# Copyright (C) 2005 Aaron Bentley <aaron.bentley@utoronto.ca>
# Copyright (C) 2005, 2006 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA


"""Progress indicators.

The usual way to use this is via bzrlib.ui.ui_factory.nested_progress_bar which
will maintain a ProgressBarStack for you.

For direct use, the factory ProgressBar will return an auto-detected progress
bar that should match your terminal type. You can manually create a
ProgressBarStack too if you need multiple levels of cooperating progress bars.
Note that bzrlib's internal functions use the ui module, so if you are using
bzrlib it really is best to use bzrlib.ui.ui_factory.
"""

# TODO: Optionally show elapsed time instead/as well as ETA; nicer
# when the rate is unpredictable

import sys
import time
import os

from bzrlib.lazy_import import lazy_import
lazy_import(globals(), """
from bzrlib import (
    errors,
    )
""")

from bzrlib.trace import mutter


def _supports_progress(f):
    """Detect if we can use pretty progress bars on the output stream f.

    If this returns true we expect that a human may be looking at that 
    output, and that we can repaint a line to update it.
    """
    isatty = getattr(f, 'isatty', None)
    if isatty is None:
        return False
    if not isatty():
        return False
    if os.environ.get('TERM') == 'dumb':
        # e.g. emacs compile window
        return False
    return True


_progress_bar_types = {}


def ProgressBar(to_file=None, **kwargs):
    """Abstract factory"""
    if to_file is None:
        to_file = sys.stderr
    requested_bar_type = os.environ.get('BZR_PROGRESS_BAR')
    # An value of '' or not set reverts to standard processing
    if requested_bar_type in (None, ''):
        if _supports_progress(to_file):
            return TTYProgressBar(to_file=to_file, **kwargs)
        else:
            return DummyProgress(to_file=to_file, **kwargs)
    else:
        # Minor sanitation to prevent spurious errors
        requested_bar_type = requested_bar_type.lower().strip()
        # TODO: jam 20060710 Arguably we shouldn't raise an exception
        #       but should instead just disable progress bars if we
        #       don't recognize the type
        if requested_bar_type not in _progress_bar_types:
            raise errors.InvalidProgressBarType(requested_bar_type,
                                                _progress_bar_types.keys())
        return _progress_bar_types[requested_bar_type](to_file=to_file, **kwargs)

 
class ProgressBarStack(object):
    """A stack of progress bars."""

    def __init__(self,
                 to_file=None,
                 show_pct=False,
                 show_spinner=True,
                 show_eta=False,
                 show_bar=True,
                 show_count=True,
                 to_messages_file=None,
                 klass=None):
        """Setup the stack with the parameters the progress bars should have."""
        if to_file is None:
            to_file = sys.stderr
        if to_messages_file is None:
            to_messages_file = sys.stdout
        self._to_file = to_file
        self._show_pct = show_pct
        self._show_spinner = show_spinner
        self._show_eta = show_eta
        self._show_bar = show_bar
        self._show_count = show_count
        self._to_messages_file = to_messages_file
        self._stack = []
        self._klass = klass or ProgressBar

    def top(self):
        if len(self._stack) != 0:
            return self._stack[-1]
        else:
            return None

    def bottom(self):
        if len(self._stack) != 0:
            return self._stack[0]
        else:
            return None

    def get_nested(self):
        """Return a nested progress bar."""
        if len(self._stack) == 0:
            func = self._klass
        else:
            func = self.top().child_progress
        new_bar = func(to_file=self._to_file,
                       show_pct=self._show_pct,
                       show_spinner=self._show_spinner,
                       show_eta=self._show_eta,
                       show_bar=self._show_bar,
                       show_count=self._show_count,
                       to_messages_file=self._to_messages_file,
                       _stack=self)
        self._stack.append(new_bar)
        return new_bar

    def return_pb(self, bar):
        """Return bar after its been used."""
        if bar is not self._stack[-1]:
            raise errors.MissingProgressBarFinish()
        self._stack.pop()

 
class _BaseProgressBar(object):

    def __init__(self,
                 to_file=None,
                 show_pct=False,
                 show_spinner=False,
                 show_eta=False,
                 show_bar=True,
                 show_count=True,
                 to_messages_file=None,
                 _stack=None):
        object.__init__(self)
        if to_file is None:
            to_file = sys.stderr
        if to_messages_file is None:
            to_messages_file = sys.stdout
        self.to_file = to_file
        self.to_messages_file = to_messages_file
        self.last_msg = None
        self.last_cnt = None
        self.last_total = None
        self.show_pct = show_pct
        self.show_spinner = show_spinner
        self.show_eta = show_eta
        self.show_bar = show_bar
        self.show_count = show_count
        self._stack = _stack
        # seed throttler
        self.MIN_PAUSE = 0.1 # seconds
        now = time.time()
        # starting now
        self.start_time = now
        # next update should not throttle
        self.last_update = now - self.MIN_PAUSE - 1

    def finished(self):
        """Return this bar to its progress stack."""
        self.clear()
        assert self._stack is not None
        self._stack.return_pb(self)

    def note(self, fmt_string, *args, **kwargs):
        """Record a note without disrupting the progress bar."""
        self.clear()
        self.to_messages_file.write(fmt_string % args)
        self.to_messages_file.write('\n')

    def child_progress(self, **kwargs):
        return ChildProgress(**kwargs)


class DummyProgress(_BaseProgressBar):
    """Progress-bar standin that does nothing.

    This can be used as the default argument for methods that
    take an optional progress indicator."""
    def tick(self):
        pass

    def update(self, msg=None, current=None, total=None):
        pass

    def child_update(self, message, current, total):
        pass

    def clear(self):
        pass
        
    def note(self, fmt_string, *args, **kwargs):
        """See _BaseProgressBar.note()."""

    def child_progress(self, **kwargs):
        return DummyProgress(**kwargs)


_progress_bar_types['dummy'] = DummyProgress
_progress_bar_types['none'] = DummyProgress


class DotsProgressBar(_BaseProgressBar):

    def __init__(self, **kwargs):
        _BaseProgressBar.__init__(self, **kwargs)
        self.last_msg = None
        self.need_nl = False
        
    def tick(self):
        self.update()
        
    def update(self, msg=None, current_cnt=None, total_cnt=None):
        if msg and msg != self.last_msg:
            if self.need_nl:
                self.to_file.write('\n')
            self.to_file.write(msg + ': ')
            self.last_msg = msg
        self.need_nl = True
        self.to_file.write('.')
        
    def clear(self):
        if self.need_nl:
            self.to_file.write('\n')
        self.need_nl = False
        
    def child_update(self, message, current, total):
        self.tick()


_progress_bar_types['dots'] = DotsProgressBar

    
class TTYProgressBar(_BaseProgressBar):
    """Progress bar display object.

    Several options are available to control the display.  These can
    be passed as parameters to the constructor or assigned at any time:

    show_pct
        Show percentage complete.
    show_spinner
        Show rotating baton.  This ticks over on every update even
        if the values don't change.
    show_eta
        Show predicted time-to-completion.
    show_bar
        Show bar graph.
    show_count
        Show numerical counts.

    The output file should be in line-buffered or unbuffered mode.
    """
    SPIN_CHARS = r'/-\|'


    def __init__(self, **kwargs):
        from bzrlib.osutils import terminal_width
        _BaseProgressBar.__init__(self, **kwargs)
        self.spin_pos = 0
        self.width = terminal_width()
        self.last_updates = []
        self._max_last_updates = 10
        self.child_fraction = 0
        self._have_output = False
    
    def throttle(self, old_msg):
        """Return True if the bar was updated too recently"""
        # time.time consistently takes 40/4000 ms = 0.01 ms.
        # time.clock() is faster, but gives us CPU time, not wall-clock time
        now = time.time()
        if self.start_time is not None and (now - self.start_time) < 1:
            return True
        if old_msg != self.last_msg:
            return False
        interval = now - self.last_update
        # if interval > 0
        if interval < self.MIN_PAUSE:
            return True

        self.last_updates.append(now - self.last_update)
        # Don't let the queue grow without bound
        self.last_updates = self.last_updates[-self._max_last_updates:]
        self.last_update = now
        return False
        
    def tick(self):
        self.update(self.last_msg, self.last_cnt, self.last_total,
                    self.child_fraction)

    def child_update(self, message, current, total):
        if current is not None and total != 0:
            child_fraction = float(current) / total
            if self.last_cnt is None:
                pass
            elif self.last_cnt + child_fraction <= self.last_total:
                self.child_fraction = child_fraction
            else:
                mutter('not updating child fraction')
        if self.last_msg is None:
            self.last_msg = ''
        self.tick()

    def update(self, msg, current_cnt=None, total_cnt=None,
               child_fraction=0):
        """Update and redraw progress bar."""
        if msg is None:
            msg = self.last_msg

        if total_cnt is None:
            total_cnt = self.last_total

        if current_cnt < 0:
            current_cnt = 0
            
        if current_cnt > total_cnt:
            total_cnt = current_cnt
        
        ## # optional corner case optimisation 
        ## # currently does not seem to fire so costs more than saved.
        ## # trivial optimal case:
        ## # NB if callers are doing a clear and restore with
        ## # the saved values, this will prevent that:
        ## # in that case add a restore method that calls
        ## # _do_update or some such
        ## if (self.last_msg == msg and
        ##     self.last_cnt == current_cnt and
        ##     self.last_total == total_cnt and
        ##     self.child_fraction == child_fraction):
        ##     return

        old_msg = self.last_msg
        # save these for the tick() function
        self.last_msg = msg
        self.last_cnt = current_cnt
        self.last_total = total_cnt
        self.child_fraction = child_fraction

        # each function call takes 20ms/4000 = 0.005 ms, 
        # but multiple that by 4000 calls -> starts to cost.
        # so anything to make this function call faster
        # will improve base 'diff' time by up to 0.1 seconds.
        if self.throttle(old_msg):
            return

        if self.show_eta and self.start_time and self.last_total:
            eta = get_eta(self.start_time, self.last_cnt + self.child_fraction, 
                    self.last_total, last_updates = self.last_updates)
            eta_str = " " + str_tdelta(eta)
        else:
            eta_str = ""

        if self.show_spinner:
            spin_str = self.SPIN_CHARS[self.spin_pos % 4] + ' '            
        else:
            spin_str = ''

        # always update this; it's also used for the bar
        self.spin_pos += 1

        if self.show_pct and self.last_total and self.last_cnt:
            pct = 100.0 * ((self.last_cnt + self.child_fraction) / self.last_total)
            pct_str = ' (%5.1f%%)' % pct
        else:
            pct_str = ''

        if not self.show_count:
            count_str = ''
        elif self.last_cnt is None:
            count_str = ''
        elif self.last_total is None:
            count_str = ' %i' % (self.last_cnt)
        else:
            # make both fields the same size
            t = '%i' % (self.last_total)
            c = '%*i' % (len(t), self.last_cnt)
            count_str = ' ' + c + '/' + t 

        if self.show_bar:
            # progress bar, if present, soaks up all remaining space
            cols = self.width - 1 - len(self.last_msg) - len(spin_str) - len(pct_str) \
                   - len(eta_str) - len(count_str) - 3

            if self.last_total:
                # number of markers highlighted in bar
                markers = int(round(float(cols) * 
                              (self.last_cnt + self.child_fraction) / self.last_total))
                bar_str = '[' + ('=' * markers).ljust(cols) + '] '
            elif False:
                # don't know total, so can't show completion.
                # so just show an expanded spinning thingy
                m = self.spin_pos % cols
                ms = (' ' * m + '*').ljust(cols)
                
                bar_str = '[' + ms + '] '
            else:
                bar_str = ''
        else:
            bar_str = ''

        m = spin_str + bar_str + self.last_msg + count_str + pct_str + eta_str
        self.to_file.write('\r%-*.*s' % (self.width - 1, self.width - 1, m))
        self._have_output = True
        #self.to_file.flush()
            
    def clear(self):
        if self._have_output:
            self.to_file.write('\r%s\r' % (' ' * (self.width - 1)))
        self._have_output = False
        #self.to_file.flush()        


_progress_bar_types['tty'] = TTYProgressBar


class ChildProgress(_BaseProgressBar):
    """A progress indicator that pushes its data to the parent"""

    def __init__(self, _stack, **kwargs):
        _BaseProgressBar.__init__(self, _stack=_stack, **kwargs)
        self.parent = _stack.top()
        self.current = None
        self.total = None
        self.child_fraction = 0
        self.message = None

    def update(self, msg, current_cnt=None, total_cnt=None):
        self.current = current_cnt
        if total_cnt is not None:
            self.total = total_cnt
        self.message = msg
        self.child_fraction = 0
        self.tick()

    def child_update(self, message, current, total):
        if current is None or total == 0:
            self.child_fraction = 0
        else:
            self.child_fraction = float(current) / total
        self.tick()

    def tick(self):
        if self.current is None:
            count = None
        else:
            count = self.current+self.child_fraction
            if count > self.total:
                if __debug__:
                    mutter('clamping count of %d to %d' % (count, self.total))
                count = self.total
        self.parent.child_update(self.message, count, self.total)

    def clear(self):
        pass

    def note(self, *args, **kwargs):
        self.parent.note(*args, **kwargs)


class InstrumentedProgress(TTYProgressBar):
    """TTYProgress variant that tracks outcomes"""

    def __init__(self, *args, **kwargs):
        self.always_throttled = True
        self.never_throttle = False
        TTYProgressBar.__init__(self, *args, **kwargs)

    def throttle(self, old_message):
        if self.never_throttle:
            result =  False
        else:
            result = TTYProgressBar.throttle(self, old_message)
        if result is False:
            self.always_throttled = False


def str_tdelta(delt):
    if delt is None:
        return "-:--:--"
    delt = int(round(delt))
    return '%d:%02d:%02d' % (delt/3600,
                             (delt/60) % 60,
                             delt % 60)


def get_eta(start_time, current, total, enough_samples=3, last_updates=None, n_recent=10):
    if start_time is None:
        return None

    if not total:
        return None

    if current < enough_samples:
        return None

    if current > total:
        return None                     # wtf?

    elapsed = time.time() - start_time

    if elapsed < 2.0:                   # not enough time to estimate
        return None
    
    total_duration = float(elapsed) * float(total) / float(current)

    assert total_duration >= elapsed

    if last_updates and len(last_updates) >= n_recent:
        avg = sum(last_updates) / float(len(last_updates))
        time_left = avg * (total - current)

        old_time_left = total_duration - elapsed

        # We could return the average, or some other value here
        return (time_left + old_time_left) / 2

    return total_duration - elapsed


class ProgressPhase(object):
    """Update progress object with the current phase"""
    def __init__(self, message, total, pb):
        object.__init__(self)
        self.pb = pb
        self.message = message
        self.total = total
        self.cur_phase = None

    def next_phase(self):
        if self.cur_phase is None:
            self.cur_phase = 0
        else:
            self.cur_phase += 1
        assert self.cur_phase < self.total
        self.pb.update(self.message, self.cur_phase, self.total)