"""
Find out if Numeric of numarray is going to be used as its array package

WARNING: PyGSL has used Numeric as its core. This is to test to see
if we can support both, but sooner or later the favour has to be given
to one of these packages.

When imported this module:
     1.) Looks on the command line if it can find a flag of type
         --array-object=[Numeric|nummarray]

     2.) Tries to import these modules.

     3.) Tries to use the preferred one.

     4.) Or goes with the other one found
     
         
"""
import re
import string
import sys
import os
from distutils.errors import DistutilsModuleError


packagedir = os.path.dirname(os.path.abspath(__file__))
includedir = os.path.join(packagedir, "Include", "pygsl")
pygsldir   = os.path.join(packagedir, "pygsl")
def extractpattern():
	"""
	Try to find if the array object was specified at the command line
	"""
	array_pattern = re.compile("--array-object=(.+)")
	pos=0
	array_preference = None

	result = ""
	while pos<len(sys.argv):
		match=array_pattern.match(sys.argv[pos])
		if match:
		    result=match.group(1)
		    result.strip()
		    sys.argv[pos:pos+1]=[]
		    break
		pos+=1
	return result	

def switchpreference(array_preference):
	"""
	Find out if the set preference can be used ...
	"""
	have_numeric = 0
	have_numarray = 0
	use_numeric = 0
	use_numarray = 0
	try:
		import Numeric
		have_numeric = 1
	except ImportError:
		pass

	try:
		import numarray
		have_numarray = 1
	except ImportError:
		pass

	#array_preference = 'numarray'
	if array_preference != None:
	    if array_preference == 'Numeric':
		if have_numeric == 1:
		    use_numeric = 1
		else:
		    print "Did not find the Numeric module you asked for"            
	    else:
		if array_preference == 'numarray':
		    if have_numarray == 1:
			use_numarray = 1
		    else:
			print "Did not find the numarray module you asked for"

	if use_numeric == 0 and use_numarray == 0:            
	    if have_numeric == 1:
		use_numeric = 1
	    elif have_numarray == 1:
		use_numarray = 1
	    else:
		raise  DistutilsModuleError, "I need either Numeric or nummarray!"

	if use_numeric == 1:
		#print "Using Numeric as array Package"
		use_numarray = 0
		nummodule = "Numeric"

	elif use_numarray == 1:    
		#print "Using nummarray as array Package"
		use_numeric = 0
		nummodule = "numarray"
	else:
		raise  DistutilsModuleError, "I need either Numeric or nummarray!"
	return nummodule

def writenumobj(nummodule):
	# Write the chosen module to a file so it is automatically inculded when pygsl starts up
	file = open(os.path.join(pygsldir, "_numobj.py"), "w")
	warnmsg = """
	       WARNING: File Generated during build. DO NOT MODIFY!!!
	"""
	file.write('"""\n')
	file.write(warnmsg)
	file.write('"""\n')
	file.write('\n')
	file.write('from %s import *\n\n' % nummodule)
	file.write('nummodule = "%s"\n' % nummodule)
	file.close()
	del file

	# Write the chosen module to a include header
	file = open(os.path.join(includedir, "arrayobject.h"), "w")
	file.write('/*')
	file.write(warnmsg)
	file.write('*/\n')
	#file.write('#include <%s/arrayobject.h>\n' % nummodule)
	file.write('#define PyGSL_%s 1\n' % string.upper(nummodule))
	file.close()
	del file

	# Write the chosen module to a include header
	file = open(os.path.join(pygsldir, "_mlab.py"), "w")
	file.write('"""\n')
	file.write(warnmsg)
	file.write('"""\n')
	if nummodule == "Numeric":
		file.write('from MLab import *\n')
	elif nummodule == "numarray":
		file.write('from numarray.linear_algebra.mlab import *\n')
	else:
		raise ValueError, "Unknown array object ", nummodule
	file.close()
	del file


def read_numobj():
	"""
	read the nummodule from the file
	"""
	path = os.path.join(pygsldir, "_numobj.py")
	g = {}
	l = {}
	execfile(path, g, l)
	return l['nummodule']

def build_guess():
	"""
	Find out which array module to use ...
	"""
	# See if --array-object was given on the command line
	tmp =  extractpattern()
	# If not return the last selection if possible ....
	if tmp == "":
		try:
			return  read_numobj()
		except IOError:
			print "No Numobj was selected, trying to find one."
			pass		
		except ImportError:
			print "Array object found in pygsl._numobj can not be importet!"
			pass
		
	# If given, find out if it can be used ...	
	nummodule = switchpreference(tmp)
	# find out if it is a change ...
	last = None
	try:
		last = read_numobj()
	except IOError:
		pass 
	if last == None or last != nummodule:
		print "Please make sure that all modules are built with the same setting."
		print "e.g. remove the build directory and start the build process again!"
		writenumobj(nummodule)
	return nummodule

def read_from_numobj():
	try:
		return read_numobj()
	except IOError:
		return build_guess()	

nummodule = None

if "build" in sys.argv:
	nummodule = build_guess()
else:
	nummodule = read_from_numobj()
assert(nummodule)

print "Using '%s' as array object" %  nummodule