refactor(tracker): group Model methods, with each group in one source file

tracker/midi.go

@@ -0,0 +1,77 @@
+package tracker
+
+import (
+	"fmt"
+	"strings"
+)
+
+type (
+	MIDIModel   Model
+	MIDIContext interface {
+		InputDevices(yield func(deviceName string) bool)
+		Open(deviceName string) error
+		Close()
+		IsOpen() bool
+	}
+)
+
+func (m *Model) MIDI() *MIDIModel { return (*MIDIModel)(m) }
+
+// InputDevices can be iterated to get string names of all the MIDI input
+// devices.
+func (m *MIDIModel) InputDevices(yield func(deviceName string) bool) { m.midi.InputDevices(yield) }
+
+// IsOpen returns true if a midi device is currently open.
+func (m *MIDIModel) IsOpen() bool { return m.midi.IsOpen() }
+
+// InputtingNotes returns a Bool controlling whether the MIDI events are used
+// just to trigger instruments, or if the note events are used to input notes to
+// the note table.
+func (m *MIDIModel) InputtingNotes() Bool { return MakeBool((*midiInputtingNotes)(m)) }
+
+type midiInputtingNotes Model
+
+func (m *midiInputtingNotes) Value() bool       { return m.broker.mIDIEventsToGUI.Load() }
+func (m *midiInputtingNotes) SetValue(val bool) { m.broker.mIDIEventsToGUI.Store(val) }
+
+// Open returns an Action to open the MIDI input device with a given name.
+func (m *MIDIModel) Open(deviceName string) Action {
+	return MakeAction(openMIDI{Item: deviceName, Model: (*Model)(m)})
+}
+
+type openMIDI struct {
+	Item string
+	*Model
+}
+
+func (s openMIDI) Do() {
+	m := s.Model
+	if err := s.Model.midi.Open(s.Item); err == nil {
+		message := fmt.Sprintf("Opened MIDI device: %s", s.Item)
+		m.Alerts().Add(message, Info)
+	} else {
+		message := fmt.Sprintf("Could not open MIDI device: %s", s.Item)
+		m.Alerts().Add(message, Error)
+	}
+}
+
+// FindMIDIDeviceByPrefix finds the MIDI input device whose name starts with the given
+// prefix. It returns the full device name and true if found, or an empty string
+// and false if not found.
+func FindMIDIDeviceByPrefix(c MIDIContext, prefix string) (deviceName string, ok bool) {
+	for input := range c.InputDevices {
+		if strings.HasPrefix(input, prefix) {
+			return input, true
+		}
+	}
+	return "", false
+}
+
+// NullMIDIContext is a mockup MIDIContext if you don't want to create a real
+// one.
+type NullMIDIContext struct{}
+
+func (m NullMIDIContext) InputDevices(yield func(string) bool) {}
+func (m NullMIDIContext) Open(deviceName string) error         { return nil }
+func (m NullMIDIContext) Close()                               {}
+func (m NullMIDIContext) IsOpen() bool                         { return false }