From dcc23910946c50b924fcaed5a98e97445459dcd3 Mon Sep 17 00:00:00 2001
From: Pim Kunis <pim@kunis.nl>
Date: Sat, 10 Oct 2020 20:30:28 +0200
Subject: [PATCH] Add option to repeat schedule in player. Add end time of a
 schedule. Fix negative wait times.

---
 lib/midi_tools/player.ex | 92 ++++++++++++++++++++++++++++------------
 1 file changed, 65 insertions(+), 27 deletions(-)

diff --git a/lib/midi_tools/player.ex b/lib/midi_tools/player.ex
index 366ce77..8a30af5 100644
--- a/lib/midi_tools/player.ex
+++ b/lib/midi_tools/player.ex
@@ -1,4 +1,4 @@
-defmodule Player do
+defmodule MIDITools.Player do
   use GenServer
 
   # Client API
@@ -7,67 +7,105 @@ defmodule Player do
     GenServer.start_link(__MODULE__, arg, name: __MODULE__)
   end
 
-  def set_schedule(schedule) do
-    GenServer.call(__MODULE__, {:set_schedule, schedule})
+  def set_schedule(schedule, end_time) do
+    GenServer.call(__MODULE__, {:set_schedule, schedule, end_time})
   end
 
   def play do
     GenServer.call(__MODULE__, :play)
   end
 
+  def set_repeat(repeat) do
+    GenServer.call(__MODULE__, {:set_repeat, repeat})
+  end
+
   # Server callbacks
 
   @impl true
   def init(_arg) do
     {:ok, synth} = MIDISynth.start_link([])
     epoch = Timex.epoch() |> Timex.to_datetime()
-    {:ok, %{timer: nil, schedule: [], schedule_left: [], start_time: epoch, synth: synth}}
+
+    {:ok,
+     %{
+       timer: nil,
+       schedule: [],
+       schedule_left: [],
+       start_time: epoch,
+       end_time: 0,
+       synth: synth,
+       repeat: false
+     }}
   end
 
   @impl true
-  def handle_call({:set_schedule, schedule}, _from, state) do
-    {:reply, :ok, %{state | schedule: schedule, schedule_left: schedule}}
+  def handle_call({:set_schedule, schedule, end_time}, _from, state) do
+    {:reply, :ok, %{state | schedule: schedule, schedule_left: schedule, end_time: end_time}}
   end
 
-  def handle_call(:play, _from, %{schedule_left: schedule_left} = state) do
+  def handle_call(:play, _from, %{timer: timer} = state) when timer != nil do
+    {:reply, :already_started, state}
+  end
+
+  def handle_call(:play, _from, %{schedule: schedule} = state) do
     start_time = Timex.now()
-    state = %{state | start_time: start_time}
-    timer = start_timer(schedule_left, start_time)
-    {:reply, :ok, %{state | timer: timer}}
+    timer = start_timer(schedule, start_time)
+    {:reply, :ok, %{state | timer: timer, start_time: start_time, schedule_left: schedule}}
+  end
+
+  def handle_call({:set_repeat, repeat}, _from, state) do
+    {:reply, :ok, %{state | repeat: repeat}}
   end
 
   @impl true
   def handle_info(
         :play,
-        %{schedule_left: schedule_left, start_time: start_time, synth: synth} = state
+        %{
+          schedule_left: schedule_left,
+          start_time: start_time,
+          synth: synth,
+          repeat: repeat,
+          end_time: end_time,
+          schedule: schedule
+        } = state
       ) do
-    schedule_left = play_next_midi(schedule_left, start_time, synth)
-    {:noreply, %{state | schedule_left: schedule_left}}
+    {timer, schedule_left} = play_next_command(schedule_left, start_time, synth)
+    state = %{state | timer: timer, schedule_left: schedule_left}
+
+    if repeat and schedule_left == [] do
+      start_time = DateTime.add(start_time, end_time, :millisecond)
+      timer = start_timer(schedule, start_time)
+      {:noreply, %{state | start_time: start_time, timer: timer, schedule_left: schedule}}
+    else
+      {:noreply, state}
+    end
   end
 
-  defp play_next_midi([], _start_time, _synth), do: []
+  # Private functions
 
-  defp play_next_midi([{offset, command} | next_schedule] = schedule_left, start_time, synth) do
+  defp start_timer([], _start_time), do: nil
+
+  defp start_timer([{offset, _command} | _], start_time) do
+    next_time = DateTime.add(start_time, offset, :millisecond)
+    delay = max(Timex.diff(next_time, Timex.now(), :millisecond), 0)
+    Process.send_after(self(), :play, delay)
+  end
+
+  defp play_next_command([], _start_time, _synth), do: {nil, []}
+
+  defp play_next_command([{offset, command} | next_schedule] = schedule_left, start_time, synth) do
     next_time = DateTime.add(start_time, offset, :millisecond)
     micro_diff = Timex.diff(next_time, Timex.now(), :microsecond)
 
     if micro_diff < 500 do
       # Play command, and try to play next command too.
       MIDISynth.midi(synth, command)
-      play_next_midi(next_schedule, start_time, synth)
+      play_next_command(next_schedule, start_time, synth)
     else
       # Command is too far in the future, schedule next timer.
-      delay = ceil(micro_diff / 1000)
-      Process.send_after(self(), :play, delay)
-      schedule_left
+      delay = max(ceil(micro_diff / 1000), 0)
+      timer = Process.send_after(self(), :play, delay)
+      {timer, schedule_left}
     end
   end
-
-  defp start_timer([], _start_time), do: nil
-
-  defp start_timer([{offset, _command} | _], start_time) do
-    next_time = DateTime.add(start_time, offset, :millisecond)
-    delay = Timex.diff(next_time, Timex.now(), :millisecond)
-    Process.send_after(self(), :play, delay)
-  end
 end