"""
PatchUtils.py

This module defines some functions for patching Python code.
"""

import string
import os

def AskYN(prompt):
	if os.name == 'mac':
		import EasyDialogs
		butn = EasyDialogs.AskYesNoCancel(prompt, default=9)
		if butn == 1: return 'Y'
		if butn == 0: return 'N'
		raise 'userCanceled'
	while 1:
		ans = raw_input(prompt)[:1]
		if ans=='y' or ans=='Y': return 'Y'
		if ans=='n' or ans=='N': return 'N'

class Patch:
	"class Patch: keeps info on one file being patched"
	
	def __init__(self, basepath, filename, idtag):
		"constructor: make a backup of the file, and read the contents into memory."
		self.path = os.path.join(basepath, filename)
		self.lines = []
		self._MakeBackup()
		self._Read()
		idtag = string.strip(idtag)
		
		patchnote = "### PATCHED: "
		patchnotelen = len(patchnote)
		patches = []
		i = 0
		while self.lines[i][:patchnotelen] == patchnote:
			patches.append(string.strip(self.lines[i][patchnotelen:]))
			i = i+1

		if patches:
			print "Previous patches:", string.join(patches)

		if idtag in patches:
			print "Patch '%s' has already been applied." % idtag
			if len(patches) > 1:
				print "WARNING: Removing patches will remove ALL previous patches!"
			if AskYN("Remove previous patches?") == 'Y': self._RestoreFromBackup()

		# finally, insert patch note
		self.lines.insert(0, patchnote + idtag + '\n')
			
	
	def _MakeBackup(self):
		try:
			# if we already have a backup file, do nothing
			open(self.path+".bak",'r')
			return
		except: pass
		fin = open(self.path,'r')
		fout = open(self.path+".bak",'w')
		fout.writelines(fin.readlines())

	def _RestoreFromBackup(self):
		print "Restoring %s from backup" % self.path
		self.lines = open(self.path+".bak",'r').readlines()		
		open(self.path,'w').writelines(self.lines)
		self.qtyLines = len(self.lines)

	def _Read(self):
		print "\nReading", self.path
		self.lines = open(self.path, 'r').readlines()
		self.qtyLines = len(self.lines)

	def Write(self):
		open(self.path, 'w').writelines(self.lines)
		print "%s lines written to %s" % (len(self.lines), self.path)
	
	def _FindLine(self, x, callerName):
		lineno = None
		for i in range(self.qtyLines):
			if string.find(self.lines[i], x) >= 0:
				if lineno is not None:
					raise callerName+"_NotUnique", x
				lineno = i
		if lineno is None:
			raise callerName+"_NotFound", x
		return lineno
		
	def InsertAfter(self, x, data):
		lineno = self._FindLine(x, "InsertAfter")
		# we've found it; now, insert after this line
		datalines = string.split(data,'\n')
		print "Inserting %d line(s) after line %d" % (len(datalines), lineno)
		for line in datalines:
			lineno = lineno + 1
			self.lines.insert(lineno, line+'\n')
		self.qtyLines = len(self.lines)
	
	def InsertBefore(self, x, data):
		lineno = self._FindLine(x, "InsertBefore")
		# we've found it; now, insert before this line
		datalines = string.split(data,'\n')
		print "Inserting %d line(s) before line %d" % (len(datalines), lineno)
		datalines.reverse()
		for line in datalines:
			self.lines.insert(lineno, line+'\n')
		self.qtyLines = len(self.lines)

	def ReplaceLine(self, x, data):
		lineno = self._FindLine(x, "ReplaceLine")
		# we've found it; now, replace this line with the given ones
		del self.lines[lineno]
		datalines = string.split(data,'\n')
		print "Substituting %d line(s) for line %d" % (len(datalines), lineno)
		for line in datalines:
			self.lines.insert(lineno, line+'\n')
			lineno = lineno + 1
		self.qtyLines = len(self.lines)