try:
    from mod_python import apache, util
except ImportError:
    from dummy import apache, util
import py

from base import handler_decorator

class thumbnail(handler_decorator):
    """generate and return a thumbnail for an image"""

    def __init__(self, size, 
            condition=lambda r: 'thumbnail' in r.path_info.split('/')):
        self.size = size
        self.condition = condition
        
    def handler(self, orghandler, request):
        from mimetypes import guess_type
    
        # load the original data (maybe from cache)
        # see if they want a thumbnail
        if not self.condition(request):
            return orghandler(request)

        fpath = py.path.local(request.filename)
        cached = self.get_cached(request)
        if cached is not None:
            request.content_type = guess_type(fpath.basename)[0]
            return cached
        data = orghandler(request)

        if (not request.content_type.startswith('image/') or
                type(data) not in [str, unicode]):
            return data
        
        tdata = self.create_thumbnail(fpath, data, request.content_type)
        self.cache(fpath, tdata)
        return tdata

    def create_thumbnail(self, fpath, data, itype):
        from PIL import Image
        from StringIO import StringIO
        image = Image.open(StringIO(data))
        image.thumbnail((self.size, self.size), Image.ANTIALIAS)
        s = StringIO()
        image.save(s, itype.split('/')[1])
        return s.getvalue()

    # XXX should lock here, not thread-safe!!!
    def get_cached(self, request):
        fpath = py.path.local(request.filename)
        cpath = self.create_cachepath(fpath)
        tdata = None
        if not cpath.check() or cpath.mtime() < fpath.mtime():
            return None
        return cpath.read()

    def create_cachepath(self, fpath):
        return fpath.dirpath() / ('.thumbnail_%s' % (fpath.basename,))

    def cache(self, fpath, data):
        cpath = self.create_cachepath(fpath)
        cpath.write(data)