1 files changed, 58 insertions, 0 deletions
diff --git a/Sources/Watcher.swift b/Sources/Watcher.swift
new file mode 100644
index 0000000..c7ca85a
--- /dev/null
+++ b/Sources/Watcher.swift
@@ -0,0 +1,58 @@
+import Logging
+import ServiceLifecycle
+import SystemPackage
+import _NIOFileSystem
+
+struct Watcher: Service {
+  let directory: FilePath
+  let logger: Logger
+  let suffix: String
+
+  func run() async {
+    let sleepInhibitor = SleepInhibitor()
+
+    while !Task.isCancelled {
+      let isDownloading: Bool
+      do {
+        isDownloading = try await FileSystem.shared.withDirectoryHandle(atPath: self.directory) {
+          try await $0.listContents().contains {
+            $0.name.extension?.hasSuffix(self.suffix) ?? false
+          }
+        }
+      } catch is CancellationError {
+        return
+      } catch {
+        self.logger.error("Failed to check directory: \(error)")
+        return
+      }
+
+      switch (isDownloading, await sleepInhibitor.isInhibitingSleep) {
+      case (true, false):
+        self.logger.debug("Ongoing downloads found, inhibiting sleep")
+        do {
+          try await sleepInhibitor.create(
+            name: "caffeinate-downloads",
+            details: "There are files being downloaded"
+          )
+        } catch {
+          self.logger.error("Failed to create assertion: \(error)")
+        }
+
+      case (false, true):
+        self.logger.debug("No ongoing downloads found, allowing sleep")
+        do {
+          try await sleepInhibitor.release()
+        } catch {
+          self.logger.error("Failed to release assertion: \(error)")
+        }
+
+      default:
+        break
+      }
+
+      guard (try? await Task.sleep(for: .seconds(30))) != nil else {
+        return
+      }
+    }
+  }
+}