src/blackd/__init__.py

   1 import asyncio
   2 import logging
   3 import sys
   4 from concurrent.futures import Executor, ProcessPoolExecutor
   5 from datetime import datetime
   6 from functools import partial
   7 from multiprocessing import freeze_support
   8 from typing import Set, Tuple
   9
  10 try:
  11     from aiohttp import web
  12     import aiohttp_cors
  13 except ImportError as ie:
  14     print(
  15         f"aiohttp dependency is not installed: {ie}. "
  16         + "Please re-install black with the '[d]' extra install "
  17         + "to obtain aiohttp_cors: `pip install black[d]`",
  18         file=sys.stderr,
  19     )
  20     sys.exit(-1)
  21
  22 import black
  23 from black.concurrency import maybe_install_uvloop
  24 import click
  25
  26 from _black_version import version as __version__
  27
  28 # This is used internally by tests to shut down the server prematurely
  29 _stop_signal = asyncio.Event()
  30
  31 # Request headers
  32 PROTOCOL_VERSION_HEADER = "X-Protocol-Version"
  33 LINE_LENGTH_HEADER = "X-Line-Length"
  34 PYTHON_VARIANT_HEADER = "X-Python-Variant"
  35 SKIP_STRING_NORMALIZATION_HEADER = "X-Skip-String-Normalization"
  36 SKIP_MAGIC_TRAILING_COMMA = "X-Skip-Magic-Trailing-Comma"
  37 FAST_OR_SAFE_HEADER = "X-Fast-Or-Safe"
  38 DIFF_HEADER = "X-Diff"
  39
  40 BLACK_HEADERS = [
  41     PROTOCOL_VERSION_HEADER,
  42     LINE_LENGTH_HEADER,
  43     PYTHON_VARIANT_HEADER,
  44     SKIP_STRING_NORMALIZATION_HEADER,
  45     SKIP_MAGIC_TRAILING_COMMA,
  46     FAST_OR_SAFE_HEADER,
  47     DIFF_HEADER,
  48 ]
  49
  50 # Response headers
  51 BLACK_VERSION_HEADER = "X-Black-Version"
  52
  53
  54 class InvalidVariantHeader(Exception):
  55     pass
  56
  57
  58 @click.command(context_settings={"help_option_names": ["-h", "--help"]})
  59 @click.option(
  60     "--bind-host", type=str, help="Address to bind the server to.", default="localhost"
  61 )
  62 @click.option("--bind-port", type=int, help="Port to listen on", default=45484)
  63 @click.version_option(version=black.__version__)
  64 def main(bind_host: str, bind_port: int) -> None:
  65     logging.basicConfig(level=logging.INFO)
  66     app = make_app()
  67     ver = black.__version__
  68     black.out(f"blackd version {ver} listening on {bind_host} port {bind_port}")
  69     web.run_app(app, host=bind_host, port=bind_port, handle_signals=True, print=None)
  70
  71
  72 def make_app() -> web.Application:
  73     app = web.Application()
  74     executor = ProcessPoolExecutor()
  75
  76     cors = aiohttp_cors.setup(app)
  77     resource = cors.add(app.router.add_resource("/"))
  78     cors.add(
  79         resource.add_route("POST", partial(handle, executor=executor)),
  80         {
  81             "*": aiohttp_cors.ResourceOptions(
  82                 allow_headers=(*BLACK_HEADERS, "Content-Type"), expose_headers="*"
  83             )
  84         },
  85     )
  86
  87     return app
  88
  89
  90 async def handle(request: web.Request, executor: Executor) -> web.Response:
  91     headers = {BLACK_VERSION_HEADER: __version__}
  92     try:
  93         if request.headers.get(PROTOCOL_VERSION_HEADER, "1") != "1":
  94             return web.Response(
  95                 status=501, text="This server only supports protocol version 1"
  96             )
  97         try:
  98             line_length = int(
  99                 request.headers.get(LINE_LENGTH_HEADER, black.DEFAULT_LINE_LENGTH)
 100             )
 101         except ValueError:
 102             return web.Response(status=400, text="Invalid line length header value")
 103
 104         if PYTHON_VARIANT_HEADER in request.headers:
 105             value = request.headers[PYTHON_VARIANT_HEADER]
 106             try:
 107                 pyi, versions = parse_python_variant_header(value)
 108             except InvalidVariantHeader as e:
 109                 return web.Response(
 110                     status=400,
 111                     text=f"Invalid value for {PYTHON_VARIANT_HEADER}: {e.args[0]}",
 112                 )
 113         else:
 114             pyi = False
 115             versions = set()
 116
 117         skip_string_normalization = bool(
 118             request.headers.get(SKIP_STRING_NORMALIZATION_HEADER, False)
 119         )
 120         skip_magic_trailing_comma = bool(
 121             request.headers.get(SKIP_MAGIC_TRAILING_COMMA, False)
 122         )
 123         fast = False
 124         if request.headers.get(FAST_OR_SAFE_HEADER, "safe") == "fast":
 125             fast = True
 126         mode = black.FileMode(
 127             target_versions=versions,
 128             is_pyi=pyi,
 129             line_length=line_length,
 130             string_normalization=not skip_string_normalization,
 131             magic_trailing_comma=not skip_magic_trailing_comma,
 132         )
 133         req_bytes = await request.content.read()
 134         charset = request.charset if request.charset is not None else "utf8"
 135         req_str = req_bytes.decode(charset)
 136         then = datetime.utcnow()
 137
 138         loop = asyncio.get_event_loop()
 139         formatted_str = await loop.run_in_executor(
 140             executor, partial(black.format_file_contents, req_str, fast=fast, mode=mode)
 141         )
 142
 143         # Only output the diff in the HTTP response
 144         only_diff = bool(request.headers.get(DIFF_HEADER, False))
 145         if only_diff:
 146             now = datetime.utcnow()
 147             src_name = f"In\t{then} +0000"
 148             dst_name = f"Out\t{now} +0000"
 149             loop = asyncio.get_event_loop()
 150             formatted_str = await loop.run_in_executor(
 151                 executor,
 152                 partial(black.diff, req_str, formatted_str, src_name, dst_name),
 153             )
 154
 155         return web.Response(
 156             content_type=request.content_type,
 157             charset=charset,
 158             headers=headers,
 159             text=formatted_str,
 160         )
 161     except black.NothingChanged:
 162         return web.Response(status=204, headers=headers)
 163     except black.InvalidInput as e:
 164         return web.Response(status=400, headers=headers, text=str(e))
 165     except Exception as e:
 166         logging.exception("Exception during handling a request")
 167         return web.Response(status=500, headers=headers, text=str(e))
 168
 169
 170 def parse_python_variant_header(value: str) -> Tuple[bool, Set[black.TargetVersion]]:
 171     if value == "pyi":
 172         return True, set()
 173     else:
 174         versions = set()
 175         for version in value.split(","):
 176             if version.startswith("py"):
 177                 version = version[len("py") :]
 178             if "." in version:
 179                 major_str, *rest = version.split(".")
 180             else:
 181                 major_str = version[0]
 182                 rest = [version[1:]] if len(version) > 1 else []
 183             try:
 184                 major = int(major_str)
 185                 if major not in (2, 3):
 186                     raise InvalidVariantHeader("major version must be 2 or 3")
 187                 if len(rest) > 0:
 188                     minor = int(rest[0])
 189                     if major == 2 and minor != 7:
 190                         raise InvalidVariantHeader(
 191                             "minor version must be 7 for Python 2"
 192                         )
 193                 else:
 194                     # Default to lowest supported minor version.
 195                     minor = 7 if major == 2 else 3
 196                 version_str = f"PY{major}{minor}"
 197                 if major == 3 and not hasattr(black.TargetVersion, version_str):
 198                     raise InvalidVariantHeader(f"3.{minor} is not supported")
 199                 versions.add(black.TargetVersion[version_str])
 200             except (KeyError, ValueError):
 201                 raise InvalidVariantHeader("expected e.g. '3.7', 'py3.5'")
 202         return False, versions
 203
 204
 205 def patched_main() -> None:
 206     maybe_install_uvloop()
 207     freeze_support()
 208     black.patch_click()
 209     main()
 210
 211
 212 if __name__ == "__main__":
 213     patched_main()