"""
Parser for HTML forms, that fills in defaults and errors.  See
``render``.
"""

import HTMLParser
import cgi
import re
from htmlentitydefs import name2codepoint

__all__ = ['render', 'htmlliteral', 'default_formatter',
           'none_formatter', 'escape_formatter',
           'FillingParser']

def render(form, defaults=None, errors=None, use_all_keys=False,
           error_formatters=None, add_attributes=None,
           auto_insert_errors=True, auto_error_formatter=None,
           text_as_default=False, listener=None, encoding=None,
           error_class='error'):
    """
    Render the ``form`` (which should be a string) given the defaults
    and errors.  Defaults are the values that go in the input fields
    (overwriting any values that are there) and errors are displayed
    inline in the form (and also effect input classes).  Returns the
    rendered string.

    If ``auto_insert_errors`` is true (the default) then any errors
    for which ``<form:error>`` tags can't be found will be put just
    above the associated input field, or at the top of the form if no
    field can be found.

    If ``use_all_keys`` is true, if there are any extra fields from
    defaults or errors that couldn't be used in the form it will be an
    error.

    ``error_formatters`` is a dictionary of formatter names to
    one-argument functions that format an error into HTML.  Some
    default formatters are provided if you don't provide this.

    ``error_class`` is the class added to input fields when there is
    an error for that field.

    ``add_attributes`` is a dictionary of field names to a dictionary
    of attribute name/values.  If the name starts with ``+`` then the
    value will be appended to any existing attribute (e.g.,
    ``{'+class': ' important'}``).

    ``auto_error_formatter`` is used to create the HTML that goes
    above the fields.  By default it wraps the error message in a span
    and adds a ``<br>``.

    If ``text_as_default`` is true (default false) then ``<input
    type=unknown>`` will be treated as text inputs.

    ``listener`` can be an object that watches fields pass; the only
    one currently is in ``htmlfill_schemabuilder.SchemaBuilder``
    
    ``encoding`` specifies an encoding to assume when mixing str and 
    unicode text in the template.
    """
    if defaults is None:
        defaults = {}
    if auto_insert_errors and auto_error_formatter is None:
        auto_error_formatter = default_formatter
    p = FillingParser(
        defaults=defaults, errors=errors,
        use_all_keys=use_all_keys,
        error_formatters=error_formatters,
        add_attributes=add_attributes,
        auto_error_formatter=auto_error_formatter,
        text_as_default=text_as_default,
        listener=listener, encoding=encoding,
        error_class=error_class,
        )
    p.feed(form)
    p.close()
    return p.text()
        

class htmlliteral(object):

    def __init__(self, html, text=None):
        if text is None:
            text = re.sub(r'<.*?>', '', html)
            text = html.replace('&gt;', '>')
            text = html.replace('&lt;', '<')
            text = html.replace('&quot;', '"')
            # @@: Not very complete
        self.html = html
        self.text = text

    def __str__(self):
        return self.text

    def __repr__(self):
        return '<%s html=%r text=%r>' % (self.html, self.text)

    def __html__(self):
        return self.html

def html_quote(v):
    if v is None:
        return ''
    elif hasattr(v, '__html__'):
        return v.__html__()
    elif isinstance(v, basestring):
        return cgi.escape(v, 1)
    else:
        # @@: Should this be unicode(v) or str(v)?
        return cgi.escape(str(v), 1)

def default_formatter(error):
    """
    Formatter that escapes the error, wraps the error in a span with
    class ``error-message``, and adds a ``<br>``
    """
    return '<span class="error-message">%s</span><br />\n' % html_quote(error)

def none_formatter(error):
    """
    Formatter that does nothing, no escaping HTML, nothin'
    """
    return error

def escape_formatter(error):
    """
    Formatter that escapes HTML, no more.
    """
    return html_quote(error)

def escapenl_formatter(error):
    """
    Formatter that escapes HTML, and translates newlines to ``<br>``
    """
    error = html_quote(error)
    error = error.replace('\n', '<br>\n')
    return error

class FillingParser(HTMLParser.HTMLParser):
    r"""
    Fills HTML with default values, as in a form.

    Examples::

        >>> defaults = {'name': 'Bob Jones',
        ...             'occupation': 'Crazy Cultist',
        ...             'address': '14 W. Canal\nNew Guinea',
        ...             'living': 'no',
        ...             'nice_guy': 0}
        >>> parser = FillingParser(defaults)
        >>> parser.feed('<input type="text" name="name" value="fill">\
        ... <select name="occupation"><option value="">Default</option>\
        ... <option value="Crazy Cultist">Crazy cultist</option>\
        ... </select> <textarea cols=20 style="width: 100%" name="address">An address\
        ... </textarea> <input type="radio" name="living" value="yes">\
        ... <input type="radio" name="living" value="no">\
        ... <input type="checkbox" name="nice_guy" checked="checked">')
        >>> print parser.text()
        <input type="text" name="name" value="Bob Jones">
        <select name="occupation">
        <option value="">Default</option>
        <option value="Crazy Cultist" selected="selected">Crazy cultist</option>
        </select>
        <textarea cols=20 style="width: 100%" name="address">14 W. Canal
        New Guinea</textarea>
        <input type="radio" name="living" value="yes">
        <input type="radio" name="living" value="no" selected="selected">
        <input type="checkbox" name="nice_guy">
    """

    def __init__(self, defaults, errors=None, use_all_keys=False,
                 error_formatters=None, error_class='error',
                 add_attributes=None, listener=None,
                 auto_error_formatter=None,
                 text_as_default=False, encoding=None):
        HTMLParser.HTMLParser.__init__(self)
        self._content = []
        self.source = None
        self.lines = None
        self.source_pos = None
        self.defaults = defaults
        self.in_textarea = None
        self.in_select = None
        self.skip_next = False        
        self.errors = errors or {}
        if isinstance(self.errors, (str, unicode)):
            self.errors = {None: self.errors}
        self.in_error = None
        self.skip_error = False
        self.use_all_keys = use_all_keys
        self.used_keys = {}
        self.used_errors = {}
        if error_formatters is None:
            self.error_formatters = default_formatter_dict
        else:
            self.error_formatters = error_formatters
        self.error_class = error_class
        self.add_attributes = add_attributes or {}
        self.listener = listener
        self.auto_error_formatter = auto_error_formatter
        self.text_as_default = text_as_default
        self.encoding = encoding

    def feed(self, data):
        self.data_is_str = isinstance(data, str)
        self.source = data
        self.lines = data.split('\n')
        self.source_pos = 1, 0
        if self.listener:
            self.listener.reset()
        HTMLParser.HTMLParser.feed(self, data)

    def close(self):
        self.handle_misc(None)
        HTMLParser.HTMLParser.close(self)
        unused_errors = self.errors.copy()
        for key in self.used_errors.keys():
            if unused_errors.has_key(key):
                del unused_errors[key]
        if self.auto_error_formatter:
            for key, value in unused_errors.items():
                error_message = self.auto_error_formatter(value)
                error_message = '<!-- for: %s -->\n%s' % (key, error_message)
                self.insert_at_marker(
                    key, error_message)
            unused_errors = {}
        if self.use_all_keys:
            unused = self.defaults.copy()
            for key in self.used_keys.keys():
                if unused.has_key(key):
                    del unused[key]
            assert not unused, (
                "These keys from defaults were not used in the form: %s"
                % unused.keys())
            if unused_errors:
                error_text = []
                for key in unused_errors.keys():
                    error_text.append("%s: %s" % (key, self.errors[key]))
                assert False, (
                    "These errors were not used in the form: %s" % 
                    ', '.join(error_text))
        if self.encoding is not None:
            new_content = []
            for item in self._content:
                if isinstance(item, str):
                    item = item.decode(self.encoding)
                new_content.append(item)
            self._content = new_content
        try:
            self._text = ''.join([
                t for t in self._content if not isinstance(t, tuple)])
        except UnicodeDecodeError, e:
            if self.data_is_str:
                e.reason += (
                    " the form was passed in as an encoded string, but "
                    "some data or error messages were unicode strings; "
                    "the form should be passed in as a unicode string")
            else:
                e.reason += (
                    " the form was passed in as an unicode string, but "
                    "some data or error message was an encoded string; "
                    "the data and error messages should be passed in as "
                    "unicode strings")
            raise

    def add_key(self, key):
        self.used_keys[key] = 1

    _entityref_re = re.compile('&([a-zA-Z][-.a-zA-Z\d]*);')
    _charref_re = re.compile('&#(\d+|[xX][a-fA-F\d]+);')

    def unescape(self, s):
        s = self._entityref_re.sub(self._sub_entityref, s)
        s = self._charref_re.sub(self._sub_charref, s)
        return s

    def _sub_entityref(self, match):
        name = match.group(1)
        if name not in name2codepoint:
            # If we don't recognize it, pass it through as though it
            # wasn't an entity ref at all
            return match.group(0)
        return unichr(name2codepoint[name])

    def _sub_charref(self, match):
        num = match.group(1)
        if num.lower().startswith('x'):
            num = int(num[1:], 16)
        else:
            num = int(num)
        return unichr(num)

    def handle_starttag(self, tag, attrs, startend=False):
        self.write_pos()
        if tag == 'input':
            self.handle_input(attrs, startend)
        elif tag == 'textarea':
            self.handle_textarea(attrs)
        elif tag == 'select':
            self.handle_select(attrs)
        elif tag == 'option':
            self.handle_option(attrs)
            return
        elif tag == 'form:error':
            self.handle_error(attrs)
            return
        elif tag == 'form:iferror':
            self.handle_iferror(attrs)
            return
        else:
            return
        if self.listener:
            self.listener.listen_input(self, tag, attrs)

    def handle_misc(self, whatever):
        self.write_pos()
    handle_charref = handle_misc
    handle_entityref = handle_misc
    handle_data = handle_misc
    handle_comment = handle_misc
    handle_decl = handle_misc
    handle_pi = handle_misc
    unknown_decl = handle_misc

    def handle_endtag(self, tag):
        self.write_pos()
        if tag == 'textarea':
            self.handle_end_textarea()
        elif tag == 'select':
            self.handle_end_select()
        elif tag == 'form:iferror':
            self.handle_end_iferror()

    def handle_startendtag(self, tag, attrs):
        return self.handle_starttag(tag, attrs, True)

    def handle_iferror(self, attrs):
        name = self.get_attr(attrs, 'name')
        notted = False
        if name.startswith('not '):
            notted = True
            name = name.split(None, 1)[1]
        assert name, "Name attribute in <iferror> required (%s)" % self.getpos()
        self.in_error = name
        ok = self.errors.get(name)
        if notted:
            ok = not ok
        if not ok:
            self.skip_error = True
        self.skip_next = True

    def handle_end_iferror(self):
        self.in_error = None
        self.skip_error = False
        self.skip_next = True

    def handle_error(self, attrs):
        name = self.get_attr(attrs, 'name')
        formatter = self.get_attr(attrs, 'format') or 'default'
        if name is None:
            name = self.in_error
        assert name is not None, (
            "Name attribute in <form:error> required if not contained in "
            "<form:iferror> (%i:%i)" % self.getpos())
        error = self.errors.get(name, '')
        if error:
            error = self.error_formatters[formatter](error)
            self.write_text(error)
        self.skip_next = True
        self.used_errors[name] = 1

    def handle_input(self, attrs, startend):
        t = (self.get_attr(attrs, 'type') or 'text').lower()
        name = self.get_attr(attrs, 'name')
        self.write_marker(name)
        value = self.defaults.get(name)
        if self.add_attributes.has_key(name):
            for attr_name, attr_value in self.add_attributes[name].items():
                if attr_name.startswith('+'):
                    attr_name = attr_name[1:]
                    self.set_attr(attrs, attr_name,
                                  self.get_attr(attrs, attr_name, '')
                                  + attr_value)
                else:
                    self.set_attr(attrs, attr_name, attr_value)
        if (self.error_class
            and self.errors.get(self.get_attr(attrs, 'name'))):
            self.add_class(attrs, self.error_class)
        if t in ('text', 'hidden'):
            if value is None:
                value = self.get_attr(attrs, 'value', '')
            self.set_attr(attrs, 'value', value)
            self.write_tag('input', attrs, startend)
            self.skip_next = True
            self.add_key(name)
        elif t == 'checkbox':
            selected = False
            if not self.get_attr(attrs, 'value'):
                selected = value
            elif self.selected_multiple(value, self.get_attr(attrs, 'value')):
                selected = True
            if selected:
                self.set_attr(attrs, 'checked', 'checked')
            else:
                self.del_attr(attrs, 'checked')
            self.write_tag('input', attrs, startend)
            self.skip_next = True
            self.add_key(name)
        elif t == 'radio':
            if str(value) == self.get_attr(attrs, 'value'):
                self.set_attr(attrs, 'checked', 'checked')
            else:
                self.del_attr(attrs, 'checked')
            self.write_tag('input', attrs, startend)
            self.skip_next = True
            self.add_key(name)
        elif t == 'file':
            pass # don't skip next
        elif t == 'password':
            self.set_attr(attrs, 'value', value or
                          self.get_attr(attrs, 'value', ''))
            self.write_tag('input', attrs, startend)
            self.skip_next = True
            self.add_key(name)
        elif t == 'image':
            self.set_attr(attrs, 'src', value or
                          self.get_attr(attrs, 'src', ''))
            self.write_tag('input', attrs, startend)
            self.skip_next = True
            self.add_key(name)
        elif t == 'submit' or t == 'reset' or t == 'button':
            self.set_attr(attrs, 'value', value or
                          self.get_attr(attrs, 'value', ''))
            self.write_tag('input', attrs, startend)
            self.skip_next = True
            self.add_key(name)
        elif self.text_as_default:
            if value is None:
                value = self.get_attr(attrs, 'value', '')
            self.set_attr(attrs, 'value', value)
            self.write_tag('input', attrs, startend)
            self.skip_next = True
            self.add_key(name)
        else:
            assert 0, "I don't know about this kind of <input>: %s (pos: %s)" \
                   % (t, self.getpos())

    def handle_textarea(self, attrs):
        name = self.get_attr(attrs, 'name')
        self.write_marker(name)
        if (self.error_class
            and self.errors.get(name)):
            self.add_class(attrs, self.error_class)
        self.write_tag('textarea', attrs)
        value = self.defaults.get(name, '')
        self.write_text(html_quote(value))
        self.write_text('</textarea>')
        self.in_textarea = True
        self.add_key(name)

    def handle_end_textarea(self):
        self.in_textarea = False
        self.skip_next = True

    def handle_select(self, attrs):
        name = self.get_attr(attrs, 'name', False)
        if name:
            self.write_marker(name)
        if (self.error_class
            and self.errors.get(name)):
            self.add_class(attrs, self.error_class)
        self.in_select = self.get_attr(attrs, 'name', False)
        self.write_tag('select', attrs)
        self.skip_next = True
        self.add_key(self.in_select)

    def handle_end_select(self):
        self.in_select = None

    def handle_option(self, attrs):
        assert self.in_select is not None, (
            "<option> outside of <select>: line %i, column %i"
            % self.getpos())
        if self.in_select != False:
            default = self.defaults.get(self.in_select, '')

            if self.selected_multiple(self.defaults.get(self.in_select, ''),
                                      self.get_attr(attrs, 'value')):
                self.set_attr(attrs, 'selected', 'selected')
                self.add_key(self.in_select)
            else:
                self.del_attr(attrs, 'selected')
        self.write_tag('option', attrs)
        self.skip_next = True

    def selected_multiple(self, obj, value):
        """
        Returns true/false if obj indicates that value should be
        selected.  If obj has a __contains__ method it is used, otherwise
        identity is used.
        """
        if obj is None:
            return value == ""
        if isinstance(obj, (str, unicode)):
            return obj == value
        if hasattr(obj, '__contains__'):
            if value in obj:
                return True
        if hasattr(obj, '__iter__'):
            for inner in obj:
                if str(inner) == value:
                    return True
        return str(obj) == value

    def write_text(self, text):
        self._content.append(text)

    def write_marker(self, marker):
        self._content.append((marker,))

    def insert_at_marker(self, marker, text):
        for i, item in enumerate(self._content):
            if item == (marker,):
                self._content.insert(i, text)
                break
        else:
            self._content.insert(0, text)

    def write_tag(self, tag, attrs, startend=False):
        attr_text = ''.join([' %s="%s"' % (n, html_quote(v))
                             for (n, v) in attrs
                             if not n.startswith('form:')])
        if startend:
            attr_text += " /"
        self.write_text('<%s%s>' % (tag, attr_text))

    def write_pos(self):
        cur_line, cur_offset = self.getpos()
        if self.in_textarea or self.skip_error:
            self.source_pos = self.getpos()
            return
        if self.skip_next:
            self.skip_next = False
            self.source_pos = self.getpos()
            return
        if cur_line == self.source_pos[0]:
            self.write_text(
                self.lines[cur_line-1][self.source_pos[1]:cur_offset])
        else:
            self.write_text(
                self.lines[self.source_pos[0]-1][self.source_pos[1]:])
            self.write_text('\n')
            for i in range(self.source_pos[0]+1, cur_line):
                self.write_text(self.lines[i-1])
                self.write_text('\n')
            self.write_text(self.lines[cur_line-1][:cur_offset])
        self.source_pos = self.getpos()

    def get_attr(self, attr, name, default=None):
        for n, value in attr:
            if n.lower() == name:
                return value
        return default

    def set_attr(self, attr, name, value):
        for i in range(len(attr)):
            if attr[i][0].lower() == name:
                attr[i] = (name, value)
                return
        attr.append((name, value))

    def del_attr(self, attr, name):
        for i in range(len(attr)):
            if attr[i][0].lower() == name:
                del attr[i]
                break

    def add_class(self, attr, class_name):
        current = self.get_attr(attr, 'class', '')
        new = current + ' ' + class_name
        self.set_attr(attr, 'class', new.strip())
            
    def text(self):
        try:
            return self._text
        except AttributeError:
            raise Exception(
                "You must .close() a parser instance before getting "
                "the text from it")

# This can potentially be extended globally
default_formatter_dict = {'default': default_formatter,
                          'none': none_formatter,
                          'escape': escape_formatter,
                          'escapenl': escapenl_formatter}
