from FileMetadataExtractor import FileMetadataExtractor
import os
from RSS import ns
import PIL.Image
from Tags import Names
from time import strptime, strftime

class JpegExifExtractor(FileMetadataExtractor):
    def extract(self, f, item):
        if not os.path.splitext(f)[1] in (".jpg", ".jpeg"): return
        i = PIL.Image.open(f)
        exif = i._getexif()
        if exif is None: return
        
        def setString(exifTag, rdfTag):
            try:
                val = exif[exifTag]
                if val: item[rdfTag] = str(val)
            except KeyError:
                pass

        def setRational(exifTag, rdfTag):
            try:
                val = exif[exifTag]
                if val and len(val) == 2: item[rdfTag] = "%d/%d" % val
            except KeyError:
                pass

        def setDate(exifTag, rdfTag):
            try:
                val = exif[exifTag]
                if val:
                    t = strptime(val, "%Y:%m:%d %H:%M:%S")
                    item[rdfTag] = strftime("%Y-%m-%dT%H:%M:%SZ", t)
            except KeyError:
                pass

        setString (Names['ImageDescription'], (ns.exif, "imageDescription"))
        setString (Names['ImageDescription'], (ns.rss10, "title")) # TODO: change to desc
        setString (Names['Artist'], (ns.exif, "artist"))
        setString (Names['Artist'], (ns.dc, "creator"))
        setString (Names['DateTime'], (ns.exif, "dateTime"))
        setDate (Names['DateTime'], (ns.dc, "date"))
        setString (Names['Copyright'], (ns.dc, "rights"))

        setRational (Names['ExposureTime'], (ns.exif, "exposureTime"))
        setRational (Names['FNumber'], (ns.exif, "fNumber"))
        setString (Names['ISOSpeedRatings'], (ns.exif, "isoSpeedRatings"))
        setRational (Names['FocalLength'], (ns.exif, "focalLength"))