import re
import six
from six.moves import filter
from six.moves import map

import django
from django import forms
from django.core.files.uploadedfile import InMemoryUploadedFile
from django.forms.util import flatatt
from django.forms.widgets import FileInput
from django.template import Context
from django.template.loader import render_to_string
from django.utils import formats
from django.utils.encoding import force_text
from django.utils.html import format_html
from django.utils.safestring import mark_safe


class ImageInput(FileInput):
    """
    Widget providing a input element for file uploads based on the
    Django ``FileInput`` element. It hides the actual browser-specific
    input element and shows the available image for images that have
    been previously uploaded. Selecting the image will open the file
    dialog and allow for selecting a new or replacing image file.
    """
    template_name = 'partials/image_input_widget.html'
    attrs = {'accept': 'image/*'}

    def render(self, name, value, attrs=None):
        """
        Render the ``input`` field based on the defined ``template_name``. The
        image URL is take from *value* and is provided to the template as
        ``image_url`` context variable relative to ``MEDIA_URL``. Further
        attributes for the ``input`` element are provide in ``input_attrs`` and
        contain parameters specified in *attrs* and *name*.
        If *value* contains no valid image URL an empty string will be provided
        in the context.
        """
        final_attrs = self.build_attrs(attrs, type=self.input_type, name=name)
        if not value or isinstance(value, InMemoryUploadedFile):
            # can't display images that aren't stored
            image_url = ''
        else:
            image_url = final_attrs['value'] = force_text(
                self._format_value(value))

        return render_to_string(self.template_name, Context({
            'input_attrs': flatatt(final_attrs),
            'image_url': image_url,
            'image_id': "%s-image" % final_attrs['id'],
        }))


class WYSIWYGTextArea(forms.Textarea):

    def __init__(self, *args, **kwargs):
        kwargs.setdefault('attrs', {})
        kwargs['attrs'].setdefault('class', '')
        kwargs['attrs']['class'] += ' wysiwyg'
        super(WYSIWYGTextArea, self).__init__(*args, **kwargs)


def datetime_format_to_js_date_format(format):
    """
    Convert a Python datetime format to a date format suitable for use with JS
    date pickers
    """
    converted = format
    replacements = {
        '%Y': 'yy',
        '%m': 'mm',
        '%d': 'dd',
        '%H:%M': '',
    }
    for search, replace in replacements.items():
        converted = converted.replace(search, replace)
    return converted.strip()


def datetime_format_to_js_time_format(format):
    """
    Convert a Python datetime format to a time format suitable for use with JS
    date pickers
    """
    converted = format
    replacements = {
        '%Y': '',
        '%m': '',
        '%d': '',
        '%H': 'HH',
        '%M': 'mm',
    }
    for search, replace in replacements.items():
        converted = converted.replace(search, replace)

    converted = re.sub('[-/][^%]', '', converted)

    return converted.strip()


def add_js_formats(widget):
    """
    Set data attributes for date and time format on a widget
    """
    attrs = {
        'data-dateFormat': datetime_format_to_js_date_format(
            widget.format),
        'data-timeFormat': datetime_format_to_js_time_format(
            widget.format)
    }
    widget.attrs.update(attrs)


class DatePickerInput(forms.DateInput):
    """
    DatePicker input that uses the jQuery UI datepicker.  Data attributes are
    used to pass the date format to the JS
    """
    def __init__(self, *args, **kwargs):
        super(DatePickerInput, self).__init__(*args, **kwargs)
        add_js_formats(self)


class DateTimePickerInput(forms.DateTimeInput):
    # Build a widget which uses the locale datetime format but without seconds.
    # We also use data attributes to pass these formats to the JS datepicker.

    def __init__(self, *args, **kwargs):
        include_seconds = kwargs.pop('include_seconds', False)
        super(DateTimePickerInput, self).__init__(*args, **kwargs)

        # Django 1.7+ has format default as 0
        if django.VERSION >= (1, 7):
            self.format = self.format or formats.get_format(self.format_key)[0]

        if self.format and not include_seconds:
            self.format = re.sub(':?%S', '', self.format)
        add_js_formats(self)


class AdvancedSelect(forms.Select):
    """
    Customised Select widget that allows a list of disabled values to be passed
    to the constructor.  Django's default Select widget doesn't allow this so
    we have to override the render_option method and add a section that checks
    for whether the widget is disabled.
    """

    def __init__(self, attrs=None, choices=(), disabled_values=()):
        self.disabled_values = set(force_text(v) for v in disabled_values)
        super(AdvancedSelect, self).__init__(attrs, choices)

    def render_option(self, selected_choices, option_value, option_label):
        option_value = force_text(option_value)
        if option_value in self.disabled_values:
            selected_html = mark_safe(' disabled="disabled"')
        elif option_value in selected_choices:
            selected_html = mark_safe(' selected="selected"')
            if not self.allow_multiple_selected:
                # Only allow for a single selection.
                selected_choices.remove(option_value)
        else:
            selected_html = ''
        return format_html(u'<option value="{0}"{1}>{2}</option>',
                           option_value,
                           selected_html,
                           force_text(option_label))


class RemoteSelect(forms.Widget):
    """
    Somewhat reusable widget that allows AJAX lookups in combination with
    select2.
    Requires setting the URL of a lookup view either as class attribute or when
    constructing
    """
    is_multiple = False
    css = 'select2 input-xlarge'
    lookup_url = None

    def __init__(self, *args, **kwargs):
        if 'lookup_url' in kwargs:
            self.lookup_url = kwargs.pop('lookup_url')
        if self.lookup_url is None:
            raise ValueError(
                "RemoteSelect requires a lookup ULR")
        super(RemoteSelect, self).__init__(*args, **kwargs)

    def format_value(self, value):
        return six.text_type(value or '')

    def value_from_datadict(self, data, files, name):
        value = data.get(name, None)
        if value is None:
            return value
        else:
            return six.text_type(value)

    def render(self, name, value, attrs=None, choices=()):
        attrs = self.build_attrs(attrs, **{
            'type': 'hidden',
            'class': self.css,
            'name': name,
            'data-ajax-url': self.lookup_url,
            'data-multiple': 'multiple' if self.is_multiple else '',
            'value': self.format_value(value),
            'data-required': 'required' if self.is_required else '',
            })
        return mark_safe(u'<input %s>' % flatatt(attrs))


class MultipleRemoteSelect(RemoteSelect):
    is_multiple = True
    css = 'select2 input-xxlarge'

    def format_value(self, value):
        if value:
            return ','.join(map(six.text_type, filter(bool, value)))
        else:
            return ''

    def value_from_datadict(self, data, files, name):
        value = data.get(name, None)
        if value is None:
            return []
        else:
            return list(filter(bool, value.split(',')))