#!/usr/bin/env python3

# Copyright 2021 Google Inc.
#
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

import hashlib
import json
import os
import platform
import re
import stat
import sys
import tempfile
import zipfile

from urllib.request import urlopen


def sha256sum(path):
  try:
    with open(path, 'rb') as f:
      return hashlib.sha256(f.read()).hexdigest()
  except OSError:
    return ''


os.chdir(os.path.join(os.path.dirname(__file__), os.pardir))

OS  = {'darwin': 'mac', 'linux': 'linux', 'linux2': 'linux', 'win32': 'windows'}[sys.platform]
cpu = {'aarch64': 'arm64', 'amd64': 'amd64', 'arm64': 'arm64', 'x86_64': 'amd64'}[platform.machine().lower()]
platform = '%s-%s' % (OS, cpu)
sk = 'sk'
if 'windows' in platform:
  sk = 'sk.exe'

# Find the version of 'sk' requested by DEPS.
with open('DEPS', 'rb') as f:
  deps = f.read().decode()
found = re.findall(r"'sk_tool_revision':\s*'(\S+)'", deps)
if len(found) != 1:
  print('Unable to find sk_tool_revision in DEPS', file=sys.stderr)
  exit(1)
desired_version = found[0]

# Determine which version (if any) we currently have.
sk_path = os.path.join('bin', sk)
current_sha256 = sha256sum(sk_path)
sk_version_path = os.path.join('bin', 'sk.version')

# When we download 'sk', we write the version information to a file so we can
# keep track of which version we have. Read the file to determine whether the
# current version matches what we want.
current_version = {
  'version': '',
  'sha256': '',
}
try:
  with open(sk_version_path, 'r', encoding='utf8') as f:
    current_version = json.load(f)
except OSError:
  pass

if desired_version != current_version['version']:
  print('Version "%s" requested by DEPS differs from current version "%s"' % (
      desired_version, current_version['version']))
elif current_sha256 != current_version['sha256']:
  print('sha256 sum "%s" does not match last-downloaded version "%s"' % (
      current_sha256, current_version['sha256']))
else:
  print('Already up to date.')
  exit(0)

print('Fetching %s at %s for platform %s' % (sk, desired_version, platform))

# Download sk.
skzip = os.path.join(tempfile.mkdtemp(), 'sk.zip')
with open(skzip, 'wb') as f:
  url = 'https://chrome-infra-packages.appspot.com/dl/skia/tools/sk/%s/+/%s' % (
      platform, desired_version)
  f.write(urlopen(url).read())

with zipfile.ZipFile(skzip, 'r') as f:
  f.extract(sk, 'bin')

if not 'windows' in platform:
  uid = os.getuid()
  gid = os.getgid()
  os.chown(sk_path, uid, gid)
  os.chmod(sk_path, stat.S_IRUSR | stat.S_IWUSR | stat.S_IXUSR |
                    stat.S_IRGRP                | stat.S_IXGRP |
                    stat.S_IROTH                | stat.S_IXOTH )

# Write the downloaded version info to a file.
current_version['version'] = desired_version
current_version['sha256'] = sha256sum(sk_path)
with open(sk_version_path, 'w', encoding='utf8') as f:
  json.dump(current_version, f, sort_keys=True, indent=2)