import os.path
import ldap

def get_exception_name(output):
    """Reads the stderr output of another Python command and grabs the
    fully qualified exception name"""
    lines = output.split("\n")
    for line in lines[1:]: # skip the "traceback" line
        line = line.rstrip()
        if line[0] == ' ': continue
        if line[-1] == ":":
            return line[:-1]
        else:
            return line

def get_dir_user(dir):
    """Finds the username of the person who owns this directory, via LDAP.
    Only works for directories under web_scripts"""
    dir = os.path.realpath(dir)
    homedir, _, _ = dir.partition("/web_scripts")
    if homedir == dir: return None
    con = ldap.initialize('ldap://scripts.mit.edu')
    return con.search_s(
            "ou=People,dc=scripts,dc=mit,dc=edu", # base
            ldap.SCOPE_SUBTREE, # default
            "homeDirectory=" + homedir, # search
            ['uid'] # attr
        )[0][1]["uid"][0]  # unwrap the result

def get_dir_url(dir):
    """Finds the URL a path would correspond to in the filesystem"""
    _, _, path = dir.partition("/web_scripts")
    return "http://%s.scripts.mit.edu%s" % (get_dir_user(dir), path)