First version of the CLI

It’s pretty basic, and it only works on macOS for now.

3 files changed, 136 insertions, 0 deletions

diff --git a/Sources/Main.swift b/Sources/Main.swift
new file mode 100644
index 0000000..9ffff7e
--- /dev/null
+++ b/Sources/Main.swift
@@ -0,0 +1,30 @@
+import ArgumentParser
+import Foundation
+import Logging
+import ServiceLifecycle
+import SystemPackage
+
+@main
+struct EntryPoint: AsyncParsableCommand {
+  @Option(help: "Directory to search for ongoing downloads.", transform: { FilePath($0) })
+  var directory = FilePath("\(NSHomeDirectory())/Downloads")
+
+  @Option(help: "Suffix of ongoing downloads.")
+  var suffix = "part"
+
+  @Flag(help: "Enable verbose output.")
+  var verbose = false
+
+  func run() async throws {
+    var logger = Logger(label: "caffeinate-downloads")
+    if self.verbose {
+      logger.logLevel = .debug
+    }
+
+    try await ServiceGroup(
+      services: [Watcher(directory: self.directory, logger: logger, suffix: self.suffix)],
+      cancellationSignals: [.sigint, .sigquit],
+      logger: logger
+    ).run()
+  }
+}
diff --git a/Sources/SleepInhibitor.swift b/Sources/SleepInhibitor.swift
new file mode 100644
index 0000000..0cfe895
--- /dev/null
+++ b/Sources/SleepInhibitor.swift
@@ -0,0 +1,48 @@
+import IOKit.pwr_mgt
+
+actor SleepInhibitor {
+  var assertionID = IOPMAssertionID?.none
+  var isInhibitingSleep: Bool { self.assertionID != nil }
+
+  func create(name: String, details: String) throws {
+    guard self.assertionID == nil else {
+      return
+    }
+
+    var assertionID = IOPMAssertionID(0)
+    let ioReturn = IOPMAssertionCreateWithDescription(
+      kIOPMAssertionTypePreventUserIdleSystemSleep as CFString,
+      name as CFString,
+      details as CFString,
+      nil, nil, 0, nil,
+      &assertionID
+    )
+    guard ioReturn == kIOReturnSuccess else {
+      throw SleepInhibitorError(ioReturn: ioReturn)
+    }
+    self.assertionID = assertionID
+  }
+
+  func release() throws {
+    guard let assertionID = self.assertionID else {
+      return
+    }
+
+    let ioReturn = IOPMAssertionRelease(assertionID)
+    guard ioReturn == kIOReturnSuccess else {
+      throw SleepInhibitorError(ioReturn: ioReturn)
+    }
+    self.assertionID = nil
+  }
+}
+
+struct SleepInhibitorError: CustomStringConvertible, Error {
+  let ioReturn: IOReturn
+
+  var description: String {
+    guard let cString = mach_error_string(self.ioReturn) else {
+      return self.ioReturn.description
+    }
+    return String(cString: cString)
+  }
+}
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
+      }
+    }
+  }
+}