import re
import sys

from .ansi import AnsiFore, AnsiBack, AnsiStyle, Style
from .winterm import WinTerm, WinColor, WinStyle
from .win32 import windll


if windll is not None:
    winterm = WinTerm()


def is_a_tty(stream):
    return hasattr(stream, 'isatty') and stream.isatty()


class StreamWrapper(object):
    '''
    Wraps a stream (such as stdout), acting as a transparent proxy for all
    attribute access apart from method 'write()', which is delegated to our
    Converter instance.
    '''
    def __init__(self, wrapped, converter):
        # double-underscore everything to prevent clashes with names of
        # attributes on the wrapped stream object.
        self.__wrapped = wrapped
        self.__convertor = converter

    def __getattr__(self, name):
        return getattr(self.__wrapped, name)

    def write(self, text):
        self.__convertor.write(text)


class AnsiToWin32(object):
    '''
    Implements a 'write()' method which, on Windows, will strip ANSI character
    sequences from the text, and if outputting to a tty, will convert them into
    win32 function calls.
    '''
    ANSI_RE = re.compile('\033\[((?:\d|;)*)([a-zA-Z])')

    def __init__(self, wrapped, convert=None, strip=None, autoreset=False):
        # The wrapped stream (normally sys.stdout or sys.stderr)
        self.wrapped = wrapped

        # should we reset colors to defaults after every .write()
        self.autoreset = autoreset

        # create the proxy wrapping our output stream
        self.stream = StreamWrapper(wrapped, self)

        on_windows = sys.platform.startswith('win')

        # should we strip ANSI sequences from our output?
        if strip is None:
            strip = on_windows
        self.strip = strip

        # should we should convert ANSI sequences into win32 calls?
        if convert is None:
            convert = on_windows and is_a_tty(wrapped)
        self.convert = convert

        # dict of ansi codes to win32 functions and parameters
        self.win32_calls = self.get_win32_calls()

        # are we wrapping stderr?
        self.on_stderr = self.wrapped is sys.stderr


    def should_wrap(self):
        '''
        True if this class is actually needed. If false, then the output
        stream will not be affected, nor will win32 calls be issued, so
        wrapping stdout is not actually required. This will generally be
        False on non-Windows platforms, unless optional functionality like
        autoreset has been requested using kwargs to init()
        '''
        return self.convert or self.strip or self.autoreset


    def get_win32_calls(self):
        if self.convert and winterm:
            return {
                AnsiStyle.RESET_ALL: (winterm.reset_all, ),
                AnsiStyle.BRIGHT: (winterm.style, WinStyle.BRIGHT),
                AnsiStyle.DIM: (winterm.style, WinStyle.NORMAL),
                AnsiStyle.NORMAL: (winterm.style, WinStyle.NORMAL),
                AnsiFore.BLACK: (winterm.fore, WinColor.BLACK),
                AnsiFore.RED: (winterm.fore, WinColor.RED),
                AnsiFore.GREEN: (winterm.fore, WinColor.GREEN),
                AnsiFore.YELLOW: (winterm.fore, WinColor.YELLOW),
                AnsiFore.BLUE: (winterm.fore, WinColor.BLUE),
                AnsiFore.MAGENTA: (winterm.fore, WinColor.MAGENTA),
                AnsiFore.CYAN: (winterm.fore, WinColor.CYAN),
                AnsiFore.WHITE: (winterm.fore, WinColor.GREY),
                AnsiFore.RESET: (winterm.fore, ),
                AnsiBack.BLACK: (winterm.back, WinColor.BLACK),
                AnsiBack.RED: (winterm.back, WinColor.RED),
                AnsiBack.GREEN: (winterm.back, WinColor.GREEN),
                AnsiBack.YELLOW: (winterm.back, WinColor.YELLOW),
                AnsiBack.BLUE: (winterm.back, WinColor.BLUE),
                AnsiBack.MAGENTA: (winterm.back, WinColor.MAGENTA),
                AnsiBack.CYAN: (winterm.back, WinColor.CYAN),
                AnsiBack.WHITE: (winterm.back, WinColor.GREY),
                AnsiBack.RESET: (winterm.back, ),
            }


    def write(self, text):
        if self.strip or self.convert:
            self.write_and_convert(text)
        else:
            self.wrapped.write(text)
            self.wrapped.flush()
        if self.autoreset:
            self.reset_all()


    def reset_all(self):
        if self.convert:
            self.call_win32('m', (0,))
        elif is_a_tty(self.wrapped):
            self.wrapped.write(Style.RESET_ALL)


    def write_and_convert(self, text):
        '''
        Write the given text to our wrapped stream, stripping any ANSI
        sequences from the text, and optionally converting them into win32
        calls.
        '''
        cursor = 0
        for match in self.ANSI_RE.finditer(text):
            start, end = match.span()
            self.write_plain_text(text, cursor, start)
            self.convert_ansi(*match.groups())
            cursor = end
        self.write_plain_text(text, cursor, len(text))


    def write_plain_text(self, text, start, end):
        if start < end:
            self.wrapped.write(text[start:end])
            self.wrapped.flush()


    def convert_ansi(self, paramstring, command):
        if self.convert:
            params = self.extract_params(paramstring)
            self.call_win32(command, params)


    def extract_params(self, paramstring):
        def split(paramstring):
            for p in paramstring.split(';'):
                if p != '':
                    yield int(p)
        return tuple(split(paramstring))


    def call_win32(self, command, params):
        if params == []:
            params = [0]
        if command == 'm':
            for param in params:
                if param in self.win32_calls:
                    func_args = self.win32_calls[param]
                    func = func_args[0]
                    args = func_args[1:]
                    kwargs = dict(on_stderr=self.on_stderr)
                    func(*args, **kwargs)
        elif command in ('H', 'f'): # set cursor position
            func = winterm.set_cursor_position
            func(params, on_stderr=self.on_stderr)
        elif command in ('J'):
            func = winterm.erase_data
            func(params, on_stderr=self.on_stderr)