#!/usr/bin/env python
# -*- coding: utf-8 -*-

# ***************************************************************************
# *   Copyright (C) 2015, Paul Lutus                                        *
# *                                                                         *
# *   This program is free software; you can redistribute it and/or modify  *
# *   it under the terms of the GNU General Public License as published by  *
# *   the Free Software Foundation; either version 2 of the License, or     *
# *   (at your option) any later version.                                   *
# *                                                                         *
# *   This program is distributed in the hope that it will be useful,       *
# *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
# *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
# *   GNU General Public License for more details.                          *
# *                                                                         *
# *   You should have received a copy of the GNU General Public License     *
# *   along with this program; if not, write to the                         *
# *   Free Software Foundation, Inc.,                                       *
# *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
# ***************************************************************************

# Created on Nov 12, 2015 11:43:51 AM

from sympy import *

import re,sys,os

# in LaTeX rendering, this separates
# certain two-letter variables for readability

def padspace(s):
  return re.sub(r'(fv|ir|pv|pb|pmt|np)',r'\1\,',s)

var('pv fv np pmt ir pb')

# the base equation from which all others are derived

bfa = ((pb*ir+1)*pmt-(ir+1)**np*((pb*ir*pmt)+pmt+ir*pv))/ir
bfe = fv - bfa

print('Base financial equation:\n')

eq = Equality(fv,bfa)

pprint(eq)

print('In LaTeX form:\n')

pprint(padspace(latex(eq)))

for lat in (True,False):
  print('\n*** Result for %s' % ('viewing','Webpage')[lat])
  results = []
  # for payment at end|beginning
  for p in (0,1):
    print('\n*** Payment at %s\n' % ('End','Beginning')[p])
    # solve for each variable
    for v in (pv,fv,np,pmt):
      q = solve(bfe,v)[0].subs({pb:p}).simplify()
      results.append(q)
      # create insertable LaTeX block for Web page
      if(lat):
        print(r'\begin{equation}')
        print(str(v) + ' = ' + padspace(latex(q)))
        print(r'\end{equation}')
      else:
        pprint(Equality(v,q))

# declare functional forms of the equations
  
fpv = lambdify((fv,np,pmt,ir),results[0])
ffv = lambdify((pv,np,pmt,ir),results[1])
fnp = lambdify((pv,fv,pmt,ir),results[2])
fpmt = lambdify((pv,fv,np,ir),results[3])

ppmt = fpmt(0,100000,200,0.01)

print('\nExample problem:\n')
  
# test the functions for consistency
# using an example problem
  
print(ffv(0,200,ppmt,0.01))
print(fpv(100000,200,ppmt,0.01))
print(fpmt(0,100000,200,0.01))
print(fnp(0,100000,ppmt,0.01))
  
print('\nRound Robin Calculation:\n')

y = ffv(0,200,ppmt,0.01)
print(y)
x = fpv(y,200,ppmt,0.01)
print(x)