#!/usr/bin/env python
# -*- coding: utf-8 -*-

# This file is part of passerelle-atreal-openads - a Publik connector to openADS
#
# Copyright (C) 2019 Atreal
#
# This program is free software: you can redistribute it and/or modify it
# under the terms of the GNU Affero General Public License as published
# by the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

"""Utilities functions."""

import json
import base64
import datetime
import re
import hashlib
import copy
import mimetypes
import sys

from django.urls import reverse_lazy
from django.utils import six
from django.utils.encoding import force_text
from django.utils.six.moves.html_parser import HTMLParser


def to_dash_case(camel_str):
    """Convert a string formatted from camel case to dash case (like snake case with dash)."""
    converted = re.sub('(.)([A-Z][a-z]+)', r'\1-\2', camel_str)
    return re.sub('([a-z0-9])([A-Z])', r'\1-\2', converted).lower()


# from: https://stackoverflow.com/a/13848698
def force_encoded_string_output(func, default_enc='utf-8'):
    """Decorator function that return the result converted to str type."""
    if sys.version_info.major < 3:
        def _func(*args, **kwargs):
            return func(*args, **kwargs).encode(sys.stdout.encoding or default_enc)
        return _func
    return func


class MLStripper(HTMLParser, object):
    """HTML parser that removes html tags."""
    def __init__(self):
        super(MLStripper, self).__init__()
        self.fed = []

    def handle_data(self, data):
        self.fed.append(data)

    def get_data(self):
        """Get the stripped data as a string."""
        return ''.join(self.fed)


def strip_tags(html):
    """Remove html tags from a string."""
    stripper = MLStripper()
    stripper.feed(html)
    return stripper.get_data()


def clean_spaces(text):
    """Remove extra spaces an line breaks from a string."""
    text = text.replace('\n', ' ')
    text = text.replace('\r', ' ')
    text = text.replace('\t', ' ')
    text = text.replace('\\n', ' ')
    text = text.replace('\\r', ' ')
    text = text.replace('\\t', ' ')
    return re.sub(r'  +', ' ', text).strip()


def normalize(value):
    """Normalize a value to be send to openADS.API."""
    if value is None:
        return ''
    if not isinstance(value, six.text_type):
        value = force_text(value)
    return clean_spaces(value)


def get_file_data(path, b64=True):
    """Return the content of a file as a string, in base64 if specified."""
    with open(path, 'rb') as file_pt:
        if b64:
            return base64.b64encode(file_pt.read())
        return file_pt.read()


# copy-pasted from 'wcs/qommon/misc.py'
def get_file_digest(content, chunk_size=100000):
    """Return a hash for the content specified."""
    digest = hashlib.sha256()
    content.seek(0)

    def read_chunk():
        """Read 'chunk_size' amount of data from the content."""
        return content.read(chunk_size)

    for chunk in iter(read_chunk, b''):
        digest.update(chunk)
    return digest.hexdigest()


def get_upload_path(instance, filename=None):
    """Return a relative upload path for a file."""
    fn_ref = instance.orig_filename if instance.orig_filename else filename
    # file_hash and content_type attribute are updated on file save()
    # so if the file was not yet saved, it may have those attributes undefined
    # this is why we update them here, if they are empty
    instance.update_file_hash(only_if_empty=True)
    instance.update_content_type(only_if_empty=True)
    # be careful:
    #   * openADS accept only filename less than 50 chars
    #   * name should be unique, even if the content is the same
    return 'to_openADS__%s__%s%s' % (
        datetime.datetime.now().strftime('%Y-%m-%d_%Hh%Mm%Ss%f'),
        instance.file_hash[:4],
        get_file_extension(fn_ref, instance.content_type)[:5]
    )


def get_file_extension(filename, mimetype=None):
    """Return the extension of the file, according to its filename or specified mimetype."""
    file_extension = None
    if filename and '.' in filename:
        file_extension = re.sub(r'^.*\.', '.', filename)
    elif mimetype:
        file_extension = mimetypes.guess_extension(mimetype)
    return file_extension if file_extension else ''


# pylint: disable=invalid-encoded-data
def trunc_str_values(value, limit, visited=None, truncate_text=u'…'):
    """Truncate a string value (not dict keys) and append a truncate text."""

    if visited is None:
        visited = []
    if value not in visited:
        if isinstance(value, six.string_types) and len(value) > limit:
            value = value[:limit] + truncate_text
        elif isinstance(value, (dict, list, tuple)):
            visited.append(value)
            iterator = value.iteritems() if isinstance(value, dict) else enumerate(value)
            for _key, _value in iterator:
                value[_key] = trunc_str_values(_value, limit, visited, truncate_text)
    return value


@six.python_2_unicode_compatible
class DictDumper(object):
    """Helper to dump a dictionary to a string representation with lazy processing.

       Only applied when dict is converted to string (lazy processing):
         - long strings truncated (after the dict has been 'deep' copied)
         - (optionaly) dict converted with json.dumps instead of unicode().
    """

    def __init__(self, dic, max_str_len=255, use_json_dumps=True):
        """ arguments:
             - dic             string   the dict to dump
             - max_str_len     integer  the maximul length of string values
             - use_json_dumps  boolean  True to use json.dumps() else it uses unicode()
        """
        self.dic = dic
        self.max_str_len = max_str_len
        self.use_json_dumps = use_json_dumps

    @force_encoded_string_output
    def __repr__(self):
        return u'DictDumper(dic=%r,max_str_len=%r,use_json_dumps=%r)' % (
            self.dic, self.max_str_len, self.use_json_dumps)

    def __str__(self):
        dict_trunc = trunc_str_values(copy.deepcopy(self.dic), self.max_str_len)
        dict_ref = json.dumps(dict_trunc) if self.use_json_dumps else dict_trunc
        return force_text(dict_ref)


class BaseModel(object):
    """A class that provide basic usefull functions.
       Intended for all models to extends it.
    """

    @classmethod
    def get_verbose_name(cls):
        """Return the verbose name of the class (helper for META option)."""
        # pylint: disable=no-member
        return cls._meta.verbose_name

    @classmethod
    def get_verbose_name_plural(cls):
        """Return the plural form of the verbose name of the class (helper for META option)."""
        # pylint: disable=no-member
        return cls._meta.verbose_name_plural

    @classmethod
    def get_class_name(cls):
        """Return the object class name."""
        return cls.__name__

    @classmethod
    def get_class_name_plural(cls):
        """Return the plural form of the object class name."""
        return cls.get_class_name() + 's'

    @classmethod
    def get_class_name_dash_case(cls):
        """Return the object class name formatted to dash case."""
        return to_dash_case(cls.get_class_name())

    @classmethod
    def get_class_name_plural_dash_case(cls):
        """Return the plural form of the object class name
           formatted to dash case.
        """
        return to_dash_case(cls.get_class_name_plural())

    @classmethod
    def get_class_name_title(cls):
        """Return the object class name formatted to 'title' case."""
        return cls.get_class_name_dash_case().replace('-', ' ').title()

    @classmethod
    def get_class_name_plural_title(cls):
        """Return the plural form of the object class name
           formatted to 'title' case.
        """
        return cls.get_class_name_plural_dash_case().replace('-', ' ').title()

    @classmethod
    def get_fields(cls):
        """Return the fields of the class (helper for META option)."""
        # pylint: disable=no-member
        return cls._meta.get_fields(include_parents=True, include_hidden=False)

    @force_encoded_string_output
    def __str__(self):
        return force_text(self)

    # mainly for the view
    def get_fields_kv(self):
        """Return the model's list of field's key value."""
        # pylint: disable=no-member
        return [(field, getattr(self, field.name, None)) for field in self._meta.get_fields()]

    def get_url_name(self, prefix='', plural=False):
        """Return a base name for url for this object."""
        class_name_dash_case = self.__class__.get_class_name_dash_case()
        if plural:
            class_name_dash_case = self.__class__.get_class_name_plural_dash_case()
        return '%s%s' % (prefix + '-' if prefix else '', class_name_dash_case)

    def get_url_params(self, primary_key=True):
        """Return the parameters for 'reverse()' to build url for this object."""
        # pylint: disable=no-member
        return {'pk': self.id} if primary_key else {}

    def get_absolute_url(self):
        """Return the 'absolute' url for this object."""
        return reverse_lazy(self.get_url_name('view'), kwargs=self.get_url_params())

    def get_edit_url(self):
        """Return the 'edit' url for this object."""
        return reverse_lazy(self.get_url_name('edit'), kwargs=self.get_url_params())

    def get_delete_url(self):
        """Return the 'delete' url for this object."""
        return reverse_lazy(self.get_url_name('delete'), kwargs=self.get_url_params())

    def get_list_url(self):
        """Return the 'list' url for this object."""
        return reverse_lazy(self.get_url_name('list', True), kwargs=self.get_url_params(False))