#
#  Copyright (c) 2007 Helmut Merz helmutm@cy55.de
#
#  This program is free software; you can redistribute it and/or modify
#  it under the terms of the GNU General Public License as published by
#  the Free Software Foundation; either version 2 of the License, or
#  (at your option) any later version.
#
#  This program is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU General Public License for more details.
#
#  You should have received a copy of the GNU General Public License
#  along with this program; if not, write to the Free Software
#  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
#

"""
Schemas and Fields.

$Id$
"""

from zope import schema
from zope.interface import Interface, Attribute
from zope.i18nmessageid import MessageFactory

from cybertools.composer.interfaces import ITemplate, IComponent

_ = MessageFactory('zope')


class ISchema(ITemplate):
    """ Represents an ordered sequence of fields.
    """

    name = schema.ASCII(
                title=_(u'Schema name'),
                description=_(u'The internal name of the schema; will be used '
                'to identify data fields of instance objects that '
                'are associated with this schema.'),
                required=True,)
    title = schema.TextLine(
                title=_(u'Title'),
                description=_(u'The title of the schema'),
                required=True,)
    description = schema.Text(
                title=_(u'Description'),
                description=_(u'A brief description of the item.'),
                required=False,)

    fields = Attribute('The components the schema is built up of. '
                'Should be a sequence of IField objects.')
    manager = Attribute('A manager object that may provide special '
                'features, e.g. a factory for objects to be associated '
                'with this schema.')


class IField(IComponent):
    """ May be used for data entry or display.
    """

    name = schema.ASCII(
                title=_(u'Field name'),
                description=_(u'The internal name of the field'),
                required=True,)
    title = schema.TextLine(
                title=_(u'Title'),
                description=_(u'The title or label of the field'),
                required=True,)
    description = schema.Text(
                title=_(u'Description'),
                description=_(u'A brief description of the field'),
                required=False,)
    fieldType = schema.Choice(
                title=_(u'Field type'),
                description=_(u'The type of the field'),
                required=True,
                default='textline',
                values=('textline', 'textarea', 'date', 'checkbox'))
    defaultValue = schema.TextLine(
                title=_(u'Default'),
                description=_(u'Value with which to pre-set the field contents'),
                required=False,)
    required = schema.Bool(
                title=_(u'Required'),
                description=_(u'Must a value been entered into this field?'),
                required=False,)
    width = schema.Int(
                title=_(u'Width'),
                description=_(u'The horizontal size of the field in pixels'),
                default=300,
                required=False,)
    height = schema.Int(
                title=_(u'Height'),
                description=_(u'The vertical size of the field in lines '
                        '(only for type textarea)'),
                default=3,
                required=False,)
    # validator = schema.Text(),
    # marshaller = schema.Text(),

    def marshallValue(value):
        """ Return a string (possibly unicode) representation of the
            value given that may be used for editing.
        """

    def displayValue(value):
        """ Return a string (possibly unicode) representation of the
            value given that may be used for presentation.
        """

    def unmarshallValue(strValue):
        """ Return the internal (real) value corresponding to the string
            value given.
        """

    def validateValue(value):
        """ Check if the value given is valid. Return an object implementing
            IFieldState.
        """


class IFieldState(Interface):
    """ Represents the state of a field used for editing.
    """

    name = Attribute('Field name.')
    change = Attribute('A tuple ``(oldValue, newValue)`` or None.')
    errors = Attribute('A sequence of error infos.')
    severity = Attribute("An integer giving a state or error "
                    "code, 0 meaning 'OK'.")


class IFormState(Interface):
    """ Represents the state of all fields when editing.
    """

    fieldStates = Attribute('A mapping ``{fieldName: fieldState, ...}``.')
    changed = Attribute('True if one of the fields has been changed or False.')
    severity = Attribute("An integer giving an overall state or error "
                    "code, typically the maximum of the field states' "
                    "severities.")


# clients

class IClient(Interface):
    """ An fairly abstract interface for objects to be used as clients
        for other objects (e.g. services).
    """

    manager = Attribute('The object that cares for this client.')


class IClientFactory(Interface):
    """ Creates client objects.
    """

    def __call__():
        """ Creates and returns a client object.
        """


class IClientManager(Interface):
    """ Cares for a client typically providing schemas.
    """

    clients = Attribute('A collection of client objects (e.g. persons) '
                'associated with this client manager.')
    clientSchemas = Attribute('A collection of schema objects '
                'that describe the data fields of the client '
                'objects.')

    def addClient(client):
        """ Add the client object given to the collection of clients.
        """