Add version check and prompt for self update

Sources/Swiftly/Install.swift

@@ -82,7 +82,10 @@ struct Install: SwiftlyCommand {
     }
 
     mutating func run(_ ctx: SwiftlyCoreContext) async throws {
-        try await validateSwiftly(ctx)
+        let versionUpdateReminder = try await validateSwiftly(ctx)
+        defer {
+            versionUpdateReminder()
+        }
 
         var config = try await Config.load(ctx)
 

Sources/Swiftly/List.swift

@@ -38,7 +38,11 @@ struct List: SwiftlyCommand {
     }
 
     mutating func run(_ ctx: SwiftlyCoreContext) async throws {
-        try await validateSwiftly(ctx)
+        let versionUpdateReminder = try await validateSwiftly(ctx)
+        defer {
+            versionUpdateReminder()
+        }
+
         let selector = try self.toolchainSelector.map { input in
             try ToolchainSelector(parsing: input)
         }

Sources/Swiftly/ListAvailable.swift

@@ -44,7 +44,11 @@ struct ListAvailable: SwiftlyCommand {
     }
 
     mutating func run(_ ctx: SwiftlyCoreContext) async throws {
-        try await validateSwiftly(ctx)
+        let versionUpdateReminder = try await validateSwiftly(ctx)
+        defer {
+            versionUpdateReminder()
+        }
+
         let selector = try self.toolchainSelector.map { input in
             try ToolchainSelector(parsing: input)
         }

Sources/Swiftly/Run.swift

@@ -58,7 +58,10 @@ struct Run: SwiftlyCommand {
     }
 
     mutating func run(_ ctx: SwiftlyCoreContext) async throws {
-        try await validateSwiftly(ctx)
+        let versionUpdateReminder = try await validateSwiftly(ctx)
+        defer {
+            versionUpdateReminder()
+        }
 
         // Handle the specific case where help is requested of the run subcommand
         if command == ["--help"] {

Sources/Swiftly/SelfUpdate.swift

@@ -21,7 +21,7 @@ struct SelfUpdate: SwiftlyCommand {
     }
 
     mutating func run(_ ctx: SwiftlyCoreContext) async throws {
-        try await validateSwiftly(ctx)
+        let _ = try await validateSwiftly(ctx)
 
         let swiftlyBin = Swiftly.currentPlatform.swiftlyBinDir(ctx) / "swiftly"
         guard try await fs.exists(atPath: swiftlyBin) else {

Sources/Swiftly/Swiftly.swift

@@ -93,7 +93,7 @@ extension Data {
 }
 
 extension SwiftlyCommand {
-    public mutating func validateSwiftly(_ ctx: SwiftlyCoreContext) async throws {
+    public mutating func validateSwiftly(_ ctx: SwiftlyCoreContext) async throws -> () -> Void {
         for requiredDir in Swiftly.requiredDirectories(ctx) {
             guard try await fs.exists(atPath: requiredDir) else {
                 do {
@@ -107,5 +107,23 @@ extension SwiftlyCommand {
 
         // Verify that the configuration exists and can be loaded
         _ = try await Config.load(ctx)
+
+        let swiftlyRelease = try await ctx.httpClient.getCurrentSwiftlyRelease()
+        let shouldUpdateSwiftly = try swiftlyRelease.swiftlyVersion > SwiftlyCore.version
+
+        return {
+            if shouldUpdateSwiftly {
+                let updateMessage = """
+                -----------------------------
+                A new release of swiftly is available
+                Please run `swiftly self-update` to update.
+                -----------------------------\n
+                """
+
+                if let data = updateMessage.data(using: .utf8) {
+                    FileHandle.standardError.write(data)
+                }
+            }
+        }
     }
 }

Sources/Swiftly/Uninstall.swift

@@ -48,7 +48,11 @@ struct Uninstall: SwiftlyCommand {
     }
 
     mutating func run(_ ctx: SwiftlyCoreContext) async throws {
-        try await validateSwiftly(ctx)
+        let versionUpdateReminder = try await validateSwiftly(ctx)
+        defer {
+            versionUpdateReminder()
+        }
+
         let startingConfig = try await Config.load(ctx)
 
         let toolchains: [ToolchainVersion]

Sources/Swiftly/Update.swift

@@ -83,7 +83,11 @@ struct Update: SwiftlyCommand {
     }
 
     public mutating func run(_ ctx: SwiftlyCoreContext) async throws {
-        try await validateSwiftly(ctx)
+        let versionUpdateReminder = try await validateSwiftly(ctx)
+        defer {
+            versionUpdateReminder()
+        }
+
         var config = try await Config.load(ctx)
 
         guard let parameters = try await self.resolveUpdateParameters(ctx, &config) else {

Sources/Swiftly/Use.swift

@@ -60,7 +60,11 @@ struct Use: SwiftlyCommand {
     }
 
     mutating func run(_ ctx: SwiftlyCoreContext) async throws {
-        try await validateSwiftly(ctx)
+        let versionUpdateReminder = try await validateSwiftly(ctx)
+        defer {
+            versionUpdateReminder()
+        }
+
         var config = try await Config.load(ctx)
 
         // This is the bare use command where we print the selected toolchain version (or the path to it)