Add JSON output for use command

Documentation/SwiftlyDocs.docc/swiftly-cli-reference.md

@@ -152,7 +152,7 @@ Note that listing available snapshots before the latest release (major and minor
 Set the in-use or default toolchain. If no toolchain is provided, print the currently in-use toolchain, if any.
 
 ```
-swiftly use [--print-location] [--global-default] [--assume-yes] [--verbose] [<toolchain>] [--version] [--help]
+swiftly use [--print-location] [--global-default] [--format=<format>] [--assume-yes] [--verbose] [<toolchain>] [--version] [--help]
 ```
 
 **--print-location:**
@@ -165,6 +165,11 @@ swiftly use [--print-location] [--global-default] [--assume-yes] [--verbose] [<t
 *Set the global default toolchain that is used when there are no .swift-version files.*
 
 
+**--format=\<format\>:**
+
+*Output format (text, json)*
+
+
 **--assume-yes:**
 
 *Disable confirmation prompts by assuming 'yes'*

Sources/Swiftly/OutputSchema.swift

@@ -0,0 +1,57 @@
+import Foundation
+import SwiftlyCore
+
+struct LocationInfo: OutputData {
+    let path: String
+
+    init(path: String) {
+        self.path = path
+    }
+
+    var description: String {
+        self.path
+    }
+}
+
+struct ToolchainInfo: OutputData {
+    let version: ToolchainVersion
+    let source: ToolchainSource?
+
+    var description: String {
+        var message = String(describing: self.version)
+        if let source = source {
+            message += " (\(source.description))"
+        }
+        return message
+    }
+}
+
+struct ToolchainSetInfo: OutputData {
+    let version: ToolchainVersion
+    let previousVersion: ToolchainVersion?
+    let isGlobal: Bool
+    let versionFile: String?
+
+    var description: String {
+        var message = self.isGlobal ? "The global default toolchain has been set to `\(self.version)`" : "The file `\(self.versionFile ?? ".swift-version")` has been set to `\(self.version)`"
+        if let previousVersion = previousVersion {
+            message += " (was \(previousVersion.name))"
+        }
+
+        return message
+    }
+}
+
+enum ToolchainSource: Codable, CustomStringConvertible {
+    case swiftVersionFile(String)
+    case globalDefault
+
+    var description: String {
+        switch self {
+        case let .swiftVersionFile(path):
+            return path
+        case .globalDefault:
+            return "default"
+        }
+    }
+}

Sources/Swiftly/Swiftly.swift

@@ -51,8 +51,8 @@ public struct Swiftly: SwiftlyCommand {
         ]
     )
 
-    public static func createDefaultContext() -> SwiftlyCoreContext {
-        SwiftlyCoreContext()
+    public static func createDefaultContext(format: SwiftlyCore.OutputFormat = .text) -> SwiftlyCoreContext {
+        SwiftlyCoreContext(format: format)
     }
 
     /// The list of directories that swiftly needs to exist in order to execute.

Sources/Swiftly/Use.swift

@@ -14,6 +14,9 @@ struct Use: SwiftlyCommand {
     @Flag(name: .shortAndLong, help: "Set the global default toolchain that is used when there are no .swift-version files.")
     var globalDefault: Bool = false
 
+    @Option(name: .long, help: "Output format (text, json)")
+    var format: SwiftlyCore.OutputFormat = .text
+
     @OptionGroup var root: GlobalOptions
 
     @Argument(help: ArgumentHelp(
@@ -56,7 +59,7 @@ struct Use: SwiftlyCommand {
     var toolchain: String?
 
     mutating func run() async throws {
-        try await self.run(Swiftly.createDefaultContext())
+        try await self.run(Swiftly.createDefaultContext(format: self.format))
     }
 
     mutating func run(_ ctx: SwiftlyCoreContext) async throws {
@@ -84,21 +87,20 @@ struct Use: SwiftlyCommand {
             }
 
             if self.printLocation {
-                // Print the toolchain location and exit
-                await ctx.message("\(Swiftly.currentPlatform.findToolchainLocation(ctx, selectedVersion))")
+                let location = LocationInfo(path: "\(Swiftly.currentPlatform.findToolchainLocation(ctx, selectedVersion))")
+                await ctx.output(location)
                 return
             }
 
-            var message = "\(selectedVersion)"
-
-            switch result {
+            let source: ToolchainSource? = switch result {
             case let .swiftVersionFile(versionFile, _, _):
-                message += " (\(versionFile))"
+                .swiftVersionFile("\(versionFile)")
             case .globalDefault:
-                message += " (default)"
+                .globalDefault
             }
 
-            await ctx.message(message)
+            let toolchainInfo = ToolchainInfo(version: selectedVersion, source: source)
+            await ctx.output(toolchainInfo)
 
             return
         }
@@ -110,8 +112,7 @@ struct Use: SwiftlyCommand {
         let selector = try ToolchainSelector(parsing: toolchain)
 
         guard let toolchain = config.listInstalledToolchains(selector: selector).max() else {
-            await ctx.message("No installed toolchains match \"\(toolchain)\"")
-            return
+            throw SwiftlyError(message: "No installed toolchains match \"\(toolchain)\"")
         }
 
         try await Self.execute(ctx, toolchain, globalDefault: self.globalDefault, assumeYes: self.root.assumeYes, &config)
@@ -121,13 +122,14 @@ struct Use: SwiftlyCommand {
     static func execute(_ ctx: SwiftlyCoreContext, _ toolchain: ToolchainVersion, globalDefault: Bool, assumeYes: Bool = true, _ config: inout Config) async throws {
         let (selectedVersion, result) = try await selectToolchain(ctx, config: &config, globalDefault: globalDefault)
 
-        var message: String
+        let isGlobal: Bool
+        let configFile: String?
 
         if case let .swiftVersionFile(versionFile, _, _) = result {
             // We don't care in this case if there were any problems with the swift version files, just overwrite it with the new value
             try toolchain.name.write(to: versionFile, atomically: true)
-
-            message = "The file `\(versionFile)` has been set to `\(toolchain)`"
+            isGlobal = false
+            configFile = "\(versionFile)"
         } else if let newVersionFile = try await findNewVersionFile(ctx), !globalDefault {
             if !assumeYes {
                 await ctx.message("A new file `\(newVersionFile)` will be created to set the new in-use toolchain for this project. Alternatively, you can set your default globally with the `--global-default` flag. Proceed with creating this file?")
@@ -139,19 +141,21 @@ struct Use: SwiftlyCommand {
             }
 
             try toolchain.name.write(to: newVersionFile, atomically: true)
-
-            message = "The file `\(newVersionFile)` has been set to `\(toolchain)`"
+            isGlobal = false
+            configFile = "\(newVersionFile)"
         } else {
             config.inUse = toolchain
             try config.save(ctx)
-            message = "The global default toolchain has been set to `\(toolchain)`"
-        }
-
-        if let selectedVersion {
-            message += " (was \(selectedVersion.name))"
+            isGlobal = true
+            configFile = nil
         }
 
-        await ctx.message(message)
+        await ctx.output(ToolchainSetInfo(
+            version: toolchain,
+            previousVersion: selectedVersion,
+            isGlobal: isGlobal,
+            versionFile: configFile
+        ))
     }
 
     static func findNewVersionFile(_ ctx: SwiftlyCoreContext) async throws -> FilePath? {

Sources/SwiftlyCore/OutputFormatter.swift

@@ -0,0 +1,44 @@
+import ArgumentParser
+import Foundation
+
+public enum OutputFormat: String, Sendable, CaseIterable, ExpressibleByArgument {
+    case text
+    case json
+
+    public var description: String {
+        self.rawValue
+    }
+}
+
+public protocol OutputFormatter {
+    func format(_ data: OutputData) -> String
+}
+
+public protocol OutputData: Codable, CustomStringConvertible {
+    var description: String { get }
+}
+
+public struct TextOutputFormatter: OutputFormatter {
+    public init() {}
+
+    public func format(_ data: OutputData) -> String {
+        data.description
+    }
+}
+
+public struct JSONOutputFormatter: OutputFormatter {
+    public init() {}
+
+    public func format(_ data: OutputData) -> String {
+        let encoder = JSONEncoder()
+        encoder.outputFormatting = [.prettyPrinted, .sortedKeys]
+
+        let jsonData = try? encoder.encode(data)
+
+        guard let jsonData = jsonData, let result = String(data: jsonData, encoding: .utf8) else {
+            return "{}"
+        }
+
+        return result
+    }
+}

Sources/SwiftlyCore/SwiftlyCore.swift

@@ -37,68 +37,91 @@ public struct SwiftlyCoreContext: Sendable {
     /// The output handler to use, if any.
     public var outputHandler: (any OutputHandler)?
 
-    /// The input probider to use, if any
+    /// The output handler for error streams
+    public var errorOutputHandler: (any OutputHandler)?
+
+    /// The input provider to use, if any
     public var inputProvider: (any InputProvider)?
 
-    public init() {
+    /// The terminal info provider
+    public var terminal: any Terminal
+
+    /// The format
+    public var format: OutputFormat = .text
+
+    public init(format: SwiftlyCore.OutputFormat = .text) {
         self.httpClient = SwiftlyHTTPClient(httpRequestExecutor: HTTPRequestExecutorImpl())
         self.currentDirectory = fs.cwd
+        self.format = format
+        self.terminal = SystemTerminal()
     }
 
     public init(httpClient: SwiftlyHTTPClient) {
         self.httpClient = httpClient
         self.currentDirectory = fs.cwd
+        self.terminal = SystemTerminal()
     }
 
     /// Pass the provided string to the set output handler if any.
     /// If no output handler has been set, just print to stdout.
-    public func print(_ string: String = "", terminator: String? = nil) async {
+    public func print(_ string: String = "") async {
         guard let handler = self.outputHandler else {
-            if let terminator {
-                Swift.print(string, terminator: terminator)
-            } else {
-                Swift.print(string)
-            }
+            Swift.print(string)
             return
         }
-        await handler.handleOutputLine(string + (terminator ?? ""))
+        await handler.handleOutputLine(string)
     }
 
     public func message(_ string: String = "", terminator: String? = nil) async {
-        // Get terminal size or use default width
-        let terminalWidth = self.getTerminalWidth()
-        let wrappedString = string.isEmpty ? string : string.wrapText(to: terminalWidth)
-        await self.print(wrappedString, terminator: terminator)
+        let wrappedString = self.wrappedMessage(string) + (terminator ?? "")
+
+        if self.format == .json {
+            await self.printError(wrappedString)
+            return
+        } else {
+            await self.print(wrappedString)
+        }
     }
 
-    /// Detects the terminal width in columns
-    private func getTerminalWidth() -> Int {
-#if os(macOS) || os(Linux)
-        var size = winsize()
-#if os(OpenBSD)
-        // TIOCGWINSZ is a complex macro, so we need the flattened value.
-        let tiocgwinsz = UInt(0x4008_7468)
-        let result = ioctl(STDOUT_FILENO, tiocgwinsz, &size)
-#else
-        let result = ioctl(STDOUT_FILENO, UInt(TIOCGWINSZ), &size)
-#endif
+    private func wrappedMessage(_ string: String) -> String {
+        let terminalWidth = self.terminal.width()
+        return string.isEmpty ? string : string.wrapText(to: terminalWidth)
+    }
 
-        if result == 0 && Int(size.ws_col) > 0 {
-            return Int(size.ws_col)
+    public func printError(_ string: String = "") async {
+        if let handler = self.errorOutputHandler {
+            await handler.handleOutputLine(string)
+        } else {
+            if let data = (string + "\n").data(using: .utf8) {
+                try? FileHandle.standardError.write(contentsOf: data)
+            }
         }
-#endif
-        return 80 // Default width if terminal size detection fails
+    }
+
+    public func output(_ data: OutputData) async {
+        let formattedOutput: String
+        switch self.format {
+        case .text:
+            formattedOutput = TextOutputFormatter().format(data)
+        case .json:
+            formattedOutput = JSONOutputFormatter().format(data)
+        }
+        await self.print(formattedOutput)
     }
 
     public func readLine(prompt: String) async -> String? {
-        await self.print(prompt, terminator: ": \n")
+        await self.message(prompt, terminator: ": \n")
         guard let provider = self.inputProvider else {
             return Swift.readLine(strippingNewline: true)
         }
         return await provider.readLine()
     }
 
     public func promptForConfirmation(defaultBehavior: Bool) async -> Bool {
+        if self.format == .json {
+            await self.message("Assuming \(defaultBehavior ? "yes" : "no") due to JSON format")
+            return defaultBehavior
+        }
         let options: String
         if defaultBehavior {
             options = "(Y/n)"
@@ -112,7 +135,7 @@ public struct SwiftlyCoreContext: Sendable {
                         ?? (defaultBehavior ? "y" : "n")).lowercased()
 
             guard ["y", "n", ""].contains(answer) else {
-                await self.print(
+                await self.message(
                     "Please input either \"y\" or \"n\", or press ENTER to use the default.")
                 continue
             }

Sources/SwiftlyCore/Terminal.swift

@@ -0,0 +1,28 @@
+import Foundation
+
+/// Protocol retrieving terminal properties
+public protocol Terminal: Sendable {
+    /// Detects the terminal width in columns
+    func width() -> Int
+}
+
+public struct SystemTerminal: Terminal {
+    /// Detects the terminal width in columns
+    public func width() -> Int {
+#if os(macOS) || os(Linux)
+        var size = winsize()
+#if os(OpenBSD)
+        // TIOCGWINSZ is a complex macro, so we need the flattened value.
+        let tiocgwinsz = UInt(0x4008_7468)
+        let result = ioctl(STDOUT_FILENO, tiocgwinsz, &size)
+#else
+        let result = ioctl(STDOUT_FILENO, UInt(TIOCGWINSZ), &size)
+#endif
+
+        if result == 0 && Int(size.ws_col) > 0 {
+            return Int(size.ws_col)
+        }
+#endif
+        return 80 // Default width if terminal size detection fails
+    }
+}