from datetime import datetime
import functools
import hashlib
import json

from dateutil.parser import parse
from sqlalchemy.types import TypeDecorator, TEXT
from flask import g, request, Markup
from markdown import markdown as md
import parsedatetime

from panoramix import db


class memoized(object):
   """Decorator that caches a function's return value each time it is called.
   If called later with the same arguments, the cached value is returned, and
   not re-evaluated.
   """
   def __init__(self, func):
      self.func = func
      self.cache = {}
   def __call__(self, *args):
      try:
         return self.cache[args]
      except KeyError:
         value = self.func(*args)
         self.cache[args] = value
         return value
      except TypeError:
         # uncachable -- for instance, passing a list as an argument.
         # Better to not cache than to blow up entirely.
         return self.func(*args)
   def __repr__(self):
      """Return the function's docstring."""
      return self.func.__doc__
   def __get__(self, obj, objtype):
      """Support instance methods."""
      return functools.partial(self.__call__, obj)


def parse_human_datetime(s):
    """
    Use the parsedatetime lib to return ``datetime.datetime`` from human
    generated strings

    >>> parse_human_datetime('2015-04-03')
    datetime.datetime(2015, 4, 3, 0, 0)
    >>> parse_human_datetime('2/3/1969')
    datetime.datetime(1969, 2, 3, 0, 0)
    >>> parse_human_datetime("now") <= datetime.now()
    True
    >>> parse_human_datetime("yesterday") <= datetime.now()
    >>> date.today() - timedelta(1) == parse_human_datetime('yesterday').date()
    True
    """
    try:
        dttm = parse(s)
    except:
        cal = parsedatetime.Calendar()
        dttm = dttm_from_timtuple(cal.parse(s)[0])
    return dttm


def dttm_from_timtuple(d):
    return datetime(
        d.tm_year, d.tm_mon, d.tm_mday, d.tm_hour, d.tm_min, d.tm_sec)


def merge_perm(sm, permission_name, view_menu_name):
    pv = sm.find_permission_view_menu(permission_name, view_menu_name)
    if not pv:
        sm.add_permission_view_menu(permission_name, view_menu_name)


def parse_human_timedelta(s):
    """
    Use the parsedatetime lib to return ``datetime.datetime`` from human
    generated strings

    >>> parse_human_datetime("now") <= datetime.now()
    True
    """
    cal = parsedatetime.Calendar()
    dttm = dttm_from_timtuple(datetime.now().timetuple())
    d = cal.parse(s, dttm)[0]
    d = datetime(
        d.tm_year, d.tm_mon, d.tm_mday, d.tm_hour, d.tm_min, d.tm_sec)
    return d - dttm


class JSONEncodedDict(TypeDecorator):
    """Represents an immutable structure as a json-encoded string."""
    impl = TEXT
    def process_bind_param(self, value, dialect):
        if value is not None:
            value = json.dumps(value)

        return value

    def process_result_value(self, value, dialect):
        if value is not None:
            value = json.loads(value)
        return value


class ColorFactory(object):
    BNB_COLORS = [
        "#007A87",
        "#00D1C1",
        "#565A5C",
        "#7B0051",
        "#898C8C",
        "#8CE071",
        "#4EDED2",
        "#4FA3AB",
        "#9CA299",
        "#A14D83",
        "#B4A76C",
        "#C9BF97",
        "#FF5A5F",
        "#FFAA91",
        "#FFB400",
        "#FFC4B3",
        "#FFCA4F",
    ]

    def __init__(self, hash_based=True):
        self.d = {}
        self.hash_based = hash_based

    def get(self, s):
        if self.hash_based:
            s = s.encode('utf-8')
            h = hashlib.md5(s)
            i = int(h.hexdigest(), 16)
        else:
            if s not in self.d:
                self.d[s] = len(self.d)
            i = self.d[s]
        return self.BNB_COLORS[i % len(self.BNB_COLORS)]


def init():
    """
    Inits the Panoramix application with security roles and such
    """
    from panoramix import appbuilder
    from panoramix import models
    from flask_appbuilder.security.sqla import models as ab_models
    sm = appbuilder.sm
    alpha = sm.add_role("Alpha")
    admin = sm.add_role("Admin")

    merge_perm(sm, 'all_datasource_access', 'all_datasource_access')

    perms = db.session.query(ab_models.PermissionView).all()
    for perm in perms:
        if perm.view_menu.name not in (
                'UserDBModelView', 'RoleModelView', 'ResetPasswordView',
                'Security'):
            sm.add_permission_role(alpha, perm)
        sm.add_permission_role(admin, perm)
    gamma = sm.add_role("Gamma")
    for perm in perms:
        s = perm.permission.name
        if(
                perm.view_menu.name not in (
                    'UserDBModelView',
                    'RoleModelView',
                    'ResetPasswordView',
                    'Security') and
                perm.permission.name not in (
                    'can_edit',
                    'can_add',
                    'can_save',
                    'can_download',
                    'muldelete',
                    'all_datasource_access',
                    'datasource_access',
                )):
            sm.add_permission_role(gamma, perm)
    session = db.session()
    table_perms = [
            table.perm for table in session.query(models.SqlaTable).all()]
    table_perms += [
            table.perm for table in session.query(models.Datasource).all()]
    for table_perm in table_perms:
        merge_perm(sm, 'datasource_access', table.perm)


def log_this(f):
    '''
    Decorator to log user actions
    '''
    @functools.wraps(f)
    def wrapper(*args, **kwargs):
        user_id = None
        if g.user:
            user_id = g.user.id
        from panoramix import models
        log = models.Log(
            action=f.__name__,
            json=json.dumps(request.args.to_dict()),
            user_id=user_id)

        db.session.add(log)
        db.session.commit()

        return f(*args, **kwargs)
    return wrapper


def datetime_f(dttm):
    if dttm:
        dttm = dttm.isoformat()
        now_iso = datetime.now().isoformat()
        if now_iso[:10] == dttm[:10]:
            dttm = dttm[11:]
        elif now_iso[:4] == dttm[:4]:
            dttm = dttm[5:]
    return Markup("<nobr>{}</nobr>".format(dttm))


def json_iso_dttm_ser(obj):
    """
    json serializer that deals with dates
    usage: json.dumps(object, default=utils.json_ser)
    """
    if isinstance(obj, datetime):
        obj = obj.isoformat()
    return obj


def markdown(s):
    return md(s, [
        'markdown.extensions.tables',
        'markdown.extensions.fenced_code',
        'markdown.extensions.codehilite',])


def readfile(filepath):
    with open(filepath) as f:
        content = f.read()
    return content