import bpy
import math


def maybeDispose(name):
    obj = bpy.data.objects.get(name)
    if not obj is None:
        obj.name = "discard"
        bpy.context.scene.objects.unlink(obj)


def fakeData():
    rval = []
    for x in range(100+1):
        y = (x*x)/100 + 4*math.sin(x/2)
        rval.append( [ x,y] )
    return rval


def makeCurve(name, data):
    curve = bpy.data.curves.new(name, 'CURVE')
    spline = curve.splines.new('BEZIER')
    spline.bezier_points.add(len(data) - 1)
    for i,xy in enumerate(data):
        xyz = [ xy[0], xy[1], 0 ]
        spline.bezier_points[i].co = xyz
        spline.bezier_points[i].handle_left = xyz
        spline.bezier_points[i].handle_right = xyz
    curve.bevel_object = bpy.data.objects["line"]
    return curve


def animateCurveBevel(obj, f1, f2):
    obj.data.keyframe_insert(data_path="bevel_factor_end", frame=f2)
    obj.data.bevel_factor_end = 0
    obj.data.keyframe_insert(data_path="bevel_factor_end", frame=f1)
    anim = obj.data.animation_data.action.fcurves[0]
    anim.keyframe_points[0].interpolation = 'LINEAR'

def animateCurveBevelBad(obj, f1, f2):
    obj.keyframe_insert(data_path="data.bevel_factor_end", frame=f2)
    obj.data.bevel_factor_end = 0
    obj.keyframe_insert(data_path="data.bevel_factor_end", frame=f1)
    anim = obj.animation_data.action.fcurves[0]
    anim.keyframe_points[0].interpolation = 'LINEAR'

def frameForX(idx, nPoints, f0, f9):
    return f0 + (f9-f0) *idx/(nPoints-1)

def setVisibility(obj, f1, f2):

    if not f2 is None:
        obj.keyframe_insert(data_path='hide', frame= bpy.context.scene.frame_end+10)
    obj.keyframe_insert(data_path='hide_render', frame=f1)
    obj.keyframe_insert(data_path='hide', frame=f1)
    obj.hide = True
    obj.hide_render = True
    obj.keyframe_insert(data_path='hide', frame=0)
    obj.keyframe_insert(data_path='hide_render', frame=0)
    if not f2 is None:
        obj.keyframe_insert(data_path='hide', frame=f2)
        obj.keyframe_insert(data_path='hide_render', frame=f2)


def makeText(text, loc, f1, f2):
    curve = bpy.data.curves.new("label", 'FONT')
    curve.body = text
    o1 = bpy.data.objects.new("label", curve)
    bpy.context.scene.objects.link(o1)
    o1.location = loc
    if not f1 is None:
        setVisibility(o1, f1, f2)
    o1.parent = bpy.data.objects["font folder"]
    
    curve.materials.append(bpy.data.materials["text"])

    return o1


def make2Text(text1, text2, loc, f1, f2):
    o1 = makeText(text1, loc, f1, f2)
    o2 = makeText(text2, loc, f1, f2)
    o1.data.align = 'RIGHT'

    return (o1, o2)


def lookUp(data, f0, f9, frame):
    f1 = -1

    for i,xy  in enumerate(data):
        f2 = frameForX(i, len(data), f0, f9)
        f3 = frameForX(i+1, len(data), f0, f9)
        if frame<f3:
            return xy
        f1 = f2

    return data[-1]

#
#

name = "graph"


for obj in bpy.data.objects:
    if obj.name[:5] == "label":
        obj.name = "discard"
        bpy.context.scene.objects.unlink(obj)

maybeDispose(name)

data = fakeData()

obj = bpy.data.objects.new(name, makeCurve(name, data))
obj.scale = (0.1,0.1,0.1)
bpy.context.scene.objects.link(obj)
bpy.context.scene.objects.active = obj
obj.select = True
obj.data.materials.append(bpy.data.materials["graph"])


f0 = 31
f9 = f0+ 5*bpy.context.scene.render.fps

animateCurveBevel(obj, 31, f9)

if False:
    # animating text by creating hundreds of individual text objects that pop in and out
    f1 = -1
    for i,xy  in enumerate(data):
        f2 = frameForX(i, len(data), f0, f9)
        f3 = frameForX(i+1, len(data), f0, f9)
        if (i+1 >= len(data)):
            f3 = None
        if (f2>f1):
            make2Text("x=%d,"%xy[0], "y=%.1f"%xy[1], [4,6,1], f2, f3)
        f1 = f2
else:
    # animating text by hooking into the frame_change_pre callback.

    # Thanks: http://blender.stackexchange.com/questions/7904/dynamic-text-in-animation

    # wipe out any preexisting handlers. Hope that doesn't ruin anyone's day.
    bpy.app.handlers.frame_change_pre.clear()

    # make the two text objects.
    (t1, t2) = make2Text("x=?,", "y=?", [4,6,1], None, None)
    tdata1 = t1.data
    tdata2 = t2.data

    def adjustText(scene):
        """
        Update the body on the text labels to be correct for each frame.
        """
        xy = lookUp(data, f0, f9, scene.frame_current)
        tdata1.body = "x=%d,"%xy[0]
        tdata2.body = "y=%.1f"%xy[1]
    bpy.app.handlers.frame_change_pre.append(adjustText)

#