class Form():

  FORM_BEGIN  = '<form method="POST">\n'</form>

  FORM_END    = '\n'

  GROUP_BEGIN = '<fieldset>\n'</fieldset>

  GROUP_END   = '\n'

  TITLE_BEGIN = '<legend>'</legend>

  TITLE_END   = '\n'

  FIELD_BEGIN = '
'

  FIELD_END   = '\n'

  NAME_BEGIN  = ''

  NAME_END    = '\n'

  VALUE_BEGIN = '
'

  VALUE_END   = '\n'

  BEGIN       = FORM_BEGIN + GROUP_BEGIN

  END         = GROUP_END + FORM_END

  def __init__(self, request):

    self.request = request

    self.answer = self.request.answer

    self.content = ''

  def title(self, title):

    return self.TITLE_BEGIN \

         + self.answer.te(title) \

         + self.TITLE_END

  def name(self, name):

    return self.NAME_BEGIN \

         + self.answer.te(name) \

         + self.NAME_END

  def value_raw(self, raw):

    return self.VALUE_BEGIN \

         + raw \

         + self.VALUE_END

  def input(self, name, type, value = None):

    type = self.answer.e(type)

    name = self.answer.e(name)

    value = self.answer.encodedfield(name) if value is None else self.answer.e(value)

    content = '

    if type: content += ' type="' + type + '"'

    if name: content += ' name="' + name + '"'

    if value: content += ' value="' + value + '"'

    content += ' />'

    return content

  def checkbox(self, name, value = None):

    name = self.answer.e(name)

    value = bool(self.answer.fields.get(name) if value is None else value)

    content = '

    if name: content += ' name="' + name + '"'

    if value: content += ' checked'

    content += ' />'

    return content

  def select(self, name, variants, value = None):

    name = self.answer.e(name)

    value = self.answer.encodedfield(name) if value is None else self.answer.e(value)

    content = '

    if name: content += ' name="' + name + '"'

    content += '>\n'

    for k, v in variants.items():

      kk = self.answer.e(k)

      if kk:

        content += '

        if kk == value: content += 'selected'

        content += '>'

        content += self.answer.te(v)

        content += '\n'

    content += '\n'

    return content

  def textarea(self, name, value = None):

    name = self.answer.e(name)

    value = self.answer.encodedfield(name) if value is None else self.answer.e(value)

    content = '

    if name: content += ' name="' + name + '"'

    content += '>\n'

    content += value

    content += ''

    return content

  def field_raw(self, name, raw):

    content = self.FIELD_BEGIN;

    content += self.name(name)

    content += self.value_raw(raw)

    content += self.FIELD_END;

    return content

  def add_field_raw(self, name, raw):

    self.content += self.field_raw(name, raw)

  def add_hidden(self, name, value):

    self.content += self.input(name, 'hidden', '' if value is None else value)

  def add_input(self, title, *args, **kvargs):

    self.add_field_raw(title, self.input(*args, **kvargs))

  def add_checkbox(self, title, *args, **kvargs):

    self.add_field_raw(title, self.checkbox(*args, **kvargs))

  def add_select(self, title, *args, **kvargs):

    self.add_field_raw(title, self.select(*args, **kvargs))

  def add_textarea(self, title, *args, **kvargs):

    self.add_field_raw(title, self.textarea(*args, **kvargs))

  def add_submit(self, title = 'Submit'):

    self.add_field_raw('', self.input('', 'submit', self.answer.t(title)))

  def begin(self, title, action):

    self.content += self.BEGIN

    if title: self.content += self.title(title)

    if action: self.add_hidden('action', action)

  def end(self):

    self.content += self.END