"""

This is a python script to concatenate two Photoshop curves.
That is, if you have an acv file called CURVE and another called
DELTA, you run
python catacv.py CURVE DELTA NEW
and it applies DELTA first, then CURVE, yielding a new curve called NEW.

You might use it when working on curves with QTR. If you know your 
base curve is pretty good, but you want to tweak it with another known
curve, you can use this to concatenate the two curves. I use it with
curves generated by David Eisenlord's script for digital negatives.

The sample points on the new curve - that is, the x-coordinates of the new curve -
come from the main CURVE, not the DELTA. Resampling curves is an exercise
left to the reader. The script won't behave well if the curves aren't
for the same number of channels (grayscale is all I've used.)


The extraction of the curves from the acv files are from here:

 https://github.com/vbalnt/filterizer
"""

from struct import unpack, pack
from scipy import interpolate

import numpy
import scipy

import sys

class Filter:

 def __init__(self, name):
   self.name = name
   self.curves = []

 def read_from_file(self, acv_file_path):
   with open(acv_file_path, 'rb') as acv_file:
	 self.curves = self._read_curves(acv_file)
   self.polynomials = self._find_coefficients()

 def write_to_file(self, acv_file_path):
 	with open(acv_file_path, 'wb') as acv_file:
 		acv_file.write(pack('!hh', 4, len(self.curves)))
 		for curve in self.curves:
 			acv_file.write(pack('!h', len(curve)))
 			for (x, y) in curve:
 				acv_file.write(pack('!hh', y, x))

 def _read_curves(self, acv_file):
   _, nr_curves = unpack('!hh', acv_file.read(4))
   curves = []
   for i in xrange(0, nr_curves):
	 curve = []
	 num_curve_points, = unpack('!h', acv_file.read(2))
	 for j in xrange(0, num_curve_points):
	   y, x = unpack('!hh', acv_file.read(4))
	   curve.append((x,y))
	 curves.append(curve)

   return curves

 def _find_coefficients(self):
   polynomials = []
   for curve in self.curves:
	 xdata = [x[0] for x in curve]
	 ydata = [x[1] for x in curve]
	 p = interpolate.interp1d(xdata, ydata, kind='cubic')
	 polynomials.append(p)
   return polynomials

 def get_r(self):
   return self.polynomials[1]

 def get_g(self):
   return self.polynomials[2]

 def get_b(self):
   return self.polynomials[3]

 def get_c(self):
   return self.polynomials[0]
 def apply_filter(self, apply_to, new_filter):
	ncurves = len(apply_to.curves)
	curveno = 0
	for curve in apply_to.curves:
		newcurve = []
		p = self.polynomials[curveno]
		for (x,y) in curve:
			newcurve.append((x, numpy.floor(p(y)+0.5).clip(0,255)))
		curveno += 1
		new_filter.curves.append(newcurve)
	
	return #something if necessary filter_array.astype(numpy.uint8)

 def print_filter(self):
	print self.name
	for curve in self.curves:
		for (x, y) in curve:
			print x, y
class FilterManager:

 def __init__(self):
   self.filters = {}
   #add some stuff here

 def add_filter(self,filter_obj):
   # Overwrites if such a filter already exists
   # NOTE: Fix or not to fix?
   self.filters[filter_obj.name] = filter_obj

 
if __name__ == '__main__':

 if len(sys.argv) < 4:
	print "Wrong number of arguments"
	print """  Usage: \
			python catacv.py curvefile deltacurve resultcurve """
 else:
	img_filter = Filter('crgb')
	img_filter.read_from_file(sys.argv[1])
	delta_filter = Filter('delta')
	delta_filter.read_from_file(sys.argv[2])
	new_filter = Filter('new')

	filter_manager = FilterManager()
	filter_manager.add_filter(img_filter)
	filter_manager.add_filter(delta_filter)
	filter_manager.add_filter(new_filter)
	
	delta_filter.apply_filter(img_filter, new_filter)
	img_filter.print_filter()
	new_filter.print_filter()
	new_filter.write_to_file(sys.argv[3])