import locale, os
from urlparse import urljoin

import RSS
ns = RSS.ns

def _load_extractors(names):
    l = []
    for s in names:
        m = __import__(s, globals(), locals(), [])
        l.append(getattr(m, s)())
    return l

file_extractors = _load_extractors(("FileStatExtractor", "FileMimeExtractor", "StaticRDFExtractor", "PngCommentExtractor", "JpegCommentExtractor", "JpegExifExtractor", "ThumbnailFileExtractor"))
dir_extractors = _load_extractors(("DirTitleExtractor", "DirRDFExtractor"))

IMAGE_TYPES = (".png", ".jpg", ".jpeg")

sortingmap = {
    # TODO: extend to contain function? i.e. ((ns.rss10, 'title'), locale.strcoll)
    "date": (ns.dc, 'date'),
    "title": (ns.rss10, 'title')
    }

def generate_rss(path, baseurl, verbose=False):
    # Bit of a hack for os.path.basename to work
    if path[-1:] == '/': path = path[:-1]
    
    rss = RSS.TrackingChannel()
    
    channel = {}
    channel[(ns.rss10, "link")] = baseurl
    channel[(ns.dc, "title")] = os.path.basename(path)
    for extractor in dir_extractors:
        extractor.extract(path, channel)
    rss.setMD((ns.rss10, "channel"), channel)

    # TODO: remove the crappy thumbnail check
    files = [f for f in os.listdir(path) if not f.startswith("thumb-")] ; files.sort()
    for f in [os.path.join(path, f) for f in files]:
        if not os.path.isfile(f): continue
        if not os.path.splitext(f)[1] in IMAGE_TYPES: continue
        if verbose:
            import sys; sys.stderr.write("Scanning %s\n" % f)
        
        item = {}
        item[(ns.rss10, 'link')] = urljoin(baseurl, os.path.basename(f))
        item[(ns.rss10, 'title')] = os.path.splitext(os.path.basename(f))[0]
        item[(ns.dc, 'type')] = "image"
        for extractor in file_extractors:
            try:
                extractor.extract(f, item)
            except Exception,e:
                import sys; sys.stderr.write("Exception %s for %s\n" % (e, f))
        rss.addItem(item, -1)

    # Set rss:title from dc:title
    if not channel.has_key((ns.rss10, "title")):
        channel[(ns.rss10, "title")] = channel[(ns.dc, "title")]
    # Set rss:description from the optional dc:description
    if not channel.has_key((ns.rss10, "description")) and channel.has_key((ns.dc, "description")):
        channel[(ns.rss10, "description")] = channel[(ns.dc, "description")]
    # If there is not a channel-wide dc:date, set one now
    if not channel.has_key((ns.dc, "date")):
        from W3CDate import W3CDate
        latest = W3CDate("1970-01-01") # Dummy date, would like an epoch variable
        for item in [rss.getItem(i) for i in rss.listItems()]:
            thisdate = W3CDate(item[(ns.dc, "date")])
            if thisdate > latest: latest = thisdate
        channel[(ns.dc, "date")] = latest.getISO8601()

    # Possibly sort the RSS
    sortkey = channel.get((ns.rawk, "sort-key"), None)
    if (sortkey):
        sortorder = channel.get((ns.rawk, "sort-order"), None)
        def sorter(a, b):
            aa = rss.getItem(a)[key] ; bb = rss.getItem(b)[key]
            if sortorder == "up":
                return locale.strcoll(aa, bb)
            else:
                return locale.strcoll(bb, aa)
        key = sortingmap[sortkey]
        rss.listItems().sort(sorter)

    return rss