# 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.
"""utilities methods and classes for reporters

Copyright (c) 2000-2003 LOGILAB S.A. (Paris, FRANCE).
http://www.logilab.fr/ -- mailto:contact@logilab.fr
"""

import sys

CMPS = ['=', '-', '+']

def diff_string(old, new):
	"""given a old and new int value, return a string representing the
	difference
	"""
	diff = abs(old - new)
	diff_str = "%s%s" % (CMPS[cmp(old, new)], diff and ('%.2f' % diff) or '')
	return diff_str


class EmptyReport(Exception):
	"""raised when a report is empty and so should not be displayed"""

class BaseReporter:
	"""base class for reporters"""

	extension = ''

	def __init__(self, output=None):
		self.linter = None
		self.include_ids = None
		self.section = 0
		self.out = None
		self.set_output(output)

	def set_output(self, output=None):
		"""set output stream"""
		if output is None:
			output = sys.stdout
		self.out = output

	def writeln(self, string=''):
		"""write a line in the output buffer"""
#		print >> self.out, string
		pass

	def display_results(self, layout):
		"""display results encapsulated in the layout tree"""
		self.section = 0
		if self.include_ids and hasattr(layout, 'report_id'):
			layout.children[0].children[0].data += ' (%s)' % layout.report_id
		self._display(layout)

	def _display(self, layout):
		"""display the layout"""
		raise NotImplementedError()

