import argparse
import os
import platform
import sys
from typing import List, Optional, Tuple, Union

import requests
from pygments import __version__ as pygments_version
from requests import __version__ as requests_version

from . import __version__ as httpie_version
from .cli.constants import OUT_REQ_BODY, OUT_REQ_HEAD, OUT_RESP_BODY, OUT_RESP_HEAD
from .client import collect_messages
from .context import Environment
from .downloads import Downloader
from .output.writer import write_message, write_stream, MESSAGE_SEPARATOR_BYTES
from .plugins.registry import plugin_manager
from .status import ExitStatus, http_status_to_exit_status


# noinspection PyDefaultArgument
def main(args: List[Union[str, bytes]] = sys.argv, env=Environment()) -> ExitStatus:
    """
    The main function.

    Pre-process args, handle some special types of invocations,
    and run the main program with error handling.

    Return exit status code.

    """
    program_name, *args = args
    env.program_name = os.path.basename(program_name)
    args = decode_raw_args(args, env.stdin_encoding)
    plugin_manager.load_installed_plugins()

    from .cli.definition import parser

    if env.config.default_options:
        args = env.config.default_options + args

    include_debug_info = '--debug' in args
    include_traceback = include_debug_info or '--traceback' in args

    if include_debug_info:
        print_debug_info(env)
        if args == ['--debug']:
            return ExitStatus.SUCCESS

    exit_status = ExitStatus.SUCCESS

    try:
        parsed_args = parser.parse_args(
            args=args,
            env=env,
        )
    except KeyboardInterrupt:
        env.stderr.write('\n')
        if include_traceback:
            raise
        exit_status = ExitStatus.ERROR_CTRL_C
    except SystemExit as e:
        if e.code != ExitStatus.SUCCESS:
            env.stderr.write('\n')
            if include_traceback:
                raise
            exit_status = ExitStatus.ERROR
    else:
        try:
            exit_status = program(
                args=parsed_args,
                env=env,
            )
        except KeyboardInterrupt:
            env.stderr.write('\n')
            if include_traceback:
                raise
            exit_status = ExitStatus.ERROR_CTRL_C
        except SystemExit as e:
            if e.code != ExitStatus.SUCCESS:
                env.stderr.write('\n')
                if include_traceback:
                    raise
                exit_status = ExitStatus.ERROR
        except requests.Timeout:
            exit_status = ExitStatus.ERROR_TIMEOUT
            env.log_error(f'Request timed out ({parsed_args.timeout}s).')
        except requests.TooManyRedirects:
            exit_status = ExitStatus.ERROR_TOO_MANY_REDIRECTS
            env.log_error(
                f'Too many redirects'
                f' (--max-redirects={parsed_args.max_redirects}).'
            )
        except Exception as e:
            # TODO: Further distinction between expected and unexpected errors.
            msg = str(e)
            if hasattr(e, 'request'):
                request = e.request
                if hasattr(request, 'url'):
                    msg = (
                        f'{msg} while doing a {request.method}'
                        f' request to URL: {request.url}'
                    )
            env.log_error(f'{type(e).__name__}: {msg}')
            if include_traceback:
                raise
            exit_status = ExitStatus.ERROR

    return exit_status


def get_output_options(
    args: argparse.Namespace,
    message: Union[requests.PreparedRequest, requests.Response]
) -> Tuple[bool, bool]:
    return {
        requests.PreparedRequest: (
            OUT_REQ_HEAD in args.output_options,
            OUT_REQ_BODY in args.output_options,
        ),
        requests.Response: (
            OUT_RESP_HEAD in args.output_options,
            OUT_RESP_BODY in args.output_options,
        ),
    }[type(message)]


def program(args: argparse.Namespace, env: Environment) -> ExitStatus:
    """
    The main program without error handling.

    """
    # TODO: Refactor and drastically simplify, especially so that the separator logic is elsewhere.
    exit_status = ExitStatus.SUCCESS
    downloader = None
    initial_request: Optional[requests.PreparedRequest] = None
    final_response: Optional[requests.Response] = None

    def separate():
        getattr(env.stdout, 'buffer', env.stdout).write(MESSAGE_SEPARATOR_BYTES)

    def request_body_read_callback(chunk: bytes):
        should_pipe_to_stdout = bool(
            # Request body output desired
            OUT_REQ_BODY in args.output_options
            # & not `.read()` already pre-request (e.g., for  compression)
            and initial_request
            # & non-EOF chunk
            and chunk
        )
        if should_pipe_to_stdout:
            msg = requests.PreparedRequest()
            msg.is_body_upload_chunk = True
            msg.body = chunk
            msg.headers = initial_request.headers
            write_message(requests_message=msg, env=env, args=args, with_body=True, with_headers=False)

    try:
        if args.download:
            args.follow = True  # --download implies --follow.
            downloader = Downloader(output_file=args.output_file, progress_file=env.stderr, resume=args.download_resume)
            downloader.pre_request(args.headers)
        messages = collect_messages(args=args, config_dir=env.config.directory,
                                    request_body_read_callback=request_body_read_callback)
        force_separator = False
        prev_with_body = False

        # Process messages as they’re generated
        for message in messages:
            is_request = isinstance(message, requests.PreparedRequest)
            with_headers, with_body = get_output_options(args=args, message=message)
            do_write_body = with_body
            if prev_with_body and (with_headers or with_body) and (force_separator or not env.stdout_isatty):
                # Separate after a previous message with body, if needed. See test_tokens.py.
                separate()
            force_separator = False
            if is_request:
                if not initial_request:
                    initial_request = message
                    is_streamed_upload = not isinstance(message.body, (str, bytes))
                    if with_body:
                        do_write_body = not is_streamed_upload
                        force_separator = is_streamed_upload and env.stdout_isatty
            else:
                final_response = message
                if args.check_status or downloader:
                    exit_status = http_status_to_exit_status(http_status=message.status_code, follow=args.follow)
                    if exit_status != ExitStatus.SUCCESS and (not env.stdout_isatty or args.quiet):
                        env.log_error(f'HTTP {message.raw.status} {message.raw.reason}', level='warning')
            write_message(requests_message=message, env=env, args=args, with_headers=with_headers,
                          with_body=do_write_body)
            prev_with_body = with_body

        # Cleanup
        if force_separator:
            separate()
        if downloader and exit_status == ExitStatus.SUCCESS:
            # Last response body download.
            download_stream, download_to = downloader.start(
                initial_url=initial_request.url,
                final_response=final_response,
            )
            write_stream(stream=download_stream, outfile=download_to, flush=False)
            downloader.finish()
            if downloader.interrupted:
                exit_status = ExitStatus.ERROR
                env.log_error(
                    f'Incomplete download: size={downloader.status.total_size};'
                    f' downloaded={downloader.status.downloaded}'
                )
        return exit_status

    finally:
        if downloader and not downloader.finished:
            downloader.failed()
        if not isinstance(args, list) and args.output_file and args.output_file_specified:
            args.output_file.close()


def print_debug_info(env: Environment):
    env.stderr.writelines([
        f'HTTPie {httpie_version}\n',
        f'Requests {requests_version}\n',
        f'Pygments {pygments_version}\n',
        f'Python {sys.version}\n{sys.executable}\n',
        f'{platform.system()} {platform.release()}',
    ])
    env.stderr.write('\n\n')
    env.stderr.write(repr(env))
    env.stderr.write('\n')


def decode_raw_args(
    args: List[Union[str, bytes]],
    stdin_encoding: str
) -> List[str]:
    """
    Convert all bytes args to str
    by decoding them using stdin encoding.

    """
    return [
        arg.decode(stdin_encoding)
        if type(arg) is bytes else arg
        for arg in args
    ]
