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_SOURCE_FIRST_LINE = "X-Skip-Source-First-Line"
  34 SKIP_STRING_NORMALIZATION_HEADER = "X-Skip-String-Normalization"
  35 SKIP_MAGIC_TRAILING_COMMA = "X-Skip-Magic-Trailing-Comma"
  36 PREVIEW = "X-Preview"
  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_SOURCE_FIRST_LINE,
  45     SKIP_STRING_NORMALIZATION_HEADER,
  46     SKIP_MAGIC_TRAILING_COMMA,
  47     PREVIEW,
  48     FAST_OR_SAFE_HEADER,
  49     DIFF_HEADER,
  50 ]
  51
  52 # Response headers
  53 BLACK_VERSION_HEADER = "X-Black-Version"
  54
  55
  56 class InvalidVariantHeader(Exception):
  57     pass
  58
  59
  60 @click.command(context_settings={"help_option_names": ["-h", "--help"]})
  61 @click.option(
  62     "--bind-host", type=str, help="Address to bind the server to.", default="localhost"
  63 )
  64 @click.option("--bind-port", type=int, help="Port to listen on", default=45484)
  65 @click.version_option(version=black.__version__)
  66 def main(bind_host: str, bind_port: int) -> None:
  67     logging.basicConfig(level=logging.INFO)
  68     app = make_app()
  69     ver = black.__version__
  70     black.out(f"blackd version {ver} listening on {bind_host} port {bind_port}")
  71     web.run_app(app, host=bind_host, port=bind_port, handle_signals=True, print=None)
  72
  73
  74 def make_app() -> web.Application:
  75     app = web.Application(
  76         middlewares=[cors(allow_headers=(*BLACK_HEADERS, "Content-Type"))]
  77     )
  78     executor = ProcessPoolExecutor()
  79     app.add_routes([web.post("/", partial(handle, executor=executor))])
  80     return app
  81
  82
  83 async def handle(request: web.Request, executor: Executor) -> web.Response:
  84     headers = {BLACK_VERSION_HEADER: __version__}
  85     try:
  86         if request.headers.get(PROTOCOL_VERSION_HEADER, "1") != "1":
  87             return web.Response(
  88                 status=501, text="This server only supports protocol version 1"
  89             )
  90         try:
  91             line_length = int(
  92                 request.headers.get(LINE_LENGTH_HEADER, black.DEFAULT_LINE_LENGTH)
  93             )
  94         except ValueError:
  95             return web.Response(status=400, text="Invalid line length header value")
  96
  97         if PYTHON_VARIANT_HEADER in request.headers:
  98             value = request.headers[PYTHON_VARIANT_HEADER]
  99             try:
 100                 pyi, versions = parse_python_variant_header(value)
 101             except InvalidVariantHeader as e:
 102                 return web.Response(
 103                     status=400,
 104                     text=f"Invalid value for {PYTHON_VARIANT_HEADER}: {e.args[0]}",
 105                 )
 106         else:
 107             pyi = False
 108             versions = set()
 109
 110         skip_string_normalization = bool(
 111             request.headers.get(SKIP_STRING_NORMALIZATION_HEADER, False)
 112         )
 113         skip_magic_trailing_comma = bool(
 114             request.headers.get(SKIP_MAGIC_TRAILING_COMMA, False)
 115         )
 116         skip_source_first_line = bool(
 117             request.headers.get(SKIP_SOURCE_FIRST_LINE, False)
 118         )
 119         preview = bool(request.headers.get(PREVIEW, False))
 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             skip_source_first_line=skip_source_first_line,
 128             string_normalization=not skip_string_normalization,
 129             magic_trailing_comma=not skip_magic_trailing_comma,
 130             preview=preview,
 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         header = ""
 138         if skip_source_first_line:
 139             first_newline_position: int = req_str.find("\n") + 1
 140             header = req_str[:first_newline_position]
 141             req_str = req_str[first_newline_position:]
 142
 143         loop = asyncio.get_event_loop()
 144         formatted_str = await loop.run_in_executor(
 145             executor, partial(black.format_file_contents, req_str, fast=fast, mode=mode)
 146         )
 147
 148         # Preserve CRLF line endings
 149         if req_str[req_str.find("\n") - 1] == "\r":
 150             formatted_str = formatted_str.replace("\n", "\r\n")
 151             # If, after swapping line endings, nothing changed, then say so
 152             if formatted_str == req_str:
 153                 raise black.NothingChanged
 154
 155         # Put the source first line back
 156         req_str = header + req_str
 157         formatted_str = header + formatted_str
 158
 159         # Only output the diff in the HTTP response
 160         only_diff = bool(request.headers.get(DIFF_HEADER, False))
 161         if only_diff:
 162             now = datetime.utcnow()
 163             src_name = f"In\t{then} +0000"
 164             dst_name = f"Out\t{now} +0000"
 165             loop = asyncio.get_event_loop()
 166             formatted_str = await loop.run_in_executor(
 167                 executor,
 168                 partial(black.diff, req_str, formatted_str, src_name, dst_name),
 169             )
 170
 171         return web.Response(
 172             content_type=request.content_type,
 173             charset=charset,
 174             headers=headers,
 175             text=formatted_str,
 176         )
 177     except black.NothingChanged:
 178         return web.Response(status=204, headers=headers)
 179     except black.InvalidInput as e:
 180         return web.Response(status=400, headers=headers, text=str(e))
 181     except Exception as e:
 182         logging.exception("Exception during handling a request")
 183         return web.Response(status=500, headers=headers, text=str(e))
 184
 185
 186 def parse_python_variant_header(value: str) -> Tuple[bool, Set[black.TargetVersion]]:
 187     if value == "pyi":
 188         return True, set()
 189     else:
 190         versions = set()
 191         for version in value.split(","):
 192             if version.startswith("py"):
 193                 version = version[len("py") :]
 194             if "." in version:
 195                 major_str, *rest = version.split(".")
 196             else:
 197                 major_str = version[0]
 198                 rest = [version[1:]] if len(version) > 1 else []
 199             try:
 200                 major = int(major_str)
 201                 if major not in (2, 3):
 202                     raise InvalidVariantHeader("major version must be 2 or 3")
 203                 if len(rest) > 0:
 204                     minor = int(rest[0])
 205                     if major == 2:
 206                         raise InvalidVariantHeader("Python 2 is not supported")
 207                 else:
 208                     # Default to lowest supported minor version.
 209                     minor = 7 if major == 2 else 3
 210                 version_str = f"PY{major}{minor}"
 211                 if major == 3 and not hasattr(black.TargetVersion, version_str):
 212                     raise InvalidVariantHeader(f"3.{minor} is not supported")
 213                 versions.add(black.TargetVersion[version_str])
 214             except (KeyError, ValueError):
 215                 raise InvalidVariantHeader("expected e.g. '3.7', 'py3.5'") from None
 216         return False, versions
 217
 218
 219 def patched_main() -> None:
 220     maybe_install_uvloop()
 221     freeze_support()
 222     black.patch_click()
 223     main()
 224
 225
 226 if __name__ == "__main__":
 227     patched_main()