Remove dependency on apollo CLI for fetching schema

.gitignore

@@ -58,7 +58,9 @@ scripts/apollo.tar.gz
 SwiftScripts/ApolloCLI
 Tests/ApolloCodegenTests/scripts
 Tests/ApolloCodegenTests/scripts directory
+Tests/ApolloCodegenTests/Schema
+Tests/ApolloCodegenTests/Output
 SwiftScripts/.build-**
 
 # Local Netlify folder
-.netlify
+.netlify

Sources/ApolloCodegenLib/ApolloCLI.swift

@@ -20,11 +20,11 @@ public struct ApolloCLI {
     let lock = try waitForCLIFolderLock(cliFolderURL: cliFolderURL, timeout: timeout)
     defer { lock.unlock() }
 
-    try CLIDownloader.downloadIfNeeded(cliFolderURL: cliFolderURL, timeout: timeout)
+    try CLIDownloader.downloadIfNeeded(to: cliFolderURL, timeout: timeout)
 
     if !(try CLIExtractor.validateSHASUMOfDownloadedFile(in: cliFolderURL)) {
       CodegenLogger.log("Downloaded zip file has incorrect SHASUM, forcing redownload")
-      try CLIDownloader.forceRedownload(cliFolderURL: cliFolderURL, timeout: timeout)
+      try CLIDownloader.forceRedownload(to: cliFolderURL, timeout: timeout)
     }
 
     let binaryFolderURL = try CLIExtractor.extractCLIIfNeeded(from: cliFolderURL)

Sources/ApolloCodegenLib/ApolloSchemaDownloadConfiguration.swift

@@ -0,0 +1,97 @@
+import Foundation
+
+/// A configuration object that defines behavior for schema download.
+public struct ApolloSchemaDownloadConfiguration {
+
+  /// How to attempt to download your schema
+  public enum DownloadMethod: Equatable {
+
+    /// The Apollo Schema Registry, which serves as a central hub for managing your data graph.
+    case apolloRegistry(_ settings: ApolloRegistrySettings)
+    /// GraphQL Introspection connecting to the specified URL.
+    case introspection(endpointURL: URL)
+
+    public struct ApolloRegistrySettings: Equatable {
+      /// The API key to use when retrieving your schema from the Apollo Registry.
+      public let apiKey: String
+      /// The identifier of the graph to fetch. Can be found in Apollo Studio.
+      public let graphID: String
+      /// The variant of the graph in the registry.
+      public let variant: String?
+
+      /// Designated initializer
+      ///
+      /// - Parameters:
+      ///   - apiKey: The API key to use when retrieving your schema.
+      ///   - graphID: The identifier of the graph to fetch. Can be found in Apollo Studio.
+      ///   - variant: The variant of the graph to fetch. Defaults to "current", which will return whatever is set to the current variant.
+      public init(apiKey: String,
+                  graphID: String,
+                  variant: String = "current") {
+        self.apiKey = apiKey
+        self.graphID = graphID
+        self.variant = variant
+      }
+    }
+
+    public static func == (lhs: DownloadMethod, rhs: DownloadMethod) -> Bool {
+      switch (lhs, rhs) {
+      case (.introspection(let lhsURL), introspection(let rhsURL)):
+        return lhsURL == rhsURL
+      case (.apolloRegistry(let lhsSettings), .apolloRegistry(let rhsSettings)):
+        return lhsSettings == rhsSettings
+      default:
+        return false
+      }
+    }
+
+  }
+
+  public struct HTTPHeader: Equatable, CustomDebugStringConvertible {
+    let key: String
+    let value: String
+
+    public var debugDescription: String {
+      "\(key): \(value)"
+    }
+  }
+
+  /// How to download your schema. Supports the Apollo Registry and GraphQL Introspection methods.
+  let downloadMethod: DownloadMethod
+  /// The maximum time to wait before indicating that the download timed out, in seconds. Defaults to 30 seconds.
+  let downloadTimeout: Double
+  /// Any additional headers to include when retrieving your schema. Defaults to nil.
+  let headers: [HTTPHeader]
+  /// The URL of the folder in which the downloaded schema should be written.
+  let outputURL: URL
+
+  /// Designated Initializer
+  ///
+  /// - Parameters:
+  ///   - downloadMethod: How to download your schema.
+  ///   - downloadTimeout: The maximum time to wait before indicating that the download timed out, in seconds. Defaults to 30 seconds.
+  ///   - headers: [optional] Any additional headers to include when retrieving your schema. Defaults to nil
+  ///   - outputFolderURL: The URL of the folder in which the downloaded schema should be written
+  ///   - schemaFilename: The name, without an extension, for your schema file. Defaults to `"schema"
+  public init(using downloadMethod: DownloadMethod,
+              timeout downloadTimeout: Double = 30.0,
+              headers: [HTTPHeader] = [],
+              outputFolderURL: URL,
+              schemaFilename: String = "schema") {
+    self.downloadMethod = downloadMethod
+    self.downloadTimeout = downloadTimeout
+    self.headers = headers
+    self.outputURL = outputFolderURL.appendingPathComponent("\(schemaFilename).graphqls")
+  }
+}
+
+extension ApolloSchemaDownloadConfiguration: CustomDebugStringConvertible {
+  public var debugDescription: String {
+    return """
+      downloadMethod: \(self.downloadMethod)
+      downloadTimeout: \(self.downloadTimeout)
+      headers: \(self.headers)
+      outputURL: \(self.outputURL)
+      """
+  }
+}