import os
import shlex

from wizard import shell, util

def get_sql_credentials(vars=None):
    """
    Attempts to determine a user's MySQL credentials.  They are
    returned as a three-tuple (host, user, password).
    """
    sh = shell.Shell()
    host = os.getenv("WIZARD_MYSQL_HOST")
    user = os.getenv("WIZARD_MYSQL_USER")
    password = os.getenv("WIZARD_MYSQL_PASSWORD")
    if host is not None and user is not None and password is not None:
        return (host, user, password)
    # XXX: this is very fragile
    elif vars and "WIZARD_DBSERVER" in vars and "WIZARD_DBUSER" in vars and "WIZARD_DBPASSWORD" in vars:
        return (shlex.split(vars[x])[0] for x in ("WIZARD_DBSERVER", "WIZARD_DBUSER", "WIZARD_DBPASSWORD"))
    try:
        tuple = sh.eval("/mit/scripts/sql/bin/get-password").split()
        if len(tuple) == 3:
            return tuple
        return None
    except CallError:
        return None

def get_web_host_and_path(dir=None):
    """
    Attempts to determine webhost and path for the current directory
    as it would be accessible from the web.  Works only for scripts
    servers.  Returns a tuple web_host, web_path, or None if it failed.
    """
    # XXX: THIS CODE SUCKS
    host = os.getenv("WIZARD_WEB_HOST")
    path = os.getenv("WIZARD_WEB_PATH")
    if host is not None and path is not None:
        return (host, path)
    if not dir:
        dir = os.getcwd()
    _, _, web_path = dir.partition("/web_scripts")
    if not web_path:
        return None
    return (util.get_dir_owner(dir) + ".scripts.mit.edu", web_path)

def get_quota_usage_and_limit(dir=None):
    """
    Returns a tuple (quota usage, quota limit).  Works only for scripts
    servers.  Values are in KiB.  Returns ``(0, None)`` if we couldn't figure it out.
    """
    # XXX: The correct way is to implement Python modules implementing
    # bindings for all the appropriate interfaces
    def parse_last_quote(ret):
        return ret.rstrip('\'').rpartition('\'')[2]
    if dir is None:
        dir = os.getcwd()
    sh = shell.Shell()
    try:
        cell = parse_last_quote(sh.eval("fs", "whichcell", "-path", dir))
    except shell.CallError:
        return (0, None)
    mount = None
    while dir:
        try:
            volume = parse_last_quote(sh.eval("fs", "lsmount", dir))[1:]
            break
        except shell.CallError:
            dir = os.path.dirname(dir)
    if not volume: return (0, None)
    try:
        result = sh.eval("vos", "examine", "-id", volume, "-cell", cell).splitlines()
    except shell.CallError:
        return (0, None)
    usage = int(result[0].split()[3])
    limit = int(result[3].split()[1]) # XXX: FRAGILE
    return (usage, limit)

# XXX: Possibly in the wrong module
def get_disk_usage(dir=None):
    """
    Recursively determines the disk usage of a directory, excluding
    .git directories.  Value is in bytes.
    """
    if dir is None: dir = os.getcwd()
    return int(shell.Shell().eval("du", "--exclude=.git", "-s", dir).split()[0])