# -*- coding: utf-8 -*-
# Part of Odoo, Flectra. See LICENSE file for full copyright and licensing details.

import logging
import re
import unicodedata

from flectra import _, api, fields, models
from flectra.exceptions import ValidationError
from flectra.tools import ustr
from flectra.tools.safe_eval import safe_eval

_logger = logging.getLogger(__name__)


# Inspired by http://stackoverflow.com/questions/517923
def remove_accents(input_str):
    """Suboptimal-but-better-than-nothing way to replace accented
    latin letters by an ASCII equivalent. Will obviously change the
    meaning of input_str and work only for some cases"""
    input_str = ustr(input_str)
    nkfd_form = unicodedata.normalize('NFKD', input_str)
    return u''.join([c for c in nkfd_form if not unicodedata.combining(c)])


class Alias(models.Model):
    """A Mail Alias is a mapping of an email address with a given Flectra Document
       model. It is used by Flectra's mail gateway when processing incoming emails
       sent to the system. If the recipient address (To) of the message matches
       a Mail Alias, the message will be either processed following the rules
       of that alias. If the message is a reply it will be attached to the
       existing discussion on the corresponding record, otherwise a new
       record of the corresponding model will be created.

       This is meant to be used in combination with a catch-all email configuration
       on the company's mail server, so that as soon as a new mail.alias is
       created, it becomes immediately usable and Flectra will accept email for it.
     """
    _name = 'mail.alias'
    _description = "Email Aliases"
    _rec_name = 'alias_name'
    _order = 'alias_model_id, alias_name'

    alias_name = fields.Char('Alias Name', help="The name of the email "
                                                "alias, e.g. 'jobs' if you "
                                                "want to catch emails for <jobs@example.flectrahq.com>")
    alias_model_id = fields.Many2one('ir.model', 'Aliased Model', required=True, ondelete="cascade",
                                     help="The model (Flectra Document Kind) to which this alias "
                                          "corresponds. Any incoming email that does not reply to an "
                                          "existing record will cause the creation of a new record "
                                          "of this model (e.g. a Project Task)",
                                      # hack to only allow selecting mail_thread models (we might
                                      # (have a few false positives, though)
                                      domain="[('field_id.name', '=', 'message_ids')]")
    alias_user_id = fields.Many2one('res.users', 'Owner', defaults=lambda self: self.env.user,
                                    help="The owner of records created upon receiving emails on this alias. "
                                         "If this field is not set the system will attempt to find the right owner "
                                         "based on the sender (From) address, or will use the Administrator account "
                                         "if no system user is found for that address.")
    alias_defaults = fields.Text('Default Values', required=True, default='{}',
                                 help="A Python dictionary that will be evaluated to provide "
                                      "default values when creating new records for this alias.")
    alias_force_thread_id = fields.Integer(
        'Record Thread ID',
        help="Optional ID of a thread (record) to which all incoming messages will be attached, even "
             "if they did not reply to it. If set, this will disable the creation of new records completely.")
    alias_domain = fields.Char('Alias domain', compute='_get_alias_domain',
                               default=lambda self: self.env["ir.config_parameter"].sudo().get_param("mail.catchall.domain"))
    alias_parent_model_id = fields.Many2one(
        'ir.model', 'Parent Model',
        help="Parent model holding the alias. The model holding the alias reference "
             "is not necessarily the model given by alias_model_id "
             "(example: project (parent_model) and task (model))")
    alias_parent_thread_id = fields.Integer('Parent Record Thread ID', help="ID of the parent record holding the alias (example: project holding the task creation alias)")
    alias_contact = fields.Selection([
        ('everyone', 'Everyone'),
        ('partners', 'Authenticated Partners'),
        ('followers', 'Followers only')], default='everyone',
        string='Alias Contact Security', required=True,
        help="Policy to post a message on the document using the mailgateway.\n"
             "- everyone: everyone can post\n"
             "- partners: only authenticated partners\n"
             "- followers: only followers of the related document or members of following channels\n")

    _sql_constraints = [
        ('alias_unique', 'UNIQUE(alias_name)', 'Unfortunately this email alias is already used, please choose a unique one')
    ]

    @api.multi
    def _get_alias_domain(self):
        alias_domain = self.env["ir.config_parameter"].sudo().get_param("mail.catchall.domain")
        for record in self:
            record.alias_domain = alias_domain

    @api.one
    @api.constrains('alias_defaults')
    def _check_alias_defaults(self):
        try:
            dict(safe_eval(self.alias_defaults))
        except Exception:
            raise ValidationError(_('Invalid expression, it must be a literal python dictionary definition e.g. "{\'field\': \'value\'}"'))

    @api.model
    def create(self, vals):
        """ Creates an email.alias record according to the values provided in ``vals``,
            with 2 alterations: the ``alias_name`` value may be suffixed in order to
            make it unique (and certain unsafe characters replaced), and
            he ``alias_model_id`` value will set to the model ID of the ``model_name``
            context value, if provided.
        """
        model_name = self._context.get('alias_model_name')
        parent_model_name = self._context.get('alias_parent_model_name')
        if vals.get('alias_name'):
            vals['alias_name'] = self._clean_and_make_unique(vals.get('alias_name'))
        if model_name:
            model = self.env['ir.model']._get(model_name)
            vals['alias_model_id'] = model.id
        if parent_model_name:
            model = self.env['ir.model']._get(parent_model_name)
            vals['alias_parent_model_id'] = model.id
        return super(Alias, self).create(vals)

    @api.multi
    def write(self, vals):
        """"give a unique alias name if given alias name is already assigned"""
        if vals.get('alias_name') and self.ids:
            vals['alias_name'] = self._clean_and_make_unique(vals.get('alias_name'), alias_ids=self.ids)
        return super(Alias, self).write(vals)

    @api.multi
    def name_get(self):
        """Return the mail alias display alias_name, including the implicit
           mail catchall domain if exists from config otherwise "New Alias".
           e.g. `jobs@mail.flectrahq.com` or `jobs` or 'New Alias'
        """
        res = []
        for record in self:
            if record.alias_name and record.alias_domain:
                res.append((record['id'], "%s@%s" % (record.alias_name, record.alias_domain)))
            elif record.alias_name:
                res.append((record['id'], "%s" % (record.alias_name)))
            else:
                res.append((record['id'], _("Inactive Alias")))
        return res

    @api.model
    def _find_unique(self, name, alias_ids=False):
        """Find a unique alias name similar to ``name``. If ``name`` is
           already taken, make a variant by adding an integer suffix until
           an unused alias is found.
        """
        sequence = None
        while True:
            new_name = "%s%s" % (name, sequence) if sequence is not None else name
            domain = [('alias_name', '=', new_name)]
            if alias_ids:
                domain += [('id', 'not in', alias_ids)]
            if not self.search(domain):
                break
            sequence = (sequence + 1) if sequence else 2
        return new_name

    @api.model
    def _clean_and_make_unique(self, name, alias_ids=False):
        # when an alias name appears to already be an email, we keep the local part only
        name = remove_accents(name).lower().split('@')[0]
        name = re.sub(r'[^\w+.]+', '-', name)
        return self._find_unique(name, alias_ids=alias_ids)

    @api.multi
    def open_document(self):
        if not self.alias_model_id or not self.alias_force_thread_id:
            return False
        return {
            'view_type': 'form',
            'view_mode': 'form',
            'res_model': self.alias_model_id.model,
            'res_id': self.alias_force_thread_id,
            'type': 'ir.actions.act_window',
        }

    @api.multi
    def open_parent_document(self):
        if not self.alias_parent_model_id or not self.alias_parent_thread_id:
            return False
        return {
            'view_type': 'form',
            'view_mode': 'form',
            'res_model': self.alias_parent_model_id.model,
            'res_id': self.alias_parent_thread_id,
            'type': 'ir.actions.act_window',
        }


class AliasMixin(models.AbstractModel):
    """ A mixin for models that inherits mail.alias. This mixin initializes the
        alias_id column in database, and manages the expected one-to-one
        relation between your model and mail aliases.
    """
    _name = 'mail.alias.mixin'
    _inherits = {'mail.alias': 'alias_id'}

    alias_id = fields.Many2one('mail.alias', string='Alias', ondelete="restrict", required=True)

    def get_alias_model_name(self, vals):
        """ Return the model name for the alias. Incoming emails that are not
            replies to existing records will cause the creation of a new record
            of this alias model. The value may depend on ``vals``, the dict of
            values passed to ``create`` when a record of this model is created.
        """
        return None

    def get_alias_values(self):
        """ Return values to create an alias, or to write on the alias after its
            creation.
        """
        return {'alias_parent_thread_id': self.id}

    @api.model
    def create(self, vals):
        """ Create a record with ``vals``, and create a corresponding alias. """
        record = super(AliasMixin, self.with_context(
            alias_model_name=self.get_alias_model_name(vals),
            alias_parent_model_name=self._name,
        )).create(vals)
        record.alias_id.sudo().write(record.get_alias_values())
        return record

    @api.multi
    def unlink(self):
        """ Delete the given records, and cascade-delete their corresponding alias. """
        aliases = self.mapped('alias_id')
        res = super(AliasMixin, self).unlink()
        aliases.unlink()
        return res

    @api.model_cr_context
    def _init_column(self, name):
        """ Create aliases for existing rows. """
        super(AliasMixin, self)._init_column(name)
        if name != 'alias_id':
            return

        # both self and the alias model must be present in 'ir.model'
        IM = self.env['ir.model']
        IM._reflect_model(self)
        IM._reflect_model(self.env[self.get_alias_model_name({})])

        alias_ctx = {
            'alias_model_name': self.get_alias_model_name({}),
            'alias_parent_model_name': self._name,
        }
        alias_model = self.env['mail.alias'].sudo().with_context(alias_ctx).browse([])

        child_ctx = {
            'active_test': False,       # retrieve all records
            'prefetch_fields': False,   # do not prefetch fields on records
        }
        child_model = self.sudo().with_context(child_ctx).browse([])

        for record in child_model.search([('alias_id', '=', False)]):
            # create the alias, and link it to the current record
            alias = alias_model.create(record.get_alias_values())
            record.with_context({'mail_notrack': True}).alias_id = alias
            _logger.info('Mail alias created for %s %s (id %s)',
                         record._name, record.display_name, record.id)

    def _alias_check_contact(self, message, message_dict, alias):
        """ Main mixin method that inheriting models may inherit in order
        to implement a specifc behavior. """
        return self._alias_check_contact_on_record(self, message, message_dict, alias)

    def _alias_check_contact_on_record(self, record, message, message_dict, alias):
        """ Generic method that takes a record not necessarily inheriting from
        mail.alias.mixin. """
        author = self.env['res.partner'].browse(message_dict.get('author_id', False))
        if alias.alias_contact == 'followers':
            if not record.ids:
                return {
                    'error_message': _('incorrectly configured alias (unknown reference record)'),
                }
            if not hasattr(record, "message_partner_ids") or not hasattr(record, "message_channel_ids"):
                return {
                    'error_message': _('incorrectly configured alias'),
                }
            accepted_partner_ids = record.message_partner_ids | record.message_channel_ids.mapped('channel_partner_ids')
            if not author or author not in accepted_partner_ids:
                return {
                    'error_message': _('restricted to followers'),
                }
        elif alias.alias_contact == 'partners' and not author:
            return {
                'error_message': _('restricted to known authors')
            }
        return True