5 files changed, 118 insertions, 83 deletions

diff --git a/src/audio/include/audio_converter.hpp b/src/audio/include/audio_converter.hpp
index c2ebde60..232b5d8e 100644
--- a/src/audio/include/audio_converter.hpp
+++ b/src/audio/include/audio_converter.hpp
@@ -6,9 +6,11 @@
 
 #pragma once
 
+#include <stdint.h>
 #include <cstdint>
 #include <memory>
 
+#include "audio_events.hpp"
 #include "audio_sink.hpp"
 #include "audio_source.hpp"
 #include "codec.hpp"
@@ -30,18 +32,23 @@ class SampleConverter {
 
   auto SetOutput(std::shared_ptr<IAudioOutput>) -> void;
 
-  auto ConvertSamples(cpp::span<sample::Sample>,
-                      const IAudioOutput::Format& format,
-                      bool is_eos) -> void;
+  auto beginStream(std::shared_ptr<TrackInfo>) -> void;
+  auto continueStream(cpp::span<sample::Sample>) -> void;
+  auto endStream() -> void;
 
  private:
   auto Main() -> void;
 
-  auto SetTargetFormat(const IAudioOutput::Format& format) -> void;
-  auto HandleSamples(cpp::span<sample::Sample>, bool) -> size_t;
+  auto handleBeginStream(std::shared_ptr<TrackInfo>) -> void;
+  auto handleContinueStream(size_t samples_available) -> void;
+  auto handleEndStream() -> void;
+
+  auto handleSamples(cpp::span<sample::Sample>) -> size_t;
+
+  auto sendToSink(cpp::span<sample::Sample>) -> void;
 
   struct Args {
-    IAudioOutput::Format format;
+    std::shared_ptr<TrackInfo>* track;
     size_t samples_available;
     bool is_end_of_stream;
   };
@@ -59,6 +66,8 @@ class SampleConverter {
   IAudioOutput::Format source_format_;
   IAudioOutput::Format target_format_;
   size_t leftover_bytes_;
+
+  uint32_t samples_sunk_;
 };
 
 }  // namespace audio
diff --git a/src/audio/include/audio_decoder.hpp b/src/audio/include/audio_decoder.hpp
index b8aac710..89f0f43c 100644
--- a/src/audio/include/audio_decoder.hpp
+++ b/src/audio/include/audio_decoder.hpp
@@ -20,25 +20,6 @@
 namespace audio {
 
 /*
- * Sample-based timer for the current elapsed playback time.
- */
-class Timer {
- public:
-  Timer(std::shared_ptr<Track>, const codecs::ICodec::OutputFormat& format, uint32_t current_seconds = 0);
-
-  auto AddSamples(std::size_t) -> void;
-
- private:
-  std::shared_ptr<Track> track_;
-
-  uint32_t current_seconds_;
-  uint32_t current_sample_in_second_;
-  uint32_t samples_per_second_;
-
-  uint32_t total_duration_seconds_;
-};
-
-/*
  * Handle to a persistent task that takes bytes from the given source, decodes
  * them into sample::Sample (normalised to 16 bit signed PCM), and then
  * forwards the resulting stream to the given converter.
@@ -65,7 +46,6 @@ class Decoder {
 
   std::shared_ptr<codecs::IStream> stream_;
   std::unique_ptr<codecs::ICodec> codec_;
-  std::unique_ptr<Timer> timer_;
 
   std::optional<codecs::ICodec::OutputFormat> current_format_;
   std::optional<IAudioOutput::Format> current_sink_format_;
diff --git a/src/audio/include/audio_events.hpp b/src/audio/include/audio_events.hpp
index a8533646..b8a0dba6 100644
--- a/src/audio/include/audio_events.hpp
+++ b/src/audio/include/audio_events.hpp
@@ -9,8 +9,10 @@
 #include <stdint.h>
 #include <cstdint>
 #include <memory>
+#include <optional>
 #include <string>
 
+#include "audio_sink.hpp"
 #include "tinyfsm.hpp"
 
 #include "track.hpp"
@@ -18,24 +20,82 @@
 
 namespace audio {
 
-struct Track {
+/*
+ * Struct encapsulating information about the decoder's current track.
+ */
+struct TrackInfo {
+  /*
+   * Audio tags extracted from the file. May be absent for files without any
+   * parseable tags.
+   */
   std::shared_ptr<database::TrackTags> tags;
-  std::shared_ptr<database::TrackData> db_info;
 
-  uint32_t duration;
-  uint32_t bitrate_kbps;
+  /*
+   * URI that the current track was retrieved from. This is currently always a
+   * file path on the SD card.
+   */
+  std::string uri;
+
+  /*
+   * The length of this track in seconds. This is either retrieved from the
+   * track's tags, or sometimes computed. It may therefore sometimes be
+   * inaccurate or missing.
+   */
+  std::optional<uint32_t> duration;
+
+  /* The offset in seconds that this file's decoding started from. */
+  std::optional<uint32_t> start_offset;
+
+  /* The approximate bitrate of this track in its original encoded form. */
+  std::optional<uint32_t> bitrate_kbps;
+
+  /* The encoded format of the this track. */
   codecs::StreamType encoding;
-  std::string filepath;
-};
 
-struct PlaybackStarted : tinyfsm::Event {};
+  IAudioOutput::Format format;
+};
 
+/*
+ * Event emitted by the audio FSM when the state of the audio pipeline has
+ * changed. This is usually once per second while a track is playing, plus one
+ * event each when a track starts or finishes.
+ */
 struct PlaybackUpdate : tinyfsm::Event {
-  uint32_t seconds_elapsed;
-  std::shared_ptr<Track> track;
+  /*
+   * The track that is currently being decoded by the audio pipeline. May be
+   * absent if there is no current track.
+   */
+  std::shared_ptr<TrackInfo> current_track;
+
+  /*
+   * How long the current track has been playing for, in seconds. Will always
+   * be present if current_track is present.
+   */
+  std::optional<uint32_t> track_position;
+
+  /* Whether or not the current track is currently being output to a sink. */
+  bool paused;
+};
+
+/*
+ * Sets a new track to be decoded by the audio pipeline, replacing any
+ * currently playing track.
+ */
+struct SetTrack : tinyfsm::Event {
+  std::variant<std::string, database::TrackId, std::monostate> new_track;
+  std::optional<uint32_t> seek_to_second;
+
+  enum Transition {
+    kHardCut,
+    kGapless,
+    // TODO: kCrossFade
+  };
+  Transition transition;
 };
 
-struct PlaybackStopped : tinyfsm::Event {};
+struct TogglePlayPause : tinyfsm::Event {
+  std::optional<bool> set_to;
+};
 
 struct QueueUpdate : tinyfsm::Event {
   bool current_changed;
@@ -49,15 +109,6 @@ struct QueueUpdate : tinyfsm::Event {
   Reason reason;
 };
 
-struct PlayFile : tinyfsm::Event {
-  std::string filename;
-};
-
-struct SeekFile : tinyfsm::Event {
-  uint32_t offset;
-  std::string filename;
-};
-
 struct StepUpVolume : tinyfsm::Event {};
 struct StepDownVolume : tinyfsm::Event {};
 struct SetVolume : tinyfsm::Event {
@@ -83,17 +134,21 @@ struct SetVolumeLimit : tinyfsm::Event {
   int limit_db;
 };
 
-struct TogglePlayPause : tinyfsm::Event {};
-
 struct OutputModeChanged : tinyfsm::Event {};
 
 namespace internal {
 
-struct InputFileOpened : tinyfsm::Event {};
-struct InputFileClosed : tinyfsm::Event {};
-struct InputFileFinished : tinyfsm::Event {};
+struct StreamStarted : tinyfsm::Event {
+  std::shared_ptr<TrackInfo> track;
+  IAudioOutput::Format src_format;
+  IAudioOutput::Format dst_format;
+};
+
+struct StreamUpdate : tinyfsm::Event {
+  uint32_t samples_sunk;
+};
 
-struct AudioPipelineIdle : tinyfsm::Event {};
+struct StreamEnded : tinyfsm::Event {};
 
 }  // namespace internal
 
diff --git a/src/audio/include/audio_fsm.hpp b/src/audio/include/audio_fsm.hpp
index 13e241be..60afb321 100644
--- a/src/audio/include/audio_fsm.hpp
+++ b/src/audio/include/audio_fsm.hpp
@@ -6,6 +6,7 @@
 
 #pragma once
 
+#include <stdint.h>
 #include <deque>
 #include <memory>
 #include <vector>
@@ -41,6 +42,14 @@ class AudioState : public tinyfsm::Fsm<AudioState> {
   /* Fallback event handler. Does nothing. */
   void react(const tinyfsm::Event& ev) {}
 
+  void react(const QueueUpdate&);
+  void react(const SetTrack&);
+  void react(const TogglePlayPause&);
+
+  void react(const internal::StreamStarted&);
+  void react(const internal::StreamUpdate&);
+  void react(const internal::StreamEnded&);
+
   void react(const StepUpVolume&);
   void react(const StepDownVolume&);
   virtual void react(const system_fsm::HasPhonesChanged&);
@@ -56,19 +65,10 @@ class AudioState : public tinyfsm::Fsm<AudioState> {
   virtual void react(const system_fsm::StorageMounted&) {}
   virtual void react(const system_fsm::BluetoothEvent&);
 
-  virtual void react(const PlayFile&) {}
-  virtual void react(const SeekFile&) {}
-  virtual void react(const QueueUpdate&) {}
-  virtual void react(const PlaybackUpdate&) {}
-  void react(const TogglePlayPause&);
-
-  virtual void react(const internal::InputFileOpened&) {}
-  virtual void react(const internal::InputFileClosed&) {}
-  virtual void react(const internal::InputFileFinished&) {}
-  virtual void react(const internal::AudioPipelineIdle&) {}
-
  protected:
   auto clearDrainBuffer() -> void;
+  auto awaitEmptyDrainBuffer() -> void;
+
   auto playTrack(database::TrackId id) -> void;
   auto commitVolume() -> void;
 
@@ -83,10 +83,19 @@ class AudioState : public tinyfsm::Fsm<AudioState> {
 
   static StreamBufferHandle_t sDrainBuffer;
 
-  static std::optional<database::TrackId> sCurrentTrack;
+  static std::shared_ptr<TrackInfo> sCurrentTrack;
+  static uint64_t sCurrentSamples;
+  static std::optional<IAudioOutput::Format> sDrainFormat;
+  static bool sCurrentTrackIsFromQueue;
 
-  auto readyToPlay() -> bool;
-  static bool sIsPlaybackAllowed;
+  static std::shared_ptr<TrackInfo> sNextTrack;
+  static uint64_t sNextTrackCueSamples;
+  static bool sNextTrackIsFromQueue;
+
+  static bool sIsResampling;
+  static bool sIsPaused;
+
+  auto currentPositionSeconds() -> std::optional<uint32_t>;
 };
 
 namespace states {
@@ -94,7 +103,6 @@ namespace states {
 class Uninitialised : public AudioState {
  public:
   void react(const system_fsm::BootComplete&) override;
-
   void react(const system_fsm::BluetoothEvent&) override{};
 
   using AudioState::react;
@@ -102,10 +110,6 @@ class Uninitialised : public AudioState {
 
 class Standby : public AudioState {
  public:
-  void react(const PlayFile&) override;
-  void react(const SeekFile&) override;
-  void react(const internal::InputFileOpened&) override;
-  void react(const QueueUpdate&) override;
   void react(const system_fsm::KeyLockChanged&) override;
   void react(const system_fsm::StorageMounted&) override;
 
@@ -117,18 +121,6 @@ class Playback : public AudioState {
   void entry() override;
   void exit() override;
 
-  void react(const system_fsm::HasPhonesChanged&) override;
-
-  void react(const PlayFile&) override;
-  void react(const SeekFile&) override;
-  void react(const QueueUpdate&) override;
-  void react(const PlaybackUpdate&) override;
-
-  void react(const internal::InputFileOpened&) override;
-  void react(const internal::InputFileClosed&) override;
-  void react(const internal::InputFileFinished&) override;
-  void react(const internal::AudioPipelineIdle&) override;
-
   using AudioState::react;
 };
 
diff --git a/src/audio/include/audio_sink.hpp b/src/audio/include/audio_sink.hpp
index 85c23f5c..e11f3ce0 100644
--- a/src/audio/include/audio_sink.hpp
+++ b/src/audio/include/audio_sink.hpp
@@ -11,7 +11,6 @@
 
 #include "esp_heap_caps.h"
 #include "freertos/FreeRTOS.h"
-#include "idf_additions.h"
 
 namespace audio {