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 PREVIEW = "X-Preview"
  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     PREVIEW,
  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         middlewares=[cors(allow_headers=(*BLACK_HEADERS, "Content-Type"))]
  75     )
  76     executor = ProcessPoolExecutor()
  77     app.add_routes([web.post("/", partial(handle, executor=executor))])
  78     return app
  79
  80
  81 async def handle(request: web.Request, executor: Executor) -> web.Response:
  82     headers = {BLACK_VERSION_HEADER: __version__}
  83     try:
  84         if request.headers.get(PROTOCOL_VERSION_HEADER, "1") != "1":
  85             return web.Response(
  86                 status=501, text="This server only supports protocol version 1"
  87             )
  88         try:
  89             line_length = int(
  90                 request.headers.get(LINE_LENGTH_HEADER, black.DEFAULT_LINE_LENGTH)
  91             )
  92         except ValueError:
  93             return web.Response(status=400, text="Invalid line length header value")
  94
  95         if PYTHON_VARIANT_HEADER in request.headers:
  96             value = request.headers[PYTHON_VARIANT_HEADER]
  97             try:
  98                 pyi, versions = parse_python_variant_header(value)
  99             except InvalidVariantHeader as e:
 100                 return web.Response(
 101                     status=400,
 102                     text=f"Invalid value for {PYTHON_VARIANT_HEADER}: {e.args[0]}",
 103                 )
 104         else:
 105             pyi = False
 106             versions = set()
 107
 108         skip_string_normalization = bool(
 109             request.headers.get(SKIP_STRING_NORMALIZATION_HEADER, False)
 110         )
 111         skip_magic_trailing_comma = bool(
 112             request.headers.get(SKIP_MAGIC_TRAILING_COMMA, False)
 113         )
 114         preview = bool(request.headers.get(PREVIEW, False))
 115         fast = False
 116         if request.headers.get(FAST_OR_SAFE_HEADER, "safe") == "fast":
 117             fast = True
 118         mode = black.FileMode(
 119             target_versions=versions,
 120             is_pyi=pyi,
 121             line_length=line_length,
 122             string_normalization=not skip_string_normalization,
 123             magic_trailing_comma=not skip_magic_trailing_comma,
 124             preview=preview,
 125         )
 126         req_bytes = await request.content.read()
 127         charset = request.charset if request.charset is not None else "utf8"
 128         req_str = req_bytes.decode(charset)
 129         then = datetime.utcnow()
 130
 131         loop = asyncio.get_event_loop()
 132         formatted_str = await loop.run_in_executor(
 133             executor, partial(black.format_file_contents, req_str, fast=fast, mode=mode)
 134         )
 135
 136         # Preserve CRLF line endings
 137         if req_str[req_str.find("\n") - 1] == "\r":
 138             formatted_str = formatted_str.replace("\n", "\r\n")
 139             # If, after swapping line endings, nothing changed, then say so
 140             if formatted_str == req_str:
 141                 raise black.NothingChanged
 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:
 190                         raise InvalidVariantHeader("Python 2 is not supported")
 191                 else:
 192                     # Default to lowest supported minor version.
 193                     minor = 7 if major == 2 else 3
 194                 version_str = f"PY{major}{minor}"
 195                 if major == 3 and not hasattr(black.TargetVersion, version_str):
 196                     raise InvalidVariantHeader(f"3.{minor} is not supported")
 197                 versions.add(black.TargetVersion[version_str])
 198             except (KeyError, ValueError):
 199                 raise InvalidVariantHeader("expected e.g. '3.7', 'py3.5'") from None
 200         return False, versions
 201
 202
 203 def patched_main() -> None:
 204     maybe_install_uvloop()
 205     freeze_support()
 206     black.patch_click()
 207     main()
 208
 209
 210 if __name__ == "__main__":
 211     patched_main()