import re
import time
import pytz

from django import forms
from django.core.files.uploadedfile import SimpleUploadedFile
from django.core.exceptions import ObjectDoesNotExist
from django.forms.util import ErrorList
from django.utils.translation import ugettext_lazy as _
import requests

from boards.mdx_neboard import formatters
from boards.models.post import TITLE_MAX_LENGTH
from boards.models import Tag, Post
from neboard import settings
import boards.settings as board_settings


CONTENT_TYPE_IMAGE = (
    'image/jpeg',
    'image/png',
    'image/gif',
    'image/bmp',
)

REGEX_TAGS = re.compile(r'^[\w\s\d]+$', re.UNICODE)

VETERAN_POSTING_DELAY = 5

ATTRIBUTE_PLACEHOLDER = 'placeholder'
ATTRIBUTE_ROWS = 'rows'

LAST_POST_TIME = 'last_post_time'
LAST_LOGIN_TIME = 'last_login_time'
TEXT_PLACEHOLDER = _('Type message here. Use formatting panel for more advanced usage.')
TAGS_PLACEHOLDER = _('music images i_dont_like_tags')

LABEL_TITLE = _('Title')
LABEL_TEXT = _('Text')
LABEL_TAG = _('Tag')
LABEL_SEARCH = _('Search')

ERROR_SPEED = _('Please wait %s seconds before sending message')

TAG_MAX_LENGTH = 20

IMAGE_DOWNLOAD_CHUNK_BYTES = 100000

HTTP_RESULT_OK = 200

TEXTAREA_ROWS = 4


def get_timezones():
    timezones = []
    for tz in pytz.common_timezones:
        timezones.append((tz, tz),)
    return timezones


class FormatPanel(forms.Textarea):
    """
    Panel for text formatting. Consists of buttons to add different tags to the
    form text area.
    """

    def render(self, name, value, attrs=None):
        output = '<div id="mark-panel">'
        for formatter in formatters:
            output += '<span class="mark_btn"' + \
                      ' onClick="addMarkToMsg(\'' + formatter.format_left + \
                      '\', \'' + formatter.format_right + '\')">' + \
                      formatter.preview_left + formatter.name + \
                      formatter.preview_right + '</span>'

        output += '</div>'
        output += super(FormatPanel, self).render(name, value, attrs=None)

        return output


class PlainErrorList(ErrorList):
    def __unicode__(self):
        return self.as_text()

    def as_text(self):
        return ''.join(['(!) %s ' % e for e in self])


class NeboardForm(forms.Form):
    """
    Form with neboard-specific formatting.
    """

    def as_div(self):
        """
        Returns this form rendered as HTML <as_div>s.
        """

        return self._html_output(
            # TODO Do not show hidden rows in the list here
            normal_row='<div class="form-row">'
                       '<div class="form-label">'
                       '%(label)s'
                       '</div>'
                       '<div class="form-input">'
                       '%(field)s'
                       '</div>'
                       '</div>'
                       '<div class="form-row">'
                       '%(help_text)s'
                       '</div>',
            error_row='<div class="form-row">'
                      '<div class="form-label"></div>'
                      '<div class="form-errors">%s</div>'
                      '</div>',
            row_ender='</div>',
            help_text_html='%s',
            errors_on_separate_row=True)

    def as_json_errors(self):
        errors = []

        for name, field in list(self.fields.items()):
            if self[name].errors:
                errors.append({
                    'field': name,
                    'errors': self[name].errors.as_text(),
                })

        return errors


class PostForm(NeboardForm):

    title = forms.CharField(max_length=TITLE_MAX_LENGTH, required=False,
                            label=LABEL_TITLE)
    text = forms.CharField(
        widget=FormatPanel(attrs={
            ATTRIBUTE_PLACEHOLDER: TEXT_PLACEHOLDER,
            ATTRIBUTE_ROWS: TEXTAREA_ROWS,
        }),
        required=False, label=LABEL_TEXT)
    image = forms.ImageField(required=False, label=_('Image'),
                             widget=forms.ClearableFileInput(
                                 attrs={'accept': 'image/*'}))
    image_url = forms.CharField(required=False, label=_('Image URL'),
                                widget=forms.TextInput(
                                    attrs={ATTRIBUTE_PLACEHOLDER:
                                               'http://example.com/image.png'}))

    # This field is for spam prevention only
    email = forms.CharField(max_length=100, required=False, label=_('e-mail'),
                            widget=forms.TextInput(attrs={
                                'class': 'form-email'}))
    threads = forms.CharField(required=False, label=_('Additional threads'),
            widget=forms.TextInput(attrs={ATTRIBUTE_PLACEHOLDER:
                '123 456 789'}))

    session = None
    need_to_ban = False

    def clean_title(self):
        title = self.cleaned_data['title']
        if title:
            if len(title) > TITLE_MAX_LENGTH:
                raise forms.ValidationError(_('Title must have less than %s '
                                              'characters') %
                                            str(TITLE_MAX_LENGTH))
        return title

    def clean_text(self):
        text = self.cleaned_data['text'].strip()
        if text:
            if len(text) > board_settings.MAX_TEXT_LENGTH:
                raise forms.ValidationError(_('Text must have less than %s '
                                              'characters') %
                                            str(board_settings
                                            .MAX_TEXT_LENGTH))
        return text

    def clean_image(self):
        image = self.cleaned_data['image']

        if image:
            self.validate_image_size(image.size)

        return image

    def clean_image_url(self):
        url = self.cleaned_data['image_url']

        image = None
        if url:
            image = self._get_image_from_url(url)

            if not image:
                raise forms.ValidationError(_('Invalid URL'))
            else:
                self.validate_image_size(image.size)

        return image

    def clean_threads(self):
        threads_str = self.cleaned_data['threads']

        if len(threads_str) > 0:
            threads_id_list = threads_str.split(' ')

            threads = list()

            for thread_id in threads_id_list:
                try:
                    thread = Post.objects.get(id=int(thread_id))
                    if not thread.is_opening() or thread.get_thread().archived:
                        raise ObjectDoesNotExist()
                    threads.append(thread)
                except (ObjectDoesNotExist, ValueError):
                    raise forms.ValidationError(_('Invalid additional thread list'))

            return threads

    def clean(self):
        cleaned_data = super(PostForm, self).clean()

        if cleaned_data['email']:
            self.need_to_ban = True
            raise forms.ValidationError('A human cannot enter a hidden field')

        if not self.errors:
            self._clean_text_image()

        if not self.errors and self.session:
            self._validate_posting_speed()

        return cleaned_data

    def get_image(self):
        """
        Gets image from file or URL.
        """

        image = self.cleaned_data['image']
        return image if image else self.cleaned_data['image_url']

    def _clean_text_image(self):
        text = self.cleaned_data.get('text')
        image = self.get_image()

        if (not text) and (not image):
            error_message = _('Either text or image must be entered.')
            self._errors['text'] = self.error_class([error_message])

    def _validate_posting_speed(self):
        can_post = True

        posting_delay = settings.POSTING_DELAY

        if board_settings.LIMIT_POSTING_SPEED:
            now = time.time()

            current_delay = 0
            need_delay = False

            if not LAST_POST_TIME in self.session:
                self.session[LAST_POST_TIME] = now

                need_delay = True
            else:
                last_post_time = self.session.get(LAST_POST_TIME)
                current_delay = int(now - last_post_time)

                need_delay = current_delay < posting_delay

            if need_delay:
                error_message = ERROR_SPEED % str(posting_delay
                        - current_delay)
                self._errors['text'] = self.error_class([error_message])

                can_post = False

            if can_post:
                self.session[LAST_POST_TIME] = now

    def validate_image_size(self, size: int):
        if size > board_settings.MAX_IMAGE_SIZE:
            raise forms.ValidationError(
                _('Image must be less than %s bytes')
                % str(board_settings.MAX_IMAGE_SIZE))

    def _get_image_from_url(self, url: str) -> SimpleUploadedFile:
        """
        Gets an image file from URL.
        """

        img_temp = None

        try:
            # Verify content headers
            response_head = requests.head(url, verify=False)
            content_type = response_head.headers['content-type'].split(';')[0]
            if content_type in CONTENT_TYPE_IMAGE:
                length_header = response_head.headers.get('content-length')
                if length_header:
                    length = int(length_header)
                    self.validate_image_size(length)
                # Get the actual content into memory
                response = requests.get(url, verify=False, stream=True)

                # Download image, stop if the size exceeds limit
                size = 0
                content = b''
                for chunk in response.iter_content(IMAGE_DOWNLOAD_CHUNK_BYTES):
                    size += len(chunk)
                    self.validate_image_size(size)
                    content += chunk

                if response.status_code == HTTP_RESULT_OK and content:
                    # Set a dummy file name that will be replaced
                    # anyway, just keep the valid extension
                    filename = 'image.' + content_type.split('/')[1]
                    img_temp = SimpleUploadedFile(filename, content,
                                                  content_type)
        except Exception:
            # Just return no image
            pass

        return img_temp


class ThreadForm(PostForm):

    tags = forms.CharField(
        widget=forms.TextInput(attrs={ATTRIBUTE_PLACEHOLDER: TAGS_PLACEHOLDER}),
        max_length=100, label=_('Tags'), required=True)

    def clean_tags(self):
        tags = self.cleaned_data['tags'].strip()

        if not tags or not REGEX_TAGS.match(tags):
            raise forms.ValidationError(
                _('Inappropriate characters in tags.'))

        required_tag_exists = False
        for tag in tags.split():
            try:
                Tag.objects.get(name=tag.strip().lower(), required=True)
                required_tag_exists = True
                break
            except ObjectDoesNotExist:
                pass

        if not required_tag_exists:
            all_tags = Tag.objects.filter(required=True)
            raise forms.ValidationError(
                _('Need at least one of the tags: ')
                + ', '.join([tag.name for tag in all_tags]))

        return tags

    def clean(self):
        cleaned_data = super(ThreadForm, self).clean()

        return cleaned_data


class SettingsForm(NeboardForm):

    theme = forms.ChoiceField(choices=settings.THEMES, label=_('Theme'))
    image_viewer = forms.ChoiceField(choices=settings.IMAGE_VIEWERS, label=_('Image view mode'))
    username = forms.CharField(label=_('User name'), required=False)
    timezone = forms.ChoiceField(choices=get_timezones(), label=_('Time zone'))

    def clean_username(self):
        username = self.cleaned_data['username']

        if username and not REGEX_TAGS.match(username):
            raise forms.ValidationError(_('Inappropriate characters.'))

        return username


class SearchForm(NeboardForm):
    query = forms.CharField(max_length=500, label=LABEL_SEARCH, required=False)