feat: add entry point

library_generation/README.md

@@ -1,8 +1,8 @@
 # Generate a repository containing GAPIC Client Libraries
 
-The script, `generate_repo.py`, allows you to generate a repository containing
-GAPIC client libraries (a monorepo, for example, google-cloud-java) from a
-configuration file.
+The script, `entry_point.py`, allows you to generate a repository containing
+GAPIC client libraries with googleapis commit history (a monorepo, for example,
+google-cloud-java) from a configuration file.
 
 ## Environment
 
@@ -17,30 +17,27 @@ In order to generate a version for each library, a versions.txt has to exist
 in `repository_path`.
 Please refer to [Repository path](#repository-path--repositorypath---optional) for more information.
 
-## Parameters to generate a repository using `generate_repo.py`
+## Parameters to generate a repository using `entry_point.py`
 
-### Generation configuration yaml (`generation_config_yaml`)
+### Baseline generation configuration yaml (`baseline_generation_config`)
 
-A path to a configuration file containing parameters to generate the repository.
-Please refer [Configuration to generate a repository](#configuration-to-generate-a-repository) 
-for more information.
-
-### Target library API shortname (`target_library_api_shortname`), optional
+An absolute or relative path to a generation_config.yaml.
+This config file is used for commit history generation, not library
+generation.
 
-If specified, the libray whose `api_shortname` equals to `target_library_api_shortname`
-will be generated; otherwise all libraries in the configuration file will be
-generated.
-This can be useful when you just want to generate one library for debugging
-purposes.
+### Current generation configuration yaml (`current_generation_config`)
 
-The default value is an empty string, which means all libraries will be generated.
+An absolute or relative path to a configuration file containing parameters to
+generate the repository.
+Please refer [Configuration to generate a repository](#configuration-to-generate-a-repository)
+for more information.
 
 ### Repository path (`repository_path`), optional
 
 The path to where the generated repository goes.
 
 The default value is the current working directory when running the script.
-For example, `cd google-cloud-java && python generate_repo.py ...` without
+For example, `cd google-cloud-java && python entry_point.py ...` without
 specifying the `--repository_path` option will modify the `google-cloud-java`
 repository the user `cd`'d into.
 
@@ -49,7 +46,9 @@ right version for each library.
 Please refer [here](go/java-client-releasing#versionstxt-manifest) for more info
 of versions.txt.
 
-## Output of `generate_repo.py`
+## Output of `entry_point.py`
+
+### GAPIC libraries
 
 For each module (e.g. `google-cloud-java/java-asset`), the following files/folders
 will be created/modified:
@@ -73,6 +72,11 @@ will be created/modified:
 | pom.xml (repo root dir)     | Always generated from inputs                                             |
 | versions.txt                | New entries will be added if they don’t exist                            |
 
+### googleapis commit history
+
+If both `baseline_generation_config` and `current_generation_config` are
+specified, and they contain different googleapis commit, the commit history will
+be generated into `pr_description.txt` in the `repository_path`.
 
 ## Configuration to generate a repository
 
@@ -184,20 +188,23 @@ libraries:
       - proto_path: google/cloud/asset/v1p7beta1
 ```
 
-## An example to generate a repository using `generate_repo.py`
+## An example to generate a repository using `entry_point.py`
 
 ```bash
 # install python module (allows the `library_generation` module to be imported from anywhere)
 python -m pip install -r library_generation/requirements.in
+# install library_generation module
+python -m pip install library_generation
 # generate the repository
-python -m library_generation/generate_repo.py generate \
---generation-config-yaml=/path/to/config-file \
+python -m library_generation/entry_point.py generate \
+--baseline-generation-config=/path/to/baseline_config_file \
+--current-generation-config=/path/to/current_config_file \
 --repository-path=/path/to/repository
 ```
 
-## An example of generated repository using `generate_repo.py`
+## An example of generated repository using `entry_point.py`
 
-If you run `generate_repo.py` with the example [configuration](#an-example-of-generation-configuration)
+If you run `entry_point.py` with the example [configuration](#an-example-of-generation-configuration)
 shown above, the repository structure is:
 ```
 $repository_path

library_generation/cli/entry_point.py

@@ -0,0 +1,141 @@
+# Copyright 2024 Google LLC
+#
+# 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
+#
+#     https://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 os
+
+import click as click
+from library_generation.generate_pr_description import generate_pr_descriptions
+from library_generation.generate_repo import generate_from_yaml
+from library_generation.model.generation_config import from_yaml
+from library_generation.utils.generation_config_comparator import compare_config
+
+
+@click.group(invoke_without_command=False)
+@click.pass_context
+@click.version_option(message="%(version)s")
+def main(ctx):
+    pass
+
+
+@main.command()
+@click.option(
+    "--baseline-generation-config",
+    required=False,
+    default=None,
+    type=str,
+    help="""
+    Absolute or relative path to a generation_config.yaml.
+    This config file is used for commit history generation, not library
+    generation.
+    """,
+)
+@click.option(
+    "--current-generation-config",
+    required=False,
+    default=None,
+    type=str,
+    help="""
+    Absolute or relative path to a generation_config.yaml that contains the
+    metadata about library generation.
+    """,
+)
+@click.option(
+    "--repository-path",
+    type=str,
+    default=".",
+    show_default=True,
+    help="""
+    The repository path to which the generated files
+    will be sent.
+    If not specified, the repository will be generated to the current working
+    directory.
+    """,
+)
+def generate(
+    baseline_generation_config: str,
+    current_generation_config: str,
+    repository_path: str,
+):
+    """
+    Compare baseline generation config and current generation config and
+    generate changed libraries based on current generation config with commit
+    history.
+
+    If baseline generation config is not specified but current generation
+    config is specified, generate all libraries based on current generation
+    config without commit history.
+
+    If current generation config is not specified but baseline generation
+    config is specified, raise FileNotFoundError because current generation
+    config should be the source of truth of library generation.
+
+    If both baseline generation config and current generation config are not
+    specified, generate all libraries based on the default generation config,
+    which is generation_config.yaml in the current working directory. Raise
+    FileNotFoundError if the default config does not exist.
+
+    The commit history, if generated, will be available in
+    repository_path/pr_description.txt.
+    """
+    default_generation_config = f"{os.getcwd()}/generation_config.yaml"
+
+    if baseline_generation_config is None and current_generation_config is None:
+        if not os.path.isfile(default_generation_config):
+            raise FileNotFoundError(
+                f"{default_generation_config} does not exist. "
+                "A valid generation config has to be passed in as "
+                "current_generation_config or exist in the current working "
+                "directory."
+            )
+        current_generation_config = default_generation_config
+    elif current_generation_config is None:
+        raise FileNotFoundError(
+            "current_generation_config is not specified when "
+            "baseline_generation_config is specified. "
+            "current_generation_config should be the source of truth of "
+            "library generation."
+        )
+
+    current_generation_config = os.path.abspath(current_generation_config)
+    repository_path = os.path.abspath(repository_path)
+    if not baseline_generation_config:
+        # Execute full generation based on current_generation_config if
+        # baseline_generation_config is not specified.
+        # Do not generate pull request description.
+        generate_from_yaml(
+            config=from_yaml(current_generation_config),
+            repository_path=repository_path,
+        )
+        return
+
+    # Compare two generation configs and only generate changed libraries.
+    # Generate pull request description.
+    baseline_generation_config = os.path.abspath(baseline_generation_config)
+    config_change = compare_config(
+        baseline_config=from_yaml(baseline_generation_config),
+        current_config=from_yaml(current_generation_config),
+    )
+    generate_from_yaml(
+        config=config_change.current_config,
+        repository_path=repository_path,
+        target_library_names=config_change.get_changed_libraries(),
+    )
+    generate_pr_descriptions(
+        config=config_change.current_config,
+        baseline_commit=config_change.baseline_config.googleapis_commitish,
+        description_path=repository_path,
+    )
+
+
+if __name__ == "__main__":
+    main()