(#10) Add a draft version of the change tracking

src/main/kotlin/com/github/y0ung3r/gitglobalhookslocator/git/HookEvent.kt

@@ -0,0 +1,8 @@
+package com.github.y0ung3r.gitglobalhookslocator.git
+
+import java.nio.file.Path
+import java.nio.file.WatchEvent
+
+data class HookEvent(
+	val kind: WatchEvent.Kind<Path>,
+	val entry: HookEntry)

src/main/kotlin/com/github/y0ung3r/gitglobalhookslocator/git/HooksFolderVisitor.kt

@@ -0,0 +1,15 @@
+package com.github.y0ung3r.gitglobalhookslocator.git
+
+import java.nio.file.*
+import java.nio.file.attribute.BasicFileAttributes
+
+class HooksFolderVisitor(private val watchService: WatchService) : SimpleFileVisitor<Path>() {
+	override fun preVisitDirectory(directory: Path, attributes: BasicFileAttributes): FileVisitResult {
+		directory.register(
+			watchService,
+			StandardWatchEventKinds.ENTRY_CREATE,
+			StandardWatchEventKinds.ENTRY_DELETE)
+
+		return FileVisitResult.CONTINUE
+	}
+}

src/main/kotlin/com/github/y0ung3r/gitglobalhookslocator/git/ObservableHooksFolder.kt

@@ -0,0 +1,74 @@
+package com.github.y0ung3r.gitglobalhookslocator.git
+
+import com.github.y0ung3r.gitglobalhookslocator.git.extensions.getGlobalHooksPath
+import com.intellij.openapi.diagnostic.thisLogger
+import io.reactivex.rxjava3.subjects.PublishSubject
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.launch
+import java.nio.file.*
+import kotlin.io.path.nameWithoutExtension
+
+class ObservableHooksFolder(git: Git) {
+	companion object {
+		@JvmStatic
+		val supportedHooks = arrayOf(
+			"pre-commit",
+			"prepare-commit-msg",
+			"commit-msg",
+			"post-commit",
+			"applypatch-msg",
+			"pre-applypatch",
+			"post-applypatch",
+			"pre-rebase",
+			"post-rewrite",
+			"post-checkout",
+			"post-merge",
+			"pre-push",
+			"pre-auto-gc"
+		)
+	}
+
+	private var count: Int = 0
+	val hooks: PublishSubject<HookEvent>
+	val path: Path
+
+	init {
+		path = git.getGlobalHooksPath()
+
+		val files = try {
+			Files.list(path)
+		}
+		catch (exception: NoSuchFileException) {
+			thisLogger()
+				.info("Provided hooks path is not valid", exception)
+
+			emptyList<Path>()
+				.stream()
+		}
+
+		hooks = PublishSubject.create()
+
+		files
+			.filter {
+				supportedHooks.any { hookName -> it.fileName.nameWithoutExtension.contains(hookName) }
+			}
+			.map { HookEvent(StandardWatchEventKinds.ENTRY_CREATE, HookEntry.load(it)) }
+			.forEach { hooks.onNext(it) }
+
+		val watchService = FileSystems.getDefault().newWatchService()
+		Files.walkFileTree(path, HooksFolderVisitor(watchService))
+
+		val changesTrackingJob = CoroutineScope(Dispatchers.IO).launch {
+			while (true) {
+				val folderEntry = watchService.take()
+
+				folderEntry.pollEvents().forEach {
+					val hookPath = Path.of(path.toString(), it.context().toString())
+					val hookEntry = HookEntry.load(hookPath)
+					hooks.onNext(HookEvent(it.kind() as WatchEvent.Kind<Path>, hookEntry))
+				}
+			}
+		}
+	}
+}

src/test/kotlin/com/github/y0ung3r/gitglobalhookslocator/gitTests/HooksFolderTests.kt

@@ -2,12 +2,42 @@ package com.github.y0ung3r.gitglobalhookslocator.gitTests
 
 import com.github.y0ung3r.gitglobalhookslocator.git.Git
 import com.github.y0ung3r.gitglobalhookslocator.git.HooksFolder
+import com.github.y0ung3r.gitglobalhookslocator.git.ObservableHooksFolder
 import com.github.y0ung3r.gitglobalhookslocator.git.cli.CliResponse
 import com.github.y0ung3r.gitglobalhookslocator.gitTests.testEngine.HookTestBase
 import com.github.y0ung3r.gitglobalhookslocator.gitTests.testEngine.RespondInterchangeably
 import org.junit.Assert.*
 import org.junit.Test
 import java.nio.file.Path
+import java.nio.file.StandardWatchEventKinds
+
+class ObservableHooksFolderTests : HookTestBase() {
+    private companion object {
+        @JvmStatic
+        fun getGit(hooksPath: Path) = Git(
+            RespondInterchangeably(
+                CliResponse(Git.minRequiredVersion.toString()),
+                CliResponse(hooksPath.toString())
+            )
+        )
+    }
+
+    @Test
+    fun `Should observe changes`() {
+        // Arrange
+        val git = getGit(getEnabledHooksPath())
+
+        // Act
+        val sut = ObservableHooksFolder(git)
+
+        sut.hooks.subscribe {
+            assertEquals(it.kind, StandardWatchEventKinds.ENTRY_CREATE)
+        }
+
+        // Assert
+        createHook("kek")
+    }
+}
 
 class HooksFolderTests : HookTestBase() {
     private companion object {

src/test/kotlin/com/github/y0ung3r/gitglobalhookslocator/gitTests/testEngine/HookTestBase.kt

@@ -41,6 +41,17 @@ abstract class HookTestBase {
         fun getEnabledHooksPath(): Path
             = getHooksPath(ENABLED_HOOK)
 
+        @JvmStatic
+        fun createHook(hookName: String) {
+            val hookPath = getHookPath(ENABLED_HOOK, hookName).toFile()
+
+            if (hookPath.exists()) {
+                return
+            }
+
+            hookPath.createNewFile()
+        }
+
         @JvmStatic
         private fun clearTestHooks(hookType: String) {
             val hooksPath = getHooksPath(hookType)