App architecture modifications.

Now GUI and the app itself is divided into two different binaries.
The app also provides system tray icon.
Whereas the GUI can be used to configure the app.

app/src/recorder.rs

@@ -0,0 +1,113 @@
+mod pvrecorder;
+// mod cpal;
+// mod portaudio;
+
+use once_cell::sync::OnceCell;
+
+use crate::{DB, config, config::structs::RecorderType};
+
+static RECORDER_TYPE: OnceCell<RecorderType> = OnceCell::new();
+static FRAME_LENGTH: OnceCell<u32> = OnceCell::new();
+
+pub fn init() -> Result<(), ()> {
+    // set default recorder type
+    // @TODO. Make it configurable?
+    RECORDER_TYPE.set(config::DEFAULT_RECORDER_TYPE).unwrap();
+
+    // load given recorder
+    match RECORDER_TYPE.get().unwrap() {
+        RecorderType::PvRecorder => {
+            // Init Pv Recorder
+            info!("Initializing PvRecorder recording backend.");
+            FRAME_LENGTH.set(512u32).unwrap(); // pvrecorder requires frame buffer of 512
+            match pvrecorder::init_microphone(get_selected_microphone_index(), FRAME_LENGTH.get().unwrap().to_owned()) {
+                false => {
+                    error!("Recorder initialization failed.");
+
+                    return Err(())
+                },
+                _ => {
+                    info!("Recorder initialization success.");
+                }
+            }
+        },
+        RecorderType::PortAudio => {
+            // Init PortAudio
+            info!("Initializing PortAudio recording backend");
+            todo!();
+            // match portaudio::init_microphone(get_selected_microphone_index(), FRAME_LENGTH.load(Ordering::SeqCst)) {
+            //     false => {
+            //         // Switch to PortAudio recorder
+            //         error!("PortAudio audio backend failed.");
+            //     },
+            //     _ => ()
+            // }
+        },
+        RecorderType::Cpal => {
+            // Init CPAL
+            info!("Initializing CPAL recording backend");
+            todo!();
+            // match cpal::init_microphone(get_selected_microphone_index(), FRAME_LENGTH.load(Ordering::SeqCst)) {
+            //     false => {
+            //         // Switch to CPAL recorder
+            //         error!("CPAL audio backend failed.");
+            //     },
+            //     _ => ()
+            // }
+        }
+    }
+
+    Ok(())
+}
+
+pub fn read_microphone(frame_buffer: &mut [i16]) {
+    match RECORDER_TYPE.get().unwrap() {
+        RecorderType::PvRecorder => {
+            pvrecorder::read_microphone(frame_buffer);
+        },
+        RecorderType::PortAudio => {
+            todo!();
+            // portaudio::read_microphone(frame_buffer);
+        },
+        RecorderType::Cpal => {
+            // cpal::read_microphone(frame_buffer);
+            panic!("Cpal should be used via callback assignment");
+        }
+    }
+}
+
+pub fn start_recording() -> Result<(), ()> {
+    match RECORDER_TYPE.get().unwrap() {
+        RecorderType::PvRecorder => {
+            return pvrecorder::start_recording(get_selected_microphone_index(), FRAME_LENGTH.get().unwrap().to_owned());
+        },
+        RecorderType::PortAudio => {
+            todo!();
+            // portaudio::start_recording(get_selected_microphone_index(), FRAME_LENGTH.load(Ordering::SeqCst));
+        },
+        RecorderType::Cpal => {
+            todo!();
+            // cpal::start_recording(get_selected_microphone_index(), FRAME_LENGTH.load(Ordering::SeqCst));
+        }
+    }
+}
+
+pub fn stop_recording() -> Result<(), ()> {
+    match RECORDER_TYPE.get().unwrap() {
+        RecorderType::PvRecorder => {
+            pvrecorder::stop_recording()
+        },
+        RecorderType::PortAudio => {
+            todo!();
+            // portaudio::stop_recording();
+        },
+        RecorderType::Cpal => {
+            todo!();
+            // cpal::stop_recording();
+        }
+    }
+}
+
+pub fn get_selected_microphone_index() -> i32 {
+    DB.get().unwrap().microphone
+}