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