from django import template
from django.utils.safestring import mark_safe
from urllib.request import quote as urlencode
register = template.Library()

@register.simple_tag
def mailurl(*, subject=None, body=None, to=[]):
	"""TODO: Dokumentace"""
	if isinstance(to, str):
		to = [to]
	assert isinstance(to, list)
	parts = [
		f'mailto:{str.join(",", to)}',
		]
	if len(to) < 1:
		raise ValueError('Cannot mail to empty set of people')

	if subject:
		parts.append(f'subject={urlencode(subject)}')
	if body:
		parts.append(f'body={urlencode(body)}')
	
	if len(parts) > 1:
		url = parts[0] + '?' + str.join('&', parts[1:])
	else:
		url = parts[0]
	return url

@register.simple_tag
def maillink(text, subject=None, body=None, to=[], attrs=None):
	url = mailurl(subject=subject, body=body, to=to)
	if not attrs: attrs = ''
	mezera = ' '*bool(attrs)
	full_link = f'<a href="{url}"{mezera}{attrs}>{text}</a>'
	return mark_safe(full_link)