# Copyright (C) 2005-2011 Canonical Ltd
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA


"""Text UI, write output to the console.
"""

from __future__ import absolute_import

import os
import sys
import time

from bzrlib.lazy_import import lazy_import
lazy_import(globals(), """
import codecs
import getpass
import warnings

from bzrlib import (
    debug,
    progress,
    osutils,
    trace,
    )

""")

from bzrlib.ui import (
    UIFactory,
    NullProgressView,
    )


class _ChooseUI(object):

    """ Helper class for choose implementation.
    """

    def __init__(self, ui, msg, choices, default):
        self.ui = ui
        self._setup_mode()
        self._build_alternatives(msg, choices, default)

    def _setup_mode(self):
        """Setup input mode (line-based, char-based) and echo-back.

        Line-based input is used if the BZR_TEXTUI_INPUT environment
        variable is set to 'line-based', or if there is no controlling
        terminal.
        """
        if os.environ.get('BZR_TEXTUI_INPUT') != 'line-based' and \
           self.ui.stdin == sys.stdin and self.ui.stdin.isatty():
            self.line_based = False
            self.echo_back = True
        else:
            self.line_based = True
            self.echo_back = not self.ui.stdin.isatty()

    def _build_alternatives(self, msg, choices, default):
        """Parse choices string.

        Setup final prompt and the lists of choices and associated
        shortcuts.
        """
        index = 0
        help_list = []
        self.alternatives = {}
        choices = choices.split('\n')
        if default is not None and default not in range(0, len(choices)):
            raise ValueError("invalid default index")
        for c in choices:
            name = c.replace('&', '').lower()
            choice = (name, index)
            if name in self.alternatives:
                raise ValueError("duplicated choice: %s" % name)
            self.alternatives[name] = choice
            shortcut = c.find('&')
            if -1 != shortcut and (shortcut + 1) < len(c):
                help = c[:shortcut]
                help += '[' + c[shortcut + 1] + ']'
                help += c[(shortcut + 2):]
                shortcut = c[shortcut + 1]
            else:
                c = c.replace('&', '')
                shortcut = c[0]
                help = '[%s]%s' % (shortcut, c[1:])
            shortcut = shortcut.lower()
            if shortcut in self.alternatives:
                raise ValueError("duplicated shortcut: %s" % shortcut)
            self.alternatives[shortcut] = choice
            # Add redirections for default.
            if index == default:
                self.alternatives[''] = choice
                self.alternatives['\r'] = choice
            help_list.append(help)
            index += 1

        self.prompt = u'%s (%s): ' % (msg, ', '.join(help_list))

    def _getline(self):
        line = self.ui.stdin.readline()
        if '' == line:
            raise EOFError
        return line.strip()

    def _getchar(self):
        char = osutils.getchar()
        if char == chr(3): # INTR
            raise KeyboardInterrupt
        if char == chr(4): # EOF (^d, C-d)
            raise EOFError
        return char

    def interact(self):
        """Keep asking the user until a valid choice is made.
        """
        if self.line_based:
            getchoice = self._getline
        else:
            getchoice = self._getchar
        iter = 0
        while True:
            iter += 1
            if 1 == iter or self.line_based:
                self.ui.prompt(self.prompt)
            try:
                choice = getchoice()
            except EOFError:
                self.ui.stderr.write('\n')
                return None
            except KeyboardInterrupt:
                self.ui.stderr.write('\n')
                raise KeyboardInterrupt
            choice = choice.lower()
            if choice not in self.alternatives:
                # Not a valid choice, keep on asking.
                continue
            name, index = self.alternatives[choice]
            if self.echo_back:
                self.ui.stderr.write(name + '\n')
            return index


class TextUIFactory(UIFactory):
    """A UI factory for Text user interefaces."""

    def __init__(self,
                 stdin=None,
                 stdout=None,
                 stderr=None):
        """Create a TextUIFactory.
        """
        super(TextUIFactory, self).__init__()
        # TODO: there's no good reason not to pass all three streams, maybe we
        # should deprecate the default values...
        self.stdin = stdin
        self.stdout = stdout
        self.stderr = stderr
        # paints progress, network activity, etc
        self._progress_view = self.make_progress_view()

    def choose(self, msg, choices, default=None):
        """Prompt the user for a list of alternatives.

        Support both line-based and char-based editing.

        In line-based mode, both the shortcut and full choice name are valid
        answers, e.g. for choose('prompt', '&yes\n&no'): 'y', ' Y ', ' yes',
        'YES ' are all valid input lines for choosing 'yes'.

        An empty line, when in line-based mode, or pressing enter in char-based
        mode will select the default choice (if any).

        Choice is echoed back if:
        - input is char-based; which means a controlling terminal is available,
          and osutils.getchar is used
        - input is line-based, and no controlling terminal is available
        """

        choose_ui = _ChooseUI(self, msg, choices, default)
        return choose_ui.interact()

    def be_quiet(self, state):
        if state and not self._quiet:
            self.clear_term()
        UIFactory.be_quiet(self, state)
        self._progress_view = self.make_progress_view()

    def clear_term(self):
        """Prepare the terminal for output.

        This will, clear any progress bars, and leave the cursor at the
        leftmost position."""
        # XXX: If this is preparing to write to stdout, but that's for example
        # directed into a file rather than to the terminal, and the progress
        # bar _is_ going to the terminal, we shouldn't need
        # to clear it.  We might need to separately check for the case of
        self._progress_view.clear()

    def get_integer(self, prompt):
        while True:
            self.prompt(prompt)
            line = self.stdin.readline()
            try:
                return int(line)
            except ValueError:
                pass

    def get_non_echoed_password(self):
        isatty = getattr(self.stdin, 'isatty', None)
        if isatty is not None and isatty():
            # getpass() ensure the password is not echoed and other
            # cross-platform niceties
            password = getpass.getpass('')
        else:
            # echo doesn't make sense without a terminal
            password = self.stdin.readline()
            if not password:
                password = None
            elif password[-1] == '\n':
                password = password[:-1]
        return password

    def get_password(self, prompt=u'', **kwargs):
        """Prompt the user for a password.

        :param prompt: The prompt to present the user
        :param kwargs: Arguments which will be expanded into the prompt.
                       This lets front ends display different things if
                       they so choose.
        :return: The password string, return None if the user
                 canceled the request.
        """
        prompt += ': '
        self.prompt(prompt, **kwargs)
        # There's currently no way to say 'i decline to enter a password'
        # as opposed to 'my password is empty' -- does it matter?
        return self.get_non_echoed_password()

    def get_username(self, prompt, **kwargs):
        """Prompt the user for a username.

        :param prompt: The prompt to present the user
        :param kwargs: Arguments which will be expanded into the prompt.
                       This lets front ends display different things if
                       they so choose.
        :return: The username string, return None if the user
                 canceled the request.
        """
        prompt += ': '
        self.prompt(prompt, **kwargs)
        username = self.stdin.readline()
        if not username:
            username = None
        elif username[-1] == '\n':
            username = username[:-1]
        return username

    def make_progress_view(self):
        """Construct and return a new ProgressView subclass for this UI.
        """
        # with --quiet, never any progress view
        # <https://bugs.launchpad.net/bzr/+bug/320035>.  Otherwise if the
        # user specifically requests either text or no progress bars, always
        # do that.  otherwise, guess based on $TERM and tty presence.
        if self.is_quiet():
            return NullProgressView()
        elif os.environ.get('BZR_PROGRESS_BAR') == 'text':
            return TextProgressView(self.stderr)
        elif os.environ.get('BZR_PROGRESS_BAR') == 'none':
            return NullProgressView()
        elif progress._supports_progress(self.stderr):
            return TextProgressView(self.stderr)
        else:
            return NullProgressView()

    def _make_output_stream_explicit(self, encoding, encoding_type):
        if encoding_type == 'exact':
            # force sys.stdout to be binary stream on win32; 
            # NB: this leaves the file set in that mode; may cause problems if
            # one process tries to do binary and then text output
            if sys.platform == 'win32':
                fileno = getattr(self.stdout, 'fileno', None)
                if fileno:
                    import msvcrt
                    msvcrt.setmode(fileno(), os.O_BINARY)
            return TextUIOutputStream(self, self.stdout)
        else:
            encoded_stdout = codecs.getwriter(encoding)(self.stdout,
                errors=encoding_type)
            # For whatever reason codecs.getwriter() does not advertise its encoding
            # it just returns the encoding of the wrapped file, which is completely
            # bogus. So set the attribute, so we can find the correct encoding later.
            encoded_stdout.encoding = encoding
            return TextUIOutputStream(self, encoded_stdout)

    def note(self, msg):
        """Write an already-formatted message, clearing the progress bar if necessary."""
        self.clear_term()
        self.stdout.write(msg + '\n')

    def prompt(self, prompt, **kwargs):
        """Emit prompt on the CLI.
        
        :param kwargs: Dictionary of arguments to insert into the prompt,
            to allow UIs to reformat the prompt.
        """
        if type(prompt) != unicode:
            raise ValueError("prompt %r not a unicode string" % prompt)
        if kwargs:
            # See <https://launchpad.net/bugs/365891>
            prompt = prompt % kwargs
        prompt = prompt.encode(osutils.get_terminal_encoding(), 'replace')
        self.clear_term()
        self.stdout.flush()
        self.stderr.write(prompt)

    def report_transport_activity(self, transport, byte_count, direction):
        """Called by transports as they do IO.

        This may update a progress bar, spinner, or similar display.
        By default it does nothing.
        """
        self._progress_view.show_transport_activity(transport,
            direction, byte_count)

    def log_transport_activity(self, display=False):
        """See UIFactory.log_transport_activity()"""
        log = getattr(self._progress_view, 'log_transport_activity', None)
        if log is not None:
            log(display=display)

    def show_error(self, msg):
        self.clear_term()
        self.stderr.write("bzr: error: %s\n" % msg)

    def show_message(self, msg):
        self.note(msg)

    def show_warning(self, msg):
        self.clear_term()
        if isinstance(msg, unicode):
            te = osutils.get_terminal_encoding()
            msg = msg.encode(te, 'replace')
        self.stderr.write("bzr: warning: %s\n" % msg)

    def _progress_updated(self, task):
        """A task has been updated and wants to be displayed.
        """
        if not self._task_stack:
            warnings.warn("%r updated but no tasks are active" %
                (task,))
        elif task != self._task_stack[-1]:
            # We used to check it was the top task, but it's hard to always
            # get this right and it's not necessarily useful: any actual
            # problems will be evident in use
            #warnings.warn("%r is not the top progress task %r" %
            #     (task, self._task_stack[-1]))
            pass
        self._progress_view.show_progress(task)

    def _progress_all_finished(self):
        self._progress_view.clear()

    def show_user_warning(self, warning_id, **message_args):
        """Show a text message to the user.

        Explicitly not for warnings about bzr apis, deprecations or internals.
        """
        # eventually trace.warning should migrate here, to avoid logging and
        # be easier to test; that has a lot of test fallout so for now just
        # new code can call this
        if warning_id not in self.suppressed_warnings:
            self.stderr.write(self.format_user_warning(warning_id, message_args) +
                '\n')


class TextProgressView(object):
    """Display of progress bar and other information on a tty.

    This shows one line of text, including possibly a network indicator, spinner,
    progress bar, message, etc.

    One instance of this is created and held by the UI, and fed updates when a
    task wants to be painted.

    Transports feed data to this through the ui_factory object.

    The Progress views can comprise a tree with _parent_task pointers, but
    this only prints the stack from the nominated current task up to the root.
    """

    def __init__(self, term_file, encoding=None, errors="replace"):
        self._term_file = term_file
        if encoding is None:
            self._encoding = getattr(term_file, "encoding", None) or "ascii"
        else:
            self._encoding = encoding
        self._encoding_errors = errors
        # true when there's output on the screen we may need to clear
        self._have_output = False
        self._last_transport_msg = ''
        self._spin_pos = 0
        # time we last repainted the screen
        self._last_repaint = 0
        # time we last got information about transport activity
        self._transport_update_time = 0
        self._last_task = None
        self._total_byte_count = 0
        self._bytes_since_update = 0
        self._bytes_by_direction = {'unknown': 0, 'read': 0, 'write': 0}
        self._first_byte_time = None
        self._fraction = 0
        # force the progress bar to be off, as at the moment it doesn't 
        # correspond reliably to overall command progress
        self.enable_bar = False

    def _avail_width(self):
        # we need one extra space for terminals that wrap on last char
        w = osutils.terminal_width() 
        if w is None:
            return None
        else:
            return w - 1

    def _show_line(self, u):
        s = u.encode(self._encoding, self._encoding_errors)
        width = self._avail_width()
        if width is not None:
            # GZ 2012-03-28: Counting bytes is wrong for calculating width of
            #                text but better than counting codepoints.
            s = '%-*.*s' % (width, width, s)
        self._term_file.write('\r' + s + '\r')

    def clear(self):
        if self._have_output:
            self._show_line('')
        self._have_output = False

    def _render_bar(self):
        # return a string for the progress bar itself
        if self.enable_bar and (
            (self._last_task is None) or self._last_task.show_bar):
            # If there's no task object, we show space for the bar anyhow.
            # That's because most invocations of bzr will end showing progress
            # at some point, though perhaps only after doing some initial IO.
            # It looks better to draw the progress bar initially rather than
            # to have what looks like an incomplete progress bar.
            spin_str =  r'/-\|'[self._spin_pos % 4]
            self._spin_pos += 1
            cols = 20
            if self._last_task is None:
                completion_fraction = 0
                self._fraction = 0
            else:
                completion_fraction = \
                    self._last_task._overall_completion_fraction() or 0
            if (completion_fraction < self._fraction and 'progress' in
                debug.debug_flags):
                import pdb;pdb.set_trace()
            self._fraction = completion_fraction
            markers = int(round(float(cols) * completion_fraction)) - 1
            bar_str = '[' + ('#' * markers + spin_str).ljust(cols) + '] '
            return bar_str
        elif (self._last_task is None) or self._last_task.show_spinner:
            # The last task wanted just a spinner, no bar
            spin_str =  r'/-\|'[self._spin_pos % 4]
            self._spin_pos += 1
            return spin_str + ' '
        else:
            return ''

    def _format_task(self, task):
        """Format task-specific parts of progress bar.

        :returns: (text_part, counter_part) both unicode strings.
        """
        if not task.show_count:
            s = ''
        elif task.current_cnt is not None and task.total_cnt is not None:
            s = ' %d/%d' % (task.current_cnt, task.total_cnt)
        elif task.current_cnt is not None:
            s = ' %d' % (task.current_cnt)
        else:
            s = ''
        # compose all the parent messages
        t = task
        m = task.msg
        while t._parent_task:
            t = t._parent_task
            if t.msg:
                m = t.msg + ':' + m
        return m, s

    def _render_line(self):
        bar_string = self._render_bar()
        if self._last_task:
            task_part, counter_part = self._format_task(self._last_task)
        else:
            task_part = counter_part = ''
        if self._last_task and not self._last_task.show_transport_activity:
            trans = ''
        else:
            trans = self._last_transport_msg
        # the bar separates the transport activity from the message, so even
        # if there's no bar or spinner, we must show something if both those
        # fields are present
        if (task_part or trans) and not bar_string:
            bar_string = '| '
        # preferentially truncate the task message if we don't have enough
        # space
        avail_width = self._avail_width()
        if avail_width is not None:
            # if terminal avail_width is unknown, don't truncate
            current_len = len(bar_string) + len(trans) + len(task_part) + len(counter_part)
            gap = current_len - avail_width
            if gap > 0:
                task_part = task_part[:-gap-2] + '..'
        s = trans + bar_string + task_part + counter_part
        if avail_width is not None:
            if len(s) < avail_width:
                s = s.ljust(avail_width)
            elif len(s) > avail_width:
                s = s[:avail_width]
        return s

    def _repaint(self):
        s = self._render_line()
        self._show_line(s)
        self._have_output = True

    def show_progress(self, task):
        """Called by the task object when it has changed.
        
        :param task: The top task object; its parents are also included 
            by following links.
        """
        must_update = task is not self._last_task
        self._last_task = task
        now = time.time()
        if (not must_update) and (now < self._last_repaint + task.update_latency):
            return
        if now > self._transport_update_time + 10:
            # no recent activity; expire it
            self._last_transport_msg = ''
        self._last_repaint = now
        self._repaint()

    def show_transport_activity(self, transport, direction, byte_count):
        """Called by transports via the ui_factory, as they do IO.

        This may update a progress bar, spinner, or similar display.
        By default it does nothing.
        """
        # XXX: there should be a transport activity model, and that too should
        #      be seen by the progress view, rather than being poked in here.
        self._total_byte_count += byte_count
        self._bytes_since_update += byte_count
        if self._first_byte_time is None:
            # Note that this isn't great, as technically it should be the time
            # when the bytes started transferring, not when they completed.
            # However, we usually start with a small request anyway.
            self._first_byte_time = time.time()
        if direction in self._bytes_by_direction:
            self._bytes_by_direction[direction] += byte_count
        else:
            self._bytes_by_direction['unknown'] += byte_count
        if 'no_activity' in debug.debug_flags:
            # Can be used as a workaround if
            # <https://launchpad.net/bugs/321935> reappears and transport
            # activity is cluttering other output.  However, thanks to
            # TextUIOutputStream this shouldn't be a problem any more.
            return
        now = time.time()
        if self._total_byte_count < 2000:
            # a little resistance at first, so it doesn't stay stuck at 0
            # while connecting...
            return
        if self._transport_update_time is None:
            self._transport_update_time = now
        elif now >= (self._transport_update_time + 0.5):
            # guard against clock stepping backwards, and don't update too
            # often
            rate = (self._bytes_since_update
                    / (now - self._transport_update_time))
            # using base-10 units (see HACKING.txt).
            msg = ("%6dkB %5dkB/s " %
                    (self._total_byte_count / 1000, int(rate) / 1000,))
            self._transport_update_time = now
            self._last_repaint = now
            self._bytes_since_update = 0
            self._last_transport_msg = msg
            self._repaint()

    def _format_bytes_by_direction(self):
        if self._first_byte_time is None:
            bps = 0.0
        else:
            transfer_time = time.time() - self._first_byte_time
            if transfer_time < 0.001:
                transfer_time = 0.001
            bps = self._total_byte_count / transfer_time

        # using base-10 units (see HACKING.txt).
        msg = ('Transferred: %.0fkB'
               ' (%.1fkB/s r:%.0fkB w:%.0fkB'
               % (self._total_byte_count / 1000.,
                  bps / 1000.,
                  self._bytes_by_direction['read'] / 1000.,
                  self._bytes_by_direction['write'] / 1000.,
                 ))
        if self._bytes_by_direction['unknown'] > 0:
            msg += ' u:%.0fkB)' % (
                self._bytes_by_direction['unknown'] / 1000.
                )
        else:
            msg += ')'
        return msg

    def log_transport_activity(self, display=False):
        msg = self._format_bytes_by_direction()
        trace.mutter(msg)
        if display and self._total_byte_count > 0:
            self.clear()
            self._term_file.write(msg + '\n')


class TextUIOutputStream(object):
    """Decorates an output stream so that the terminal is cleared before writing.

    This is supposed to ensure that the progress bar does not conflict with bulk
    text output.
    """
    # XXX: this does not handle the case of writing part of a line, then doing
    # progress bar output: the progress bar will probably write over it.
    # one option is just to buffer that text until we have a full line;
    # another is to save and restore it

    # XXX: might need to wrap more methods

    def __init__(self, ui_factory, wrapped_stream):
        self.ui_factory = ui_factory
        self.wrapped_stream = wrapped_stream
        # this does no transcoding, but it must expose the underlying encoding
        # because some callers need to know what can be written - see for
        # example unescape_for_display.
        self.encoding = getattr(wrapped_stream, 'encoding', None)

    def flush(self):
        self.ui_factory.clear_term()
        self.wrapped_stream.flush()

    def write(self, to_write):
        self.ui_factory.clear_term()
        self.wrapped_stream.write(to_write)

    def writelines(self, lines):
        self.ui_factory.clear_term()
        self.wrapped_stream.writelines(lines)
