# Copyright (C) 2010 Canonical
#
# Authors:
#  Gary Lasker
#
# 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; version 3.
#
# 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

from softwarecenter.utils import utf8

import logging

LOG = logging.getLogger(__name__)


class NavigationHistory(object):
    """
    class to manage navigation history
    """
    MAX_NAV_ITEMS = 25  # limit number of NavItems allowed in the NavStack

    def __init__(self, back_forward_btn, options=None):
        self.stack = NavigationStack(self, self.MAX_NAV_ITEMS, options)
        self.back_forward = back_forward_btn
        self.in_replay_history_mode = False
        self._nav_back_set_sensitive(False)
        self._nav_forward_set_sensitive(False)

    def append(self, nav_item):
        """
        append a new NavigationItem to the history stack
        """
        LOG.debug("appending: '%s'" % nav_item)
        if self.in_replay_history_mode:
            return

        stack = self.stack
        # reset navigation forward stack items on a direct navigation
        stack.clear_forward_items()
        stack.append(nav_item)

        if stack.cursor >= 1:
            self._nav_back_set_sensitive(True)
        self._nav_forward_set_sensitive(False)

    def nav_forward(self):
        """
        navigate forward one item in the history stack
        """
        stack = self.stack
        nav_item, did_step = stack.step_forward()
        nav_item.navigate_to()

        self._nav_back_set_sensitive(True)
        if stack.at_end():
            if self.back_forward.right.has_focus():
                self.back_forward.left.grab_focus()
            self._nav_forward_set_sensitive(False)

    def nav_back(self):
        """
        navigate back one item in the history stack
        """

        stack = self.stack
        nav_item, did_step = stack.step_back()
        nav_item.navigate_to()

        self._nav_forward_set_sensitive(True)
        if stack.at_start():
            if self.back_forward.left.has_focus():
                self.back_forward.right.grab_focus()
            self._nav_back_set_sensitive(False)

    def clear_forward_history(self):
        """
        clear the forward history and set the corresponding forward
        navigation button insensitive, useful when navigating away
        from a pane whose contents are no longer valid (e.g. the
        purchase pane after a purchase is completed, cancelled, etc.)
        """
        self.stack.clear_forward_items()
        self._nav_forward_set_sensitive(False)

    def reset(self):
        """
        reset the navigation history by clearing the history stack and
        setting the navigation UI items insensitive
        """
        self.stack.reset()
        self._nav_back_set_sensitive(False)
        self._nav_forward_set_sensitive(False)

    def _nav_back_set_sensitive(self, is_sensitive):
        self.back_forward.left.set_sensitive(is_sensitive)
        #~ self.navhistory_back_action.set_sensitive(is_sensitive)

    def _nav_forward_set_sensitive(self, is_sensitive):
        self.back_forward.right.set_sensitive(is_sensitive)
        #~ self.navhistory_forward_action.set_sensitive(is_sensitive)


class NavigationItem(object):
    """
    class to implement navigation points to be managed in the history queues
    """

    def __init__(self, view_manager, pane, page, view_state, callback):
        self.view_manager = view_manager
        self.pane = pane
        self.page = page
        self.view_state = view_state
        self.callback = callback

    def __str__(self):
        facet = self.pane.pane_name.replace(' ', '')[:6]
        result = utf8("%s:%s %s") % (facet, self.page, self.view_state)
        return result

    def navigate_to(self):
        """
        navigate to the view that corresponds to this NavigationItem
        """
        # make sure we are in reply history mode
        self.view_manager.navhistory.in_replay_history_mode = True

        self.view_manager.display_page(self.pane, self.page,
                       self.view_state, self.callback)

        # and reset this mode again
        self.view_manager.navhistory.in_replay_history_mode = False


class NavigationStack(object):
    """
    a navigation history stack
    """

    def __init__(self, history, max_length, options=None):
        self.history = history
        self.max_length = max_length
        self.stack = []
        self.cursor = 0

        if not options or not options.display_navlog:
            return

        import softwarecenter.ui.gtk3.widgets.navlog as navlog
        self.navlog = navlog.NavLogUtilityWindow(self)

    def __len__(self):
        return len(self.stack)

    def __repr__(self):
        BOLD = "\033[1m"
        RESET = "\033[0;0m"
        s = '['
        for i, item in enumerate(self.stack):
            if i != self.cursor:
                s += str(item) + ', '
            else:
                s += BOLD + str(item) + RESET + ', '
        return s + ']'

    def __getitem__(self, item):
        return self.stack[item]

    def _isok(self, item):
        if item.page is not None and item.page < 0:
            return False
        if len(self) == 0:
            return True

        last = self[-1]
        last_vs = last.view_state
        item_vs = item.view_state
        # FIXME: This is getting messy, this stuff should be cleaned up
        # somehow...
        # hacky: special case, check for subsequent searches
        # if subsequent search, update previous item_vs.search_term
        # to current.

        # do import of Pages enum here: else drama!
        from softwarecenter.ui.gtk3.panes.availablepane import AvailablePane
        # check if both current and previous views were list views
        if (item.page == AvailablePane.Pages.LIST and
            last.page == AvailablePane.Pages.LIST):
            # first case, previous search and new seach
            if (item_vs.search_term and last_vs.search_term and
                item_vs.search_term != last_vs.search_term):
                # update last search term with current search_term
                last.view_state.search_term = item_vs.search_term
                # ... but return False, resulting in 'item' not being
                # appended
                return False

            elif (last_vs.search_term and not item_vs.search_term):
                LOG.debug("search has been cleared. ignoring history item")
                if len(self) > 1:
                    del self.stack[-1]
                    if len(self) == 1:
                        self.history._nav_back_set_sensitive(False)
                        self.history._nav_forward_set_sensitive(False)
                    LOG.debug("also remove 'spurious' list navigation item "
                        "(Bug #854047)")
                return False

        elif (item.page != AvailablePane.Pages.LIST and
              last.page == AvailablePane.Pages.LIST and
              not item_vs.search_term and last_vs.search_term):
            LOG.debug("search has been cleared. ignoring history item")
            if len(self) > 1:
                del self.stack[-1]
                if len(self) == 1:
                    self.history._nav_back_set_sensitive(False)
                    self.history._nav_forward_set_sensitive(False)
                LOG.debug("also remove 'spurious' list navigation item "
                    "(Bug #854047)")
            return False

        if item.__str__() == last.__str__():
            return False

        return True

    def append(self, item):
        if not self._isok(item):
            self.cursor = len(self.stack) - 1
            LOG.debug('A:%s' % repr(self))
            #~ print ('A:%s' % repr(self))
            return
        if len(self.stack) + 1 > self.max_length:
            self.stack.pop(1)
        self.stack.append(item)
        self.cursor = len(self.stack) - 1
        LOG.debug('A:%s' % repr(self))
        #~ print ('A:%s' % repr(self))
        if hasattr(self, "navlog"):
            self.navlog.log.notify_append(item)

    def step_back(self):
        did_step = False
        if self.cursor > 0:
            self.cursor -= 1
            did_step = True
        else:
            self.cursor = 0
        LOG.debug('B:%s' % repr(self))
        #~ print ('B:%s' % repr(self))
        if hasattr(self, "navlog") and did_step:
            self.navlog.log.notify_step_back()
        return self.stack[self.cursor], did_step

    def step_forward(self):
        did_step = False
        if self.cursor < len(self.stack) - 1:
            self.cursor += 1
            did_step = True
        else:
            self.cursor = len(self.stack) - 1
        LOG.debug('B:%s' % repr(self))
        #~ print ('B:%s' % repr(self))
        if hasattr(self, "navlog") and did_step:
            self.navlog.log.notify_step_forward()
        return self.stack[self.cursor], did_step

    def clear_forward_items(self):
        self.stack = self.stack[:(self.cursor + 1)]
        if hasattr(self, "navlog"):
            self.navlog.log.notify_clear_forward_items()

    def at_end(self):
        return self.cursor == len(self.stack) - 1

    def at_start(self):
        return self.cursor == 0

    def reset(self):
        self.stack = []
        self.cursor = 0
