"""HTML utilities suitable for global use."""

import re

import string

from django.utils.safestring import SafeData, mark_safe

from django.utils.encoding import force_unicode

from django.utils.functional import allow_lazy

from django.utils.http import urlquote

# Configuration for urlize() function.

LEADING_PUNCTUATION  = ['(', '<', '&lt;']

TRAILING_PUNCTUATION = ['.', ',', ')', '>', '\n', '>']

# List of possible strings used for bullets in bulleted lists.

DOTS = ['·', '*', '\xe2\x80\xa2', '•', '•', '•']

unencoded_ampersands_re = re.compile(r'&(?!(\w+|#\d+);)')

word_split_re = re.compile(r'(\s+)')

punctuation_re = re.compile('^(?P<lead>(?:%s)*)(?P<middle>.*?)(?P<trail>(?:%s)*)$' % \

    ('|'.join([re.escape(x) for x in LEADING_PUNCTUATION]),

    '|'.join([re.escape(x) for x in TRAILING_PUNCTUATION])))

simple_email_re = re.compile(r'^\S+@[a-zA-Z0-9._-]+\.[a-zA-Z0-9._-]+$')

link_target_attribute_re = re.compile(r'(<a [^>]*?)target=[^\s>]+')

html_gunk_re = re.compile(r'(?:<br clear="all">|<i><\/i>|<b><\/b>|<em><\/em>|<strong><\/strong>|<\/?smallcaps>|<\/?uppercase>)', re.IGNORECASE)

hard_coded_bullets_re = re.compile(r'((?:<p>(?:%s).*?[a-zA-Z].*?</p>\s*)+)' % '|'.join([re.escape(x) for x in DOTS]), re.DOTALL)

trailing_empty_content_re = re.compile(r'(?:<p>(?:&nbsp;|\s|<br \/>)*?</p>\s*)+\Z')

del x # Temporary variable

def escape(html):

    """Returns the given HTML with ampersands, quotes and carets encoded."""

    return mark_safe(force_unicode(html).replace('&', '&amp;').replace('<', '&lt;').replace('>', '&gt;').replace('"', '&quot;').replace("'", '&#39;'))

escape = allow_lazy(escape, unicode)

def conditional_escape(html):

    """

    Similar to escape(), except that it doesn't operate on pre-escaped strings.

    """

    if isinstance(html, SafeData):

        return html

    else:

        return escape(html)

def linebreaks(value, autoescape=False):

    """Converts newlines into <p> and <br />s."""

    value = re.sub(r'\r\n|\r|\n', '\n', force_unicode(value)) # normalize newlines

    paras = re.split('\n{2,}', value)

    if autoescape:

        paras = [u'<p>%s</p>' % escape(p.strip()).replace('\n', '<br />') for p in paras]

    else:

        paras = [u'<p>%s</p>' % p.strip().replace('\n', '<br />') for p in paras]

    return u'\n\n'.join(paras)

linebreaks = allow_lazy(linebreaks, unicode)

def strip_tags(value):

    """Returns the given HTML with all tags stripped."""

    return re.sub(r'<[^>]*?>', '', force_unicode(value))

strip_tags = allow_lazy(strip_tags)

def strip_spaces_between_tags(value):

    """Returns the given HTML with spaces between tags removed."""

    return re.sub(r'>\s+<', '><', force_unicode(value))

strip_spaces_between_tags = allow_lazy(strip_spaces_between_tags, unicode)

def strip_entities(value):

    """Returns the given HTML with all entities (&something;) stripped."""

    return re.sub(r'&(?:\w+|#\d+);', '', force_unicode(value))

strip_entities = allow_lazy(strip_entities, unicode)

def fix_ampersands(value):

    """Returns the given HTML with all unencoded ampersands encoded correctly."""

    return unencoded_ampersands_re.sub('&', force_unicode(value))

fix_ampersands = allow_lazy(fix_ampersands, unicode)

def urlize(text, trim_url_limit=None, nofollow=False, autoescape=False):

    """

    Converts any URLs in text into clickable links.

    Works on http://, https://, and www. links.  Links can have trailing

    punctuation (periods, commas, close-parens) and leading punctuation

    (opening parens) and it'll still do the right thing.

    If trim_url_limit is not None, the URLs in link text longer than this limit

    will truncated to trim_url_limit-3 characters and appended with an elipsis.

    If nofollow is True, the URLs in link text will get a rel="nofollow"

    attribute.

    """

    if autoescape:

        trim_url = lambda x, limit=trim_url_limit: conditional_escape(limit is not None and (len(x) > limit and ('%s...' % x[:max(0, limit - 3)])) or x)

    else:

        trim_url = lambda x, limit=trim_url_limit: limit is not None and (len(x) > limit and ('%s...' % x[:max(0, limit - 3)])) or x

    safe_input = isinstance(text, SafeData)

    words = word_split_re.split(force_unicode(text))

    nofollow_attr = nofollow and ' rel="nofollow"' or ''

    for i, word in enumerate(words):

        match = punctuation_re.match(word)

        if match:

            lead, middle, trail = match.groups()

            if safe_input:

                middle = mark_safe(middle)

            if middle.startswith('www.') or ('@' not in middle and not middle.startswith('http://') and \

                    len(middle) > 0 and middle[0] in string.ascii_letters + string.digits and \

                    (middle.endswith('.org') or middle.endswith('.net') or middle.endswith('.com'))):

                middle = 'http://%s' % middle

            if middle.startswith('http://') or middle.startswith('https://'):

                url = urlquote(middle, safe='/&=:;#?+*')

                if autoescape and not safe_input:

                    url = escape(url)

                trimmed_url = trim_url(middle)

                middle = '<a href="%s"%s>%s</a>' % (url, nofollow_attr,

                        trimmed_url)

            elif '@' in middle and not middle.startswith('www.') and \

                      not ':' in middle and simple_email_re.match(middle):

                if autoescape:

                    middle = conditional_escape(middle)

                middle = '<a href="mailto:%s">%s</a>' % (middle, middle)

            if lead + middle + trail != word:

                if autoescape and not safe_input:

                    lead, trail = escape(lead), escape(trail)

                words[i] = mark_safe('%s%s%s' % (lead, middle, trail))

            elif autoescape and not safe_input:

                words[i] = escape(word)

        elif safe_input:

            words[i] = mark_safe(word)

        elif autoescape:

            words[i] = escape(word)

    return u''.join(words)

urlize = allow_lazy(urlize, unicode)

def clean_html(text):

    """

    Clean the given HTML.  Specifically, do the following:

        * Convert <b> and <i> to <strong> and <em>.

        * Encode all ampersands correctly.

        * Remove all "target" attributes from <a> tags.

        * Remove extraneous HTML, such as presentational tags that open and

          immediately close and <br clear="all">.

        * Convert hard-coded bullets into HTML unordered lists.

        * Remove stuff like "<p>&nbsp;&nbsp;</p>", but only if it's at the

          bottom of the text.

    """

    from django.utils.text import normalize_newlines

    text = normalize_newlines(force_unicode(text))

    text = re.sub(r'<(/?)\s*b\s*>', '<\\1strong>', text)

    text = re.sub(r'<(/?)\s*i\s*>', '<\\1em>', text)

    text = fix_ampersands(text)

    # Remove all target="" attributes from <a> tags.

    text = link_target_attribute_re.sub('\\1', text)

    # Trim stupid HTML such as <br clear="all">.

    text = html_gunk_re.sub('', text)

    # Convert hard-coded bullets into HTML unordered lists.

    def replace_p_tags(match):

        s = match.group().replace('</p>', '</li>')

        for d in DOTS:

            s = s.replace('<p>%s' % d, '<li>')

        return u'<ul>\n%s\n</ul>' % s

    text = hard_coded_bullets_re.sub(replace_p_tags, text)

    # Remove stuff like "<p>&nbsp;&nbsp;</p>", but only if it's at the bottom

    # of the text.

    text = trailing_empty_content_re.sub('', text)

    return text

clean_html = allow_lazy(clean_html, unicode)