#!/usr/bin/env python

import sys
import os
import fileinput

INDEX_COLOR      = int(os.environ.get('DIFF_INDEX_COLOR', 32))
OLD_MODE_COLOR   = int(os.environ.get('DIFF_OLD_MODE_COLOR', 124))
NEW_MODE_COLOR   = int(os.environ.get('DIFF_NEW_MODE_COLOR', 28))
REMOVED_COLOR    = int(os.environ.get('DIFF_REMOVED_COLOR', 203))
ADDED_COLOR      = int(os.environ.get('DIFF_ADDED_COLOR', 2))
HUNK_START_COLOR = int(os.environ.get('DIFF_HUNK_START_COLOR', 32))

RESET_FORMAT = '\033[0m'
COLOR_FORMAT = '\033[38;5;%um'
BEGIN_REVERSE_FORMAT = '\033[7m'
END_REVERSE_FORMAT = '\033[27m'

# Everything in the unified diff format is identified by a prefix. The prefixes are:
# 'Index: ':    File marker (unified diff)
# 'diff --git': File marker (git-style diff)
# 'old mode':   File permissions mode before change
# 'new mode':   File permissions mode after change
# '---':        Defining '-' (giving the name and modification date of the file before change)
# '+++':        Defining '+' (giving the name and modification date of the file after change)
# '-':          Line before change (i.e., removed)
# '+':          Line after change (i.e., added)
# ' ':          Line that hasn't changed
# '@@':         Hunk start (@@ -start,length +start, length @@)
#
# We need to look for these prefixes in order, in order to handle '---'/'+++' before '-'/'+'. Hence the OrderedDict.
class OrderedDict(dict):
	def __init__(self, input=None):
		if input is None:
			self.keys = []
			super(OrderedDict, self).__init__()
		elif isinstance(input, dict):
			self.keys = list(input)
			super(OrderedDict, self).__init__(input)
		else:
			self.keys = [k for k, v in input]
			super(OrderedDict, self).__init__(input)
	def __iter__(self):
		return iter(self.keys)
	def __setitem__(self, k, v):
		if k not in self:
			self.keys.append(k)
		super(OrderedDict, self).__setitem__(k, v)
	def __delitem__(self, k):
		super(OrderedDict, self).__delitem__(k)
		self.keys.remove(k)

# Each value includes not only the terminal-config characters, but also the key, somewhere within it (possibly between two terminal-config strings).
# Theoretically, you could replace the key with some other string or leave it out entirely, if you wanted to, but I wouldn't recommend it.
prefixes = OrderedDict()
prefixes['---'] = (
	COLOR_FORMAT % (REMOVED_COLOR,)
	+ BEGIN_REVERSE_FORMAT 
	+ '---'
	+ END_REVERSE_FORMAT
)
prefixes['+++'] = (
	COLOR_FORMAT % (ADDED_COLOR,)
	+ BEGIN_REVERSE_FORMAT 
	+ '+++'
	+ END_REVERSE_FORMAT
)
prefixes['-'] = (
	COLOR_FORMAT % (REMOVED_COLOR,)
	+ BEGIN_REVERSE_FORMAT 
	+ '-'
	+ END_REVERSE_FORMAT
)
prefixes['+'] = (
	COLOR_FORMAT % (ADDED_COLOR,)
	+ BEGIN_REVERSE_FORMAT 
	+ '+'
	+ END_REVERSE_FORMAT
)
prefixes['old mode'] = ( # Git-style diffs only
	COLOR_FORMAT % (OLD_MODE_COLOR,)
	+ BEGIN_REVERSE_FORMAT 
	+ 'old mode'
	+ END_REVERSE_FORMAT
)
prefixes['new mode'] = ( # Git-style diffs only
	COLOR_FORMAT % (NEW_MODE_COLOR,)
	+ BEGIN_REVERSE_FORMAT 
	+ 'new mode'
	+ END_REVERSE_FORMAT
)
prefixes['Index: '] = COLOR_FORMAT % (INDEX_COLOR,) + 'Index: '
prefixes['diff --git '] = COLOR_FORMAT % (INDEX_COLOR,) + 'diff --git '
prefixes['@@'] = (
	COLOR_FORMAT % (HUNK_START_COLOR,)
	+ BEGIN_REVERSE_FORMAT
	+ '@@'
)

for line in fileinput.input():
	for prefix_to_test in prefixes:
		if line.startswith(prefix_to_test):
			sys.stdout.write(prefixes[prefix_to_test])
			line = line[len(prefix_to_test):]

	sys.stdout.write(line)

	sys.stdout.write(RESET_FORMAT)

print RESET_FORMAT