"""Finds device attributes from the graphcap

$Id: graphcap.py,v 1.5 2001/01/04 23:30:41 rlw Exp $
"""

import string, filecache

def merge(inlines):
	out = []
	outbuff = []
	for inline in inlines:
		tline = string.strip(inline)
		if len(tline) > 0 and tline[0] != '#':
			if tline[-1] == '\\':
				# continuation
				outbuff.append(tline[:-1])
			else:
				outbuff.append(tline)
				out.append(string.join(outbuff,''))
				outbuff = []
	return out

def getAliases(entry):
	# return list of aliases (and dump the comment)
	aend = string.find(entry,':')
	if aend<0:
		raise ValueError("Graphcap entry does not have any colons\n%s" % entry)
	return string.split(entry[:aend], "|")[:-1]

def getAttributes(entry):
	abeg = string.find(entry,':')
	if abeg<0:
		raise ValueError("Graphcap entry does not have any colons\n%s" % entry)
	astring = entry[abeg+1:]
	attr = {}
	attrlist = string.split(astring,':')
	for attrstr in attrlist:
		if string.strip(attrstr):
			attrname = attrstr[:2]
			attrval = attrstr[2:]
			if len(attrstr) <= 2:
				value = -1
			elif attrval[0] == '=':
				value = attrval[1:]
			elif attrval[0] == '#':
				try:
					value = int(attrval[1:])
				except ValueError:
					try:
						value = float(attrval[1:])
					except ValueError:
						print "problem reading graphcap"
						raise
			elif attrval[0] == '@':
				# implies false
				value = None
			else:
				# ignore silently, at least as long as IRAF has a bad
				# entry in its distribution (illegal colons)
				# print "problem reading graphcap attributes: ", attrstr
				# print entry
				pass
			attr[attrname] = value
	return attr

def getDevices(devlist):
	devices = {}
	for devdef in devlist:
		aliases = getAliases(devdef)
		attributes = getAttributes(devdef)
		for alias in aliases:
			devices[alias] = attributes
	return devices

class GraphCap(filecache.FileCache):

	"""Graphcap class that automatically updates if file changes"""

	def __init__(self, graphcapPath):
		filecache.FileCache.__init__(self, graphcapPath)

	def updateValue(self):
		"""Called on init and if file changes"""
		lines = open(self.filename,'r').readlines()
		mergedlines = merge(lines)
		self.dict = getDevices(mergedlines)

	def getValue(self):
		return self.dict

	def __getitem__(self, key):
		"""Get up-to-date version of dictionary"""
		dict = self.get()
		if not dict.has_key(key):
			print "Error: device not found in graphcap"
			raise KeyError
		return Device(dict, key)

	def has_key(self, key):
		dict = self.get()
		if dict.has_key(key):
			return 1
		else:
			return 0

class Device:

	def __init__(self, devices, devname):
		self.dict = devices
		self.devname = devname

	def getAttribute(self, attrName):
		dict = self.dict[self.devname]
		value = None
		while 1:
			if dict.has_key(attrName):
				value = dict[attrName]
				break
			else:
				if dict.has_key('tc'):
					nextdev = dict['tc']
					dict = self.dict[nextdev]
				else:
					break
		return value

	def __cmp__(self, other):
		if isinstance(other, Device):
			return cmp(id(self.dict[self.devname]),
					id(other.dict[other.devname]))
		else:
			return cmp(id(self), id(other))

	def __getitem__(self, key):
		return self.getAttribute(key)