First version of the CLI

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

7 files changed, 244 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
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index 0000000..24e5b0a
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+.build
diff --git a/Package.resolved b/Package.resolved
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index 0000000..14edea2
--- /dev/null
+++ b/Package.resolved
@@ -0,0 +1,78 @@
+{
+  "originHash" : "4364692988907e9672535440f83dd48704c3b22f9efcbe4257ebb73390ebea52",
+  "pins" : [
+    {
+      "identity" : "swift-argument-parser",
+      "kind" : "remoteSourceControl",
+      "location" : "https://github.com/apple/swift-argument-parser.git",
+      "state" : {
+        "revision" : "cdd0ef3755280949551dc26dee5de9ddeda89f54",
+        "version" : "1.6.2"
+      }
+    },
+    {
+      "identity" : "swift-async-algorithms",
+      "kind" : "remoteSourceControl",
+      "location" : "https://github.com/apple/swift-async-algorithms.git",
+      "state" : {
+        "revision" : "042e1c4d9d19748c9c228f8d4ebc97bb1e339b0b",
+        "version" : "1.0.4"
+      }
+    },
+    {
+      "identity" : "swift-atomics",
+      "kind" : "remoteSourceControl",
+      "location" : "https://github.com/apple/swift-atomics.git",
+      "state" : {
+        "revision" : "b601256eab081c0f92f059e12818ac1d4f178ff7",
+        "version" : "1.3.0"
+      }
+    },
+    {
+      "identity" : "swift-collections",
+      "kind" : "remoteSourceControl",
+      "location" : "https://github.com/apple/swift-collections.git",
+      "state" : {
+        "revision" : "7b847a3b7008b2dc2f47ca3110d8c782fb2e5c7e",
+        "version" : "1.3.0"
+      }
+    },
+    {
+      "identity" : "swift-log",
+      "kind" : "remoteSourceControl",
+      "location" : "https://github.com/apple/swift-log.git",
+      "state" : {
+        "revision" : "ce592ae52f982c847a4efc0dd881cc9eb32d29f2",
+        "version" : "1.6.4"
+      }
+    },
+    {
+      "identity" : "swift-nio",
+      "kind" : "remoteSourceControl",
+      "location" : "https://github.com/apple/swift-nio.git",
+      "state" : {
+        "revision" : "a24771a4c228ff116df343c85fcf3dcfae31a06c",
+        "version" : "2.88.0"
+      }
+    },
+    {
+      "identity" : "swift-service-lifecycle",
+      "kind" : "remoteSourceControl",
+      "location" : "https://github.com/swift-server/swift-service-lifecycle.git",
+      "state" : {
+        "revision" : "0fcc4c9c2d58dd98504c06f7308c86de775396ff",
+        "version" : "2.9.0"
+      }
+    },
+    {
+      "identity" : "swift-system",
+      "kind" : "remoteSourceControl",
+      "location" : "https://github.com/apple/swift-system.git",
+      "state" : {
+        "revision" : "395a77f0aa927f0ff73941d7ac35f2b46d47c9db",
+        "version" : "1.6.3"
+      }
+    }
+  ],
+  "version" : 3
+}
diff --git a/Package.swift b/Package.swift
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index 0000000..4a1ce2f
--- /dev/null
+++ b/Package.swift
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+// swift-tools-version: 6.2
+
+import PackageDescription
+
+let package = Package(
+    name: "caffeinate-downloads",
+    platforms: [.macOS(.v13)],
+    dependencies: [
+      .package(url: "https://github.com/apple/swift-argument-parser.git", from: "1.6.0"),
+      .package(url: "https://github.com/apple/swift-log.git", from: "1.6.0"),
+      .package(url: "https://github.com/apple/swift-nio.git", from: "2.88.0"),
+      .package(url: "https://github.com/apple/swift-system.git", from: "1.6.0"),
+      .package(url: "https://github.com/swift-server/swift-service-lifecycle.git", from: "2.9.0"),
+    ],
+    targets: [
+      .executableTarget(
+        name: "caffeinate-downloads",
+        dependencies: [
+          .product(name: "ArgumentParser", package: "swift-argument-parser"),
+          .product(name: "Logging", package: "swift-log"),
+          .product(name: "ServiceLifecycle", package: "swift-service-lifecycle"),
+          .product(name: "SystemPackage", package: "swift-system"),
+          .product(name: "_NIOFileSystem", package: "swift-nio"),
+        ]
+      )
+    ]
+)
diff --git a/README b/README
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index 0000000..aa3d7a3
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+++ b/README
@@ -0,0 +1,2 @@
+This is a trivial tool to prevent macOS from sleeping when Firefox is
+still downloading files.
diff --git a/Sources/Main.swift b/Sources/Main.swift
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+++ b/Sources/Main.swift
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+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
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index 0000000..0cfe895
--- /dev/null
+++ b/Sources/SleepInhibitor.swift
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+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
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index 0000000..c7ca85a
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+++ b/Sources/Watcher.swift
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+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
+      }
+    }
+  }
+}