# -*- coding: utf-8 -*-
# Part of Odoo. See LICENSE file for full copyright and licensing details.
import collections
import copy
import datetime
import fnmatch
import logging
import os
import re
import time
from dateutil.relativedelta import relativedelta
from operator import itemgetter

import json
import werkzeug
from lxml import etree
from lxml.etree import LxmlError
from lxml.builder import E

from odoo import api, fields, models, tools, SUPERUSER_ID, _
from odoo.exceptions import ValidationError
from odoo.http import request
from odoo.modules.module import get_resource_from_path, get_resource_path
from odoo.osv import orm
from odoo.tools import config, graph, ConstantMapping, SKIPPED_ELEMENT_TYPES
from odoo.tools.convert import _fix_multiple_roots
from odoo.tools.parse_version import parse_version
from odoo.tools.safe_eval import safe_eval
from odoo.tools.view_validation import valid_view
from odoo.tools.translate import encode, xml_translate, TRANSLATED_ATTRS

_logger = logging.getLogger(__name__)

MOVABLE_BRANDING = ['data-oe-model', 'data-oe-id', 'data-oe-field', 'data-oe-xpath', 'data-oe-source-id']


def keep_query(*keep_params, **additional_params):
    """
    Generate a query string keeping the current request querystring's parameters specified
    in ``keep_params`` and also adds the parameters specified in ``additional_params``.

    Multiple values query string params will be merged into a single one with comma seperated
    values.

    The ``keep_params`` arguments can use wildcards too, eg:

        keep_query('search', 'shop_*', page=4)
    """
    if not keep_params and not additional_params:
        keep_params = ('*',)
    params = additional_params.copy()
    qs_keys = request.httprequest.args.keys()
    for keep_param in keep_params:
        for param in fnmatch.filter(qs_keys, keep_param):
            if param not in additional_params and param in qs_keys:
                params[param] = request.httprequest.args.getlist(param)
    return werkzeug.urls.url_encode(params)


class ViewCustom(models.Model):
    _name = 'ir.ui.view.custom'
    _order = 'create_date desc'  # search(limit=1) should return the last customization

    ref_id = fields.Many2one('ir.ui.view', string='Original View', index=True, required=True, ondelete='cascade')
    user_id = fields.Many2one('res.users', string='User', index=True, required=True, ondelete='cascade')
    arch = fields.Text(string='View Architecture', required=True)

    @api.multi
    def name_get(self):
        return [(rec.id, rec.user_id.name) for rec in self]

    @api.model
    def name_search(self, name, args=None, operator='ilike', limit=100):
        if name:
            recs = self.search([('user_id', operator, name)] + (args or []), limit=limit)
            return recs.name_get()
        return super(ViewCustom, self).name_search(name, args=args, operator=operator, limit=limit)

    @api.model_cr_context
    def _auto_init(self):
        res = super(ViewCustom, self)._auto_init()
        self._cr.execute("SELECT indexname FROM pg_indexes WHERE indexname = 'ir_ui_view_custom_user_id_ref_id'")
        if not self._cr.fetchone():
            self._cr.execute("CREATE INDEX ir_ui_view_custom_user_id_ref_id ON ir_ui_view_custom (user_id, ref_id)")
        return res


def _hasclass(context, *cls):
    """ Checks if the context node has all the classes passed as arguments
    """
    node_classes = set(context.context_node.attrib.get('class', '').split())
    return node_classes.issuperset(cls)


def get_view_arch_from_file(filename, xmlid):
    doc = etree.parse(filename)
    node = None
    for n in doc.xpath('//*[@id="%s"]' % (xmlid)):
        if n.tag in ('template', 'record'):
            node = n
            break
    if node is None:
        # fallback search on template with implicit module name
        for n in doc.xpath('//*[@id="%s"]' % (xmlid.split('.')[1])):
            if n.tag in ('template', 'record'):
                node = n
                break
    if node is not None:
        if node.tag == 'record':
            field = node.find('field[@name="arch"]')
            _fix_multiple_roots(field)
            inner = ''.join([etree.tostring(child) for child in field.iterchildren()])
            return field.text + inner
        elif node.tag == 'template':
            # The following dom operations has been copied from convert.py's _tag_template()
            if not node.get('inherit_id'):
                node.set('t-name', xmlid)
                node.tag = 't'
            else:
                node.tag = 'data'
            node.attrib.pop('id', None)
            return etree.tostring(node)
    _logger.warning("Could not find view arch definition in file '%s' for xmlid '%s'", filename, xmlid)
    return None

xpath_utils = etree.FunctionNamespace(None)
xpath_utils['hasclass'] = _hasclass

TRANSLATED_ATTRS_RE = re.compile(r"@(%s)\b" % "|".join(TRANSLATED_ATTRS))


class View(models.Model):
    _name = 'ir.ui.view'
    _order = "priority,name,id"

    # Holds the RNG schema
    _relaxng_validator = None

    name = fields.Char(string='View Name', required=True)
    model = fields.Char(index=True)
    key = fields.Char()
    priority = fields.Integer(string='Sequence', default=16, required=True)
    type = fields.Selection([('tree', 'Tree'),
                             ('form', 'Form'),
                             ('graph', 'Graph'),
                             ('pivot', 'Pivot'),
                             ('calendar', 'Calendar'),
                             ('diagram', 'Diagram'),
                             ('gantt', 'Gantt'),
                             ('kanban', 'Kanban'),
                             ('search', 'Search'),
                             ('qweb', 'QWeb')], string='View Type')
    arch = fields.Text(compute='_compute_arch', inverse='_inverse_arch', string='View Architecture', nodrop=True)
    arch_base = fields.Text(compute='_compute_arch_base', inverse='_inverse_arch_base', string='View Architecture')
    arch_db = fields.Text(string='Arch Blob', translate=xml_translate, oldname='arch')
    arch_fs = fields.Char(string='Arch Filename')
    inherit_id = fields.Many2one('ir.ui.view', string='Inherited View', ondelete='restrict', index=True)
    inherit_children_ids = fields.One2many('ir.ui.view', 'inherit_id', string='Views which inherit from this one')
    field_parent = fields.Char(string='Child Field')
    model_data_id = fields.Many2one('ir.model.data', compute='_compute_model_data_id', string="Model Data", store=True)
    xml_id = fields.Char(string="External ID", compute='_compute_xml_id',
                         help="ID of the view defined in xml file")
    groups_id = fields.Many2many('res.groups', 'ir_ui_view_group_rel', 'view_id', 'group_id',
                                 string='Groups', help="If this field is empty, the view applies to all users. Otherwise, the view applies to the users of those groups only.")
    model_ids = fields.One2many('ir.model.data', 'res_id', domain=[('model', '=', 'ir.ui.view')], auto_join=True)
    create_date = fields.Datetime(readonly=True)
    write_date = fields.Datetime(string='Last Modification Date', readonly=True)

    mode = fields.Selection([('primary', "Base view"), ('extension', "Extension View")],
                            string="View inheritance mode", default='primary', required=True,
                            help="""Only applies if this view inherits from an other one (inherit_id is not False/Null).

* if extension (default), if this view is requested the closest primary view
is looked up (via inherit_id), then all views inheriting from it with this
view's model are applied
* if primary, the closest primary view is fully resolved (even if it uses a
different model than this one), then this view's inheritance specs
(<xpath/>) are applied, and the result is used as if it were this view's
actual arch.
""")
    active = fields.Boolean(default=True,
                            help="""If this view is inherited,
* if True, the view always extends its parent
* if False, the view currently does not extend its parent but can be enabled
         """)

    @api.depends('arch_db', 'arch_fs')
    def _compute_arch(self):
        def resolve_external_ids(arch_fs, view_xml_id):
            def replacer(m):
                xmlid = m.group('xmlid')
                if '.' not in xmlid:
                    xmlid = '%s.%s' % (view_xml_id.split('.')[0], xmlid)
                return m.group('prefix') + str(self.env['ir.model.data'].xmlid_to_res_id(xmlid))
            return re.sub(r'(?P<prefix>[^%])%\((?P<xmlid>.*?)\)[ds]', replacer, arch_fs)

        for view in self:
            arch_fs = None
            if 'xml' in config['dev_mode'] and view.arch_fs and view.xml_id:
                # It is safe to split on / herebelow because arch_fs is explicitely stored with '/'
                fullpath = get_resource_path(*view.arch_fs.split('/'))
                arch_fs = get_view_arch_from_file(fullpath, view.xml_id)
                # replace %(xml_id)s, %(xml_id)d, %%(xml_id)s, %%(xml_id)d by the res_id
                arch_fs = arch_fs and resolve_external_ids(arch_fs, view.xml_id).replace('%%', '%')
            view.arch = arch_fs or view.arch_db

    def _inverse_arch(self):
        for view in self:
            data = dict(arch_db=view.arch)
            if 'install_mode_data' in self._context:
                imd = self._context['install_mode_data']
                if '.' not in imd['xml_id']:
                    imd['xml_id'] = '%s.%s' % (imd['module'], imd['xml_id'])
                if self._name == imd['model'] and (not view.xml_id or view.xml_id == imd['xml_id']):
                    # we store the relative path to the resource instead of the absolute path, if found
                    # (it will be missing e.g. when importing data-only modules using base_import_module)
                    path_info = get_resource_from_path(imd['xml_file'])
                    if path_info:
                        data['arch_fs'] = '/'.join(path_info[0:2])
            view.write(data)

    @api.depends('arch')
    def _compute_arch_base(self):
        # 'arch_base' is the same as 'arch' without translation
        for view, view_wo_lang in zip(self, self.with_context(lang=None)):
            view.arch_base = view_wo_lang.arch

    def _inverse_arch_base(self):
        for view, view_wo_lang in zip(self, self.with_context(lang=None)):
            view_wo_lang.arch = view.arch_base

    @api.depends('write_date')
    def _compute_model_data_id(self):
        # get the first ir_model_data record corresponding to self
        domain = [('model', '=', 'ir.ui.view'), ('res_id', 'in', self.ids)]
        for data in self.env['ir.model.data'].search_read(domain, ['res_id'], order='id desc'):
            view = self.browse(data['res_id'])
            view.model_data_id = data['id']

    def _compute_xml_id(self):
        xml_ids = collections.defaultdict(list)
        domain = [('model', '=', 'ir.ui.view'), ('res_id', 'in', self.ids)]
        for data in self.env['ir.model.data'].search_read(domain, ['module', 'name', 'res_id']):
            xml_ids[data['res_id']].append("%s.%s" % (data['module'], data['name']))
        for view in self:
            view.xml_id = xml_ids.get(view.id, [''])[0]

    def _relaxng(self):
        if not self._relaxng_validator:
            with tools.file_open(os.path.join('base', 'rng', 'view.rng')) as frng:
                try:
                    relaxng_doc = etree.parse(frng)
                    self._relaxng_validator = etree.RelaxNG(relaxng_doc)
                except Exception:
                    _logger.exception('Failed to load RelaxNG XML schema for views validation')
        return self._relaxng_validator

    def _valid_inheritance(self, arch):
        """ Check whether view inheritance is based on translated attribute. """
        for node in arch.xpath('//*[@position]'):
            # inheritance may not use a translated attribute as selector
            if node.tag == 'xpath':
                match = TRANSLATED_ATTRS_RE.search(node.get('expr', ''))
                if match:
                    message = "View inheritance may not use attribute %r as a selector." % match.group(1)
                    self.raise_view_error(message, self.id)
            else:
                for attr in TRANSLATED_ATTRS:
                    if node.get(attr):
                        message = "View inheritance may not use attribute %r as a selector." % attr
                        self.raise_view_error(message, self.id)
        return True

    @api.constrains('arch_db')
    def _check_xml(self):
        # Sanity checks: the view should not break anything upon rendering!
        # Any exception raised below will cause a transaction rollback.
        for view in self:
            view_arch = etree.fromstring(encode(view.arch))
            view._valid_inheritance(view_arch)
            view_def = view.read_combined(['arch'])
            view_arch_utf8 = view_def['arch']
            if view.type != 'qweb':
                view_doc = etree.fromstring(view_arch_utf8)
                # verify that all fields used are valid, etc.
                self.postprocess_and_fields(view.model, view_doc, view.id)
                # RNG-based validation is not possible anymore with 7.0 forms
                view_docs = [view_doc]
                if view_docs[0].tag == 'data':
                    # A <data> element is a wrapper for multiple root nodes
                    view_docs = view_docs[0]
                validator = self._relaxng()
                for view_arch in view_docs:
                    version = view_arch.get('version', '7.0')
                    if parse_version(version) < parse_version('7.0') and validator and not validator.validate(view_arch):
                        for error in validator.error_log:
                            _logger.error(tools.ustr(error))
                        raise ValidationError(_('Invalid view definition'))
                    if not valid_view(view_arch):
                        raise ValidationError(_('Invalid view definition'))
        return True

    @api.constrains('type', 'groups_id')
    def _check_groups(self):
        for view in self:
            if view.type == 'qweb' and view.groups_id:
                raise ValidationError(_("Qweb view cannot have 'Groups' define on the record. Use 'groups' attributes inside the view definition"))

    @api.constrains('inherit_id')
    def _check_000_inheritance(self):
        # NOTE: constraints methods are check alphabetically. Always ensure this method will be
        #       called before other constraint metheods to avoid infinite loop in `read_combined`.
        if not self._check_recursion(parent='inherit_id'):
            raise ValidationError(_('You cannot create recursive inherited views.'))

    _sql_constraints = [
        ('inheritance_mode',
         "CHECK (mode != 'extension' OR inherit_id IS NOT NULL)",
         "Invalid inheritance mode: if the mode is 'extension', the view must"
         " extend an other view"),
    ]

    @api.model_cr_context
    def _auto_init(self):
        res = super(View, self)._auto_init()
        self._cr.execute('SELECT indexname FROM pg_indexes WHERE indexname = \'ir_ui_view_model_type_inherit_id\'')
        if not self._cr.fetchone():
            self._cr.execute('CREATE INDEX ir_ui_view_model_type_inherit_id ON ir_ui_view (model, inherit_id)')
        return res

    def _compute_defaults(self, values):
        if 'inherit_id' in values:
            values.setdefault('mode', 'extension' if values['inherit_id'] else 'primary')
        return values

    @api.model
    def create(self, values):
        if not values.get('type'):
            if values.get('inherit_id'):
                values['type'] = self.browse(values['inherit_id']).type
            else:

                try:
                    if not values.get('arch') and not values.get('arch_base'):
                        raise ValidationError(_('Missing view architecture.'))
                    values['type'] = etree.fromstring(values.get('arch') or values.get('arch_base')).tag
                except LxmlError:
                    # don't raise here, the constraint that runs `self._check_xml` will
                    # do the job properly.
                    pass

        if not values.get('name'):
            values['name'] = "%s %s" % (values.get('model'), values['type'])

        self.clear_caches()

        if 'install_mode_data' in self._context:
            # the view is created from a data file by installing a module; delay
            # the recomputation of field 'model_data_id' until its xmlid record
            # is created
            with self.env.norecompute():
                return super(View, self).create(self._compute_defaults(values))
        else:
            return super(View, self).create(self._compute_defaults(values))

    @api.multi
    def write(self, vals):
        # If view is modified we remove the arch_fs information thus activating the arch_db
        # version. An `init` of the view will restore the arch_fs for the --dev mode
        if ('arch' in vals or 'arch_base' in vals) and 'install_mode_data' not in self._context:
            vals['arch_fs'] = False

        # drop the corresponding view customizations (used for dashboards for example), otherwise
        # not all users would see the updated views
        custom_view = self.env['ir.ui.view.custom'].search([('ref_id', 'in', self.ids)])
        if custom_view:
            custom_view.unlink()

        self.clear_caches()
        return super(View, self).write(self._compute_defaults(vals))

    @api.multi
    def toggle(self):
        """ Switches between enabled and disabled statuses
        """
        for view in self:
            view.write({'active': not view.active})

    # default view selection
    @api.model
    def default_view(self, model, view_type):
        """ Fetches the default view for the provided (model, view_type) pair:
         primary view with the lowest priority.

        :param str model:
        :param int view_type:
        :return: id of the default view of False if none found
        :rtype: int
        """
        domain = [('model', '=', model), ('type', '=', view_type), ('mode', '=', 'primary')]
        return self.search(domain, limit=1).id

    #------------------------------------------------------
    # Inheritance mecanism
    #------------------------------------------------------
    @api.model
    def _get_inheriting_views_arch_domain(self, view_id, model):
        return [
            ['inherit_id', '=', view_id],
            ['model', '=', model],
            ['mode', '=', 'extension'],
            ['active', '=', True],
        ]

    @api.model
    def get_inheriting_views_arch(self, view_id, model):
        """Retrieves the architecture of views that inherit from the given view, from the sets of
           views that should currently be used in the system. During the module upgrade phase it
           may happen that a view is present in the database but the fields it relies on are not
           fully loaded yet. This method only considers views that belong to modules whose code
           is already loaded. Custom views defined directly in the database are loaded only
           after the module initialization phase is completely finished.

           :param int view_id: id of the view whose inheriting views should be retrieved
           :param str model: model identifier of the inheriting views.
           :rtype: list of tuples
           :return: [(view_arch,view_id), ...]
        """
        user_groups = self.env.user.groups_id
        conditions = self._get_inheriting_views_arch_domain(view_id, model)

        if self.pool._init and not self._context.get('load_all_views'):
            # Module init currently in progress, only consider views from
            # modules whose code is already loaded

            # Search terms inside an OR branch in a domain
            # cannot currently use relationships that are
            # not required. The root cause is the INNER JOIN
            # used to implement it.
            modules = tuple(self.pool._init_modules) + (self._context.get('install_mode_data', {}).get('module'),)
            views = self.search(conditions + [('model_ids.module', 'in', modules)])
            views = self.search(conditions + [('id', 'in', list(self._context.get('check_view_ids') or (0,)) + map(int, views))])
        else:
            views = self.search(conditions)

        return [(view.arch, view.id)
                for view in views.sudo()
                if not view.groups_id or (view.groups_id & user_groups)]

    @api.model
    def raise_view_error(self, message, view_id):
        view = self.browse(view_id)
        not_avail = _('n/a')
        message = (
            "%(msg)s\n\n" +
            _("Error context:\nView `%(view_name)s`") +
            "\n[view_id: %(viewid)s, xml_id: %(xmlid)s, "
            "model: %(model)s, parent_id: %(parent)s]"
        ) % {
            'view_name': view.name or not_avail,
            'viewid': view_id or not_avail,
            'xmlid': view.xml_id or not_avail,
            'model': view.model or not_avail,
            'parent': view.inherit_id.id or not_avail,
            'msg': message,
        }
        _logger.info(message)
        raise ValueError(message)

    def locate_node(self, arch, spec):
        """ Locate a node in a source (parent) architecture.

        Given a complete source (parent) architecture (i.e. the field
        `arch` in a view), and a 'spec' node (a node in an inheriting
        view that specifies the location in the source view of what
        should be changed), return (if it exists) the node in the
        source view matching the specification.

        :param arch: a parent architecture to modify
        :param spec: a modifying node in an inheriting view
        :return: a node in the source matching the spec
        """
        if spec.tag == 'xpath':
            nodes = arch.xpath(spec.get('expr'))
            return nodes[0] if nodes else None
        elif spec.tag == 'field':
            # Only compare the field name: a field can be only once in a given view
            # at a given level (and for multilevel expressions, we should use xpath
            # inheritance spec anyway).
            for node in arch.iter('field'):
                if node.get('name') == spec.get('name'):
                    return node
            return None

        for node in arch.iter(spec.tag):
            if isinstance(node, SKIPPED_ELEMENT_TYPES):
                continue
            if all(node.get(attr) == spec.get(attr) for attr in spec.attrib
                   if attr not in ('position', 'version')):
                # Version spec should match parent's root element's version
                if spec.get('version') and spec.get('version') != arch.get('version'):
                    return None
                return node
        return None

    def inherit_branding(self, specs_tree, view_id, root_id):
        for node in specs_tree.iterchildren(tag=etree.Element):
            xpath = node.getroottree().getpath(node)
            if node.tag == 'data' or node.tag == 'xpath' or node.get('position') or node.get('t-field'):
                self.inherit_branding(node, view_id, root_id)
            else:
                node.set('data-oe-id', str(view_id))
                node.set('data-oe-xpath', xpath)
                node.set('data-oe-model', 'ir.ui.view')
                node.set('data-oe-field', 'arch')
        return specs_tree

    @api.model
    def apply_inheritance_specs(self, source, specs_tree, inherit_id):
        """ Apply an inheriting view (a descendant of the base view)

        Apply to a source architecture all the spec nodes (i.e. nodes
        describing where and what changes to apply to some parent
        architecture) given by an inheriting view.

        :param Element source: a parent architecture to modify
        :param Elepect specs_tree: a modifying architecture in an inheriting view
        :param inherit_id: the database id of specs_arch
        :return: a modified source where the specs are applied
        :rtype: Element
        """
        # Queue of specification nodes (i.e. nodes describing where and
        # changes to apply to some parent architecture).
        specs = [specs_tree]

        while len(specs):
            spec = specs.pop(0)
            if isinstance(spec, SKIPPED_ELEMENT_TYPES):
                continue
            if spec.tag == 'data':
                specs += [c for c in spec]
                continue
            node = self.locate_node(source, spec)
            if node is not None:
                pos = spec.get('position', 'inside')
                if pos == 'replace':
                    for loc in spec.xpath(".//*[text()='$0']"):
                        loc.text = ''
                        loc.append(copy.deepcopy(node))
                    if node.getparent() is None:
                        source = copy.deepcopy(spec[0])
                    else:
                        for child in spec:
                            node.addprevious(child)
                        node.getparent().remove(node)
                elif pos == 'attributes':
                    for child in spec.getiterator('attribute'):
                        attribute = child.get('name')
                        value = child.text or ''
                        if child.get('add') or child.get('remove'):
                            assert not child.text
                            separator = child.get('separator', ',')
                            if separator == ' ':
                                separator = None    # squash spaces
                            to_add = filter(bool, map(str.strip, child.get('add', '').split(separator)))
                            to_remove = map(str.strip, child.get('remove', '').split(separator))
                            values = map(str.strip, node.get(attribute, '').split(separator))
                            value = (separator or ' ').join(filter(lambda s: s not in to_remove, values) + to_add)
                        if value:
                            node.set(attribute, value)
                        elif attribute in node.attrib:
                            del node.attrib[attribute]
                else:
                    sib = node.getnext()
                    for child in spec:
                        if pos == 'inside':
                            node.append(child)
                        elif pos == 'after':
                            if sib is None:
                                node.addnext(child)
                                node = child
                            else:
                                sib.addprevious(child)
                        elif pos == 'before':
                            node.addprevious(child)
                        else:
                            self.raise_view_error(_("Invalid position attribute: '%s'") % pos, inherit_id)
            else:
                attrs = ''.join([
                    ' %s="%s"' % (attr, spec.get(attr))
                    for attr in spec.attrib
                    if attr != 'position'
                ])
                tag = "<%s%s>" % (spec.tag, attrs)
                self.raise_view_error(_("Element '%s' cannot be located in parent view") % tag, inherit_id)

        return source

    @api.model
    def apply_view_inheritance(self, source, source_id, model, root_id=None):
        """ Apply all the (directly and indirectly) inheriting views.

        :param source: a parent architecture to modify (with parent modifications already applied)
        :param source_id: the database view_id of the parent view
        :param model: the original model for which we create a view (not
            necessarily the same as the source's model); only the inheriting
            views with that specific model will be applied.
        :return: a modified source where all the modifying architecture are applied
        """
        if root_id is None:
            root_id = source_id
        sql_inherit = self.get_inheriting_views_arch(source_id, model)
        for (specs, view_id) in sql_inherit:
            specs_tree = etree.fromstring(specs.encode('utf-8'))
            if self._context.get('inherit_branding'):
                self.inherit_branding(specs_tree, view_id, root_id)
            source = self.apply_inheritance_specs(source, specs_tree, view_id)
            source = self.apply_view_inheritance(source, view_id, model, root_id=root_id)
        return source

    @api.multi
    def read_combined(self, fields=None):
        """
        Utility function to get a view combined with its inherited views.

        * Gets the top of the view tree if a sub-view is requested
        * Applies all inherited archs on the root view
        * Returns the view with all requested fields
          .. note:: ``arch`` is always added to the fields list even if not
                    requested (similar to ``id``)
        """
        # introduce check_view_ids in context
        if 'check_view_ids' not in self._context:
            self = self.with_context(check_view_ids=[])

        check_view_ids = self._context['check_view_ids']

        # if view_id is not a root view, climb back to the top.
        root = self
        while root.mode != 'primary':
            # Add inherited views to the list of loading forced views
            # Otherwise, inherited views could not find elements created in their direct parents if that parent is defined in the same module
            check_view_ids.append(root.id)
            root = root.inherit_id

        # arch and model fields are always returned
        if fields:
            fields = list({'arch', 'model'}.union(fields))

        # read the view arch
        [view_data] = root.read(fields=fields)
        view_arch = etree.fromstring(view_data['arch'].encode('utf-8'))
        if not root.inherit_id:
            arch_tree = view_arch
        else:
            parent_view = root.inherit_id.read_combined(fields=fields)
            arch_tree = etree.fromstring(parent_view['arch'])
            arch_tree = self.apply_inheritance_specs(arch_tree, view_arch, parent_view['id'])

        if self._context.get('inherit_branding'):
            arch_tree.attrib.update({
                'data-oe-model': 'ir.ui.view',
                'data-oe-id': str(root.id),
                'data-oe-field': 'arch',
            })

        # and apply inheritance
        arch = self.apply_view_inheritance(arch_tree, root.id, self.model)

        return dict(view_data, arch=etree.tostring(arch, encoding='utf-8'))

    def _apply_group(self, model, node, modifiers, fields):
        """Apply group restrictions,  may be set at view level or model level::
           * at view level this means the element should be made invisible to
             people who are not members
           * at model level (exclusively for fields, obviously), this means
             the field should be completely removed from the view, as it is
             completely unavailable for non-members

           :return: True if field should be included in the result of fields_view_get
        """
        Model = self.env[model]

        if node.tag == 'field' and node.get('name') in Model._fields:
            field = Model._fields[node.get('name')]
            if field.groups and not self.user_has_groups(groups=field.groups):
                node.getparent().remove(node)
                fields.pop(node.get('name'), None)
                # no point processing view-level ``groups`` anymore, return
                return False
        if node.get('groups'):
            can_see = self.user_has_groups(groups=node.get('groups'))
            if not can_see:
                node.set('invisible', '1')
                modifiers['invisible'] = True
                if 'attrs' in node.attrib:
                    del node.attrib['attrs']    # avoid making field visible later
            del node.attrib['groups']
        return True

    #------------------------------------------------------
    # Postprocessing: translation, groups and modifiers
    #------------------------------------------------------
    # TODO: remove group processing from ir_qweb
    #------------------------------------------------------
    @api.model
    def postprocess(self, model, node, view_id, in_tree_view, model_fields):
        """Return the description of the fields in the node.

        In a normal call to this method, node is a complete view architecture
        but it is actually possible to give some sub-node (this is used so
        that the method can call itself recursively).

        Originally, the field descriptions are drawn from the node itself.
        But there is now some code calling fields_get() in order to merge some
        of those information in the architecture.

        """
        result = False
        fields = {}
        children = True

        modifiers = {}
        if model not in self.env:
            self.raise_view_error(_('Model not found: %(model)s') % dict(model=model), view_id)
        Model = self.env[model]

        if node.tag in ('field', 'node', 'arrow'):
            if node.get('object'):
                attrs = {}
                views = {}
                xml_form = E.form(*(f for f in node if f.tag == 'field'))
                xarch, xfields = self.with_context(base_model_name=model).postprocess_and_fields(node.get('object'), xml_form, view_id)
                views['form'] = {
                    'arch': xarch,
                    'fields': xfields,
                }
                attrs = {'views': views}
                fields = xfields
            if node.get('name'):
                attrs = {}
                field = Model._fields.get(node.get('name'))
                if field:
                    children = False
                    views = {}
                    for f in node:
                        if f.tag in ('form', 'tree', 'graph', 'kanban', 'calendar'):
                            node.remove(f)
                            xarch, xfields = self.with_context(base_model_name=model).postprocess_and_fields(field.comodel_name, f, view_id)
                            views[str(f.tag)] = {
                                'arch': xarch,
                                'fields': xfields,
                            }
                    attrs = {'views': views}
                    if field.comodel_name in self.env and field.type in ('many2one', 'many2many'):
                        Comodel = self.env[field.comodel_name]
                        node.set('can_create', 'true' if Comodel.check_access_rights('create', raise_exception=False) else 'false')
                        node.set('can_write', 'true' if Comodel.check_access_rights('write', raise_exception=False) else 'false')
                fields[node.get('name')] = attrs

                field = model_fields.get(node.get('name'))
                if field:
                    orm.transfer_field_to_modifiers(field, modifiers)

        elif node.tag in ('form', 'tree'):
            result = Model.view_header_get(False, node.tag)
            if result:
                node.set('string', result)
            in_tree_view = node.tag == 'tree'

        elif node.tag == 'calendar':
            for additional_field in ('date_start', 'date_delay', 'date_stop', 'color', 'all_day', 'attendee'):
                if node.get(additional_field):
                    fields[node.get(additional_field)] = {}

        if not self._apply_group(model, node, modifiers, fields):
            # node must be removed, no need to proceed further with its children
            return fields

        # The view architeture overrides the python model.
        # Get the attrs before they are (possibly) deleted by check_group below
        orm.transfer_node_to_modifiers(node, modifiers, self._context, in_tree_view)

        for f in node:
            if children or (node.tag == 'field' and f.tag in ('filter', 'separator')):
                fields.update(self.postprocess(model, f, view_id, in_tree_view, model_fields))

        orm.transfer_modifiers_to_node(modifiers, node)
        return fields

    def add_on_change(self, model_name, arch):
        """ Add attribute on_change="1" on fields that are dependencies of
            computed fields on the same view.
        """
        # map each field object to its corresponding nodes in arch
        field_nodes = collections.defaultdict(list)

        def collect(node, model):
            if node.tag == 'field':
                field = model._fields.get(node.get('name'))
                if field:
                    field_nodes[field].append(node)
                    if field.relational:
                        model = self.env[field.comodel_name]
            for child in node:
                collect(child, model)

        collect(arch, self.env[model_name])

        for field, nodes in field_nodes.iteritems():
            # if field should trigger an onchange, add on_change="1" on the
            # nodes referring to field
            model = self.env[field.model_name]
            if model._has_onchange(field, field_nodes):
                for node in nodes:
                    if not node.get('on_change'):
                        node.set('on_change', '1')

        return arch

    @api.model
    def _disable_workflow_buttons(self, model, node):
        """ Set the buttons in node to readonly if the user can't activate them. """
        if model is None or self.env.user.id == SUPERUSER_ID:
            # admin user can always activate workflow buttons
            return node

        # TODO handle the case of more than one workflow for a model or multiple
        # transitions with different groups and same signal
        user_group_ids = set(self.env.user.groups_id.ids)
        buttons = (n for n in node.getiterator('button') if n.get('type') != 'object')
        for button in buttons:
            query = """SELECT DISTINCT t.group_id
                         FROM wkf
                   INNER JOIN wkf_activity a ON a.wkf_id = wkf.id
                   INNER JOIN wkf_transition t ON (t.act_to = a.id)
                        WHERE wkf.osv = %s
                          AND t.signal = %s
                          AND t.group_id is NOT NULL"""
            self._cr.execute(query, (model, button.get('name')))
            group_ids = set(row[0] for row in self._cr.fetchall() if row[0])
            can_click = not group_ids or bool(user_group_ids & group_ids)
            button.set('readonly', str(int(not can_click)))
        return node

    @api.model
    def postprocess_and_fields(self, model, node, view_id):
        """ Return an architecture and a description of all the fields.

        The field description combines the result of fields_get() and
        postprocess().

        :param node: the architecture as as an etree
        :return: a tuple (arch, fields) where arch is the given node as a
            string and fields is the description of all the fields.

        """
        fields = {}
        if model not in self.env:
            self.raise_view_error(_('Model not found: %(model)s') % dict(model=model), view_id)
        Model = self.env[model]

        is_base_model = self.env.context.get('base_model_name', model) == model

        if node.tag == 'diagram':
            if node.getchildren()[0].tag == 'node':
                node_model = self.env[node.getchildren()[0].get('object')]
                node_fields = node_model.fields_get(None)
                fields.update(node_fields)
                if (not node.get("create") and
                        not node_model.check_access_rights('create', raise_exception=False) or
                        not self._context.get("create", True) and is_base_model):
                    node.set("create", 'false')
            if node.getchildren()[1].tag == 'arrow':
                arrow_fields = self.env[node.getchildren()[1].get('object')].fields_get(None)
                fields.update(arrow_fields)
        else:
            fields = Model.fields_get(None)

        node = self.add_on_change(model, node)
        fields_def = self.postprocess(model, node, view_id, False, fields)
        node = self._disable_workflow_buttons(model, node)
        if node.tag in ('kanban', 'tree', 'form', 'gantt'):
            for action, operation in (('create', 'create'), ('delete', 'unlink'), ('edit', 'write')):
                if (not node.get(action) and
                        not Model.check_access_rights(operation, raise_exception=False) or
                        not self._context.get(action, True) and is_base_model):
                    node.set(action, 'false')
        if node.tag in ('kanban',):
            group_by_name = node.get('default_group_by')
            if group_by_name in Model._fields:
                group_by_field = Model._fields[group_by_name]
                if group_by_field.type == 'many2one':
                    group_by_model = Model.env[group_by_field.comodel_name]
                    for action, operation in (('group_create', 'create'), ('group_delete', 'unlink'), ('group_edit', 'write')):
                        if (not node.get(action) and
                                not group_by_model.check_access_rights(operation, raise_exception=False) or
                                not self._context.get(action, True) and is_base_model):
                            node.set(action, 'false')

        arch = etree.tostring(node, encoding="utf-8").replace('\t', '')
        for k in fields.keys():
            if k not in fields_def:
                del fields[k]
        for field in fields_def:
            if field in fields:
                fields[field].update(fields_def[field])
            else:
                message = _("Field `%(field_name)s` does not exist") % dict(field_name=field)
                self.raise_view_error(message, view_id)
        return arch, fields

    #------------------------------------------------------
    # QWeb template views
    #------------------------------------------------------

    def _read_template_keys(self):
        """ Return the list of context keys to use for caching ``_read_template``. """
        return ['lang', 'inherit_branding', 'editable', 'translatable', 'edit_translations', 'website_id']

    # apply ormcache_context decorator unless in dev mode...
    @api.model
    @tools.conditional(
        'xml' not in config['dev_mode'],
        tools.ormcache('frozenset(self.env.user.groups_id.ids)', 'view_id',
                       'tuple(map(self._context.get, self._read_template_keys()))'),
    )
    def _read_template(self, view_id):
        arch = self.browse(view_id).read_combined(['arch'])['arch']
        arch_tree = etree.fromstring(arch)
        self.distribute_branding(arch_tree)
        root = E.templates(arch_tree)
        arch = etree.tostring(root, encoding='utf-8', xml_declaration=True)
        return arch

    @api.model
    def read_template(self, xml_id):
        return self._read_template(self.get_view_id(xml_id))

    @api.model
    def get_view_id(self, template):
        """ Return the view ID corresponding to ``template``, which may be a
        view ID or an XML ID. Note that this method may be overridden for other
        kinds of template values.
        """
        if isinstance(template, (int, long)):
            return template
        if '.' not in template:
            raise ValueError('Invalid template id: %r' % template)
        return self.env['ir.model.data'].xmlid_to_res_id(template, raise_if_not_found=True)

    def clear_cache(self):
        """ Deprecated, use `clear_caches` instead. """
        if 'xml' not in config['dev_mode']:
            self.clear_caches()

    def _contains_branded(self, node):
        return node.tag == 't'\
            or 't-raw' in node.attrib\
            or any(self.is_node_branded(child) for child in node.iterdescendants())

    def _pop_view_branding(self, element):
        distributed_branding = dict(
            (attribute, element.attrib.pop(attribute))
            for attribute in MOVABLE_BRANDING
            if element.get(attribute))
        return distributed_branding

    def distribute_branding(self, e, branding=None, parent_xpath='',
                            index_map=ConstantMapping(1)):
        if e.get('t-ignore') or e.tag == 'head':
            # remove any view branding possibly injected by inheritance
            attrs = set(MOVABLE_BRANDING)
            for descendant in e.iterdescendants(tag=etree.Element):
                if not attrs.intersection(descendant.attrib):
                    continue
                self._pop_view_branding(descendant)
            # TODO: find a better name and check if we have a string to boolean helper
            return

        node_path = e.get('data-oe-xpath')
        if node_path is None:
            node_path = "%s/%s[%d]" % (parent_xpath, e.tag, index_map[e.tag])
        if branding and not (e.get('data-oe-model') or e.get('t-field')):
            e.attrib.update(branding)
            e.set('data-oe-xpath', node_path)
        if not e.get('data-oe-model'):
            return

        if {'t-esc', 't-raw'}.intersection(e.attrib):
            # nodes which fully generate their content and have no reason to
            # be branded because they can not sensibly be edited
            self._pop_view_branding(e)
        elif self._contains_branded(e):
            # if a branded element contains branded elements distribute own
            # branding to children unless it's t-raw, then just remove branding
            # on current element
            distributed_branding = self._pop_view_branding(e)

            if 't-raw' not in e.attrib:
                # TODO: collections.Counter if remove p2.6 compat
                # running index by tag type, for XPath query generation
                indexes = collections.defaultdict(lambda: 0)
                for child in e.iterchildren(tag=etree.Element):
                    if child.get('data-oe-xpath'):
                        # injected by view inheritance, skip otherwise
                        # generated xpath is incorrect
                        self.distribute_branding(child)
                    else:
                        indexes[child.tag] += 1
                        self.distribute_branding(
                            child, distributed_branding,
                            parent_xpath=node_path, index_map=indexes)

    def is_node_branded(self, node):
        """ Finds out whether a node is branded or qweb-active (bears a
        @data-oe-model or a @t-* *which is not t-field* as t-field does not
        section out views)

        :param node: an etree-compatible element to test
        :type node: etree._Element
        :rtype: boolean
        """
        return any(
            (attr in ('data-oe-model', 'group') or (attr.startswith('t-')))
            for attr in node.attrib
        )

    @api.multi
    def translate_qweb(self, arch, lang):
        # Deprecated: templates are translated once read from database
        return arch

    @api.multi
    @tools.ormcache('self.id')
    def get_view_xmlid(self):
        domain = [('model', '=', 'ir.ui.view'), ('res_id', '=', self.id)]
        xmlid = self.env['ir.model.data'].search_read(domain, ['module', 'name'])[0]
        return '%s.%s' % (xmlid['module'], xmlid['name'])

    @api.model
    def render_template(self, template, values=None, engine='ir.qweb'):
        return self.browse(self.get_view_id(template)).render(values, engine)

    @api.multi
    def render(self, values=None, engine='ir.qweb'):
        assert isinstance(self.id, (int, long))

        qcontext = dict(
            env=self.env,
            keep_query=keep_query,
            request=request, # might be unbound if we're not in an httprequest context
            debug=request.debug if request else False,
            json=json,
            quote_plus=werkzeug.url_quote_plus,
            time=time,
            datetime=datetime,
            relativedelta=relativedelta,
            xmlid=self.key,
        )
        qcontext.update(values or {})

        return self.env[engine].render(self.id, qcontext)

    #------------------------------------------------------
    # Misc
    #------------------------------------------------------

    @api.multi
    def open_translations(self):
        """ Open a view for editing the translations of field 'arch_db'. """
        return self.env['ir.translation'].translate_fields('ir.ui.view', self.id, 'arch_db')

    @api.model
    def graph_get(self, id, model, node_obj, conn_obj, src_node, des_node, label, scale):
        def rec_name(rec):
            return (rec.name if 'name' in rec else
                    rec.x_name if 'x_name' in rec else
                    None)

        nodes = []
        nodes_name = []
        transitions = []
        start = []
        tres = {}
        labels = {}
        no_ancester = []
        blank_nodes = []

        Model = self.env[model]
        Node = self.env[node_obj]

        for model_key, model_value in Model._fields.iteritems():
            if model_value.type == 'one2many':
                if model_value.comodel_name == node_obj:
                    _Node_Field = model_key
                    _Model_Field = model_value.inverse_name
                for node_key, node_value in Node._fields.iteritems():
                    if node_value.type == 'one2many':
                        if node_value.comodel_name == conn_obj:
                             # _Source_Field = "Incoming Arrows" (connected via des_node)
                            if node_value.inverse_name == des_node:
                                _Source_Field = node_key
                             # _Destination_Field = "Outgoing Arrows" (connected via src_node)
                            if node_value.inverse_name == src_node:
                                _Destination_Field = node_key

        record = Model.browse(id)
        for line in record[_Node_Field]:
            if line[_Source_Field] or line[_Destination_Field]:
                nodes_name.append((line.id, rec_name(line)))
                nodes.append(line.id)
            else:
                blank_nodes.append({'id': line.id, 'name': rec_name(line)})

            if 'flow_start' in line and line.flow_start:
                start.append(line.id)
            elif not line[_Source_Field]:
                no_ancester.append(line.id)

            for t in line[_Destination_Field]:
                transitions.append((line.id, t[des_node].id))
                tres[str(t['id'])] = (line.id, t[des_node].id)
                label_string = ""
                if label:
                    for lbl in safe_eval(label):
                        if tools.ustr(lbl) in t and tools.ustr(t[lbl]) == 'False':
                            label_string += ' '
                        else:
                            label_string = label_string + " " + tools.ustr(t[lbl])
                labels[str(t['id'])] = (line.id, label_string)

        g = graph(nodes, transitions, no_ancester)
        g.process(start)
        g.scale(*scale)
        result = g.result_get()
        results = {}
        for node_id, node_name in nodes_name:
            results[str(node_id)] = result[node_id]
            results[str(node_id)]['name'] = node_name
        return {'nodes': results,
                'transitions': tres,
                'label': labels,
                'blank_nodes': blank_nodes,
                'node_parent_field': _Model_Field}

    @api.model
    def _validate_custom_views(self, model):
        """Validate architecture of custom views (= without xml id) for a given model.
            This method is called at the end of registry update.
        """
        query = """SELECT max(v.id)
                     FROM ir_ui_view v
                LEFT JOIN ir_model_data md ON (md.model = 'ir.ui.view' AND md.res_id = v.id)
                    WHERE md.module NOT IN (SELECT name FROM ir_module_module)
                      AND v.model = %s
                      AND v.active = true
                 GROUP BY coalesce(v.inherit_id, v.id)"""
        self._cr.execute(query, [model])

        rec = self.browse(map(itemgetter(0), self._cr.fetchall()))
        return rec.with_context({'load_all_views': True})._check_xml()

    @api.model
    def _validate_module_views(self, module):
        """Validate architecture of all the views of a given module"""
        assert not self.pool._init or module in self.pool._init_modules
        xmlid_filter = ''
        params = (module,)
        if self.pool._init:
            # only validate the views that are still existing...
            xmlid_filter = "AND md.name IN %s"
            names = tuple(
                name
                for (xmod, name), (model, res_id) in self.pool.model_data_reference_ids.items()
                if xmod == module and model == self._name
            )
            if not names:
                # no views for this module, nothing to validate
                return
            params += (names,)

        query = """SELECT max(v.id)
                     FROM ir_ui_view v
                LEFT JOIN ir_model_data md ON (md.model = 'ir.ui.view' AND md.res_id = v.id)
                    WHERE md.module = %s {0}
                 GROUP BY coalesce(v.inherit_id, v.id)""".format(xmlid_filter)
        self._cr.execute(query, params)

        for vid, in self._cr.fetchall():
            try:
                self.browse(vid)._check_xml()
            except Exception as e:
                self.raise_view_error("Can't validate view:\n%s" % (e.message or repr(e)), vid)