#
# Creates a parametric Rectellipse
# (c) fcaponi78
#
#

from __future__ import division

__Comment__ = 'Creates a parametric approximation of a rectellipse'
__Web__ = 'http://freecadweb.org/wiki/Macro_Rectellipse'
__Wiki__ = 'http://freecadweb.org/wiki/Macro_Rectellipse'
__Icon__ = ""
__Help__ = 'Run, zoom fit, and change parameters'
__Author__ = 'fcaponi78, shoogen and other contributors'
__Version__ = 0.1
__Status__ = 'alpha'
__Requires__ = ''

import FreeCAD
from FreeCAD import Part
from FreeCAD import Vector


class RectEllipseFeature:
    def __init__(self, obj):
        """Add the properties: a, b, s, createFace"""
        obj.addProperty('App::PropertyLength', 'a', 'Rectellipse',
                        'Horizontal radius').a = 16.0
        obj.addProperty('App::PropertyLength', 'b', 'Rectellipse',
                        'Vertical radius').b = 9.0
        obj.addProperty('App::PropertyFloat', 's', 'Rectellipse',
                        'Squareness (0=ellipse, 1=rectangle)').s = 0.2
        obj.addProperty('App::PropertyBool', 'createFace', 'Rectellipse',
                        'true => face; false => wire').createFace = True
        obj.Proxy = self

    def onChanged(self, feature, prop):
        if prop in ['a',  'b', 's', 'createFace']:
            self.execute(feature)

    def execute(self, feature):
        r1 = feature.a
        r2 = feature.b
        if feature.s < 0:
            feature.s = 0
        elif feature.s > 1:
            feature.s = 1
        z = 0.0
        # TODO: tweak p, so that the curve is the exact definition of a
        # rectellipse (if possible).
        p = 1.0
        # NURBS knots weigts.
        if feature.s > 0.9999999:
            # If larger than 1e7, we obtain a rhombus.
            w = 1e7
        else:
            w = 2 ** 0.5 / 2.0 / (1 - feature.s ** p)
        # TODO: use a real rectangle if feature.s close to 1.
        curve = Part.BSplineCurve()
        curve.setPeriodic()
        curve.increaseDegree(2)
        # 5 knots, 8 poles
        curve.insertKnots([i / 4 for i in (1, 2, 3)], [2] * 3)
        curve.setPole(1, Vector(0, -r2, z), 1)
        curve.setPole(2, Vector(-r1, -r2, z), w)
        curve.setPole(3, Vector(-r1, 0, z), 1)
        curve.setPole(4, Vector(-r1, r2, z), w)
        curve.setPole(5, Vector(0, r2, z), 1)
        curve.setPole(6, Vector(r1, r2, z), w)
        curve.setPole(7, Vector(r1, 0, z), 1)
        curve.setPole(8, Vector(r1, -r2, z), w)
        if feature.createFace:
            feature.Shape = Part.Face(Part.Wire(curve.toShape()))
        else:
            feature.Shape = curve.toShape()


def makeRectellipseFeature():
    doc = FreeCAD.activeDocument()
    if doc is None:
        doc = FreeCAD.newDocument()
        if doc is None:
            return
    obj = doc.addObject('Part::FeaturePython', 'RectEllipseFeature')
    obj.Label = 'RectEllipse'
    RectEllipseFeature(obj)
    obj.ViewObject.Proxy = 0

if __name__ == "__main__":
    makeRectellipseFeature()