc], key.Continue([esc])),
-    TestCase([], key.Continue([])),
-    TestCase(["$"], key.Continue(["$"])),
-    TestCase(["$", "a"], key.Continue(["$", "a"])),
-    TestCase(["$", "a", "b"], key.Continue(["$", "ab"])),
-    TestCase(["$", "ab", "\r"], key.Input("ab")),
-  ]
-
-  list.each(test_cases, fn(tc) {
-    assert tc.expected == key.from_list(tc.input)
-  })
-}

test/musicplayer/input/input_test.gleam

@@ -0,0 +1,42 @@
+import gleam/list
+import gleeunit
+
+import musicplayer/input/key.{type Key, Char, csi, esc, input_introducer as ii}
+
+pub fn main() -> Nil {
+  gleeunit.main()
+}
+
+type TestCase {
+  TestCase(input: List(String), expected: Key)
+}
+
+pub fn key_from_list_test() {
+  let base_tests = [TestCase([], key.Continue([]))]
+
+  let char_tests = [TestCase(["c"], Char("c"))]
+
+  let escape_tests = [
+    TestCase([esc, csi], key.Continue([esc, csi])),
+    TestCase([esc], key.Continue([esc])),
+
+    TestCase([esc, csi, "D"], key.Left),
+    TestCase([esc, csi, "C"], key.Right),
+    TestCase([esc, csi, "A"], key.Up),
+    TestCase([esc, csi, "B"], key.Down),
+  ]
+
+  let input_tests = [
+    TestCase([ii], key.Continue([ii])),
+    TestCase([ii, "a"], key.Continue([ii, "a"])),
+    TestCase([ii, "a", "b"], key.Continue([ii, "ab"])),
+    TestCase([ii, "ab", "\u{007F}"], key.Continue([ii, "a"])),
+    TestCase([ii, "ab", "\r"], key.Input("ab")),
+  ]
+
+  let test_cases = [base_tests, char_tests, escape_tests, input_tests]
+
+  list.each(list.flatten(test_cases), fn(tc) {
+    assert tc.expected == key.from_list(tc.input)
+  })
+}

test/musicplayer/mpv/control_test.gleam

@@ -1,9 +1,9 @@
 import gleam/list
 import gleeunit
 
-import mpv/control.{type Control}
+import musicplayer/input/key.{type Key, Char}
-import mpv/internal/control as control_internal
+import musicplayer/mpv/control.{type Control}
-import mpv/key.{type Key, Char}
+import musicplayer/mpv/internal as control_internal
 
 pub fn main() -> Nil {
   gleeunit.main()

test/musicplayer/tcp/tcp_test.gleam

@@ -3,7 +3,7 @@ import gleeunit
 import simplifile
 
 import echo_server
-import tcp/tcp
+import musicplayer/tcp/tcp
 
 pub fn main() -> Nil {
   gleeunit.main()