#! /usr/bin/python3 -t

PROG_DESC = "Outputs an SVG 'roadkill' diagram for said molecule"

import math; from math import sqrt,sin,cos,pi
import rn
import sys, os, re
import mformula
import mformula_oxocarbon
import mformula_svg


def image_name(style):
  fname = __file__
  imgname = re.sub(r'.*[/]', "", fname[0:-3]) + \
    "_style" + style
  return imgname

def image_descr(style):
  fname = __file__
  imgname = re.sub(r'.*[/]', "", fname[0:-3])
  descr = "Structural formula of " + re.sub(r'[_]', " ", imgname)
  descr += "\n" + \
    "\n" + \
    mformula_svg.style_descr(style)
  return descr

def build_formula(svg):
  ft = build_formula_third(svg) # The left third of the molecule.

  fm = mformula.obj()
  k0 = fm.add_subformula(ft, 0,  30, [0,0])
  k1 = fm.add_subformula(ft, 0, 150, [0,0])
  k2 = fm.add_subformula(ft, 0, 270, [0,0])
  fm.add_bond(k0+3,k1+0,1.5)
  fm.add_bond(k1+3,k2+0,1.5)
  fm.add_bond(k2+3,k0+0,1.5)
  return fm

def image_name(style):
  fname = __file__
  imgname = re.sub(r'.*[/]', "", fname[0:-3]) + \
    "_style" + style
  return imgname

def image_descr(style):
  fname = __file__
  imgname = re.sub(r'.*[/]', "", fname[0:-3])
  descr = "Structural formula of " + re.sub(r'[_]', " ", imgname)
  descr += "\n" + \
    "\n" + \
    mformula_svg.style_descr(style)
  return descr

def build_formula_third(svg) :
  "Builds the left 1/3 of the molecule, assumed centered at [0,0]."
  ft = mformula.obj()

  cb = svg.rel_bond_length(1.5) # Length of aromatic bonds.
  db = svg.rel_bond_length(2.0) # Relative length of double bonds.

  # Assume that the benzene ring stays hexagonal:
  R = cb                    # Radius of benzene ring.
  c30 = cos(30*pi/180)
  s30 = sin(30*pi/180)

  # Compute bending of the benzene-butylene bonds so that single bonds have length 1:
  a0 = math.asin(0.50 - R*s30) # Lift angle of radial C-C bonds.
  sys.stderr.write("a0 = %.2f\n" % (a0*180/pi))
  ca0 = cos(a0)
  sa0 = sin(a0)

  # Choose direction of C=O in carbonyls to bisect the corner andle:
  a2 = (a0 + pi/2.0)/2.0
  sys.stderr.write("a2 = %.2f\n" % (a2*180/pi))
  ca2 = cos(a2)
  sa2 = sin(a2)

  p0 = rn.scale(R, [-c30, +s30])              # Upper left carbon of benzene.
  p1 = rn.add(p0, [-ca0, +sa0])               # Upper left carbon of butylene.
  p2 = rn.add(p1, rn.scale(db, [-ca2, +sa2])) # Upper left oxygen of carboxyl.

  p3 = rn.scale(R, [-c30, -s30])              # Lower left carbon of benzene.
  p4 = rn.add(p3, [-ca0, -sa0])               # Lower left carbon of butylene.
  p5 = rn.add(p4, rn.scale(db, [-ca2, -sa2])) # Lower left oxygen of carboxyl.
  sys.stderr.write("p0--p1 = %7.5f\n" % rn.dist(p0,p1))
  sys.stderr.write("p1--p1' = %7.5f\n" % (2*p1[1]))

  k0 = ft.add_atom("C", p0, 0,0)
  k1 = ft.add_atom("C", p1, 0,0)
  k2 = ft.add_atom("O", p2, 0,0)
  k3 = ft.add_atom("C", p3, 0,0)
  k4 = ft.add_atom("C", p4, 0,0)
  k5 = ft.add_atom("O", p5, 0,0)
  ft.add_bond(k0,k3,1.5)
  ft.add_bond(k0,k1,1.0)
  ft.add_bond(k1,k2,2.0)
  ft.add_bond(k3,k4,1.0)
  ft.add_bond(k4,k5,2.0)
  ft.add_bond(k1,k4,1.0)
  return ft