Invert display and lockscreen control dependencies

afterlock/afterlock.go

@@ -1,9 +1,6 @@
 package afterlock
 
 import(
-	"after-lock/evdev"
-	"after-lock/lockscreen"
-	"after-lock/display"
 	"after-lock/atomicflag"
 	"time"
 	"sync"
@@ -11,6 +8,22 @@ import(
 )
 
 
+// Display controls and monitors the physical display
+type Display interface {
+	Suspend() error
+	IsOn() (bool, error)
+}
+
+// Lockscreen can determine whether the screensaver is active or not
+type Lockscreen interface {
+	IsActive() (bool, error)
+}
+
+// KeypressDetector can wait for keypresses
+type KeypressDetector interface {
+	BlockUntilKeypress(string) error
+}
+
 // AfterLock suspends the display when the lockscreen is active
 type AfterLock struct {
 	InitialDelay uint
@@ -19,6 +32,9 @@ type AfterLock struct {
 	wg sync.WaitGroup
 	stopFlag *atomicflag.AtomicFlag
 	keypressFlag *atomicflag.AtomicFlag
+	Display Display
+	LockScreen Lockscreen
+	KeypressDetector KeypressDetector
 }
 
 // New constructs a new AfterLock instance
@@ -30,11 +46,12 @@ func New(keyboardDeviceNode string) *AfterLock {
 	}
 }
 
-// Start starts monitoring the lockscreen/keyboard status to determine
+// Start starts monitoring the lockscreen/keyboard to determine
 // when to suspend the display.
 // Exits after the computer is unlocked
+// Requires InitialDelay, LoopDelay, Display and LockScreen to be set
 func (af *AfterLock) Start() {
-	af.checkDelaysConfigured()
+	af.checkStructConfigured()
 
 	af.wg.Add(1)
 	go af.detectKeypresses()
@@ -43,18 +60,27 @@ func (af *AfterLock) Start() {
 	af.hybernateDisplayLoop()
 }
 
-func (af *AfterLock) checkDelaysConfigured() {
+func (af *AfterLock) checkStructConfigured() {
 	if af.InitialDelay == 0 {
 		panic(errors.New("InitialDelay not configured"))
 	}
 	if af.LoopDelay == 0 {
 		panic(errors.New("LoopDelay not configured"))
 	}
+	if af.Display == nil {
+		panic(errors.New("Display not configured"))
+	}
+	if af.LockScreen == nil {
+		panic(errors.New("LockScreen not configured"))
+	}
+	if af.KeypressDetector == nil {
+		panic(errors.New("KeypressDetector not configured"))
+	}
 }
 
 func (af *AfterLock) detectKeypresses() {
 	for {
-		err := evdev.BlockUntilKeypress(af.keyboardDeviceNode)
+		err := af.KeypressDetector.BlockUntilKeypress(af.keyboardDeviceNode)
 		if err != nil {
 			panic(err)
 		}
@@ -68,7 +94,7 @@ func (af *AfterLock) detectKeypresses() {
 
 func (af *AfterLock) hybernateDisplayLoop() {
 	for {
-		screenLocked, err := lockscreen.IsActive()
+		screenLocked, err := af.LockScreen.IsActive()
 		if err != nil {
 			panic(err)
 		}
@@ -78,12 +104,12 @@ func (af *AfterLock) hybernateDisplayLoop() {
 			return
 		}
 
-		displayOn, err := display.IsOn()
+		displayOn, err := af.Display.IsOn()
 		if err != nil {
 			panic(err)
 		}
 		if displayOn {
-			err := display.Suspend()
+			err := af.Display.Suspend()
 			if err != nil {
 				panic(err)
 			}

cmd/after-lock/after-lock.go

@@ -2,10 +2,13 @@ package main
 
 import (
 	"after-lock/afterlock"
+	"after-lock/display"
+	"after-lock/keypressdetector"
 	"after-lock/lockfile"
+	"after-lock/lockscreen"
 	"fmt"
-	"runtime/debug"
 	"os"
+	"runtime/debug"
 )
 
 const (
@@ -26,6 +29,9 @@ func main() {
 	al := afterlock.New(keyboardDeviceNode)
 	al.InitialDelay = initialDelay
 	al.LoopDelay = loopDelay
+	al.Display = display.Xset{}
+	al.LockScreen = lockscreen.XDG{}
+	al.KeypressDetector = keypressdetector.Evdev{}
 
 	al.Start()
 }

display/display.go

@@ -7,8 +7,11 @@ import (
 )
 
 
-// Suspend the display using xset
-func Suspend() error {
+// Xset monitors/controls the display using xset
+type Xset struct {}
+
+// Suspend the display
+func (Xset) Suspend() error {
 	cmd := exec.Command("xset",
 		"dpms",
 		"force",
@@ -18,7 +21,7 @@ func Suspend() error {
 }
 
 // IsOn determines if the display is on
-func IsOn() (bool, error) {
+func (Xset) IsOn() (bool, error) {
 	cmd := exec.Command("xset", "q")
 	outputBytes, err := cmd.CombinedOutput()
 	if err != nil {

keypressdetector/evdev.go

@@ -1,4 +1,4 @@
-package evdev
+package keypressdetector
 
 // #cgo CFLAGS: -g -Wall
 // #include "evdev.h"
@@ -11,7 +11,11 @@ import (
 )
 
 
-func BlockUntilKeypress(devicePath string) error {
+// Evdev can detect keypresses on /dev/input devices
+type Evdev struct {}
+
+// BlockUntilKeypress waits until a key is pressed on the specified device
+func (Evdev) BlockUntilKeypress(devicePath string) error {
 	path := C.CString(devicePath)
 	defer C.free(unsafe.Pointer(path))
 

lockscreen/lockscreen.go

@@ -6,8 +6,11 @@ import (
 )
 
 
+// XDG uses qdbus to monitor the freedesktop screensaver status
+type XDG struct {}
+
 // IsActive checks whether the screen is locked (checks if the screensaver is active)
-func IsActive() (bool, error) {
+func (XDG) IsActive() (bool, error) {
 	cmd := exec.Command("qdbus",
 		"org.kde.screensaver",
 		"/ScreenSaver",