#!/usr/bin/env python
# -*- coding: UTF-8 no BOM -*-

import os,sys,string,re,numpy
from optparse import OptionParser, OptionGroup, Option, SUPPRESS_HELP

# -----------------------------
class extendedOption(Option):
# -----------------------------
# used for definition of new option parser action 'extend', which enables to take multiple option arguments
# taken from online tutorial http://docs.python.org/library/optparse.html
    
    ACTIONS = Option.ACTIONS + ("extend",)
    STORE_ACTIONS = Option.STORE_ACTIONS + ("extend",)
    TYPED_ACTIONS = Option.TYPED_ACTIONS + ("extend",)
    ALWAYS_TYPED_ACTIONS = Option.ALWAYS_TYPED_ACTIONS + ("extend",)

    def take_action(self, action, dest, opt, value, values, parser):
        if action == "extend":
            lvalue = value.split(",")
            values.ensure_value(dest, []).extend(lvalue)
        else:
            Option.take_action(self, action, dest, opt, value, values, parser)



def outStdout(cmd,locals):
  if cmd[0:3] == '(!)':
    exec(cmd[3:])
  elif cmd[0:3] == '(?)':
    cmd = eval(cmd[3:])
    print cmd
  else:
    print cmd
  return

def outFile(cmd,locals):
  if cmd[0:3] == '(!)':
    exec(cmd[3:])
  elif cmd[0:3] == '(?)':
    cmd = eval(cmd[3:])
    locals['filepointer'].write(cmd+'\n')
  else:
    locals['filepointer'].write(cmd+'\n')
  return


def output(cmds,locals,dest):
  for cmd in cmds:
    if isinstance(cmd,list):
      output(cmd,locals,dest)
    else:
      {\
      'File': outFile,\
      'Stdout': outStdout,\
      }[dest](str(cmd),locals)
  return


# +++++++++++++++++++++++++++++++++++++++++++++++++++
def vtk_writeASCII_mesh(dim,res,data):
# +++++++++++++++++++++++++++++++++++++++++++++++++++
  """ function writes data array defined on a rectilinear grid """
  N  = res[0]*res[1]*res[2]
  
  cmds = [\
          '# vtk DataFile Version 3.1',
          string.replace('powered by $Id$','\n','\\n'),
          'ASCII',
          'DATASET RECTILINEAR_GRID',
          'DIMENSIONS %i %i %i'%(res[0]+1,res[1]+1,res[2]+1),
          'X_COORDINATES %i float'%(res[0]+1),
          ' '.join(map(str,[i*dim[0]/res[0] for i in range(res[0]+1)])),
          'Y_COORDINATES %i float'%(res[1]+1),
          ' '.join(map(str,[i*dim[1]/res[1] for i in range(res[1]+1)])),
          'Z_COORDINATES %i float'%(res[2]+1),
          ' '.join(map(str,[i*dim[2]/res[2] for i in range(res[2]+1)])),
          'CELL_DATA %i'%N,
         ]
  
  for datatype in data:
    for item in data[datatype]:
      cmds += [\
               '%s %s float'%(datatype.upper()+{True:'',False:'S'}[datatype.lower().endswith('s')],item),
               'LOOKUP_TABLE default',
               [[['\t'.join(map(str,data[datatype][item][:,j,k]))] for j in range(res[1])] for k in range(res[2])]
              ]

  return cmds


# ----------------------- MAIN -------------------------------

identifiers = {
        'resolution': ['a','b','c'],
        'dimension':  ['x','y','z'],
          }
mappings = {
        'resolution': lambda x: int(x),
        'dimension':  lambda x: float(x),
          }

parser = OptionParser(option_class=extendedOption, usage='%prog [geomfile[s]]', description = """
Produce VTK rectilinear mesh of structure data from geom description

""" + string.replace('$Id$','\n','\\n')
)

(options, filenames) = parser.parse_args()

# ------------------------------------------ setup file handles ---------------------------------------  

files = []
if filenames == []:
  files.append({'name':'STDIN', 'input':sys.stdin})
else:
  for name in filenames:
    if os.path.exists(name):
      files.append({'name':name, 'input':open(name)})

# ------------------------------------------ loop over input files ---------------------------------------  

for file in files:
  if file['name'] != 'STDIN': print file['name']

  #  get labels by either read the first row, or - if keyword header is present - the last line of the header

  firstline = file['input'].readline()
  m = re.search('(\d+)\s*head', firstline.lower())
  if m:
    headerlines = int(m.group(1))
    headers  = [file['input'].readline() for i in range(headerlines)]
  else:
    headerlines = 1
    headers = firstline

  content = file['input'].readlines()
  file['input'].close()
  
  resolution = [0,0,0]
  dimension = [0.0,0.0,0.0]
  for header in headers:
    headitems = header.split()
    if headitems[0] == 'resolution':         # located resolution entry
      for i in xrange(3):
        resolution[i] = mappings['resolution'](headitems[headitems.index(identifiers['resolution'][i])+1])
    if headitems[0] == 'dimension':          # located dimension entry
      for i in xrange(3):
        dimension[i] = mappings['dimension'](headitems[headitems.index(identifiers['dimension'][i])+1])

  if resolution == [0,0,0]:
    print 'no resolution info found.'
    sys.exit(1)
  if dimension == [0.0,0.0,0.0]:
    print 'no dimension info found.'
    sys.exit(1)

  print 'resolution: %s'%(' x '.join(map(str,resolution)))
  print 'dimension:  %s'%(' x '.join(map(str,dimension)))
  
  data = {'scalar':{'structure':numpy.zeros(resolution,'i')}}
  i = 0
  for line in content:  
    for item in map(int,line.split()):
      data['scalar']['structure'][i%resolution[0],(i/resolution[0])%resolution[1],i/resolution[0]/resolution[1]] = item
      i += 1


  out = {}
  out['mesh'] = vtk_writeASCII_mesh(dimension,resolution,data)
  
  for what in out.keys():
    if file['name'] == 'STDIN':
      output(out[what],{},'Stdout')
    else:
      (head,tail) = os.path.split(file['name'])
      vtk = open(os.path.join(head,what+'_'+os.path.splitext(tail)[0]+'.vtk'), 'w')
      output(out[what],{'filepointer':vtk},'File')
      vtk.close()