ios/web/public/js_messaging/optimize_js.py

#!/usr/bin/env python3
# Copyright 2022 The Chromium Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

import argparse
import json
import os
import shutil
import sys
import tempfile

_HERE_PATH = os.path.dirname(__file__)
_SRC_PATH = os.path.normpath(os.path.join(_HERE_PATH, '..', '..', '..', '..'))

sys.path.append(os.path.join(_SRC_PATH, 'third_party', 'node'))
import node
import node_modules

def create_rollup_config(config_out_file, rollup_root_dir, path_mappings):
  """Generates a rollup config file to configure and use the path resolver
  plugin which enforces import path format."""
  plugin_path = os.path.join(os.path.abspath(_HERE_PATH),
      'rollup_plugin_src_path_resolver.mjs')

  path_mappings_json = json.dumps(path_mappings, separators=(',', ':'))

  config_content = f'''
      import src_path_resolver from '{plugin_path}';
      export default ({{
        plugins: [
          src_path_resolver('{rollup_root_dir}', '{path_mappings_json}')
        ]
      }});
      '''
  with open(config_out_file, 'w') as f:
    f.write(config_content)

def path_mappings_from_tsconfig(tsconfig_path):
  path_mappings = {}
  with open(tsconfig_path, 'r', encoding='utf-8') as tsconfig:
    tsconfig_contents = json.load(tsconfig)
    out_dir = tsconfig_contents['compilerOptions']['outDir']
    base_dir = os.path.join(os.path.dirname(tsconfig_path), out_dir)
    files = tsconfig_contents['compilerOptions']['paths']

    for file in files:
      if file.startswith('//') and file.endswith('.js'):
        script_path = file[2:]
        path_mappings[script_path] = \
            os.path.abspath(os.path.join(base_dir, script_path))

    if "references" in tsconfig_contents:
      for reference in tsconfig_contents['references']:
        reference_path = \
            os.path.join(os.path.dirname(tsconfig_path), reference['path'])
        path_mappings.update(path_mappings_from_tsconfig(reference_path))

  return path_mappings

def optimize_js(primary_script,
    js_out_file,
    dep_tsconfigs,
    skip_minification,
    output_name):
  """Creates a single output JavaScript file from `primary_script` (and any
  imported scripts) and writes it out to `js_out_file`. Script imports will be
  resolved by searching for the script path in the tsconfigs files passed to
  `dep_tsconfigs` to locate the source file. The output script will be minimized
  unless `skip_minification` is true."""

  path_mappings = {}
  if dep_tsconfigs != None:
    for tsconfig_path in dep_tsconfigs:
      path_mappings.update(path_mappings_from_tsconfig(tsconfig_path))

  output_script_dir = os.path.dirname(js_out_file)

  os.makedirs(output_script_dir, exist_ok=True)
  with tempfile.TemporaryDirectory(dir = output_script_dir) as tmp_out_dir:

    rollup_config_file = \
        os.path.join(tmp_out_dir, 'rollup.config.mjs')
    create_rollup_config(
        rollup_config_file,
        os.path.abspath(_SRC_PATH),
        path_mappings)
    rollup_processed_file = \
        os.path.join(tmp_out_dir, os.path.basename(js_out_file))

    rollup_command = [node_modules.PathToRollup(),
        primary_script,
        '--format',
        'iife',
        '--no-strict',
        '--config',
        rollup_config_file,
        '--failAfterWarnings', # Ensures script imports are correctly resolved
        '--file',
        rollup_processed_file,
        '--silent',
    ]

    if output_name != None:
      rollup_command += ['--name', output_name]

    node.RunNode(rollup_command)

    with open(rollup_processed_file, 'r', encoding='utf-8') as f:
      output = f.read()
      assert "<if expr" not in output, \
          'Unexpected <if expr> found in bundled output. Check that all ' + \
          'input files using such expressions are preprocessed.'

    if skip_minification:
      shutil.copy(rollup_processed_file, js_out_file)
    else:
      node.RunNode([
          node_modules.PathToTerser(),
          rollup_processed_file,
          '--mangle',
          '--output',
          js_out_file,
      ])

def main(argv):
  parser = argparse.ArgumentParser()
  parser.add_argument(
      '--primary-script',
      required=True,
      help="Path to the entry point javascript file to compile")
  parser.add_argument(
      '--js-out-file',
      required=True,
      help="Path to the output file for the compiled JavaScript to be written")
  parser.add_argument(
      '--dep-tsconfigs',
      required=False,
      nargs='*',
      default = None,
      help="Dependent tsconfig files to locate script imports.")
  parser.add_argument(
      '--skip-minification',
      default=False,
      action='store_true')
  parser.add_argument(
      '--output-name',
      required=False,
      default = None,
      help="The name for the exported symbols")
  args = parser.parse_args(argv)

  primary_script = os.path.abspath(args.primary_script)
  js_out_file = os.path.abspath(args.js_out_file)

  optimize_js(primary_script, js_out_file,
      args.dep_tsconfigs, args.skip_minification, args.output_name)

if __name__ == '__main__':
  main(sys.argv[1:])