"""Provides the basic web widget classes: Widget itself, plus StringWidget,
TextWidget, CheckboxWidget, etc.
"""

import struct
from quixote import get_request
from quixote.html import htmltext, htmlescape, htmltag, TemplateIO, stringify
from quixote.http_request import Upload

def subname(prefix, name):
    """Create a unique name for a sub-widget or sub-component."""
    # $ is nice because it's valid as part of a Javascript identifier
    return "%s$%s" % (prefix, name)


def merge_attrs(base, overrides):
    """({string: any}, {string: any}) -> {string: any}
    """
    items = []
    if base:
        items.extend(base.items())
    if overrides:
        items.extend(overrides.items())
    attrs = {}
    for name, val in items:
        if name.endswith('_'):
            name = name[:-1]
        attrs[name] = val
    return attrs


class WidgetValueError(Exception):
    """May be raised a widget has problems parsing its value."""

    def __init__(self, msg):
        self.msg = msg

    def __str__(self):
        return stringify(self.msg)



class Widget(object):
    """Abstract base class for web widgets.

    Instance attributes:
      name : string
      value : any
      error : string
      title : string
      hint : string
      required : bool
      attrs : {string: any}
      _parsed : bool

    Feel free to access these directly; to set them, use the 'set_*()'
    modifier methods.
    """

    REQUIRED_ERROR = 'required'

    def __init__(self, name, value=None, title="", hint="", required=False,
                 render_br=True, attrs=None, **kwattrs):
        assert self.__class__ is not Widget, "abstract class"
        self.name = name
        self.value = value
        self.error = None
        self.title = title
        self.hint = hint
        self.required = required
        self.render_br = render_br
        self.attrs = merge_attrs(attrs, kwattrs)
        self._parsed = False

    def __repr__(self):
        return "<%s at %x: %s>" % (self.__class__.__name__,
                                   id(self),
                                   self.name)

    def __str__(self):
        return "%s: %s" % (self.__class__.__name__, self.name)

    def get_name(self):
        return self.name

    def set_value(self, value):
        self.value = value

    def set_error(self, error):
        self.error = error

    def get_error(self, request=None):
        self.parse(request=request)
        return self.error

    def has_error(self, request=None):
        return bool(self.get_error(request=request))

    def clear_error(self, request=None):
        self.parse(request=request)
        self.error = None

    def set_title(self, title):
        self.title = title

    def get_title(self):
        return self.title

    def set_hint(self, hint):
        self.hint = hint

    def get_hint(self):
        return self.hint

    def is_required(self):
        return self.required

    def parse(self, request=None):
        if not self._parsed:
            self._parsed = True
            if request is None:
                request = get_request()
            if request.form or request.get_method() == 'POST':
                try:
                    self._parse(request)
                except WidgetValueError, exc:
                    self.set_error(stringify(exc))
                if (self.required and self.value is None and
                    not self.has_error()):
                    self.set_error(self.REQUIRED_ERROR)
        return self.value

    def _parse(self, request):
        # subclasses may override but this is not part of the public API
        value = request.form.get(self.name)
        if isinstance(value, basestring) and value.strip():
            self.value = value
        else:
            self.value = None

    def render_title(self, title):
        if title:
            if self.required:
                title += htmltext('<span class="required">*</span>')
            return htmltext('<div class="title">%s</div>') % title
        else:
            return ''

    def render_hint(self, hint):
        if hint:
            return htmltext('<div class="hint">%s</div>') % hint
        else:
            return ''

    def render_error(self, error):
        if error:
            return htmltext('<div class="error">%s</div>') % error
        else:
            return ''

    def render(self):
        r = TemplateIO(html=True)
        classnames = '%s widget' % self.__class__.__name__
        r += htmltext('<div class="%s">') % classnames
        r += self.render_title(self.get_title())
        r += htmltext('<div class="content">')
        r += self.render_content()
        r += self.render_hint(self.get_hint())
        r += self.render_error(self.get_error())
        r += htmltext('</div>')
        r += htmltext('</div>')
        if self.render_br:
            r += htmltext('<br class="%s" />') % classnames
        r += htmltext('\n')
        return r.getvalue()

    def render_content(self):
        raise NotImplementedError

# class Widget

# -- Fundamental widget types ------------------------------------------
# These correspond to the standard types of input tag in HTML:
#   text     StringWidget
#   password PasswordWidget
#   radio    RadiobuttonsWidget
#   checkbox CheckboxWidget
#
# and also to the other basic form elements:
#   <textarea>  TextWidget
#   <select>    SingleSelectWidget
#   <select multiple>
#               MultipleSelectWidget

class StringWidget(Widget):
    """Widget for entering a single string: corresponds to
    '<input type="text">' in HTML.

    Instance attributes:
      value : string
    """

    # This lets PasswordWidget be a trivial subclass
    HTML_TYPE = "text"

    def render_content(self):
        return htmltag("input", xml_end=True,
                       type=self.HTML_TYPE,
                       name=self.name,
                       value=self.value,
                       **self.attrs)


class FileWidget(StringWidget):
    """Subclass of StringWidget for uploading files.

    Instance attributes: none
    """

    HTML_TYPE = "file"

    def _parse(self, request):
        parsed_value = request.form.get(self.name)
        if isinstance(parsed_value, Upload):
            self.value = parsed_value
        else:
            self.value = None


class PasswordWidget(StringWidget):
    """Trivial subclass of StringWidget for entering passwords (different
    widget type because HTML does it that way).

    Instance attributes: none
    """

    HTML_TYPE = "password"


class TextWidget(Widget):
    """Widget for entering a long, multi-line string; corresponds to
    the HTML "<textarea>" tag.

    Instance attributes:
      value : string
    """

    def _parse(self, request):
        Widget._parse(self, request)
        if self.value and self.value.find("\r\n") >= 0:
            self.value = self.value.replace("\r\n", "\n")

    def render_content(self):
        return (htmltag("textarea", name=self.name, **self.attrs) +
                htmlescape(self.value or "") +
                htmltext("</textarea>"))


class CheckboxWidget(Widget):
    """Widget for a single checkbox: corresponds to "<input
    type=checkbox>".  Do not put multiple CheckboxWidgets with the same
    name in the same form.

    Instance attributes:
      value : boolean
    """

    def _parse(self, request):
        self.value = request.form.has_key(self.name)

    def render_content(self):
        return htmltag("input", xml_end=True,
                       type="checkbox",
                       name=self.name,
                       value="yes",
                       checked=self.value and "checked" or None,
                       **self.attrs)



class SelectWidget(Widget):
    """Widget for single or multiple selection; corresponds to
    <select name=...>
      <option value="Foo">Foo</option>
      ...
    </select>

    Instance attributes:
      options : [ (value:any, description:any, key:string) ]
      value : any
        The value is None or an element of dict(options.values()).
    """

    SELECTION_ERROR = "invalid value selected"

    def __init__(self, name, value=None, options=None, sort=False,
                 verify_selection=True, **kwargs):
        assert self.__class__ is not SelectWidget, "abstract class"
        Widget.__init__(self, name, value, **kwargs)
        self.options = []
        if not options:
            # The HTML and XHTML specifications require select elements to
            # contain at least one option.
            raise ValueError, "a non-empty list of 'options' is required"
        else:
            self.set_options(options, sort)
        self.verify_selection = verify_selection

    def get_allowed_values(self):
        return [item[0] for item in self.options]

    def get_descriptions(self):
        return [item[1] for item in self.options]

    def set_value(self, value):
        self.value = None
        for object, description, key in self.options:
            if value == object:
                self.value = value
                break

    def _generate_keys(self, values, descriptions):
        """Called if no keys were provided.  Try to generate a set of keys
        that will be consistent between rendering and parsing.
        """
        # try to use ZODB object IDs
        keys = []
        for value in values:
            if value is None:
                oid = ""
            else:
                oid = getattr(value, "_p_oid", None)
                if not oid:
                    break
                hi, lo = struct.unpack(">LL", oid)
                oid = "%x" % ((hi << 32) | lo)
            keys.append(oid)
        else:
            # found OID for every value
            return keys
        # can't use OIDs, try using descriptions
        used_keys = {}
        keys = map(stringify, descriptions)
        for key in keys:
            if used_keys.has_key(key):
                raise ValueError, "duplicated descriptions (provide keys)"
            used_keys[key] = 1
        return keys

    def set_options(self, options, sort=False):
        """(options: [objects:any], sort=False)
         or
           (options: [(object:any, description:any)], sort=False)
         or
           (options: [(object:any, description:any, key:any)], sort=False)
        """

        """
        Set the options list.  The list of options can be a list of objects, in
        which case the descriptions default to map(htmlescape, objects)
        applying htmlescape() to each description and
        key.
        If keys are provided they must be distinct.  If the sort keyword
        argument is true, sort the options by case-insensitive lexicographic
        order of descriptions, except that options with value None appear
        before others.
        """
        if options:
            first = options[0]
            values = []
            descriptions = []
            keys = []
            if isinstance(first, tuple):
                if len(first) == 2:
                    for value, description in options:
                        values.append(value)
                        descriptions.append(description)
                elif len(first) == 3:
                    for value, description, key in options:
                        values.append(value)
                        descriptions.append(description)
                        keys.append(stringify(key))
                else:
                    raise ValueError, 'invalid options %r' % options
            else:
                values = descriptions = options

            if not keys:
                keys = self._generate_keys(values, descriptions)

            options = zip(values, descriptions, keys)

            if sort:
                def make_sort_key(option):
                    value, description, key = option
                    if value is None:
                        return ('', option)
                    else:
                        return (stringify(description).lower(), option)
                doptions = map(make_sort_key, options)
                doptions.sort()
                options = [item[1] for item in doptions]
        self.options = options

    def _parse_single_selection(self, parsed_key, default=None):
        for value, description, key in self.options:
            if key == parsed_key:
                return value
        else:
            if self.verify_selection:
                self.error = self.SELECTION_ERROR
                return default
            elif self.options:
                return self.options[0][0]
            else:
                return default

    def set_allowed_values(self, allowed_values, descriptions=None,
                           sort=False):
        """(allowed_values:[any], descriptions:[any], sort:boolean=False)

        Set the options for this widget.  The allowed_values and descriptions
        parameters must be sequences of the same length.  The sort option
        causes the options to be sorted using case-insensitive lexicographic
        order of descriptions, except that options with value None appear
        before others.
        """
        if descriptions is None:
            self.set_options(allowed_values, sort)
        else:
            assert len(descriptions) == len(allowed_values)
            self.set_options(zip(allowed_values, descriptions), sort)

    def is_selected(self, value):
        return value == self.value

    def render_content(self):
        tags = [htmltag("select", name=self.name, **self.attrs)]
        for object, description, key in self.options:
            if self.is_selected(object):
                selected = 'selected'
            else:
                selected = None
            if description is None:
                description = ""
            r = htmltag("option", value=key, selected=selected)
            tags.append(r + htmlescape(description) + htmltext('</option>'))
        tags.append(htmltext("</select>"))
        return htmltext("\n").join(tags)


class SingleSelectWidget(SelectWidget):
    """Widget for single selection.
    """

    SELECT_TYPE = "single_select"
    MULTIPLE_SELECTION_ERROR = "cannot select multiple values"

    def _parse(self, request):
        parsed_key = request.form.get(self.name)
        if parsed_key:
            if isinstance(parsed_key, list):
                self.error = self.MULTIPLE_SELECTION_ERROR
            else:
                self.value = self._parse_single_selection(parsed_key)
        else:
            self.value = None


class RadiobuttonsWidget(SingleSelectWidget):
    """Widget for a *set* of related radiobuttons -- all have the
    same name, but different values (and only one of those values
    is returned by the whole group).

    Instance attributes:
      delim : string = None
        string to emit between each radiobutton in the group.  If
        None, a single newline is emitted.
    """

    SELECT_TYPE = "radiobuttons"

    def __init__(self, name, value=None, options=None, delim=None, **kwargs):
        SingleSelectWidget.__init__(self, name, value, options=options,
                                    **kwargs)
        if delim is None:
            self.delim = "\n"
        else:
            self.delim = delim

    def render_content(self):
        tags = []
        for object, description, key in self.options:
            if self.is_selected(object):
                checked = 'checked'
            else:
                checked = None
            r = htmltag("input", xml_end=True,
                        type="radio",
                        name=self.name,
                        value=key,
                        checked=checked,
                        **self.attrs)
            tags.append(r + htmlescape(description))
        return htmlescape(self.delim).join(tags)


class MultipleSelectWidget(SelectWidget):
    """Widget for multiple selection.

    Instance attributes:
      value : [any]
        for multipe selects, the value is None or a list of
        elements from dict(self.options).values()
    """

    SELECT_TYPE = "multiple_select"

    def __init__(self, name, value=None, options=None, **kwargs):
        SelectWidget.__init__(self, name, value, options=options,
                              multiple='multiple', **kwargs)

    def set_value(self, value):
        allowed_values = self.get_allowed_values()
        if value in allowed_values:
            self.value = [ value ]
        elif isinstance(value, (list, tuple)):
            self.value = [ element
                           for element in value
                           if element in allowed_values ] or None
        else:
            self.value = None

    def is_selected(self, value):
        if self.value is None:
            return value is None
        else:
            return value in self.value

    def _parse(self, request):
        parsed_keys = request.form.get(self.name)
        if parsed_keys:
            if isinstance(parsed_keys, list):
                self.value =  [value
                               for value, description, key in self.options
                               if key in parsed_keys] or None
            else:
                _marker = []
                value = self._parse_single_selection(parsed_keys, _marker)
                if value is _marker:
                    self.value = None
                else:
                    self.value = [value]
        else:
            self.value = None


class ButtonWidget(Widget):
    """
    Instance attributes:
      label : string
      value : boolean
    """

    HTML_TYPE = "button"

    def __init__(self, name, value=None, **kwargs):
        Widget.__init__(self, name, value=None, **kwargs)
        self.set_label(value)

    def set_label(self, label):
        self.label = label

    def get_label(self):
        return self.label

    def render_content(self):
        # slightly different behavior here, we always render the
        # tag using the 'value' passed in as a parameter.  'self.value'
        # is a boolean that is true if the button's name appears
        # in the request.
        value = (self.label and htmlescape(self.label) or None)
        return htmltag("input", xml_end=True, type=self.HTML_TYPE,
                       name=self.name, value=value, **self.attrs)

    def _parse(self, request):
        self.value = request.form.has_key(self.name)


class SubmitWidget(ButtonWidget):
    HTML_TYPE = "submit"

class ResetWidget(ButtonWidget):
    HTML_TYPE = "reset"


class HiddenWidget(Widget):
    """
    Instance attributes:
      value : string
    """

    def set_error(self, error):
        if error is not None:
            raise TypeError, 'error not allowed on hidden widgets'

    def render_content(self):
        if self.value is None:
            value = None
        else:
            value = htmlescape(self.value)
        return htmltag("input", xml_end=True,
                       type="hidden",
                       name=self.name,
                       value=value,
                       **self.attrs)

    def render(self):
        return self.render_content() # Input elements of type hidden have no decoration.

# -- Derived widget types ----------------------------------------------
# (these don't correspond to fundamental widget types in HTML,
# so they're separated)

class NumberWidget(StringWidget):
    """
    Instance attributes: none
    """

    # Parameterize the number type (either float or int) through
    # these class attributes:
    TYPE_OBJECT = None                  # eg. int, float
    TYPE_ERROR = None                   # human-readable error message

    def __init__(self, name, value=None, **kwargs):
        assert self.__class__ is not NumberWidget, "abstract class"
        assert value is None or type(value) is self.TYPE_OBJECT, (
            "form value '%s' not a %s: got %r" % (name,
                                                  self.TYPE_OBJECT,
                                                  value))
        StringWidget.__init__(self, name, value, **kwargs)

    def _parse(self, request):
        StringWidget._parse(self, request)
        if self.value is not None:
            try:
                self.value = self.TYPE_OBJECT(self.value)
            except ValueError:
                self.error = self.TYPE_ERROR


class FloatWidget(NumberWidget):
    """
    Instance attributes:
      value : float
    """
    TYPE_OBJECT = float
    TYPE_ERROR = "must be a number"


class IntWidget(NumberWidget):
    """
    Instance attributes:
      value : int
    """
    TYPE_OBJECT = int
    TYPE_ERROR = "must be an integer"


class OptionSelectWidget(SingleSelectWidget):
    """Widget for single selection with automatic submission. Parse
    will always return a value from it's options, even if the form is
    not submitted. This allows its value to be used to decide what
    other widgets need to be created in a form.  It's a powerful
    feature but it can be hard to understand what's going on.

    Instance attributes:
      value : any
    """

    SELECT_TYPE = "option_select"

    def __init__(self, name, value=None, options=None, **kwargs):
        SingleSelectWidget.__init__(self, name, value, options=options,
                                    onchange='submit()', **kwargs)

    def parse(self, request=None):
        if not self._parsed:
            if request is None:
                request = get_request()
            self._parse(request)
            self._parsed = True
        return self.value

    def _parse(self, request):
        parsed_key = request.form.get(self.name)
        if parsed_key:
            if isinstance(parsed_key, list):
                self.error = self.MULTIPLE_SELECTION_ERROR
            else:
                self.value = self._parse_single_selection(parsed_key)
        elif self.value is None:
            self.value = self.options[0][0]

    def render_content(self):
        return (SingleSelectWidget.render_content(self) +
                htmltext('<noscript>'
                         '<input type="submit" value="apply" />'
                         '</noscript>'))


class CompositeWidget(Widget):
    """
    Instance attributes:
      widgets : [Widget]
      _names : {name:string : Widget}
    """
    def __init__(self, name, value=None, **kwargs):
        Widget.__init__(self, name, value, **kwargs)
        self.widgets = []
        self._names = {}

    def _parse(self, request):
        for widget in self.widgets:
            widget.parse(request)

    def __getitem__(self, name):
        return self._names[name].parse()

    def get(self, name):
        widget = self._names.get(name)
        if widget:
            return widget.parse()
        return None

    def get_widget(self, name):
        return self._names.get(name)

    def get_widgets(self):
        return self.widgets

    def clear_error(self, request=None):
        Widget.clear_error(self, request)
        for widget in self.widgets:
            widget.clear_error(request)

    def set_widget_error(self, name, error):
        self._names[name].set_error(error)

    def has_error(self, request=None):
        has_error = False
        if Widget.has_error(self, request=request):
            has_error = True
        for widget in self.widgets:
            if widget.has_error(request=request):
                has_error = True
        return has_error

    def add(self, widget_class, name, *args, **kwargs):
        if self._names.has_key(name):
            raise ValueError, 'the name %r is already used' % name
        if self.attrs.get('disabled') and 'disabled' not in kwargs:
            kwargs['disabled'] = True
        widget = widget_class(subname(self.name, name), *args, **kwargs)
        self._names[name] = widget
        self.widgets.append(widget)

    def render_content(self):
        r = TemplateIO(html=True)
        for widget in self.get_widgets():
            r += widget.render()
        return r.getvalue()


class WidgetList(CompositeWidget):
    """A variable length list of widgets.  There is only one
    title and hint but each element of the list can have its own
    error.  You can also set an error on the WidgetList itself (e.g. as a
    result of higher-level processing).

    Instance attributes:
      element_names : [string]
    """

    def __init__(self, name, value=None,
                 element_type=StringWidget,
                 element_kwargs={},
                 add_element_label="Add row", **kwargs):
        assert value is None or type(value) is list, (
            "value '%s' not a list: got %r" % (name, value))
        assert issubclass(element_type, Widget), (
            "value '%s' element_type not a Widget: "
            "got %r" % (name, element_type))
        assert type(element_kwargs) is dict, (
            "value '%s' element_kwargs not a dict: "
            "got %r" % (name, element_kwargs))
        assert isinstance(add_element_label, (basestring, htmltext)), (
            "value '%s'add_element_label not a string: "
            "got %r" % (name, add_element_label))

        CompositeWidget.__init__(self, name, value, **kwargs)
        self.element_names = []

        self.add(HiddenWidget, 'added_elements')
        added_elements_widget = self.get_widget('added_elements')


        def add_element(value=None):
            name = "element%d" % len(self.element_names)
            self.add(element_type, name, value=value, **element_kwargs)
            self.element_names.append(name)

        # Add element widgets for initial value
        if value is not None:
            for element_value in value:
                add_element(value=element_value)

        # Add at least one additional element widget
        num_added = int(added_elements_widget.parse() or 1)
        for i in range(num_added):
            add_element()

        # Add submit to add more element widgets
        self.add(SubmitWidget, 'add_element', value=add_element_label)
        if self.get('add_element'):
            add_element()
            num_added += 1
        added_elements_widget.set_value(num_added)

    def _parse(self, request):
        values = []
        for name in self.element_names:
            value = self.get(name)
            if value is not None:
                values.append(value)
        self.value = values or None

    def render_content(self):
        r = TemplateIO(html=True)
        add_element_widget = self.get_widget('add_element')
        for widget in self.get_widgets():
            if widget is add_element_widget:
                continue
            r += widget.render()
        r += add_element_widget.render()
        return r.getvalue()

    def render(self):
        r = TemplateIO(html=True)
        r += self.render_title(self.get_title())
        add_element_widget = self.get_widget('add_element')
        for widget in self.get_widgets():
            if widget is add_element_widget:
                continue
            r += widget.render()
        r += add_element_widget.render()
        r += self.render_hint(self.get_hint())
        return r.getvalue()


class WidgetDict(CompositeWidget):
    """A variable length dict of widgets.  There is only one
    title and hint but each element of the dict can have its own
    error.  You can also set an error on the WidgetDict itself (e.g. as a
    result of higher-level processing).

    Instance attributes:
      element_names : [string]
    """

    def __init__(self, name, value=None, title='', hint='',
                 element_key_type=StringWidget,
                 element_value_type=StringWidget,
                 element_key_kwargs={},
                 element_value_kwargs={},
                 add_element_label='Add row', **kwargs):
        assert value is None or type(value) is dict, (
            'value %r not a dict: got %r' % (name, value))
        assert issubclass(element_key_type, Widget), (
            "value '%s' element_key_type not a Widget: "
            "got %r" % (name, element_key_type))
        assert issubclass(element_value_type, Widget), (
            "value '%s' element_value_type not a Widget: "
            "got %r" % (name, element_value_type))
        assert type(element_key_kwargs) is dict, (
            "value '%s' element_key_kwargs not a dict: "
            "got %r" % (name, element_key_kwargs))
        assert type(element_value_kwargs) is dict, (
            "value '%s' element_value_kwargs not a dict: "
            "got %r" % (name, element_value_kwargs))
        assert isinstance(add_element_label, (basestring, htmltext)), (
            'value %r element_name not a string: '
            'got %r' % (name, add_element_label))

        CompositeWidget.__init__(self, name, value, **kwargs)
        self.element_names = []

        self.add(HiddenWidget, 'added_elements')
        added_elements_widget = self.get_widget('added_elements')

        def add_element(key=None, value=None):
            name = 'element%d' % len(self.element_names)
            self.add(element_key_type, name + 'key',
                     value=key, render_br=False, **element_key_kwargs)
            self.add(element_value_type, name + 'value',
                     value=value, **element_value_kwargs)
            self.element_names.append(name)

        # Add element widgets for initial value
        if value is not None:
            for key, element_value in value.items():
                add_element(key=key, value=element_value)

        # Add at least one additional element widget
        num_added = int(added_elements_widget.parse() or 1)
        for i in range(num_added):
            add_element()

        # Add submit to add more element widgets
        self.add(SubmitWidget, 'add_element', value=add_element_label)
        if self.get('add_element'):
            add_element()
            num_added += 1
        added_elements_widget.set_value(num_added)

    def _parse(self, request):
        values = {}
        for name in self.element_names:
            key = self.get(name + 'key')
            value = self.get(name + 'value')
            if key and value:
                values[key] = value
        self.value = values or None

    def render_content(self):
        r = TemplateIO(html=True)
        for name in self.element_names:
            if name in ('add_element', 'added_elements'):
                continue
            key_widget = self.get_widget(name + 'key')
            value_widget = self.get_widget(name + 'value')
            r += htmltext('%s<div class="widget">: </div>%s') % (
                key_widget.render(),
                value_widget.render())
            if self.render_br:
                r += htmltext('<br clear="left" class="widget" />')
            r += htmltext('\n')
        r += self.get_widget('add_element').render()
        r += self.get_widget('added_elements').render()
        return r.getvalue()