from itertools import chain
from functools import partial

from httpie.context import Environment
from httpie.models import HTTPRequest, HTTPResponse
from httpie.input import (OUT_REQ_BODY, OUT_REQ_HEAD,
                          OUT_RESP_HEAD, OUT_RESP_BODY)
from httpie.output.processors import ProcessorManager


BINARY_SUPPRESSED_NOTICE = (
    b'\n'
    b'+-----------------------------------------+\n'
    b'| NOTE: binary data not shown in terminal |\n'
    b'+-----------------------------------------+'
)


class BinarySuppressedError(Exception):
    """An error indicating that the body is binary and won't be written,
     e.g., for terminal output)."""

    message = BINARY_SUPPRESSED_NOTICE


def write(stream, outfile, flush):
    """Write the output stream."""
    try:
        # Writing bytes so we use the buffer interface (Python 3).
        buf = outfile.buffer
    except AttributeError:
        buf = outfile

    for chunk in stream:
        buf.write(chunk)
        if flush:
            outfile.flush()


def write_with_colors_win_py3(stream, outfile, flush):
    """Like `write`, but colorized chunks are written as text
    directly to `outfile` to ensure it gets processed by colorama.
    Applies only to Windows with Python 3 and colorized terminal output.

    """
    color = b'\x1b['
    encoding = outfile.encoding
    for chunk in stream:
        if color in chunk:
            outfile.write(chunk.decode(encoding))
        else:
            outfile.buffer.write(chunk)
        if flush:
            outfile.flush()


def build_output_stream(args, env, request, response):
    """Build and return a chain of iterators over the `request`-`response`
    exchange each of which yields `bytes` chunks.

    """

    req_h = OUT_REQ_HEAD in args.output_options
    req_b = OUT_REQ_BODY in args.output_options
    resp_h = OUT_RESP_HEAD in args.output_options
    resp_b = OUT_RESP_BODY in args.output_options
    req = req_h or req_b
    resp = resp_h or resp_b

    output = []
    Stream = get_stream_type(env, args)

    if req:
        output.append(Stream(
            msg=HTTPRequest(request),
            with_headers=req_h,
            with_body=req_b))

    if req_b and resp:
        # Request/Response separator.
        output.append([b'\n\n'])

    if resp:
        output.append(Stream(
            msg=HTTPResponse(response),
            with_headers=resp_h,
            with_body=resp_b))

    if env.stdout_isatty and resp_b:
        # Ensure a blank line after the response body.
        # For terminal output only.
        output.append([b'\n\n'])

    return chain(*output)


def get_stream_type(env, args):
    """Pick the right stream type based on `env` and `args`.
    Wrap it in a partial with the type-specific args so that
    we don't need to think what stream we are dealing with.

    """
    if not env.stdout_isatty and not args.prettify:
        Stream = partial(
            RawStream,
            chunk_size=RawStream.CHUNK_SIZE_BY_LINE
            if args.stream
            else RawStream.CHUNK_SIZE
        )
    elif args.prettify:
        Stream = partial(
            PrettyStream if args.stream else BufferedPrettyStream,
            env=env,
            processor=ProcessorManager(
                env=env,
                groups=args.prettify,
                pygments_style=args.style
            ),
        )
    else:
        Stream = partial(EncodedStream, env=env)

    return Stream


class BaseStream(object):
    """Base HTTP message output stream class."""

    def __init__(self, msg, with_headers=True, with_body=True,
                 on_body_chunk_downloaded=None):
        """
        :param msg: a :class:`models.HTTPMessage` subclass
        :param with_headers: if `True`, headers will be included
        :param with_body: if `True`, body will be included

        """
        assert with_headers or with_body
        self.msg = msg
        self.with_headers = with_headers
        self.with_body = with_body
        self.on_body_chunk_downloaded = on_body_chunk_downloaded

    def _get_headers(self):
        """Return the headers' bytes."""
        return self.msg.headers.encode('utf8')

    def _iter_body(self):
        """Return an iterator over the message body."""
        raise NotImplementedError()

    def __iter__(self):
        """Return an iterator over `self.msg`."""
        if self.with_headers:
            yield self._get_headers()
            yield b'\r\n\r\n'

        if self.with_body:
            try:
                for chunk in self._iter_body():
                    yield chunk
                    if self.on_body_chunk_downloaded:
                        self.on_body_chunk_downloaded(chunk)
            except BinarySuppressedError as e:
                if self.with_headers:
                    yield b'\n'
                yield e.message


class RawStream(BaseStream):
    """The message is streamed in chunks with no processing."""

    CHUNK_SIZE = 1024 * 100
    CHUNK_SIZE_BY_LINE = 1

    def __init__(self, chunk_size=CHUNK_SIZE, **kwargs):
        super(RawStream, self).__init__(**kwargs)
        self.chunk_size = chunk_size

    def _iter_body(self):
        return self.msg.iter_body(self.chunk_size)


class EncodedStream(BaseStream):
    """Encoded HTTP message stream.

    The message bytes are converted to an encoding suitable for
    `self.env.stdout`. Unicode errors are replaced and binary data
    is suppressed. The body is always streamed by line.

    """
    CHUNK_SIZE = 1

    def __init__(self, env=Environment(), **kwargs):

        super(EncodedStream, self).__init__(**kwargs)

        if env.stdout_isatty:
            # Use the encoding supported by the terminal.
            output_encoding = env.stdout_encoding
        else:
            # Preserve the message encoding.
            output_encoding = self.msg.encoding

        # Default to utf8 when unsure.
        self.output_encoding = output_encoding or 'utf8'

    def _iter_body(self):

        for line, lf in self.msg.iter_lines(self.CHUNK_SIZE):

            if b'\0' in line:
                raise BinarySuppressedError()

            yield line.decode(self.msg.encoding) \
                      .encode(self.output_encoding, 'replace') + lf


class PrettyStream(EncodedStream):
    """In addition to :class:`EncodedStream` behaviour, this stream applies
    content processing.

    Useful for long-lived HTTP responses that stream by lines
    such as the Twitter streaming API.

    """

    CHUNK_SIZE = 1

    def __init__(self, processor, **kwargs):
        super(PrettyStream, self).__init__(**kwargs)
        self.processor = processor

    def _get_headers(self):
        return self.processor.process_headers(
            self.msg.headers).encode(self.output_encoding)

    def _iter_body(self):
        for line, lf in self.msg.iter_lines(self.CHUNK_SIZE):
            if b'\0' in line:
                raise BinarySuppressedError()
            yield self._process_body(line) + lf

    def _process_body(self, chunk):
        return self.processor.process_body(
            body=chunk.decode(self.msg.encoding, 'replace'),
            mime=self.msg.content_type.split(';')[0]
        ).encode(self.output_encoding, 'replace')


class BufferedPrettyStream(PrettyStream):
    """The same as :class:`PrettyStream` except that the body is fully
    fetched before it's processed.

    Suitable regular HTTP responses.

    """

    CHUNK_SIZE = 1024 * 10

    def _iter_body(self):

        # Read the whole body before prettifying it,
        # but bail out immediately if the body is binary.
        body = bytearray()
        for chunk in self.msg.iter_body(self.CHUNK_SIZE):
            if b'\0' in chunk:
                raise BinarySuppressedError()
            body.extend(chunk)

        yield self._process_body(body)