src/blackd/__init__.py

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