import bpy
import blf
import bgl
import random


def drawCallback(self):
    blf.size(0, 16, 72)
    text = ('Last changed: ' + self.currentPropName) if self.currentPropName else 'Press LEFT or RIGHT to change color, ESC to stop'

    blf.enable(0, blf.SHADOW)
    blf.shadow(0, 3, 0.0, 0.0, 0.0, 1.0)
    blf.shadow_offset(0, 2, -2)

    bgl.glColor3f(1.0, 1.0, 1.0)
    blf.position(0, 40, 40, 0)
    blf.draw(0, '(Press ESC to stop)')
    blf.position(0, 40, 70, 0)
    blf.draw(0, text)

    blf.disable(0, blf.SHADOW)



class RandomThemeOperator(bpy.types.Operator):
    bl_idname = "wm.random_theme_operator"
    bl_label = "Random Theme Operator"
    bl_options = {'REGISTER'}


    def getColorProps(self, colorsList, prop, propName, parentName=''):
        for subProp in prop.rna_type.properties:
            if subProp.identifier in {'rna_type', 'srna', 'fixed_type'}: # Ignore some properties.
                continue

            if hasattr(subProp, 'type'):
                if subProp.type == 'POINTER':
                    self.getColorProps(colorsList, getattr(prop, subProp.identifier), subProp.name, parentName if parentName else prop.name)
                elif subProp.subtype == 'COLOR_GAMMA' or subProp.subtype == 'COLOR':
                    colorsList.append(
                        (prop, subProp.identifier, parentName + ' ' + propName + ' ' + subProp.identifier)
                    )
            else:
                self.getColorProps(colorsList, getattr(prop, subProp.identifier), subProp.name, parentName if parentName else prop.name)
        return colorsList


    def updateColor(self, r, g, b):
        prop, attr, name = self.allColorsList[self.index]
        setattr(prop, attr, (r, g, b, 1.0) if len(getattr(prop, attr)) == 4 else (r, g, b))
        self.currentPropName = name


    def modal(self, context, event):
        context.area.tag_redraw()

        if event.type in {'LEFTMOUSE', 'RIGHTMOUSE', 'ESC'}:
            bpy.types.SpaceView3D.draw_handler_remove(self._handle, 'WINDOW')
            bpy.ops.ui.reset_default_theme()
            self.report({'INFO'}, 'Cancelled')
            return {'CANCELLED'}

        if event.type == 'RIGHT_ARROW' and event.value == 'PRESS':
            r, g, b = 0.1, 0.3, 0.7
            if self.lastDirection == 0:
                self.updateColor(r, g, b)
            self.index = min(self.index + 1, self.maxLimit)
            self.updateColor(r, g, b)
            self.lastDirection = 1

        elif event.type == 'LEFT_ARROW' and event.value == 'PRESS':
            r, g, b = 0.7, 0.5, 0.0
            if self.lastDirection == 1:
                self.updateColor(r, g, b)
            self.index = max(self.index - 1, 0)
            self.updateColor(r, g, b)
            self.lastDirection = 0

        return {'RUNNING_MODAL'}


    def execute(self, context):
        self.index = 0
        theme = context.user_preferences.themes[0]
        self.allColorsList = tuple(reversed(self.getColorProps([ ], theme, theme.name)))
        self.currentPropName = ''
        self.maxLimit = len(self.allColorsList)-1
        self.lastDirection = 1

        self._handle = bpy.types.SpaceView3D.draw_handler_add(drawCallback, (self,), 'WINDOW', 'POST_PIXEL')
        context.window_manager.modal_handler_add(self)
        context.area.tag_redraw()
        return {'RUNNING_MODAL'}


def register():
    bpy.utils.register_class(RandomThemeOperator)


def unregister():
    bpy.utils.unregister_class(RandomThemeOperator)


if __name__ == "__main__":
    register()

    # Go to the 3D View, press SPACE and type "random theme operator".
    # Then hold the RIGHT ARROW key.