Allow command plugin to take a dir as input

Plugins/GRPCProtobufGeneratorCommand/CommandConfig.swift

@@ -185,67 +185,68 @@ enum OptionsAndFlags: String, CaseIterable {
 }
 
 extension OptionsAndFlags {
-  func usageDescription() -> String {
-    switch self {
-    case .servers:
-      return "Generate server code. Generated by default."
-    case .noServers:
-      return "Do not generate server code. Generated by default."
-    case .clients:
-      return "Generate client code. Generated by default."
-    case .noClients:
-      return "Do not generate client code. Generated by default."
-    case .messages:
-      return "Generate message code. Generated by default."
-    case .noMessages:
-      return "Do not generate message code. Generated by default."
-    case .fileNaming:
-      return
-        "The naming scheme for output files [fullPath/pathToUnderscores/dropPath]. Defaults to fullPath."
-    case .accessLevel:
-      return
-        "The access level of the generated source [internal/public/package]. Defaults to internal."
-    case .accessLevelOnImports:
-      return "Whether imports should have explicit access levels. Defaults to false."
-    case .importPath:
-      return
-        "The directory in which to search for imports. May be specified multiple times. If none are specified the current working directory is used."
-    case .protocPath:
-      return "The path to the protoc binary."
-    case .dryRun:
-      return "Print but do not execute the protoc commands."
-    case .outputPath:
-      return "The directory into which the generated source files are created."
-    case .verbose:
-      return "Emit verbose output."
-    case .help:
-      return "Print this help."
-    }
+  static var helpText: String {
+    """
+    USAGE: swift package generate-grpc-code-from-protos [[<options> [--]] <inputs> ...
+
+    ARGUMENTS:
+      <inputs>                    The '.proto' files or directories containing them.
+
+    OPTIONS:
+      --servers/--no-servers      Generate server code (default: --servers)
+      --clients/--no-clients      Generate client code (default: --clients)
+      --messages/--no-messages    Generate message code (default: --messages)
+      --access-level <access>     Access level of generated code (internal/public/package)
+                                  (default: internal)
+      --access-level-on-imports   Whether imports have explicit access levels
+      --protoc-path <path>        Path to the protoc binary
+      --import-path <path>        Directory to search for imports, may be specified
+                                  multiple times. If none are specified the current
+                                  working directory is used.
+      --file-naming <naming>      The naming scheme for generated files
+                                  (fullPath/pathToUnderscores/dropPath)
+                                  (default: fullPath).
+      --output-path <path>        Directory to generate files into
+      --verbose                   Emit verbose output
+      --dry-run                   Print but don't execute the protoc commands
+      --help                      Print this help
+
+    EXAMPLES:
+
+      swift package generate-grpc-code-from-protos service.proto
+        Generates servers, clients, and messages from 'service.proto' into
+        the current working directory.
+
+      swift package generate-grpc-code-from-protos --no-clients --no-messages -- service1.proto service2.proto
+        Generate only servers from service1.proto and service2.proto into the
+        current working directory.
+
+      swift package generate-grpc-code-from-protos --output-path Generated --access-level public -- Protos
+        Generate server, clients, and messages from all .proto files contained
+        within the 'Protos' directory into the 'Generated' directory at the
+        public access level.
+
+      swift package --allow-writing-to-package-directory generate-grpc-code-from-protos --output-path Sources/Generated -- service.proto
+        Generates code from service.proto into the Sources/Generated directory
+        within a Swift Package without asking for permission to do so.
+
+    PERMISSIONS:
+      Swift Package Manager command plugins require permission to create files.
+      You'll be prompted to give generate-grpc-code-from-protos permission
+      when running it.
+
+      You can grant permissions by specifying --allow-writing-to-package-directory
+      or --allow-writing-to-directory to the swift package command.
+
+      See swift package plugin --help for more info.
+    """
   }
 
   static func printHelp(requested: Bool) {
-    let printMessage: (String) -> Void
     if requested {
-      printMessage = { message in print(message) }
+      print(Self.helpText)
     } else {
-      printMessage = Stderr.print
-    }
-
-    printMessage(
-      "Usage: swift package generate-grpc-code-from-protos [flags] [\(CommandConfig.parameterGroupSeparator)] [input files]"
-    )
-    printMessage("")
-    printMessage("Flags:")
-    printMessage("")
-
-    let spacing = 3
-    let maxLength =
-      (OptionsAndFlags.allCases.map(\.rawValue).max(by: { $0.count < $1.count })?.count ?? 0)
-      + spacing
-    for flag in OptionsAndFlags.allCases {
-      printMessage(
-        "  --\(flag.rawValue.padding(toLength: maxLength, withPad: " ", startingAt: 0))\(flag.usageDescription())"
-      )
+      Stderr.print(Self.helpText)
     }
   }
 }

Plugins/GRPCProtobufGeneratorCommand/CommandPluginError.swift

@@ -47,15 +47,15 @@ extension CommandPluginError: CustomStringConvertible {
 
     case .invalidInputFiles(let files):
       var lines: [String] = []
-      lines.append("Invalid input file(s)")
+      lines.append("Found \(files.count) invalid input file(s)")
       lines.append("")
-      lines.append("Found \(files.count) input(s) not ending in '.proto':")
+      lines.append("The following don't exist or aren't '.proto' files or directories:")
       for file in files {
         lines.append("- \(file)")
       }
       lines.append("")
       lines.append("All options must be before '--', and all input files must be")
-      lines.append("after '--'. Input files must end in '.proto'.")
+      lines.append("after '--'. Inputs be '.proto' files or directories.")
       lines.append("")
       lines.append("See --help for more information.")
       return lines.joined(separator: "\n")

Plugins/GRPCProtobufGeneratorCommand/Plugin.swift

@@ -57,13 +57,10 @@ struct GRPCProtobufGeneratorCommandPlugin {
     }
 
     // Split the input into options and input files.
-    let (flagsAndOptions, inputFiles) = self.splitArgs(arguments)
+    let (flagsAndOptions, inputs) = self.splitArgs(arguments)
 
     // Check the input files all look like protos
-    let nonProtoInputs = inputFiles.filter { !$0.hasSuffix(".proto") }
-    if !nonProtoInputs.isEmpty {
-      throw CommandPluginError.invalidInputFiles(nonProtoInputs)
-    }
+    let (inputFiles, extraImportPaths) = try self.checkAndExpandInputs(inputs)
 
     if inputFiles.isEmpty {
       throw CommandPluginError.missingInputFile
@@ -101,7 +98,7 @@ struct GRPCProtobufGeneratorCommandPlugin {
         config: config,
         fileNaming: config.fileNaming,
         inputFiles: inputFileURLs,
-        protoDirectoryPaths: config.importPaths,
+        protoDirectoryPaths: config.importPaths + extraImportPaths,
         protocGenGRPCSwiftPath: protocGenGRPCSwiftPath,
         outputDirectory: outputDirectory
       )
@@ -124,7 +121,7 @@ struct GRPCProtobufGeneratorCommandPlugin {
         config: config,
         fileNaming: config.fileNaming,
         inputFiles: inputFileURLs,
-        protoDirectoryPaths: config.importPaths,
+        protoDirectoryPaths: config.importPaths + extraImportPaths,
         protocGenSwiftPath: protocGenSwiftPath,
         outputDirectory: outputDirectory
       )
@@ -159,6 +156,50 @@ struct GRPCProtobufGeneratorCommandPlugin {
 
     return (options, inputs)
   }
+
+  private func checkAndExpandInputs(
+    _ files: [String]
+  ) throws -> (protos: [String], directories: [String]) {
+    let fileManager = FileManager.default
+    var invalidInputFiles = [String]()
+    var protos = [String]()
+    var dirs = [String]()
+
+    for file in files {
+      // Check that each file:
+      // a) exists, and
+      // b) is either a '.proto' file or a directory.
+      //
+      // If the file is a directory then all '.proto' files within the directory
+      // are added as input files.
+      var isDirectory = ObjCBool(false)
+      let exists = fileManager.fileExists(atPath: file, isDirectory: &isDirectory)
+
+      if !exists {
+        invalidInputFiles.append(file)
+      } else if isDirectory.boolValue {
+        dirs.append(file)
+        // Do a deep traversal of the directory.
+        if var enumerator = fileManager.enumerator(atPath: file) {
+          while let path = enumerator.nextObject() as? String {
+            if path.hasSuffix(".proto") {
+              protos.append(path)
+            }
+          }
+        }
+      } else if file.hasSuffix(".proto") {
+        protos.append(file)
+      } else {
+        invalidInputFiles.append(file)
+      }
+    }
+
+    if !invalidInputFiles.isEmpty {
+      throw CommandPluginError.invalidInputFiles(invalidInputFiles)
+    }
+
+    return (protos, dirs)
+  }
 }
 
 /// Execute a single invocation of `protoc`, printing output and if in verbose mode the invocation