Initial release

Sources/KnotchyCore/Setup/ContainerRuntime.swift

@@ -0,0 +1,55 @@
+import Foundation
+
+/// Apple's container runtime: the release Knotchy installs, and how an installed one is judged.
+public enum ContainerRuntime {
+    public struct Release: Equatable, Sendable {
+        public let version: String
+        public let url: URL
+        public let sha256: String
+        public let size: Int64
+
+        public init(version: String, url: URL, sha256: String, size: Int64) {
+            self.version = version
+            self.url = url
+            self.sha256 = sha256
+            self.size = size
+        }
+    }
+
+    /// The only package Knotchy ever installs. Bump it only after testing a new release.
+    public static let pinned = Release(
+        version: "1.4.1",
+        url: URL(string: "https://github.com/apple/container/releases/download/1.4.1/container-1.4.1-installer-signed.pkg")!,
+        sha256: "c0d2716afefbb194c93fae662e9cae7cc186bcbcf746816608ec673dd648a6a4",
+        size: 117_773_865)
+    public static let minimumVersion = "1.4.0"
+
+    public static func version(in output: String) -> String? {
+        output.firstMatch(of: #/container CLI version (\d+(?:\.\d+)+)/#).map { String($0.1) }
+    }
+
+    /// Output Knotchy can't read counts as current, so a new format can never cause a downgrade.
+    public static func status(versionOutput: String?) -> RuntimeStatus {
+        guard let versionOutput else { return .missing }
+        guard let found = version(in: versionOutput) else { return .current(nil) }
+        return isOlder(found, than: minimumVersion) ? .outdated(found) : .current(found)
+    }
+
+    public static func isOlder(_ version: String, than other: String) -> Bool {
+        let lhs = version.split(separator: ".").map { Int($0) ?? 0 }
+        let rhs = other.split(separator: ".").map { Int($0) ?? 0 }
+        for index in 0..<max(lhs.count, rhs.count) {
+            let a = index < lhs.count ? lhs[index] : 0
+            let b = index < rhs.count ? rhs[index] : 0
+            if a != b { return a < b }
+        }
+        return false
+    }
+}
+
+public enum RuntimeStatus: Equatable, Sendable {
+    case missing
+    case outdated(String)
+    /// nil: installed, but its version couldn't be read.
+    case current(String?)
+}