import os
import sys
import struct

from ._compat import raw_input, text_type, string_types, \
     isatty, strip_ansi, get_winterm_size, DEFAULT_COLUMNS, WIN
from .utils import echo
from .exceptions import Abort, UsageError
from .types import convert_type
from .globals import resolve_color_default


# The prompt functions to use.  The doc tools currently override these
# functions to customize how they work.
visible_prompt_func = raw_input

_ansi_colors = ('black', 'red', 'green', 'yellow', 'blue', 'magenta',
                'cyan', 'white', 'reset')
_ansi_reset_all = '\033[0m'


def hidden_prompt_func(prompt):
    import getpass
    return getpass.getpass(prompt)


def _build_prompt(text, suffix, show_default=False, default=None):
    prompt = text
    if default is not None and show_default:
        prompt = '%s [%s]' % (prompt, default)
    return prompt + suffix


def prompt(text, default=None, hide_input=False,
           confirmation_prompt=False, type=None,
           value_proc=None, prompt_suffix=': ',
           show_default=True, err=False):
    """Prompts a user for input.  This is a convenience function that can
    be used to prompt a user for input later.

    If the user aborts the input by sending a interrupt signal, this
    function will catch it and raise a :exc:`Abort` exception.

    .. versionadded:: 6.0
       Added unicode support for cmd.exe on Windows.

    .. versionadded:: 4.0
       Added the `err` parameter.

    :param text: the text to show for the prompt.
    :param default: the default value to use if no input happens.  If this
                    is not given it will prompt until it's aborted.
    :param hide_input: if this is set to true then the input value will
                       be hidden.
    :param confirmation_prompt: asks for confirmation for the value.
    :param type: the type to use to check the value against.
    :param value_proc: if this parameter is provided it's a function that
                       is invoked instead of the type conversion to
                       convert a value.
    :param prompt_suffix: a suffix that should be added to the prompt.
    :param show_default: shows or hides the default value in the prompt.
    :param err: if set to true the file defaults to ``stderr`` instead of
                ``stdout``, the same as with echo.
    """
    result = None

    def prompt_func(text):
        f = hide_input and hidden_prompt_func or visible_prompt_func
        try:
            # Write the prompt separately so that we get nice
            # coloring through colorama on Windows
            echo(text, nl=False, err=err)
            return f('')
        except (KeyboardInterrupt, EOFError):
            # getpass doesn't print a newline if the user aborts input with ^C.
            # Allegedly this behavior is inherited from getpass(3).
            # A doc bug has been filed at https://bugs.python.org/issue24711
            if hide_input:
                echo(None, err=err)
            raise Abort()

    if value_proc is None:
        value_proc = convert_type(type, default)

    prompt = _build_prompt(text, prompt_suffix, show_default, default)

    while 1:
        while 1:
            value = prompt_func(prompt)
            if value:
                break
            # If a default is set and used, then the confirmation
            # prompt is always skipped because that's the only thing
            # that really makes sense.
            elif default is not None:
                return default
        try:
            result = value_proc(value)
        except UsageError as e:
            echo('Error: %s' % e.message, err=err)
            continue
        if not confirmation_prompt:
            return result
        while 1:
            value2 = prompt_func('Repeat for confirmation: ')
            if value2:
                break
        if value == value2:
            return result
        echo('Error: the two entered values do not match', err=err)


def confirm(text, default=False, abort=False, prompt_suffix=': ',
            show_default=True, err=False):
    """Prompts for confirmation (yes/no question).

    If the user aborts the input by sending a interrupt signal this
    function will catch it and raise a :exc:`Abort` exception.

    .. versionadded:: 4.0
       Added the `err` parameter.

    :param text: the question to ask.
    :param default: the default for the prompt.
    :param abort: if this is set to `True` a negative answer aborts the
                  exception by raising :exc:`Abort`.
    :param prompt_suffix: a suffix that should be added to the prompt.
    :param show_default: shows or hides the default value in the prompt.
    :param err: if set to true the file defaults to ``stderr`` instead of
                ``stdout``, the same as with echo.
    """
    prompt = _build_prompt(text, prompt_suffix, show_default,
                           default and 'Y/n' or 'y/N')
    while 1:
        try:
            # Write the prompt separately so that we get nice
            # coloring through colorama on Windows
            echo(prompt, nl=False, err=err)
            value = visible_prompt_func('').lower().strip()
        except (KeyboardInterrupt, EOFError):
            raise Abort()
        if value in ('y', 'yes'):
            rv = True
        elif value in ('n', 'no'):
            rv = False
        elif value == '':
            rv = default
        else:
            echo('Error: invalid input', err=err)
            continue
        break
    if abort and not rv:
        raise Abort()
    return rv


def get_terminal_size():
    """Returns the current size of the terminal as tuple in the form
    ``(width, height)`` in columns and rows.
    """
    # If shutil has get_terminal_size() (Python 3.3 and later) use that
    if sys.version_info >= (3, 3):
        import shutil
        shutil_get_terminal_size = getattr(shutil, 'get_terminal_size', None)
        if shutil_get_terminal_size:
            sz = shutil_get_terminal_size()
            return sz.columns, sz.lines

    if get_winterm_size is not None:
        return get_winterm_size()

    def ioctl_gwinsz(fd):
        try:
            import fcntl
            import termios
            cr = struct.unpack(
                'hh', fcntl.ioctl(fd, termios.TIOCGWINSZ, '1234'))
        except Exception:
            return
        return cr

    cr = ioctl_gwinsz(0) or ioctl_gwinsz(1) or ioctl_gwinsz(2)
    if not cr:
        try:
            fd = os.open(os.ctermid(), os.O_RDONLY)
            try:
                cr = ioctl_gwinsz(fd)
            finally:
                os.close(fd)
        except Exception:
            pass
    if not cr or not cr[0] or not cr[1]:
        cr = (os.environ.get('LINES', 25),
              os.environ.get('COLUMNS', DEFAULT_COLUMNS))
    return int(cr[1]), int(cr[0])


def echo_via_pager(text, color=None):
    """This function takes a text and shows it via an environment specific
    pager on stdout.

    .. versionchanged:: 3.0
       Added the `color` flag.

    :param text: the text to page.
    :param color: controls if the pager supports ANSI colors or not.  The
                  default is autodetection.
    """
    color = resolve_color_default(color)
    if not isinstance(text, string_types):
        text = text_type(text)
    from ._termui_impl import pager
    return pager(text + '\n', color)


def progressbar(iterable=None, length=None, label=None, show_eta=True,
                show_percent=None, show_pos=False,
                item_show_func=None, fill_char='#', empty_char='-',
                bar_template='%(label)s  [%(bar)s]  %(info)s',
                info_sep='  ', width=36, file=None, color=None):
    """This function creates an iterable context manager that can be used
    to iterate over something while showing a progress bar.  It will
    either iterate over the `iterable` or `length` items (that are counted
    up).  While iteration happens, this function will print a rendered
    progress bar to the given `file` (defaults to stdout) and will attempt
    to calculate remaining time and more.  By default, this progress bar
    will not be rendered if the file is not a terminal.

    The context manager creates the progress bar.  When the context
    manager is entered the progress bar is already displayed.  With every
    iteration over the progress bar, the iterable passed to the bar is
    advanced and the bar is updated.  When the context manager exits,
    a newline is printed and the progress bar is finalized on screen.

    No printing must happen or the progress bar will be unintentionally
    destroyed.

    Example usage::

        with progressbar(items) as bar:
            for item in bar:
                do_something_with(item)

    Alternatively, if no iterable is specified, one can manually update the
    progress bar through the `update()` method instead of directly
    iterating over the progress bar.  The update method accepts the number
    of steps to increment the bar with::

        with progressbar(length=chunks.total_bytes) as bar:
            for chunk in chunks:
                process_chunk(chunk)
                bar.update(chunks.bytes)

    .. versionadded:: 2.0

    .. versionadded:: 4.0
       Added the `color` parameter.  Added a `update` method to the
       progressbar object.

    :param iterable: an iterable to iterate over.  If not provided the length
                     is required.
    :param length: the number of items to iterate over.  By default the
                   progressbar will attempt to ask the iterator about its
                   length, which might or might not work.  If an iterable is
                   also provided this parameter can be used to override the
                   length.  If an iterable is not provided the progress bar
                   will iterate over a range of that length.
    :param label: the label to show next to the progress bar.
    :param show_eta: enables or disables the estimated time display.  This is
                     automatically disabled if the length cannot be
                     determined.
    :param show_percent: enables or disables the percentage display.  The
                         default is `True` if the iterable has a length or
                         `False` if not.
    :param show_pos: enables or disables the absolute position display.  The
                     default is `False`.
    :param item_show_func: a function called with the current item which
                           can return a string to show the current item
                           next to the progress bar.  Note that the current
                           item can be `None`!
    :param fill_char: the character to use to show the filled part of the
                      progress bar.
    :param empty_char: the character to use to show the non-filled part of
                       the progress bar.
    :param bar_template: the format string to use as template for the bar.
                         The parameters in it are ``label`` for the label,
                         ``bar`` for the progress bar and ``info`` for the
                         info section.
    :param info_sep: the separator between multiple info items (eta etc.)
    :param width: the width of the progress bar in characters, 0 means full
                  terminal width
    :param file: the file to write to.  If this is not a terminal then
                 only the label is printed.
    :param color: controls if the terminal supports ANSI colors or not.  The
                  default is autodetection.  This is only needed if ANSI
                  codes are included anywhere in the progress bar output
                  which is not the case by default.
    """
    from ._termui_impl import ProgressBar
    color = resolve_color_default(color)
    return ProgressBar(iterable=iterable, length=length, show_eta=show_eta,
                       show_percent=show_percent, show_pos=show_pos,
                       item_show_func=item_show_func, fill_char=fill_char,
                       empty_char=empty_char, bar_template=bar_template,
                       info_sep=info_sep, file=file, label=label,
                       width=width, color=color)


def clear():
    """Clears the terminal screen.  This will have the effect of clearing
    the whole visible space of the terminal and moving the cursor to the
    top left.  This does not do anything if not connected to a terminal.

    .. versionadded:: 2.0
    """
    if not isatty(sys.stdout):
        return
    # If we're on Windows and we don't have colorama available, then we
    # clear the screen by shelling out.  Otherwise we can use an escape
    # sequence.
    if WIN:
        os.system('cls')
    else:
        sys.stdout.write('\033[2J\033[1;1H')


def style(text, fg=None, bg=None, bold=None, dim=None, underline=None,
          blink=None, reverse=None, reset=True):
    """Styles a text with ANSI styles and returns the new string.  By
    default the styling is self contained which means that at the end
    of the string a reset code is issued.  This can be prevented by
    passing ``reset=False``.

    Examples::

        click.echo(click.style('Hello World!', fg='green'))
        click.echo(click.style('ATTENTION!', blink=True))
        click.echo(click.style('Some things', reverse=True, fg='cyan'))

    Supported color names:

    * ``black`` (might be a gray)
    * ``red``
    * ``green``
    * ``yellow`` (might be an orange)
    * ``blue``
    * ``magenta``
    * ``cyan``
    * ``white`` (might be light gray)
    * ``reset`` (reset the color code only)

    .. versionadded:: 2.0

    :param text: the string to style with ansi codes.
    :param fg: if provided this will become the foreground color.
    :param bg: if provided this will become the background color.
    :param bold: if provided this will enable or disable bold mode.
    :param dim: if provided this will enable or disable dim mode.  This is
                badly supported.
    :param underline: if provided this will enable or disable underline.
    :param blink: if provided this will enable or disable blinking.
    :param reverse: if provided this will enable or disable inverse
                    rendering (foreground becomes background and the
                    other way round).
    :param reset: by default a reset-all code is added at the end of the
                  string which means that styles do not carry over.  This
                  can be disabled to compose styles.
    """
    bits = []
    if fg:
        try:
            bits.append('\033[%dm' % (_ansi_colors.index(fg) + 30))
        except ValueError:
            raise TypeError('Unknown color %r' % fg)
    if bg:
        try:
            bits.append('\033[%dm' % (_ansi_colors.index(bg) + 40))
        except ValueError:
            raise TypeError('Unknown color %r' % bg)
    if bold is not None:
        bits.append('\033[%dm' % (1 if bold else 22))
    if dim is not None:
        bits.append('\033[%dm' % (2 if dim else 22))
    if underline is not None:
        bits.append('\033[%dm' % (4 if underline else 24))
    if blink is not None:
        bits.append('\033[%dm' % (5 if blink else 25))
    if reverse is not None:
        bits.append('\033[%dm' % (7 if reverse else 27))
    bits.append(text)
    if reset:
        bits.append(_ansi_reset_all)
    return ''.join(bits)


def unstyle(text):
    """Removes ANSI styling information from a string.  Usually it's not
    necessary to use this function as Click's echo function will
    automatically remove styling if necessary.

    .. versionadded:: 2.0

    :param text: the text to remove style information from.
    """
    return strip_ansi(text)


def secho(text, file=None, nl=True, err=False, color=None, **styles):
    """This function combines :func:`echo` and :func:`style` into one
    call.  As such the following two calls are the same::

        click.secho('Hello World!', fg='green')
        click.echo(click.style('Hello World!', fg='green'))

    All keyword arguments are forwarded to the underlying functions
    depending on which one they go with.

    .. versionadded:: 2.0
    """
    return echo(style(text, **styles), file=file, nl=nl, err=err, color=color)


def edit(text=None, editor=None, env=None, require_save=True,
         extension='.txt', filename=None):
    r"""Edits the given text in the defined editor.  If an editor is given
    (should be the full path to the executable but the regular operating
    system search path is used for finding the executable) it overrides
    the detected editor.  Optionally, some environment variables can be
    used.  If the editor is closed without changes, `None` is returned.  In
    case a file is edited directly the return value is always `None` and
    `require_save` and `extension` are ignored.

    If the editor cannot be opened a :exc:`UsageError` is raised.

    Note for Windows: to simplify cross-platform usage, the newlines are
    automatically converted from POSIX to Windows and vice versa.  As such,
    the message here will have ``\n`` as newline markers.

    :param text: the text to edit.
    :param editor: optionally the editor to use.  Defaults to automatic
                   detection.
    :param env: environment variables to forward to the editor.
    :param require_save: if this is true, then not saving in the editor
                         will make the return value become `None`.
    :param extension: the extension to tell the editor about.  This defaults
                      to `.txt` but changing this might change syntax
                      highlighting.
    :param filename: if provided it will edit this file instead of the
                     provided text contents.  It will not use a temporary
                     file as an indirection in that case.
    """
    from ._termui_impl import Editor
    editor = Editor(editor=editor, env=env, require_save=require_save,
                    extension=extension)
    if filename is None:
        return editor.edit(text)
    editor.edit_file(filename)


def launch(url, wait=False, locate=False):
    """This function launches the given URL (or filename) in the default
    viewer application for this file type.  If this is an executable, it
    might launch the executable in a new session.  The return value is
    the exit code of the launched application.  Usually, ``0`` indicates
    success.

    Examples::

        click.launch('http://click.pocoo.org/')
        click.launch('/my/downloaded/file', locate=True)

    .. versionadded:: 2.0

    :param url: URL or filename of the thing to launch.
    :param wait: waits for the program to stop.
    :param locate: if this is set to `True` then instead of launching the
                   application associated with the URL it will attempt to
                   launch a file manager with the file located.  This
                   might have weird effects if the URL does not point to
                   the filesystem.
    """
    from ._termui_impl import open_url
    return open_url(url, wait=wait, locate=locate)


# If this is provided, getchar() calls into this instead.  This is used
# for unittesting purposes.
_getchar = None


def getchar(echo=False):
    """Fetches a single character from the terminal and returns it.  This
    will always return a unicode character and under certain rare
    circumstances this might return more than one character.  The
    situations which more than one character is returned is when for
    whatever reason multiple characters end up in the terminal buffer or
    standard input was not actually a terminal.

    Note that this will always read from the terminal, even if something
    is piped into the standard input.

    .. versionadded:: 2.0

    :param echo: if set to `True`, the character read will also show up on
                 the terminal.  The default is to not show it.
    """
    f = _getchar
    if f is None:
        from ._termui_impl import getchar as f
    return f(echo)


def pause(info='Press any key to continue ...', err=False):
    """This command stops execution and waits for the user to press any
    key to continue.  This is similar to the Windows batch "pause"
    command.  If the program is not run through a terminal, this command
    will instead do nothing.

    .. versionadded:: 2.0

    .. versionadded:: 4.0
       Added the `err` parameter.

    :param info: the info string to print before pausing.
    :param err: if set to message goes to ``stderr`` instead of
                ``stdout``, the same as with echo.
    """
    if not isatty(sys.stdin) or not isatty(sys.stdout):
        return
    try:
        if info:
            echo(info, nl=False, err=err)
        try:
            getchar()
        except (KeyboardInterrupt, EOFError):
            pass
    finally:
        if info:
            echo(err=err)
