Add filter CLI command

Author: simonjbeaumont

Sources/swift-openapi-generator/FilterCommand.swift

@@ -0,0 +1,99 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the SwiftOpenAPIGenerator open source project
+//
+// Copyright (c) 2023 Apple Inc. and the SwiftOpenAPIGenerator project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of SwiftOpenAPIGenerator project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+import ArgumentParser
+import Foundation
+import _OpenAPIGeneratorCore
+import Yams
+import OpenAPIKit
+import OpenAPIKit30
+
+struct _FilterCommand: AsyncParsableCommand {
+    static var configuration = CommandConfiguration(
+        commandName: "filter",
+        abstract: "Filter an OpenAPI document",
+        discussion: """
+            Filtering rules are provided in a YAML configuration file.
+
+            Example configuration file contents:
+
+            ```yaml
+            \(try! YAMLEncoder().encode(sampleConfig))
+            ```
+            """
+    )
+
+    @Option(help: "Path to a YAML configuration file.")
+    var config: URL
+
+    @Argument(help: "Path to the OpenAPI document, either in YAML or JSON.")
+    var docPath: URL
+
+    func parseOpenAPIDocument(_ documentData: Data) throws -> OpenAPIKit.OpenAPI.Document {
+        let decoder = YAMLDecoder()
+
+        struct OpenAPIVersionedDocument: Decodable {
+            var openapi: String
+        }
+
+        let versionedDocument = try decoder.decode(OpenAPIVersionedDocument.self, from: documentData)
+
+        let document: OpenAPIKit.OpenAPI.Document
+        switch versionedDocument.openapi {
+        case "3.0.0", "3.0.1", "3.0.2", "3.0.3":
+            let document30x = try decoder.decode(OpenAPIKit30.OpenAPI.Document.self, from: documentData)
+            document = document30x.convert(to: .v3_1_0)
+        case "3.1.0":
+            document = try decoder.decode(OpenAPIKit.OpenAPI.Document.self, from: documentData)
+        default:
+            fatalError("Unsupported OpenAPI version found: \(versionedDocument.openapi)")
+        }
+        return document
+    }
+
+    func run() async throws {
+        let configData = try Data(contentsOf: config)
+        let config = try YAMLDecoder().decode(_UserConfig.self, from: configData)
+        let document = try timing("Parsing document", parseOpenAPIDocument(Data(contentsOf: docPath)))
+        try document.validate()
+        guard let documentFilter = config.filter else {
+            FileHandle.standardError.write("warning: No filter config provided\n")
+            FileHandle.standardOutput.write(try YAMLEncoder().encode(document))
+            return
+        }
+        let filteredDocument = try timing("Filtering document", documentFilter.filter(document))
+        FileHandle.standardOutput.write(try YAMLEncoder().encode(filteredDocument))
+    }
+}
+
+private func timing<Output>(_ title: String, operation: () throws -> Output) rethrows -> Output {
+    FileHandle.standardError.write("\(title)...\n")
+    let start = Date.timeIntervalSinceReferenceDate
+    let result = try operation()
+    let diff = Date.timeIntervalSinceReferenceDate - start
+    FileHandle.standardError.write(String(format: "\(title) complete! (%.2fs)\n", diff))
+    return result
+}
+
+private func timing<Output>(_ title: String, _ operation: @autoclosure () throws -> Output) rethrows -> Output {
+    try timing(title, operation: operation)
+}
+
+private let sampleConfig = _UserConfig(
+    generate: [],
+    filter: DocumentFilter(
+        tags: ["greetings"],
+        paths: ["/greeting"],
+        schemas: ["Greeting"]
+    )
+)

Sources/swift-openapi-generator/Tool.swift

@@ -19,7 +19,8 @@ struct _Tool: AsyncParsableCommand {
         commandName: "swift-openapi-generator",
         abstract: "Generate Swift client and server code from an OpenAPI document",
         subcommands: [
-            _GenerateCommand.self
+            _FilterCommand.self,
+            _GenerateCommand.self,
         ]
     )
 }

Sources/swift-openapi-generator/UserConfig.swift

@@ -39,6 +39,7 @@ struct _UserConfig: Codable {
     enum CodingKeys: String, CaseIterable, CodingKey {
         case generate
         case additionalImports
+        case filter
         case featureFlags
     }
 }