# Python imports

# Lib imports
import gi
gi.require_version('Gtk', '3.0')
from gi.repository import Gtk

# Application imports
from ..widgets.image_list import ImageList



class ImageListScroll(Gtk.ScrolledWindow):
    def __init__(self):
        super(ImageListScroll, self).__init__()

        self.image_list_widget = None
        self.size  = 0
        self.start = 0
        self.end   = settings.get_max_ring_thumbnail_list()

        self._setup_styling()
        self._setup_signals()
        self._subscribe_to_events()
        self._load_widgets()

        self.show_all()


    def _setup_styling(self):
        self.set_vexpand(True)
        self.set_overlay_scrolling(False)

    def _setup_signals(self):
        self.connect("edge-reached", self._handle_edge_reached)
        self.connect("edge-overshot", self._handle_edge_reached)

    def _subscribe_to_events(self):
        event_system.subscribe("update_list_size_constraints", self._update_list_size_constraints)

    def _load_widgets(self):
        self.image_list_widget = ImageList()
        self.add(self.image_list_widget)

    # TODO: Setup to load range start/end values from settings,
    # NOTE: Must align with ImageList start/end limits too
    def _update_list_size_constraints(self, size):
        self.size  = size
        self.start = 0
        self.end   = settings.get_max_ring_thumbnail_list()

    def _handle_edge_reached(self, widget, edge):
        children    = self.image_list_widget.get_children()
        vadjustment = self.get_vadjustment()
        vvalue      = vadjustment.get_value()

        if edge == Gtk.PositionType.TOP:
            if self.start >= 1:
                self.start -= 1
                self._unload_image(children[self.end])
                children[self.start].show()
                self.end -= 1

                vadjustment.set_value(vvalue + 1)
        if edge == Gtk.PositionType.BOTTOM:
            if (self.end + 1) < self.size:
                self.end += 1
                self._unload_image(children[self.start])

                if not children[self.end].is_loaded:
                    children[self.end].load_pixbuf()

                children[self.end].show()
                self.start += 1
                vadjustment.set_value(vvalue - 1)

    def _unload_image(self, child):
        child.hide()
        # child.image.clear()
        child.is_loaded = False