import os.path
import numpy as npy
from collections import OrderedDict
from expread import expread
from expwrite import expwrite

def expcoarsen(newfile,oldfile,resolution):
	""" 
	EXPCOARSEN - coarsen an exp contour

	This routine read an Argus file and remove points with respect to
	the resolution (in meters) given in input. 

	Usage:
	  expcoarsen(newfile,oldfile,resolution)

	Example:
	   expcoarsen('DomainOutline.exp','Antarctica.exp',4000)
	""" 

	#Some checks
	if not os.path.exists(oldfile):
		raise OSError("expcoarsen error message: file '%s' not found!" % oldfile)
	if os.path.exists(newfile):
		choice=raw_input('A file ' + newfile + ' already exists, do you want to modify it? (y/n)')
		if choice not in 'y': 
			print('no modification done ... exiting')
			return 0

	#Get exp oldfile
	contours=expread(oldfile)
	newcontours=[]

	for contour in  contours:
		
		numpoints=npy.size(contour['x'])

		j=0
		x=contour['x']
		y=contour['y']

		#stop if we have reached end of profile (always keep the last point)
		while j<numpoints-1:

			#see whether we keep this point or not
			distance=npy.sqrt((x[j]-x[j+1])**2+(y[j]-y[j+1])**2)
			if distance<resolution and j<numpoints-2:   #do not remove last point
				x=npy.delete(x,j+1,0)
				y=npy.delete(y,j+1,0)
				numpoints=numpoints-1
			else:
				division=int(npy.floor(distance/resolution)+1)
				if division>=2:
					xi=npy.linspace(x[j],x[j+1],division)
					yi=npy.linspace(y[j],y[j+1],division)
					
					x=npy.hstack((x[0:j+1],xi[1:-1],x[j+1:]))
					y=npy.hstack((y[0:j+1],yi[1:-1],y[j+1:]))

					#update current point
					j=j+1+division-2
					numpoints=numpoints+division-2
				else:
					#update current point
					j=j+1
		
		if npy.size(x)>1:
			#keep the (x,y) contour arond
			newcontour=OrderedDict()
			newcontour['nods']=npy.size(x)
			newcontour['density']=contour['density']
			newcontour['x']=x
			newcontour['y']=y
			newcontours.append(newcontour)

	#write output
	expwrite(newcontours,newfile)