import gtk
import gedit

#todo: these should be real options
#todo: options to only draw leading/trailing stuff

DRAW_TABS   = True
DRAW_SPACES = True


def draw_tab_at_iter(view, event, iter):
    if not DRAW_TABS:
        return

    rect = view.get_iter_location(iter)
    x, y = view.buffer_to_window_coords (gtk.TEXT_WINDOW_TEXT, rect.x, rect.y + rect.height / 2)
    # should we use the insensitive color? no idea if it's a good guess
    event.window.draw_line(view.style.text_gc[gtk.STATE_NORMAL], x + 4, y, x + rect.width - 4, y)

def draw_space_at_iter(view, event, iter):
    if not DRAW_SPACES:
        return

    rect = view.get_iter_location(iter)
    x, y = view.buffer_to_window_coords (gtk.TEXT_WINDOW_TEXT, rect.x + rect.width / 2, rect.y + rect.height / 2)
    event.window.draw_point(view.style.text_gc[gtk.STATE_NORMAL], x, y)

def draw_tabs_and_spaces(view, event, start, end):
    i = start.copy();
    while i.compare(end) < 0:
        if i.get_char() == '\t':
            draw_tab_at_iter (view, event, i)
        elif i.get_char() == ' ':
            draw_space_at_iter (view, event, i)
        if not i.forward_char():
            break

class DrawSpacesHelper(object):
    def expose_cb(self, view, event):
        if event.window == view.get_window(gtk.TEXT_WINDOW_TEXT):
            y = view.window_to_buffer_coords(gtk.TEXT_WINDOW_TEXT, event.area.x, event.area.y)[1]
            s = view.get_line_at_y(y)[0]
            e = view.get_line_at_y(y + event.area.height)[0]
            draw_tabs_and_spaces(view, event, s, e)

    def attach(self, view):
        self._view = view
        self.expose_id = view.connect('expose-event', self.expose_cb)

    def detach(self):
        self._view.disconnect(self.expose_id)


class DrawSpacesPlugin(gedit.Plugin):
    def __init__(self):
        gedit.Plugin.__init__(self)

    def activate(self, window):
        for view in window.get_views():
            self._create_view_helper(view)

        tab_added_id = window.connect("tab_added",
                                      lambda w, t: self._create_view_helper(t.get_view()))
        window.set_data("DrawSpacesPluginHandlerId", tab_added_id)

    def deactivate(self, window):
        tab_added_id = window.get_data("DrawSpacesPluginHandlerId")
        window.disconnect(tab_added_id)
        window.set_data("DrawSpacesPluginHandlerId", None)

        for view in window.get_views():
            self._destroy_view_helper(view)

    def update_ui(self, window):
        pass

    def _create_view_helper(self, view):
        helper = DrawSpacesHelper()
        helper.attach(view)
        view.set_data("DrawSpacesHelper", helper)

    def _destroy_view_helper(self, view):
        helper = view.get_data("DrawSpacesHelper")
        helper.detach()
        view.set_data("DrawSpacesHelper", None)