"""
This module is part of the 'blup' package and defines a font class as well as
some methods to load fonts from files and draw text on frames.

"""

import re

class FontFileError(Exception):
	def __init__(self, value):
		self.__value = value
	def __str__(self):
		return repr(self.__value) 

class Font(object):
	
	def __init__(self):
		self.__chars = {}
		self.__spacing = 1
		self.__height = -1
	
	@property
	def spacing(self):
		return self.__spacing
	
	@spacing.setter
	def spacing(self, value):
		if type(self.value) == int and self.value > 0:
			self.__spacing = value
		else:
			raise ValueError('illegal spacing given')

	@property
	def height(self):
		if self.__height == -1:
			raise ValueError('this font does not contain any characters')
		else:
			return self.__height
		
	def __setitem__(self, item, value):
		height = len(value)
		if self.__height == -1:
			self.__height = height
		elif height != self.__height:
			raise ValueError('character height does not match font height')

		if len(set(map(len, value))) != 1:
			raise ValueError('character lines differ in width')

		allowedValues = set([0,1])
		for line in value:
			if set(line) != allowedValues:
				raise ValueError('character contains invalid pixel value')

		self.__chars[item] = value
	
	def __getitem__(self, item):
		return self.__chars[item]


charPixels = None
def load(filename):
	f = open(filename, 'r')
	data = f.read()

	f = Font()
	for line in f:
		m = re.match('^\s*§(\d+)\s*$', line)
		if m:
			f.spacing = int(m.group(1))
			continue

		m = re.match('^\s*@(\d+)\|(\d+)\s*$', line)
		if m:
			charCode = int(m.group(1))
			charWidth = int(m.group(2))
			charPixels = []
			continue

		m = re.match('^\s*([01]+)\s*$', line)
		if m and charPixels != None:
			charRow = m.group(1)
			if len(charRow) < charWidth:
				raise FontFileError('char row does not contain enough pixels')
			row = []
			for i in xrange(charWidth):
				row.append(int(charRow[i]))
			charPixels.append(row)

			continue