Mini Shell

import asyncio
import enum
import io
import json
import mimetypes
import os
import warnings
from abc import ABC, abstractmethod
from itertools import chain
from typing import (
    IO,
    TYPE_CHECKING,
    Any,
    ByteString,
    Dict,
    Final,
    Iterable,
    Optional,
    TextIO,
    Tuple,
    Type,
    Union,
)

from multidict import CIMultiDict

from . import hdrs
from .abc import AbstractStreamWriter
from .helpers import (
    _SENTINEL,
    content_disposition_header,
    guess_filename,
    parse_mimetype,
    sentinel,
)
from .streams import StreamReader
from .typedefs import JSONEncoder, _CIMultiDict

__all__ = (
    "PAYLOAD_REGISTRY",
    "get_payload",
    "payload_type",
    "Payload",
    "BytesPayload",
    "StringPayload",
    "IOBasePayload",
    "BytesIOPayload",
    "BufferedReaderPayload",
    "TextIOPayload",
    "StringIOPayload",
    "JsonPayload",
    "AsyncIterablePayload",
)

TOO_LARGE_BYTES_BODY: Final[int] = 2**20  # 1 MB

if TYPE_CHECKING:
    from typing import List


class LookupError(Exception):
    pass


class Order(str, enum.Enum):
    normal = "normal"
    try_first = "try_first"
    try_last = "try_last"


def get_payload(data: Any, *args: Any, **kwargs: Any) -> "Payload":
    return PAYLOAD_REGISTRY.get(data, *args, **kwargs)


def register_payload(
    factory: Type["Payload"], type: Any, *, order: Order = Order.normal
) -> None:
    PAYLOAD_REGISTRY.register(factory, type, order=order)


class payload_type:
    def __init__(self, type: Any, *, order: Order = Order.normal) -> None:
        self.type = type
        self.order = order

    def __call__(self, factory: Type["Payload"]) -> Type["Payload"]:
        register_payload(factory, self.type, order=self.order)
        return factory


PayloadType = Type["Payload"]
_PayloadRegistryItem = Tuple[PayloadType, Any]


class PayloadRegistry:
    """Payload registry.

    note: we need zope.interface for more efficient adapter search
    """

    def __init__(self) -> None:
        self._first: List[_PayloadRegistryItem] = []
        self._normal: List[_PayloadRegistryItem] = []
        self._last: List[_PayloadRegistryItem] = []

    def get(
        self,
        data: Any,
        *args: Any,
        _CHAIN: "Type[chain[_PayloadRegistryItem]]" = chain,
        **kwargs: Any,
    ) -> "Payload":
        if isinstance(data, Payload):
            return data
        for factory, type in _CHAIN(self._first, self._normal, self._last):
            if isinstance(data, type):
                return factory(data, *args, **kwargs)

        raise LookupError()

    def register(
        self, factory: PayloadType, type: Any, *, order: Order = Order.normal
    ) -> None:
        if order is Order.try_first:
            self._first.append((factory, type))
        elif order is Order.normal:
            self._normal.append((factory, type))
        elif order is Order.try_last:
            self._last.append((factory, type))
        else:
            raise ValueError(f"Unsupported order {order!r}")


class Payload(ABC):

    _default_content_type: str = "application/octet-stream"
    _size: Optional[int] = None

    def __init__(
        self,
        value: Any,
        headers: Optional[
            Union[_CIMultiDict, Dict[str, str], Iterable[Tuple[str, str]]]
        ] = None,
        content_type: Union[str, None, _SENTINEL] = sentinel,
        filename: Optional[str] = None,
        encoding: Optional[str] = None,
        **kwargs: Any,
    ) -> None:
        self._encoding = encoding
        self._filename = filename
        self._headers: _CIMultiDict = CIMultiDict()
        self._value = value
        if content_type is not sentinel and content_type is not None:
            self._headers[hdrs.CONTENT_TYPE] = content_type
        elif self._filename is not None:
            content_type = mimetypes.guess_type(self._filename)[0]
            if content_type is None:
                content_type = self._default_content_type
            self._headers[hdrs.CONTENT_TYPE] = content_type
        else:
            self._headers[hdrs.CONTENT_TYPE] = self._default_content_type
        self._headers.update(headers or {})

    @property
    def size(self) -> Optional[int]:
        """Size of the payload."""
        return self._size

    @property
    def filename(self) -> Optional[str]:
        """Filename of the payload."""
        return self._filename

    @property
    def headers(self) -> _CIMultiDict:
        """Custom item headers"""
        return self._headers

    @property
    def _binary_headers(self) -> bytes:
        return (
            "".join([k + ": " + v + "\r\n" for k, v in self.headers.items()]).encode(
                "utf-8"
            )
            + b"\r\n"
        )

    @property
    def encoding(self) -> Optional[str]:
        """Payload encoding"""
        return self._encoding

    @property
    def content_type(self) -> str:
        """Content type"""
        return self._headers[hdrs.CONTENT_TYPE]

    def set_content_disposition(
        self,
        disptype: str,
        quote_fields: bool = True,
        _charset: str = "utf-8",
        **params: Any,
    ) -> None:
        """Sets ``Content-Disposition`` header."""
        self._headers[hdrs.CONTENT_DISPOSITION] = content_disposition_header(
            disptype, quote_fields=quote_fields, _charset=_charset, **params
        )

    @abstractmethod
    async def write(self, writer: AbstractStreamWriter) -> None:
        """Write payload.

        writer is an AbstractStreamWriter instance:
        """


class BytesPayload(Payload):
    def __init__(self, value: ByteString, *args: Any, **kwargs: Any) -> None:
        if not isinstance(value, (bytes, bytearray, memoryview)):
            raise TypeError(f"value argument must be byte-ish, not {type(value)!r}")

        if "content_type" not in kwargs:
            kwargs["content_type"] = "application/octet-stream"

        super().__init__(value, *args, **kwargs)

        if isinstance(value, memoryview):
            self._size = value.nbytes
        else:
            self._size = len(value)

        if self._size > TOO_LARGE_BYTES_BODY:
            kwargs = {"source": self}
            warnings.warn(
                "Sending a large body directly with raw bytes might"
                " lock the event loop. You should probably pass an "
                "io.BytesIO object instead",
                ResourceWarning,
                **kwargs,
            )

    async def write(self, writer: AbstractStreamWriter) -> None:
        await writer.write(self._value)


class StringPayload(BytesPayload):
    def __init__(
        self,
        value: str,
        *args: Any,
        encoding: Optional[str] = None,
        content_type: Optional[str] = None,
        **kwargs: Any,
    ) -> None:

        if encoding is None:
            if content_type is None:
                real_encoding = "utf-8"
                content_type = "text/plain; charset=utf-8"
            else:
                mimetype = parse_mimetype(content_type)
                real_encoding = mimetype.parameters.get("charset", "utf-8")
        else:
            if content_type is None:
                content_type = "text/plain; charset=%s" % encoding
            real_encoding = encoding

        super().__init__(
            value.encode(real_encoding),
            encoding=real_encoding,
            content_type=content_type,
            *args,
            **kwargs,
        )


class StringIOPayload(StringPayload):
    def __init__(self, value: IO[str], *args: Any, **kwargs: Any) -> None:
        super().__init__(value.read(), *args, **kwargs)


class IOBasePayload(Payload):
    _value: IO[Any]

    def __init__(
        self, value: IO[Any], disposition: str = "attachment", *args: Any, **kwargs: Any
    ) -> None:
        if "filename" not in kwargs:
            kwargs["filename"] = guess_filename(value)

        super().__init__(value, *args, **kwargs)

        if self._filename is not None and disposition is not None:
            if hdrs.CONTENT_DISPOSITION not in self.headers:
                self.set_content_disposition(disposition, filename=self._filename)

    async def write(self, writer: AbstractStreamWriter) -> None:
        loop = asyncio.get_event_loop()
        try:
            chunk = await loop.run_in_executor(None, self._value.read, 2**16)
            while chunk:
                await writer.write(chunk)
                chunk = await loop.run_in_executor(None, self._value.read, 2**16)
        finally:
            await loop.run_in_executor(None, self._value.close)


class TextIOPayload(IOBasePayload):
    _value: TextIO

    def __init__(
        self,
        value: TextIO,
        *args: Any,
        encoding: Optional[str] = None,
        content_type: Optional[str] = None,
        **kwargs: Any,
    ) -> None:

        if encoding is None:
            if content_type is None:
                encoding = "utf-8"
                content_type = "text/plain; charset=utf-8"
            else:
                mimetype = parse_mimetype(content_type)
                encoding = mimetype.parameters.get("charset", "utf-8")
        else:
            if content_type is None:
                content_type = "text/plain; charset=%s" % encoding

        super().__init__(
            value,
            content_type=content_type,
            encoding=encoding,
            *args,
            **kwargs,
        )

    @property
    def size(self) -> Optional[int]:
        try:
            return os.fstat(self._value.fileno()).st_size - self._value.tell()
        except OSError:
            return None

    async def write(self, writer: AbstractStreamWriter) -> None:
        loop = asyncio.get_event_loop()
        try:
            chunk = await loop.run_in_executor(None, self._value.read, 2**16)
            while chunk:
                data = (
                    chunk.encode(encoding=self._encoding)
                    if self._encoding
                    else chunk.encode()
                )
                await writer.write(data)
                chunk = await loop.run_in_executor(None, self._value.read, 2**16)
        finally:
            await loop.run_in_executor(None, self._value.close)


class BytesIOPayload(IOBasePayload):
    @property
    def size(self) -> int:
        position = self._value.tell()
        end = self._value.seek(0, os.SEEK_END)
        self._value.seek(position)
        return end - position


class BufferedReaderPayload(IOBasePayload):
    @property
    def size(self) -> Optional[int]:
        try:
            return os.fstat(self._value.fileno()).st_size - self._value.tell()
        except OSError:
            # data.fileno() is not supported, e.g.
            # io.BufferedReader(io.BytesIO(b'data'))
            return None


class JsonPayload(BytesPayload):
    def __init__(
        self,
        value: Any,
        encoding: str = "utf-8",
        content_type: str = "application/json",
        dumps: JSONEncoder = json.dumps,
        *args: Any,
        **kwargs: Any,
    ) -> None:

        super().__init__(
            dumps(value).encode(encoding),
            content_type=content_type,
            encoding=encoding,
            *args,
            **kwargs,
        )


if TYPE_CHECKING:
    from typing import AsyncIterable, AsyncIterator

    _AsyncIterator = AsyncIterator[bytes]
    _AsyncIterable = AsyncIterable[bytes]
else:
    from collections.abc import AsyncIterable, AsyncIterator

    _AsyncIterator = AsyncIterator
    _AsyncIterable = AsyncIterable


class AsyncIterablePayload(Payload):

    _iter: Optional[_AsyncIterator] = None

    def __init__(self, value: _AsyncIterable, *args: Any, **kwargs: Any) -> None:
        if not isinstance(value, AsyncIterable):
            raise TypeError(
                "value argument must support "
                "collections.abc.AsyncIterable interface, "
                "got {!r}".format(type(value))
            )

        if "content_type" not in kwargs:
            kwargs["content_type"] = "application/octet-stream"

        super().__init__(value, *args, **kwargs)

        self._iter = value.__aiter__()

    async def write(self, writer: AbstractStreamWriter) -> None:
        if self._iter:
            try:
                # iter is not None check prevents rare cases
                # when the case iterable is used twice
                while True:
                    chunk = await self._iter.__anext__()
                    await writer.write(chunk)
            except StopAsyncIteration:
                self._iter = None


class StreamReaderPayload(AsyncIterablePayload):
    def __init__(self, value: StreamReader, *args: Any, **kwargs: Any) -> None:
        super().__init__(value.iter_any(), *args, **kwargs)


PAYLOAD_REGISTRY = PayloadRegistry()
PAYLOAD_REGISTRY.register(BytesPayload, (bytes, bytearray, memoryview))
PAYLOAD_REGISTRY.register(StringPayload, str)
PAYLOAD_REGISTRY.register(StringIOPayload, io.StringIO)
PAYLOAD_REGISTRY.register(TextIOPayload, io.TextIOBase)
PAYLOAD_REGISTRY.register(BytesIOPayload, io.BytesIO)
PAYLOAD_REGISTRY.register(BufferedReaderPayload, (io.BufferedReader, io.BufferedRandom))
PAYLOAD_REGISTRY.register(IOBasePayload, io.IOBase)
PAYLOAD_REGISTRY.register(StreamReaderPayload, StreamReader)
# try_last for giving a chance to more specialized async interables like
# multidict.BodyPartReaderPayload override the default
PAYLOAD_REGISTRY.register(AsyncIterablePayload, AsyncIterable, order=Order.try_last)