%pylab inline
import ephem
from shapely.geometry import LineString, Point

UMa = {
# star proper name: (abbreviation, hipparcos #),
'dubhe': ('αUMa', 54061),
'merak': ('βUMa', 53910),
'phecda':('γUMa', 58001),
'megrez':('δUMa', 59774),
'alioth':('εUMa', 62956),
'mizar': ('ζUMa', 65378),
'alcor': ('80UMa',65477),
'alcaid':('ηUMa', 67301),
}

def get_hip(name):
    for const_name in UMa.keys():
        if(name.lower() == const_name.lower()):
            return UMa[const_name][1]

constellationship = 'UMa 7 67301 65378 65378 62956 62956 59774 59774 54061 54061 53910 53910 58001 58001 59774'

BLUE = '#268bd2'
BASE03 = '#002b36'

def plot_line(ax, ob):
    x, y = ob.xy
    ax.plot(x, y, color=BLUE, linewidth=3, solid_capstyle='round', zorder=1)

def plot_pt(ax, ob):
    x, y = ob.xy
    ax.plot(x, y, 'o',color=BASE03, zorder=1)
    
def linear_interpolate(x0,y0,x1,y1,x=None,y=None):
    # if not passed any x or y, assume want bisection pt
    if(x==None and y==None):
        x=(x0+x1)/2.
        y=(y0+y1)/2.
    elif(y==None):
        y=y0+(y1-y0)*(x-x0)/(x1-x0)
    elif(x==None):
        x=x0+(x1-x0)*(y-y0)/(y1-y0)
    return x,y

def const(const,years=None,epochs=None,title=None,lines=None,plot_pts=False):
    tau = 2.0 * pi
    degree = tau / 360.0
    hour = tau / 24.0
    this_year = ephem.now().tuple()[0]

    if(years is None and epochs is None):
        years = [this_year]
        epochs = [this_year]
    elif(years is None):
        years = [this_year]
    elif(epochs is None):
        epochs = [this_year]
    
    n = len(years)*len(epochs)
    y = 0
    e = 0
    
    fig = pyplot.figure(1,figsize(8*n,5),dpi=180)
    
    for year in years:
        y += 1
        for epoch in epochs:
            e += 1
            
            s = []

            for star in const.keys():
                s.append(ephem.star(star.capitalize()))
        
            for i in range(len(s)):
                if(year is None and epoch is None):
                    s[i].compute(this_year,epoch=this_year)
                elif(epoch is None):
                    s[i].compute(year,epoch=this_year)
                elif(year is None):
                    s[i].compute(this_year,epoch=epoch)
                else:
                    s[i].compute(year,epoch=epoch)
                    
            ra_list = [star.a_ra / hour for star in s]
            dec_list = [star.a_dec / degree for star in s]
            
            mag_array = np.array([star.mag for star in s])
            size_array = (5 - mag_array) ** 1.5 * 4
            
            ax = fig.add_subplot(1,n,e)
            if(title is None):
                this_title = 'year={}, epoch={}'.format(year,epoch)
            else:
                this_title = '{}: year={}, epoch={}'.format(title,year,epoch)
            pyplot.title(this_title)
            if(lines!=None):
                segs = lines.split()
                segs.remove(segs[0])
                #ns = segs[0]
                segs.remove(segs[0])
                for i in range(len(segs)):
                    segs[i] = int(segs[i])
                
                for i in range(0,len(segs),2):
                    star1 = segs[i]
                    star2 = segs[i+1]
                    pt1=pt2=(0.,0.)
                    for j in range(len(s)):
                        if(get_hip(s[j].name) == star1):
                            pt1 = (ra_list[j],dec_list[j])
                        if(get_hip(s[j].name) == star2):
                            pt2 = (ra_list[j],dec_list[j])
                    # gotta check if the lines cross the bounds
                    p = .25 # NOTE: using 25%
                    ub_x = 24. # upper bound (RA)
                    lb_x = 0.  # lower bound (RA)
                    if((pt1[0]>ub_x*(1.-p)) and (pt2[0]<(lb_x+(ub_x*p)))):
                            if(lines!=None):
                                #print('crosses higher to lower: ({},{})'.format(pt1,pt2))
                                # amend left
                                est_pt1 = linear_interpolate(pt1[0],pt1[1],pt2[0]+ub_x,pt2[1],ub_x)
                                # amend right
                                est_pt2 = (lb_x,est_pt1[1])
                                l1 = LineString([est_pt1,pt1])
                                plot_line(ax,l1)
                                l2 = LineString([pt2,est_pt2])
                                plot_line(ax,l2)
                            if(plot_pts):
                                plot_pt(ax,l1)
                                plot_pt(ax,l2)
                            axis([0.0,24.0,-90.0,90.0])
                    elif((pt2[0]>ub_x*(1.-p)) and (pt1[0]<(lb_x+(ub_x*p)))):
                            if(lines!=None):
                                #print('crosses lower to higher: ({},{})'.format(pt1,pt2))
                                # amend left
                                est_pt1 = linear_interpolate(pt1[0]+ub_x,pt1[1],pt2[0],pt2[1],ub_x)
                                # amend right
                                est_pt2 = (lb_x,est_pt1[1])
                                l1 = LineString([est_pt2,pt1])
                                plot_line(ax,l1)
                                l2 = LineString([pt2,est_pt1])
                                plot_line(ax,l2)
                            if(plot_pts):
                                plot_pt(ax,l1)
                                plot_pt(ax,l2)
                            axis([0.0,24.0,-90.0,90.0])
                    else:
                        l = LineString([pt1,pt2])
                        if(lines!=None):
                            plot_line(ax,l)
                        if(plot_pts):
                            plot_pt(ax,l)
            gca().xaxis.grid(True)
            gca().yaxis.grid(True)
            gca().invert_xaxis()
    return s

ancient_e = const(UMa,lines=constellationship,plot_pts=True,title='Big Dipper')
#savefig('uma.png')

ancient_e = const(UMa,epochs=['-100000'],lines=constellationship,plot_pts=True,title='Big Dipper')
#savefig('uma_epoch.png')

ancient_ey = const(UMa,years=['-100000'],epochs=['-100000'],lines=constellationship,plot_pts=True,title='Big Dipper')
#savefig('uma_epoch_and_year.png')

ancient_y = const(UMa,years=['-100000'],lines=constellationship,plot_pts=True,title='Big Dipper')
#savefig('uma_year')

ancient_y = const(UMa,years=['-100000','2014','100000'],lines=constellationship,plot_pts=True,title='Big Dipper')
#savefig('uma_changing_year.png')

ancient_y = const(UMa,epochs=['-100000','2014','100000'],lines=constellationship,plot_pts=True,title='Big Dipper')
#savefig('uma_changing_epoch.png')

ancient_y = const(UMa,years=['-100000','2014','100000'],epochs=['-100000','2014','100000'],lines=constellationship,plot_pts=True,title='Big Dipper')
#savefig('uma_epoch_year_iterations.png')