#!/usr/bin/python

import cgi
import pbutils
from os import getpid, path
from subprocess import call

MAIN_DIRECTORY = ""
BIN_CONVERT = "convert"
BIN_IDENTIFY = "identify"
BIN_COMPOSITE = "composite"

class Dither:
  def __init__(self, 
      input_file_path, 
      dither_file="1.png", 
      username="",
    ):

    self.nametag = "imDither";
    if username:
      self.username = username
    else:
      self.username = "";
    
    self.pid = str(getpid())
    self.dither_file = dither_file;
    self.original_file = input_file_path;
    self.MAX_NAME_LENGTH = 10;

    self.image_format = self.original_file.split(".")[-1]
    try:
      self.dimensions = pbutils.image_dimensions_and_test(self.original_file);
    except Exception as E:
      pbutils.error("Corrupt image")
    self.canvas_file = self.pid+"blank_canvas.png";
    self.makeCanvas();
    self.mask_file = self.pid+"mask_file"+"."+self.image_format;
    self.makeMask();
    self.result_file = self.makeResultFilename();
    self.fuseMask();

  def makeResultFilename(self):
    file_base, extension = path.splitext(self.original_file)
    if len(file_base) > self.MAX_NAME_LENGTH:
      file_base = file_base[0:self.MAX_NAME_LENGTH]
    return "%s_%s_%s%s%s" % (file_base, self.username, self.nametag, pbutils.now(), extension)

  #first step
  def makeCanvas(self):
    call([BIN_CONVERT,"-size",self.dimensions[0]+"x"+self.dimensions[1],"canvas:transparent", self.canvas_file])

  #second step use the Canvas as a background
  def makeMask(self):
    #tile the dither pattern on the canvas
    call([BIN_COMPOSITE,"-tile", self.dither_file, self.canvas_file, self.mask_file])
    
    #fuse the tiled file to create a mask
    #convert thebg.gif -compose Dst_In null: thefile.gif -matte -layers composite new.gif
    call([BIN_CONVERT, self.mask_file, "-compose", "Dst_In", "null:", self.original_file, "-matte", "-layers", "composite", self.mask_file])
    
    #cleanup
    call(["rm", self.canvas_file])
  
  #third step
  def fuseMask(self, fuse_mode="Pin_Light"):
    call([BIN_CONVERT, self.mask_file, "null:", self.original_file, "-matte", "-compose", fuse_mode, "-layers", "composite", self.result_file])
    call(["rm", self.mask_file])
  

if __name__ == "__main__":
  dither = Dither("./test.gif");