feat: add generate_library.sh without post processing (#1916)

* feat: add

* generate gapic and proto folder

* refactor utilities

* add an action to verify

* checkout googleapis-gen

* setup repo name

* add commit hash of googleapis-gen

* change secret

* change token

* change to git clone

* change user name

* add input list

* include resources folder in main

* remove grpc version in `*ServiceGrpc.java`

* change destination path

* compare generation result with googleapis-gen

* fix type in diff command

* checkout repo using checkout action

* checkout repos as nested repo

* sparse checkout googleapis

* Revert "sparse checkout googleapis"

This reverts commit 3d612f8.

* change library

* change step name

* add a readme

* make grpc version optional

* make protobuf version optional

* checkout master branch, rather than a commit hash

* allow snapshot version of generator

* download snapshot of generator parent pom

* update README

* download generator and grpc using mvn

* change error message

* add maven central mirror

* add comments in utilities

* add comments

* add an integration test

* fail fast if no file is found

* do not delete google/

* get protobuf version from WORKSPACE

* add instructions on download `google/` from googleapis

* add comments

* update description of `destination_path`

* update comments

* download dependencies using `curl`

* increase download time

* remove comment

* add samples directory in readme

* remove prerequisite about `proto_path`

* add explanation in prerequisite

* add example to generate showcase

* add a comment

.github/workflows/verify_library_generation.yaml

@@ -0,0 +1,30 @@
+on:
+  push:
+    branches:
+    - main
+  pull_request:
+    paths:
+    - library_generation/**
+
+  workflow_dispatch:
+name: verify_library_generation_against_googleapis-gen
+jobs:
+  verify_library_generation:
+    runs-on: ubuntu-22.04
+    strategy:
+      matrix:
+        java: [ 8 ]
+    steps:
+    - uses: actions/checkout@v3
+    - uses: actions/setup-java@v3
+      with:
+        java-version: ${{ matrix.java }}
+        distribution: temurin
+        cache: maven
+    - name: Run integration tests
+      run: |
+        set -x
+        library_generation/generate_library_integration_test.sh \
+        -p google/bigtable/v2 \
+        -d google-cloud-bigtable-v2-java \
+        --googleapis_gen_url https://cloud-java-bot:${{ secrets.CLOUD_JAVA_BOT_GITHUB_TOKEN }}@github.com/googleapis/googleapis-gen.git

library_generation/README.md

@@ -0,0 +1,135 @@
+# Generate GAPIC Client Library without post-processing
+
+The script, `generate_library.sh`, allows you to generate a GAPIC client library from proto files.
+
+## Environment
+
+Use Linux environment and install java runtime environment (8 or above).
+
+## Prerequisite
+Protos referenced by protos in `proto_path` (see `proto_path` below) should be copied to the current
+working directory (refers as `$cwd`, a directory contains `generate_library.sh`).
+The directory structure should be the same as import statements in protos.
+
+For example, we want to generate from `folder1/folder2/protoA`, so `proto_path` 
+should be set to `folder1/folder2` (a relative path from `$cwd`). 
+protoA imports protoB as `folder3/folder4/protoB`, then there should 
+be `folder3/folder4` (containing protoB) in `$cwd`.
+
+In order to generate a GAPIC library, you need to pull `google/` from [googleapis](https://github.com/googleapis/googleapis)
+and put it into `$cwd` since protos in `google/` are likely referenced by 
+protos from which the library are generated.
+
+## Parameters to run `generate_library.sh`
+
+You need to run the script with the following parameters.
+
+### proto_path
+A directory in `$cwd` and copy proto files into it. 
+The absolute path of `proto_path` is `$cwd/$proto_path`. 
+
+Use `-p` or `--proto_path` to specify the value.
+
+### destination_path 
+A directory within `$cwd`. 
+This is the path in which the generated library will reside. 
+The absolute path of `destination_path` is `$cwd/$destination_path`. 
+
+Use `-d` or `--destination_path` to specify the value.
+
+Note that you do not need to create `$detination_path` beforehand.
+
+The directory structure of the generated library is
+```
+$destination_path
+  |_gapic-*
+  |    |_src
+  |       |_main
+  |          |_java
+  |          |_resources
+  |       |_test
+  |_grpc-*
+  |    |_src
+  |       |_main
+  |          |_java
+  |    
+  |_proto-*
+  |    |_src
+  |       |_main
+  |          |_java
+  |          |_proto
+  |_samples
+      |_snippets
+          |_generated
+```
+You can't build the library as-is since it does not have `pom.xml` or `build.gradle`.
+To use the library, copy the generated files to the corresponding directory
+of a library repository, e.g., `google-cloud-java`.
+
+### gapic_generator_version
+You can find the released version of gapic-generator-java in [maven central](https://repo1.maven.org/maven2/com/google/api/gapic-generator-java/).
+
+Use `--gapic_generator_version` to specify the value.
+
+Note that you can specify a `SNAPSHOT` version as long as you have build the SNAPSHOT of gapic-generator-java in your maven
+local repository.
+
+### protobuf_version (optional)
+You can find the released version of protobuf in [GitHub](https://github.com/protocolbuffers/protobuf/releases/).
+The default value is defined in `gapic-generator-java-pom-parent/pom.xml`.
+
+Use `--protobuf_version` to specify the value.
+
+Note that if specified, the version should be compatible with gapic-generator-java.
+
+### grpc_version (optional)
+You can find the released version of grpc in [maven central](https://repo1.maven.org/maven2/io/grpc/protoc-gen-grpc-java/).
+The default value is defined in `gapic-generator-java-pom-parent/pom.xml`.
+
+Use `--grpc_version` to specify the value.
+
+Note that if specified, the version should be compatible with gapic-generator-java.
+
+### transport (optional)
+One of GAPIC options passed to the generator. The value is either `grpc` or `grpc+rest`.
+The default value is `grpc`.
+
+Use `--transport` to specify the value.
+
+### rest_numeric_enums (optional)
+One of GAPIC options passed to the generator. The value is either `true` or `false`.
+The default value is `true`.
+
+Use `--rest_numeric_enums` to specify the value.
+
+### include_samples (optional)
+Whether generates code samples. The value is either `true` or `false`. 
+The default value is `true`.
+
+Use `--include_samples` to specify the value.
+
+## An example to generate a client library
+```
+library_generation/generate_library.sh \
+-p google/cloud/confidentialcomputing/v1 \
+-d google-cloud-confidentialcomputing-v1-java \
+--gapic_generator_version 2.24.0 \
+--protobuf_version 23.2 \
+--grpc_version 1.55.1 \
+--transport grpc+rest \
+--rest_numeric_enums true \
+--include_samples true
+```
+
+## An example to generate showcase client
+```
+library_generation/generate_library.sh \
+-p schema/google/showcase/v1beta1 \ # google/ should be in library_generation/.
+-d output \
+--gapic_generator_version 2.24.0 \
+--protobuf_version 23.2 \
+--grpc_version 1.55.1 \
+--transport grpc+rest \
+--rest_numeric_enums false \
+--include_samples false
+```

library_generation/gapic-generator-java-wrapper

@@ -0,0 +1,7 @@
+#!/usr/bin/env bash
+
+set -e
+
+# Wrap gapic-generator-java.jar because protoc requires the plugin to be executable.
+working_directory=$(dirname "$(readlink -f "$0")")
+exec java -classpath "$working_directory/gapic-generator-java-$gapic_generator_version.jar" com.google.api.generator.Main

library_generation/generate_library.sh

@@ -0,0 +1,160 @@
+#!/usr/bin/env bash
+
+set -eo pipefail
+
+# parse input parameters
+while [[ $# -gt 0 ]]
+do
+key="$1"
+case $key in
+    -p|--proto_path)
+    proto_path="$2"
+    shift
+    ;;
+    -d|--destination_path)
+    destination_path="$2"
+    shift
+    ;;
+    --gapic_generator_version)
+    gapic_generator_version="$2"
+    # export this variable so that it can be used in gapic-generator-java-wrapper.sh
+    export gapic_generator_version
+    shift
+    ;;
+    --protobuf_version)
+    protobuf_version="$2"
+    shift
+    ;;
+    --grpc_version)
+    grpc_version="$2"
+    shift
+    ;;
+    --transport)
+    transport="$2"
+    shift
+    ;;
+    --rest_numeric_enums)
+    rest_numeric_enums="$2"
+    shift
+    ;;
+    --include_samples)
+    include_samples="$2"
+    shift
+    ;;
+    *)
+    echo "Invalid option: [$1]"
+    exit 1
+    ;;
+esac
+shift # past argument or value
+done
+
+working_directory=$(dirname "$(readlink -f "$0")")
+# source utility functions
+cd "$working_directory"
+source ./utilities.sh
+
+if [ -z "$protobuf_version" ]; then
+  protobuf_version=$(get_protobuf_version "$gapic_generator_version")
+fi
+
+if [ -z "$grpc_version" ]; then
+  grpc_version=$(get_grpc_version "$gapic_generator_version")
+fi
+
+if [ -z "$transport" ]; then
+  transport="grpc"
+fi
+
+if [ -z "$rest_numeric_enums" ]; then
+  rest_numeric_enums="true"
+fi
+
+if [ -z "$include_samples" ]; then
+  include_samples="true"
+fi
+
+cd "$working_directory"
+mkdir -p "$destination_path"
+destination_path="$working_directory/$destination_path"
+##################### Section 0 #####################
+# prepare tooling
+#####################################################
+cd "$working_directory"
+# the order of services entries in gapic_metadata.json is relevant to the
+# order of proto file, sort the proto files with respect to their name to
+# get a fixed order.
+proto_files=$(find "$proto_path" -type f  -name "*.proto" | sort)
+folder_name=$(extract_folder_name "$destination_path")
+# download gapic-generator-java, protobuf and grpc plugin.
+download_tools "$gapic_generator_version" "$protobuf_version" "$grpc_version"
+##################### Section 1 #####################
+# generate grpc-*/
+#####################################################
+cd "$working_directory"
+"$protoc_path"/protoc "--plugin=protoc-gen-rpc-plugin=$working_directory/protoc-gen-grpc-java-$grpc_version-linux-x86_64.exe" \
+"--rpc-plugin_out=:$destination_path/java_grpc.jar" \
+$proto_files
+# unzip java_grpc.jar to grpc-*/src/main/java
+unzip_src_files "grpc"
+# remove empty files in grpc-*/src/main/java
+remove_empty_files "grpc"
+# remove grpc version in *ServiceGrpc.java file so the content is identical with bazel build.
+remove_grpc_version
+###################### Section 2 #####################
+## generate gapic-*/, part of proto-*/, samples/
+######################################################
+cd "$working_directory"
+"$protoc_path"/protoc --experimental_allow_proto3_optional \
+"--plugin=protoc-gen-java_gapic=$working_directory/gapic-generator-java-wrapper" \
+"--java_gapic_out=metadata:$destination_path/java_gapic_srcjar_raw.srcjar.zip" \
+"--java_gapic_opt=$(get_gapic_opts)" \
+${proto_files} $(search_additional_protos)
+
+unzip -o -q "$destination_path/java_gapic_srcjar_raw.srcjar.zip" -d "$destination_path"
+# Sync'\''d to the output file name in Writer.java.
+unzip -o -q "$destination_path/temp-codegen.srcjar" -d "$destination_path/java_gapic_srcjar"
+# Resource name source files.
+proto_dir=$destination_path/java_gapic_srcjar/proto/src/main/java
+if [ ! -d "$proto_dir" ]; then
+  # Some APIs don'\''t have resource name helpers, like BigQuery v2.
+  # Create an empty file so we can finish building. Gating the resource name rule definition
+  # on file existences go against Bazel'\''s design patterns, so we'\''ll simply delete all empty
+  # files during the final packaging process (see java_gapic_pkg.bzl)
+  mkdir -p "$proto_dir"
+  touch "$proto_dir"/PlaceholderFile.java
+fi
+
+cd "$working_directory"
+# move java_gapic_srcjar/src/main to gapic-*/src.
+mv_src_files "gapic" "main"
+# remove empty files in gapic-*/src/main/java
+remove_empty_files "gapic"
+# move java_gapic_srcjar/src/test to gapic-*/src
+mv_src_files "gapic" "test"
+if [ "$include_samples" == "true" ]; then
+  # move java_gapic_srcjar/samples/snippets to samples/snippets
+  mv_src_files "samples" "main"
+fi
+##################### Section 3 #####################
+# generate proto-*/
+#####################################################
+cd "$working_directory"
+"$protoc_path"/protoc "--java_out=$destination_path/java_proto.jar" $proto_files
+# move java_gapic_srcjar/proto/src/main/java (generated resource name helper class)
+# to proto-*/src/main
+mv_src_files "proto" "main"
+# unzip java_proto.jar to proto-*/src/main/java
+unzip_src_files "proto"
+# remove empty files in proto-*/src/main/java
+remove_empty_files "proto"
+# copy proto files to proto-*/src/main/proto
+for proto_src in $proto_files; do
+    mkdir -p "$destination_path/proto-$folder_name/src/main/proto"
+    cp -f --parents "$proto_src" "$destination_path/proto-$folder_name/src/main/proto"
+done
+##################### Section 4 #####################
+# rm tar files
+#####################################################
+cd "$destination_path"
+rm -rf java_gapic_srcjar java_gapic_srcjar_raw.srcjar.zip java_grpc.jar java_proto.jar temp-codegen.srcjar