src/blackd/__init__.py

   1 import asyncio
   2 import logging
   3 from concurrent.futures import Executor, ProcessPoolExecutor
   4 from datetime import datetime, timezone
   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",
  63     type=str,
  64     help="Address to bind the server to.",
  65     default="localhost",
  66     show_default=True,
  67 )
  68 @click.option(
  69     "--bind-port", type=int, help="Port to listen on", default=45484, show_default=True
  70 )
  71 @click.version_option(version=black.__version__)
  72 def main(bind_host: str, bind_port: int) -> None:
  73     logging.basicConfig(level=logging.INFO)
  74     app = make_app()
  75     ver = black.__version__
  76     black.out(f"blackd version {ver} listening on {bind_host} port {bind_port}")
  77     web.run_app(app, host=bind_host, port=bind_port, handle_signals=True, print=None)
  78
  79
  80 def make_app() -> web.Application:
  81     app = web.Application(
  82         middlewares=[cors(allow_headers=(*BLACK_HEADERS, "Content-Type"))]
  83     )
  84     executor = ProcessPoolExecutor()
  85     app.add_routes([web.post("/", partial(handle, executor=executor))])
  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         skip_source_first_line = bool(
 123             request.headers.get(SKIP_SOURCE_FIRST_LINE, False)
 124         )
 125         preview = bool(request.headers.get(PREVIEW, False))
 126         fast = False
 127         if request.headers.get(FAST_OR_SAFE_HEADER, "safe") == "fast":
 128             fast = True
 129         mode = black.FileMode(
 130             target_versions=versions,
 131             is_pyi=pyi,
 132             line_length=line_length,
 133             skip_source_first_line=skip_source_first_line,
 134             string_normalization=not skip_string_normalization,
 135             magic_trailing_comma=not skip_magic_trailing_comma,
 136             preview=preview,
 137         )
 138         req_bytes = await request.content.read()
 139         charset = request.charset if request.charset is not None else "utf8"
 140         req_str = req_bytes.decode(charset)
 141         then = datetime.now(timezone.utc)
 142
 143         header = ""
 144         if skip_source_first_line:
 145             first_newline_position: int = req_str.find("\n") + 1
 146             header = req_str[:first_newline_position]
 147             req_str = req_str[first_newline_position:]
 148
 149         loop = asyncio.get_event_loop()
 150         formatted_str = await loop.run_in_executor(
 151             executor, partial(black.format_file_contents, req_str, fast=fast, mode=mode)
 152         )
 153
 154         # Preserve CRLF line endings
 155         if req_str[req_str.find("\n") - 1] == "\r":
 156             formatted_str = formatted_str.replace("\n", "\r\n")
 157             # If, after swapping line endings, nothing changed, then say so
 158             if formatted_str == req_str:
 159                 raise black.NothingChanged
 160
 161         # Put the source first line back
 162         req_str = header + req_str
 163         formatted_str = header + formatted_str
 164
 165         # Only output the diff in the HTTP response
 166         only_diff = bool(request.headers.get(DIFF_HEADER, False))
 167         if only_diff:
 168             now = datetime.now(timezone.utc)
 169             src_name = f"In\t{then}"
 170             dst_name = f"Out\t{now}"
 171             loop = asyncio.get_event_loop()
 172             formatted_str = await loop.run_in_executor(
 173                 executor,
 174                 partial(black.diff, req_str, formatted_str, src_name, dst_name),
 175             )
 176
 177         return web.Response(
 178             content_type=request.content_type,
 179             charset=charset,
 180             headers=headers,
 181             text=formatted_str,
 182         )
 183     except black.NothingChanged:
 184         return web.Response(status=204, headers=headers)
 185     except black.InvalidInput as e:
 186         return web.Response(status=400, headers=headers, text=str(e))
 187     except Exception as e:
 188         logging.exception("Exception during handling a request")
 189         return web.Response(status=500, headers=headers, text=str(e))
 190
 191
 192 def parse_python_variant_header(value: str) -> Tuple[bool, Set[black.TargetVersion]]:
 193     if value == "pyi":
 194         return True, set()
 195     else:
 196         versions = set()
 197         for version in value.split(","):
 198             if version.startswith("py"):
 199                 version = version[len("py") :]
 200             if "." in version:
 201                 major_str, *rest = version.split(".")
 202             else:
 203                 major_str = version[0]
 204                 rest = [version[1:]] if len(version) > 1 else []
 205             try:
 206                 major = int(major_str)
 207                 if major not in (2, 3):
 208                     raise InvalidVariantHeader("major version must be 2 or 3")
 209                 if len(rest) > 0:
 210                     minor = int(rest[0])
 211                     if major == 2:
 212                         raise InvalidVariantHeader("Python 2 is not supported")
 213                 else:
 214                     # Default to lowest supported minor version.
 215                     minor = 7 if major == 2 else 3
 216                 version_str = f"PY{major}{minor}"
 217                 if major == 3 and not hasattr(black.TargetVersion, version_str):
 218                     raise InvalidVariantHeader(f"3.{minor} is not supported")
 219                 versions.add(black.TargetVersion[version_str])
 220             except (KeyError, ValueError):
 221                 raise InvalidVariantHeader("expected e.g. '3.7', 'py3.5'") from None
 222         return False, versions
 223
 224
 225 def patched_main() -> None:
 226     maybe_install_uvloop()
 227     freeze_support()
 228     black.patch_click()
 229     main()
 230
 231
 232 if __name__ == "__main__":
 233     patched_main()