import unittest

from traits.api import HasTraits, Instance
from traits.etsconfig.api import ETSConfig
from traitsui.api import Item, View
from enable.component_editor import ComponentEditor

from chaco.api import Plot, ArrayPlotData
from chaco.tools.highlight_tool import HighlightTool

import numpy as np


class PlotViewer(HasTraits):
    plot = Instance(Plot)
    traits_view = View(Item('plot', editor=ComponentEditor()))


class MockEvent(HasTraits):
    pass


@unittest.skipIf(
    ETSConfig.toolkit=='null', "Skip on 'null' toolkit")
class TestHighlightTool(unittest.TestCase):

    def test_highlight_on_log_plot(self):
        # test for bug: the highlight tool raises an exception when used on
        # a loglog plot

        x = np.linspace(1, 15, 200)

        plotdata = ArrayPlotData()
        plotdata.set_data("x", x)
        plotdata.set_data("y", x*x)

        plot = Plot(plotdata)
        plot.plot(("x", "y"), index_scale='log', value_scale='log')

        # necessary for the machinery involved in _find_curve
        plot.datasources["x"].sort_order = 'ascending'
        plot.datasources["y"].sort_order = 'ascending'

        # add the highlight tool
        htool = HighlightTool(plot, threshold=20.)
        plot.tools.append(htool)

        # we create a view of the plot so that the screen bounds are set
        pv = PlotViewer(plot=plot)
        pv.edit_traits()

        # this should not raise an exception
        event = MockEvent(x=170., y=60.)
        htool._find_curve(plot.plots['plot0'], event)