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