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,
    Iterable,
    Optional,
    Text,
    TextIO,
    Tuple,
    Type,
    Union,
)

from multidict import CIMultiDict

from . import hdrs
from .abc import AbstractStreamWriter
from .helpers import (
    PY_36,
    content_disposition_header,
    guess_filename,
    parse_mimetype,
    sentinel,
)
from .streams import DEFAULT_LIMIT, 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 = 2 ** 20  # 1 MB


if TYPE_CHECKING:  # pragma: no cover
    from typing import List  # noqa


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


class PayloadRegistry:
    """Payload registry.

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

    def __init__(self) -> None:
        self._first = []  # type: List[Tuple[Type[Payload], Any]]
        self._normal = []  # type: List[Tuple[Type[Payload], Any]]
        self._last = []  # type: List[Tuple[Type[Payload], Any]]

    def get(self,
            data: Any,
            *args: Any,
            _CHAIN: Any=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: Type['Payload'],
                 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("Unsupported order {!r}".format(order))


class Payload(ABC):

    _default_content_type = 'application/octet-stream'  # type: str
    _size = None  # type: Optional[int]

    def __init__(self,
                 value: Any,
                 headers: Optional[
                     Union[
                         _CIMultiDict,
                         Dict[str, str],
                         Iterable[Tuple[str, str]]
                     ]
                 ] = None,
                 content_type: Optional[str]=sentinel,
                 filename: Optional[str]=None,
                 encoding: Optional[str]=None,
                 **kwargs: Any) -> None:
        self._encoding = encoding
        self._filename = filename
        self._headers = CIMultiDict()  # type: _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,
                                **params: Any) -> None:
        """Sets ``Content-Disposition`` header."""
        self._headers[hdrs.CONTENT_DISPOSITION] = content_disposition_header(
            disptype, quote_fields=quote_fields, **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("value argument must be byte-ish, not (!r)"
                            .format(type(value)))

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

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

        self._size = len(value)

        if self._size > TOO_LARGE_BYTES_BODY:
            if PY_36:
                kwargs = {'source': self}
            else:
                kwargs = {}
            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: Text,
                 *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):

    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, DEFAULT_LIMIT
            )
            while chunk:
                await writer.write(chunk)
                chunk = await loop.run_in_executor(
                    None, self._value.read, DEFAULT_LIMIT
                )
        finally:
            await loop.run_in_executor(None, self._value.close)


class TextIOPayload(IOBasePayload):

    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, DEFAULT_LIMIT
            )
            while chunk:
                await writer.write(chunk.encode(self._encoding))
                chunk = await loop.run_in_executor(
                    None, self._value.read, DEFAULT_LIMIT
                )
        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:  # pragma: no cover
    from typing import AsyncIterator, AsyncIterable

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

    _AsyncIterator = AsyncIterator
    _AsyncIterable = AsyncIterable


class AsyncIterablePayload(Payload):

    _iter = None  # type: Optional[_AsyncIterator]

    def __init__(self,
                 value: _AsyncIterable,
                 *args: Any,
                 **kwargs: Any) -> None:
        if not isinstance(value, AsyncIterable):
            raise TypeError("value argument must support "
                            "collections.abc.AsyncIterablebe 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)
