Introduce Zip File Builder (in Swift) (#2407)

* Introduce tooling to build the Zip file.

* Cleanup to prepare for review.

This moves argument parsing into its own file, moves some methods
into CocoaPodUtils and consolidates some related types.

* Add modulemap and Firebase.h

* Adding CoreDiagnostics, WIP

* Refactored paths into separate struct.

* Organized methods.

* Remove unused utility import.

* Properly passed in custom spec repos.

* Added licenses, outputDir argument.

* Fix the Zip command to use the working directory.

* Fixing bundles and headers being copied.

* Fixing the resources directories.

* More iterations to come closer to Released zip.

- Fixed the caching of OSS pods
- Add custom Crash objects
- Move resources around properly.

* Missing comment.

* Fix resources for MLKit and others.

* Remove unused URL extension.

* Add priorities to README, exclude Firebase.framework

* Run style.sh

* Fully ran style.sh

* Add license to files that don't have it.

* Address feedback from first review.

* Add missing custom spec repo flag.

Author: ryanwilson

.gitignore

@@ -32,6 +32,13 @@ DerivedData
 *.hmap
 *.ipa
 
+# Swift Package Manager
+*/.build
+ZipBuilder/Packages
+ZipBuilder/*.xcodeproj
+ZipBuilder/Package.resolved
+
+
 # IntelliJ
 .idea
 

ZipBuilder/.gitignore

@@ -0,0 +1,4 @@
+.DS_Store
+/.build
+/Packages
+/*.xcodeproj

ZipBuilder/FirebaseSDKs.proto

@@ -0,0 +1,41 @@
+syntax = "proto3";
+
+package ZipBuilder;
+
+// A list of all Firebase SDKs.
+message FirebaseSDKs {
+  repeated SDK sdk = 1;
+}
+
+// Represents a single SDK that should be released.
+message SDK {
+  // SDK name
+  string name = 1;
+
+  // MPM name for the blueprint. For internal use only.
+  string mpm_name = 2;
+
+  // Public version
+  string public_version = 3;
+
+  // List of MPM patterns to build
+  repeated string mpm_pattern = 4;
+
+  // An optional list of additional build flags. For internal use only.
+  BuildFlag build_flags = 5;
+
+  // List of MPM patterns to build (optional nightly override). For internal use only.
+  repeated string nightly_mpm_pattern = 6;
+
+  // Whether or not the SDK is built from open-source. For internal use only.
+  bool open_source = 7;
+
+  // Whether or not to strip the i386 architecture from the build.
+  bool strip_i386 = 8;
+}
+
+// Any extra build flags needed to build the SDK. For internal use only.
+message BuildFlag {
+  // An additional build flag needed to build the SDK
+  repeated string flag = 1;
+}

ZipBuilder/Package.swift

@@ -0,0 +1,33 @@
+// swift-tools-version:4.0
+// The swift-tools-version declares the minimum version of Swift required to build this package.
+
+/*
+ * Copyright 2019 Google
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import PackageDescription
+
+let package = Package(
+  name: "ZipBuilder",
+  dependencies: [
+    .package(url: "https://github.com/apple/swift-protobuf.git", .exact("1.2.0")),
+  ],
+  targets: [
+    .target(
+      name: "ZipBuilder",
+      dependencies: ["SwiftProtobuf"]
+    ),
+  ]
+)

ZipBuilder/README.md

@@ -0,0 +1,50 @@
+# Firebase Zip File Builder
+
+This project builds the Firebase iOS Zip file for distribution.
+More instructions to come.
+
+## Priorities
+
+The following section describes the priorities taken while building this tool and should be followed
+for any modifications.
+
+### Readable and Maintainable
+This code will rarely be modified outside of bug fixes, but read very frequently. There should be no
+"magic lines" that do multiple things. Verbosity is preferred over making the code shorter and
+performing multiple actions at once. All functions should be well documented.
+
+### Avoid Calling bash Commands Where Possible
+Instead of using `cat`, `find`, `grep`, or `perl` use `String` APIs to read the contents of a file,
+`FileManager` to properly list contents of a directory, `RegularExpression` for pattern matching,
+etc. If there's a `Foundation` API available, it should be used.
+
+### Understandable Output
+The output of the script should make it immediately obvious if there were any issues and exactly
+what those issues were, without looking at the code. It should also be very clear if the Zip file
+was properly built and output the file location.
+
+### Show Xcode and API Output on Failures
+In the event that there's an Xcode build failure, the logs should be surfaced immediately to aid
+debugging. Release engineers should not have to find the Xcode project manually. That being said, a
+link to the Xcode project file should be logged as well in case it's necessary. Same goes for errors
+logged by exceptions (ex: `FileManager`).
+
+### Testable and Debuggable
+Components and functions should be split up in a way that make them easy to test and easy to debug.
+Prefer small functions that have proper failure conditions and input validated with `guard`
+statements, throwing `fatalError` with a well written error message if it's a critical issue that
+prevents the Zip file from being built properly.
+
+### Works from the Command Line or Xcode (Environment Agnostic)
+The script should be able to run from the command line to allow for easier automation and Xcode for
+simpler debugging and maintenance.
+
+### Any Failure Exits Immediately
+The script should not continue if anything necessary for a successful Zip file fails. This includes
+things like compiling storyboards, moving resources, missing files, etc. This is to ensure the
+integrity of the zip file and that any issues during testing are SDK bugs and not related to the
+files and folders.
+
+### Prefer File `URL`s over Strings
+Instead of relying on `String`s to represent file paths, use `URL`s as soon as possible to avoid any
+missed or double slashes along with other issues.