import os, time, md5
from sugar import env
from sugar import util

class BuddyIconCache(object):
	"""Caches icons on disk and finds them based on md5 hash."""
	def __init__(self):
		ppath = env.get_profile_path()
		self._cachepath = os.path.join(ppath, "cache", "buddy-icons")
		if not os.path.exists(self._cachepath):
			os.makedirs(self._cachepath)

		self._cache = {}

		# Read all cached icons and their sums
		for fname in os.listdir(self._cachepath):
			m = md5.new()
			data = self._get_icon_data(fname)
			if len(data) == 0:
				continue
			m.update(data)
			printable_hash = util.printable_hash(m.digest())
			self._cache[printable_hash] = fname
			del m

	def _get_icon_data(self, fname):
		fd = open(os.path.join(self._cachepath, fname), "r")
		data = fd.read()
		fd.close()
		del fd
		return data

	def get_icon(self, printable_hash):
		if not isinstance(printable_hash, unicode):
			raise RuntimeError("printable_hash must be a unicode string.")
		try:
			fname = self._cache[printable_hash]
			return self._get_icon_data(fname)
		except KeyError:
			pass
		return None

	def add_icon(self, icon_data):
		if len(icon_data) == 0:
			return

		m = md5.new()
		m.update(icon_data)
		printable_hash = util.printable_hash(m.digest())
		if self._cache.has_key(printable_hash):
			del m
			return

		# Write the icon to disk and add an entry to our cache for it
		m.update(time.asctime())
		fname = util.printable_hash(m.digest())
		fd = open(os.path.join(self._cachepath, fname), "w")
		fd.write(icon_data)
		fd.close()
		self._cache[printable_hash] = fname
		del m