import os
import posixpath
import urllib
try:
    from cStringIO import StringIO
except ImportError:
    from StringIO import StringIO
from jinja2 import Environment, FileSystemLoader
import cgi
import sys

THIS_DIR = os.path.dirname(os.path.abspath(__file__))

class Mixin:
    def translate_path(self, path):
        """Translate a /-separated PATH to the local filename syntax.

        Components that mean special things to the local file system
        (e.g. drive or directory names) are ignored.  (XXX They should
        probably be diagnosed.)

        """
        # abandon query parameters
        path = path.split('?',1)[0]
        path = path.split('#',1)[0]
        path = posixpath.normpath(urllib.unquote(path))
        words = path.split('/')
        words = filter(None, words)
        path = os.getcwd()
        for word in words:
            drive, word = os.path.splitdrive(word)
            head, word = os.path.split(word)
            if word in (os.curdir, os.pardir): continue
            path = os.path.join(path, word)
        return path

    def list_directory(self, path):
        """Helper to produce a directory listing (absent index.html).

        Return value is either a file object, or None (indicating an
        error).  In either case, the headers are sent, making the
        interface the same as for send_head().

        """
        try:
            list = os.listdir(path)
        except os.error:
            self.send_error(404, "No permission to list directory")
            return None
        list.sort(key=lambda a: a.lower())
        f = StringIO()
        j2_env = Environment(loader=FileSystemLoader(THIS_DIR), trim_blocks=True)
        f.write(j2_env.get_template('templates/directory_listing.html').render(
            displayPath=cgi.escape(urllib.unquote(self.path)),
            list=list
        ))
        length = f.tell()
        f.seek(0)
        self.send_response(200)
        encoding = sys.getfilesystemencoding()
        self.send_header("Content-type", "text/html; charset=%s" % encoding)
        self.send_header("Content-Length", str(length))
        self.end_headers()
        return f

    def guess_type(self, path):
        """Guess the type of a file.

        Argument is a PATH (a filename).

        Return value is a string of the form type/subtype,
        usable for a MIME Content-type header.

        The default implementation looks the file's extension
        up in the table self.extensions_map, using application/octet-stream
        as a default; however it would be permissible (if
        slow) to look inside the data to make a better guess.

        """

        base, ext = posixpath.splitext(path)
        if ext in self.extensions_map:
            return self.extensions_map[ext]
        ext = ext.lower()
        if ext in self.extensions_map:
            return self.extensions_map[ext]
        else:
            return self.extensions_map['']
