# Copyright (C) 2006, Red Hat, Inc.
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2 of the License, or (at your option) any later version.
#
# This library 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
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the
# Free Software Foundation, Inc., 59 Temple Place - Suite 330,
# Boston, MA 02111-1307, USA.

import random
import math

import cairo
import hippo

_DISTANCE_THRESHOLD = 10.0
_FORCE_CONSTANT = 0.1

class SpreadBox(hippo.CanvasBox, hippo.CanvasItem):
	__gtype_name__ = 'SugarSpreadBox'

	def __init__(self, **kwargs):
		hippo.CanvasBox.__init__(self, **kwargs)

		self._items_to_position = []
		self._stable = False

	def add_item(self, item):
		self._items_to_position.append(item)
		self.append(item, hippo.PACK_FIXED)

	def remove_item(self, item):
		if self._items_to_position.count(item) > 0:
			self._items_to_position.remove(item)
		self.remove(item)

	def _get_item_radius(self, item):
		[width, height] = item.get_request()
		return math.sqrt(width ** 2  + height ** 2) / 2

	def _get_item_center(self, item):
		[width, height] = item.get_request()
		[x, y] = self.get_position(item)

		c_x = int(x + float(width) / 2.0)
		c_y = int(y + float(height) / 2.0)

		return [c_x, c_y]

	def _get_repulsion(self, icon1, icon2):
		[c1_x, c1_y] = self._get_item_center(icon1)
		[c2_x, c2_y] = self._get_item_center(icon2)

		a = c2_x - c1_x
		b = c2_y - c1_y

		r1 = self._get_item_radius(icon1)
		r2 = self._get_item_radius(icon2)
		distance = math.sqrt(a ** 2  + b ** 2) - r1 - r2

		if distance < _DISTANCE_THRESHOLD:
			f_x = int(math.ceil(-_FORCE_CONSTANT * float(a)))
			f_y = int(math.ceil(-_FORCE_CONSTANT * float(b)))
		else:
			f_x = 0
			f_y = 0

		return [f_x, f_y]

	def _clamp_position(self, icon, x, y):
		x = max(0, x)
		y = max(0, y)

		[item_w, item_h] = icon.get_request()
		[box_w, box_h] = self.get_allocation()

		x = min(box_w - item_w, x)
		y = min(box_h - item_h, y)

		return [x, y]

	def _spread_icons(self):
		self._stable = True

		for icon1 in self.get_children():
			vx = 0
			vy = 0

			for icon2 in self.get_children():
				if icon1 != icon2:
					[f_x, f_y] = self._get_repulsion(icon1, icon2)
					if f_x != 0 or f_y != 0:
						self._stable = False
						vx += f_x
						vy += f_y

			if vx != 0 or vy != 0:
				[x, y] = self.get_position(icon1)
				new_x = x + vx
				new_y = y + vy

				[new_x, new_y] = self._clamp_position(icon1, new_x, new_y)

				self.move(icon1, new_x, new_y)

	def do_allocate(self, width, height):
		hippo.CanvasBox.do_allocate(self, width, height)

		for item in self._items_to_position:
			[item_w, item_h] = item.get_request()

			x = int(random.random() * width - item_w)
			y = int(random.random() * height - item_h)

			[x, y] = self._clamp_position(item, x, y)
			self.move(item, x, y)

		self._items_to_position = []

		tries = 20
		self._spread_icons()
		while not self._stable and tries > 0:
			self._spread_icons()
			tries -= 1