♻️ Rework various common classes

phpmon-common/Core/Shell.swift

@@ -0,0 +1,179 @@
+//
+//  Shell.swift
+//  PHP Monitor
+//
+//  Copyright © 2021 Nico Verbruggen. All rights reserved.
+//
+
+import Cocoa
+
+public class Shell {
+    
+    // MARK: - Invoke static functions
+    
+    public static func run(
+        _ command: String,
+        requiresPath: Bool = false
+    ) {
+        Shell.user.run(command, requiresPath: requiresPath)
+    }
+    
+    public static func pipe(
+        _ command: String,
+        requiresPath: Bool = false
+    ) -> String {
+        return Shell.user.pipe(command, requiresPath: requiresPath)
+    }
+    
+    // MARK: - Singleton
+    
+    /**
+     We now require macOS 11, so no need to detect which terminal to use.
+     */
+    public var shell: String = "/bin/sh"
+    
+    /**
+     Singleton to access a user shell (with --login)
+     */
+    public static let user = Shell()
+    
+    /**
+     Runs a shell command without using the output.
+     Uses the default shell.
+     
+     - Parameter command: The command to run
+     - Parameter requiresPath: By default, the PATH is not resolved but some binaries might require this
+     */
+    private func run(
+        _ command: String,
+        requiresPath: Bool = false
+    ) {
+        // Equivalent of piping to /dev/null; don't do anything with the string
+        _ = Shell.pipe(command, requiresPath: requiresPath)
+    }
+    
+    /**
+     Runs a shell command and returns the output.
+     
+     - Parameter command: The command to run
+     - Parameter requiresPath: By default, the PATH is not resolved but some binaries might require this
+     */
+    private func pipe(
+        _ command: String,
+        requiresPath: Bool = false
+    ) -> String {
+        let shellOutput = self.executeSynchronously(command, requiresPath: requiresPath)
+        let hasError = (
+            shellOutput.standardOutput == ""
+            && shellOutput.errorOutput.lengthOfBytes(using: .utf8) > 0
+        )
+        return !hasError ? shellOutput.standardOutput : shellOutput.errorOutput
+    }
+    
+    /**
+     Runs the command and returns a `ShellOutput` object, which contains info about the process.
+     
+     - Parameter command: The command to run
+     - Parameter requiresPath: By default, the PATH is not resolved but some binaries might require this
+     - Parameter waitUntilExit: Waits for the command to complete before returning the `ShellOutput`
+     */
+    public func executeSynchronously(
+        _ command: String,
+        requiresPath: Bool = false
+    ) -> Shell.Output {
+        
+        let outputPipe = Pipe()
+        let errorPipe = Pipe()
+        
+        let task = self.createTask(for: command, requiresPath: requiresPath)
+        task.standardOutput = outputPipe
+        task.standardError = errorPipe
+        task.launch()
+        task.waitUntilExit()
+    
+        return Shell.Output(
+            standardOutput: String(
+                data: outputPipe.fileHandleForReading.readDataToEndOfFile(),
+                encoding: .utf8
+            )!,
+            errorOutput: String(
+                data: errorPipe.fileHandleForReading.readDataToEndOfFile(),
+                encoding: .utf8
+            )!,
+            task: task
+        )
+    }
+    
+    /**
+     Checks if a file exists at the provided path.
+     Uses `/bin/echo` instead of the `builtin` (which does not support `-n`).
+     */
+    public static func fileExists(_ path: String) -> Bool {
+        return Shell.pipe("if [ -f \(path) ]; then /bin/echo -n \"0\"; fi") == "0"
+    }
+    
+    /**
+     Creates a new process with the correct PATH and shell.
+     */
+    public func createTask(for command: String, requiresPath: Bool) -> Process {
+        let tailoredCommand = requiresPath
+        ? "export PATH=\(Paths.binPath):$PATH && \(command)"
+        : command
+        
+        let task = Process()
+        task.launchPath = self.shell
+        task.arguments = ["--login", "-c", tailoredCommand]
+        
+        return task
+    }
+    
+    public static func captureOutput(
+        _ task: Process,
+        didReceiveStdOutData: @escaping (String) -> Void,
+        didReceiveStdErrData: @escaping (String) -> Void
+    ) {
+        let outputPipe = Pipe()
+        let errorPipe = Pipe()
+        
+        task.standardOutput = outputPipe
+        task.standardError = errorPipe
+        
+        [(outputPipe, didReceiveStdOutData), (errorPipe, didReceiveStdErrData)].forEach {
+            (pipe: Pipe, callback: @escaping (String) -> Void) in
+            pipe.fileHandleForReading.waitForDataInBackgroundAndNotify()
+            NotificationCenter.default.addObserver(
+                forName: NSNotification.Name.NSFileHandleDataAvailable,
+                object: pipe.fileHandleForReading,
+                queue: nil
+            ) { notification in
+                if let outputString = String(data: pipe.fileHandleForReading.availableData, encoding: String.Encoding.utf8) {
+                    callback(outputString)
+                }
+                pipe.fileHandleForReading.waitForDataInBackgroundAndNotify()
+            }
+        }
+    }
+    
+    public static func haltCapturingOutput(_ task: Process) {
+        if let pipe = task.standardOutput as? Pipe {
+            NotificationCenter.default.removeObserver(pipe.fileHandleForReading)
+        }
+        if let pipe = task.standardError as? Pipe {
+            NotificationCenter.default.removeObserver(pipe.fileHandleForReading)
+        }
+    }
+    
+    public class Output {
+        public let standardOutput: String
+        public let errorOutput: String
+        public let task: Process
+        
+        init(standardOutput: String,
+             errorOutput: String,
+             task: Process) {
+            self.standardOutput = standardOutput
+            self.errorOutput = errorOutput
+            self.task = task
+        }
+    }
+}