"""Guess the MIME type of a file.

This module defines two useful functions:

guess_type(url) -- guess the MIME type and encoding of a URL.

guess_extension(type) -- guess the extension for a given MIME type.

It also contains the following, for tuning the behavior:

Data:

knownfiles -- list of files to parse
inited -- flag set when init() has been called
suffixes_map -- dictionary mapping suffixes to suffixes
encodings_map -- dictionary mapping suffixes to encodings
types_map -- dictionary mapping suffixes to types

Functions:

init([files]) -- parse a list of files, default knownfiles
read_mime_types(file) -- parse one file, return a dictionary or None

"""

import string
import posixpath

knownfiles = [
    "/usr/local/etc/httpd/conf/mime.types",
    "/usr/local/lib/netscape/mime.types",
    ]

inited = 0

def guess_type(url):
    """Guess the type of a file based on its URL.

    Return value is a tuple (type, encoding) where type is None if the
    type can't be guessed (no or unknown suffix) or a string of the
    form type/subtype, usable for a MIME Content-type header; and
    encoding is None for no encoding or the name of the program used
    to encode (e.g. compress or gzip).  The mappings are table
    driven.  Encoding suffixes are case sensitive; type suffixes are
    first tried case sensitive, then case insensitive.

    The suffixes .tgz, .taz and .tz (case sensitive!) are all mapped
    to ".tar.gz".  (This is table-driven too, using the dictionary
    suffix_map).

    """
    if not inited:
        init()
    base, ext = posixpath.splitext(url)
    while suffix_map.has_key(ext):
        base, ext = posixpath.splitext(base + suffix_map[ext])
    if encodings_map.has_key(ext):
        encoding = encodings_map[ext]
        base, ext = posixpath.splitext(base)
    else:
        encoding = None
    if types_map.has_key(ext):
        return types_map[ext], encoding
    elif types_map.has_key(string.lower(ext)):
        return types_map[string.lower(ext)], encoding
    else:
        return None, encoding

def guess_extension(type):
    """Guess the extension for a file based on its MIME type.

    Return value is a string giving a filename extension, including the
    leading dot ('.').  The extension is not guaranteed to have been
    associated with any particular data stream, but has been known to be
    used for streams of the MIME type given by `type'.  If `type' is not
    known, None is returned.
    """
    type = string.lower(type)
    for ext, stype in types_map.items():
        if type == stype:
            return ext
    return None

def init(files=None):
    global inited
    for file in files or knownfiles:
        s = read_mime_types(file)
        if s:
            for key, value in s.items():
                types_map[key] = value
    inited = 1

def read_mime_types(file):
    try:
        f = open(file)
    except IOError:
        return None
    map = {}
    while 1:
        line = f.readline()
        if not line: break
        words = string.split(line)
        for i in range(len(words)):
            if words[i][0] == '#':
                del words[i:]
                break
        if not words: continue
        type, suffixes = words[0], words[1:]
        for suff in suffixes:
            map['.'+suff] = type
    f.close()
    return map

suffix_map = {
    '.tgz': '.tar.gz',
    '.taz': '.tar.gz',
    '.tz': '.tar.gz',
}

encodings_map = {
    '.gz': 'gzip',
    '.Z': 'compress',
    }

types_map = {
    '.a': 'application/octet-stream',
    '.ai': 'application/postscript',
    '.aif': 'audio/x-aiff',
    '.aifc': 'audio/x-aiff',
    '.aiff': 'audio/x-aiff',
    '.au': 'audio/basic',
    '.avi': 'video/x-msvideo',
    '.bcpio': 'application/x-bcpio',
    '.bin': 'application/octet-stream',
    '.cdf': 'application/x-netcdf',
    '.cpio': 'application/x-cpio',
    '.csh': 'application/x-csh',
    '.dll': 'application/octet-stream',
    '.dvi': 'application/x-dvi',
    '.exe': 'application/octet-stream',
    '.eps': 'application/postscript',
    '.etx': 'text/x-setext',
    '.gif': 'image/gif',
    '.gtar': 'application/x-gtar',
    '.hdf': 'application/x-hdf',
    '.htm': 'text/html',
    '.html': 'text/html',
    '.ief': 'image/ief',
    '.jpe': 'image/jpeg',
    '.jpeg': 'image/jpeg',
    '.jpg': 'image/jpeg',
    '.latex': 'application/x-latex',
    '.man': 'application/x-troff-man',
    '.me': 'application/x-troff-me',
    '.mif': 'application/x-mif',
    '.mov': 'video/quicktime',
    '.movie': 'video/x-sgi-movie',
    '.mpe': 'video/mpeg',
    '.mpeg': 'video/mpeg',
    '.mpg': 'video/mpeg',
    '.ms': 'application/x-troff-ms',
    '.nc': 'application/x-netcdf',
    '.o': 'application/octet-stream',
    '.obj': 'application/octet-stream',
    '.oda': 'application/oda',
    '.pbm': 'image/x-portable-bitmap',
    '.pdf': 'application/pdf',
    '.pgm': 'image/x-portable-graymap',
    '.pnm': 'image/x-portable-anymap',
    '.png': 'image/png',
    '.ppm': 'image/x-portable-pixmap',
    '.py': 'text/x-python',
    '.pyc': 'application/x-python-code',
    '.ps': 'application/postscript',
    '.qt': 'video/quicktime',
    '.ras': 'image/x-cmu-raster',
    '.rgb': 'image/x-rgb',
    '.roff': 'application/x-troff',
    '.rtf': 'application/rtf',
    '.rtx': 'text/richtext',
    '.sgm': 'text/x-sgml',
    '.sgml': 'text/x-sgml',
    '.sh': 'application/x-sh',
    '.shar': 'application/x-shar',
    '.snd': 'audio/basic',
    '.so': 'application/octet-stream',
    '.src': 'application/x-wais-source',
    '.sv4cpio': 'application/x-sv4cpio',
    '.sv4crc': 'application/x-sv4crc',
    '.t': 'application/x-troff',
    '.tar': 'application/x-tar',
    '.tcl': 'application/x-tcl',
    '.tex': 'application/x-tex',
    '.texi': 'application/x-texinfo',
    '.texinfo': 'application/x-texinfo',
    '.tif': 'image/tiff',
    '.tiff': 'image/tiff',
    '.tr': 'application/x-troff',
    '.tsv': 'text/tab-separated-values',
    '.txt': 'text/plain',
    '.ustar': 'application/x-ustar',
    '.wav': 'audio/x-wav',
    '.xbm': 'image/x-xbitmap',
    '.xml': 'text/xml',
    '.xpm': 'image/x-xpixmap',
    '.xwd': 'image/x-xwindowdump',
    '.zip': 'application/zip',
    }