from tuikit.core.coords import Point, Size
from tuikit.core.theme import default_theme
from tuikit.core.signal import Signal

import logging


class Widget:

    """Base class for all widgets."""

    _num_instances = 0

    def __init__(self):
        self._num_instances += 1

        #: Widget name is used for logging etc. Not visible anywhere.
        self.name = '{}{}'.format(
            self.__class__.__name__,
            self._num_instances)

        #: Parent Widget
        self.parent = None
        #: Window owning this Widget
        self.window = None
        #: Theme
        self.theme = default_theme

        #: Position inside parent widget. Modified by layout manager.
        self.pos = Point()
        #: Actual size. Modified by layout manager.
        self._size = Size(10, 10)

        #: Requested size. Layout manager will use this when placing the widget.
        self.sizereq = Size(1, 1)
        #: Minimal size of widget. Widget will never be sized smaller than this.
        self.sizemin = Size(1, 1)
        #: Maximum size of widget. Widget will never be sized bigger than this.
        #: None means no maximum size (infinite).
        self.sizemax = Size(None, None)

        #: Cursor is position where text input will occur.
        self._cursor = Point()
        #: Cursor is displayed on screen only if the widget is focused.
        self._cursor_visible = False

        #: Hidden widget does not affect layout.
        self.hidden = False
        #: Allow keyboard focus for this widget.
        self.allow_focus = False

        self.sig_keypress = Signal(allow_stop=True)

    ## position and size ##

    @property
    def x(self):
        return self.pos.x

    @property
    def y(self):
        return self.pos.y

    @property
    def width(self):
        return self.size.w

    @property
    def height(self):
        return self.size.h

    @property
    def size(self):
        return self._size.readonly()

    def resize(self, w, h):
        self._size.update(w, h)

    ## drawing, looks ##

    def draw(self, buffer):
        """Draw self into buffer."""
        self.log.debug('Draw into %r at %s (exposed %s)',
                       buffer, buffer.origin, self.exposed(buffer))

    def set_theme(self, theme):
        self.theme = theme

    @staticmethod
    def exposed(buffer):
        """Exposed part of widget.

        Only this area needs to be drawn.

        Returns exposed Rect in widget's local coordinates,
        where 0,0 is left top corner of widget to be drawn.

        """
        return buffer.clip_rect.moved(-buffer.origin.x, -buffer.origin.y)

    @property
    def cursor(self):
        return self._cursor

    @property
    def cursor_visible(self):
        return self._cursor_visible

    ## events ##

    def resize_event(self, ev):
        self.resize(ev.w, ev.h)

    def keypress_event(self, ev):
        """Keypress event handler.

        Override to accept keyboard input.

        Returns True if event was consumed.

        Call this implementation from inherited classes
        if it does not consume the event.

        """
        if self.sig_keypress(ev):
            return True
        self.log.debug('Not consumed: %s', ev)

    ## timeouts ##

    def add_timeout(self, delay, callback, *args):
        """Register `callback` to be called after `delay` seconds."""
        self.parent.add_timeout(self, delay, callback, *args)

    def remove_timeout(self, callback, *args):
        """Unregister callback previously registered with add_timeout.

        Removes all timeouts with the `callback` and `args`.

        """
        self.parent.remove_timeout(self, callback, *args)

    ## focus ##

    def can_focus(self):
        return not self.hidden and self.allow_focus

    def has_focus(self):
        if self.parent is None:
            return True
        return (self.parent.has_focus()
            and self.parent.focus_widget == self)

    ## utilities ##

    @property
    def log(self):
        return logging.getLogger('tuikit.' + self.name)