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

from datetime import datetime
import random

from odoo import api, fields, models, _
from odoo.exceptions import UserError
from odoo.tools.safe_eval import safe_eval
from odoo.tools.translate import html_translate


class MassMailingTag(models.Model):
    """Model of categories of mass mailing, i.e. marketing, newsletter, ... """
    _name = 'mail.mass_mailing.tag'
    _description = 'Mass Mailing Tag'
    _order = 'name'

    name = fields.Char(required=True, translate=True)
    color = fields.Integer(string='Color Index')

    _sql_constraints = [
            ('name_uniq', 'unique (name)', "Tag name already exists !"),
    ]


class MassMailingList(models.Model):
    """Model of a contact list. """
    _name = 'mail.mass_mailing.list'
    _order = 'name'
    _description = 'Mailing List'

    name = fields.Char(string='Mailing List', required=True)
    active = fields.Boolean(default=True)
    create_date = fields.Datetime(string='Creation Date')
    contact_nbr = fields.Integer(compute="_compute_contact_nbr", string='Number of Contacts')

    def _compute_contact_nbr(self):
        contacts_data = self.env['mail.mass_mailing.contact'].read_group([('list_id', 'in', self.ids), ('opt_out', '!=', True)], ['list_id'], ['list_id'])
        mapped_data = dict([(c['list_id'][0], c['list_id_count']) for c in contacts_data])
        for mailing_list in self:
            mailing_list.contact_nbr = mapped_data.get(mailing_list.id, 0)

class MassMailingContact(models.Model):
    """Model of a contact. This model is different from the partner model
    because it holds only some basic information: name, email. The purpose is to
    be able to deal with large contact list to email without bloating the partner
    base."""
    _name = 'mail.mass_mailing.contact'
    _inherit = 'mail.thread'
    _description = 'Mass Mailing Contact'
    _order = 'email'
    _rec_name = 'email'

    name = fields.Char()
    email = fields.Char(required=True)
    create_date = fields.Datetime(string='Create Date')
    list_id = fields.Many2one(
        'mail.mass_mailing.list', string='Mailing List',
        ondelete='cascade', required=True, default=lambda self: self.env['mail.mass_mailing.list'].search([], limit=1, order='id desc'))
    opt_out = fields.Boolean(string='Opt Out', help='The contact has chosen not to receive mails anymore from this list')
    unsubscription_date = fields.Datetime(string='Unsubscription Date')
    message_bounce = fields.Integer(string='Bounce', help='Counter of the number of bounced emails for this contact.')

    @api.model
    def create(self, vals):
        if 'opt_out' in vals:
            vals['unsubscription_date'] = vals['opt_out'] and fields.Datetime.now()
        return super(MassMailingContact, self).create(vals)

    @api.multi
    def write(self, vals):
        if 'opt_out' in vals:
            vals['unsubscription_date'] = vals['opt_out'] and fields.Datetime.now()
        return super(MassMailingContact, self).write(vals)

    def get_name_email(self, name):
        name, email = self.env['res.partner']._parse_partner_name(name)
        if name and not email:
            email = name
        if email and not name:
            name = email
        return name, email

    @api.model
    def name_create(self, name):
        name, email = self.get_name_email(name)
        contact = self.create({'name': name, 'email': email})
        return contact.name_get()[0]

    @api.model
    def add_to_list(self, name, list_id):
        name, email = self.get_name_email(name)
        contact = self.create({'name': name, 'email': email, 'list_id': list_id})
        return contact.name_get()[0]

    @api.multi
    def message_get_default_recipients(self):
        return dict((record.id, {'partner_ids': [], 'email_to': record.email, 'email_cc': False}) for record in self)


class MassMailingStage(models.Model):

    """Stage for mass mailing campaigns. """
    _name = 'mail.mass_mailing.stage'
    _description = 'Mass Mailing Campaign Stage'
    _order = 'sequence'

    name = fields.Char(required=True, translate=True)
    sequence = fields.Integer()


class MassMailingCampaign(models.Model):
    """Model of mass mailing campaigns. """
    _name = "mail.mass_mailing.campaign"
    _description = 'Mass Mailing Campaign'
    _rec_name = "campaign_id"
    _inherits = {'utm.campaign': 'campaign_id'}

    stage_id = fields.Many2one('mail.mass_mailing.stage', string='Stage', required=True, 
        default=lambda self: self.env['mail.mass_mailing.stage'].search([], limit=1))
    user_id = fields.Many2one(
        'res.users', string='Responsible',
        required=True, default=lambda self: self.env.uid)
    campaign_id = fields.Many2one('utm.campaign', 'campaign_id',
        required=True, ondelete='cascade',  help="This name helps you tracking your different campaign efforts, e.g. Fall_Drive, Christmas_Special")
    source_id = fields.Many2one('utm.source', string='Source',
            help="This is the link source, e.g. Search Engine, another domain,or name of email list", default=lambda self: self.env.ref('utm.utm_source_newsletter'))
    medium_id = fields.Many2one('utm.medium', string='Medium',
            help="This is the delivery method, e.g. Postcard, Email, or Banner Ad", default=lambda self: self.env.ref('utm.utm_medium_email'))
    tag_ids = fields.Many2many(
        'mail.mass_mailing.tag', 'mail_mass_mailing_tag_rel',
        'tag_id', 'campaign_id', string='Tags')
    mass_mailing_ids = fields.One2many(
        'mail.mass_mailing', 'mass_mailing_campaign_id',
        string='Mass Mailings')
    unique_ab_testing = fields.Boolean(string='AB Testing',
        help='If checked, recipients will be mailed only once, allowing to send '
             'various mailings in a single campaign to test the effectiveness '
             'of the mailings.')
    color = fields.Integer(string='Color Index')
    clicks_ratio = fields.Integer(compute="_compute_clicks_ratio", string="Number of clicks")
    # stat fields
    total = fields.Integer(compute="_compute_statistics")
    scheduled = fields.Integer(compute="_compute_statistics")
    failed = fields.Integer(compute="_compute_statistics")
    sent = fields.Integer(compute="_compute_statistics", string="Sent Emails")
    delivered = fields.Integer(compute="_compute_statistics")
    opened = fields.Integer(compute="_compute_statistics")
    replied = fields.Integer(compute="_compute_statistics")
    bounced = fields.Integer(compute="_compute_statistics")
    received_ratio = fields.Integer(compute="_compute_statistics", string='Received Ratio')
    opened_ratio = fields.Integer(compute="_compute_statistics", string='Opened Ratio')
    replied_ratio = fields.Integer(compute="_compute_statistics", string='Replied Ratio')
    bounced_ratio = fields.Integer(compute="_compute_statistics", string='Bounced Ratio')
    total_mailings = fields.Integer(compute="_compute_total_mailings", string='Mailings')

    def _compute_clicks_ratio(self):
        self.env.cr.execute("""
            SELECT COUNT(DISTINCT(stats.id)) AS nb_mails, COUNT(DISTINCT(clicks.mail_stat_id)) AS nb_clicks, stats.mass_mailing_campaign_id AS id
            FROM mail_mail_statistics AS stats
            LEFT OUTER JOIN link_tracker_click AS clicks ON clicks.mail_stat_id = stats.id
            WHERE stats.mass_mailing_campaign_id IN %s
            GROUP BY stats.mass_mailing_campaign_id
        """, (tuple(self.ids), ))

        campaign_data = self.env.cr.dictfetchall()
        mapped_data = dict([(c['id'], 100 * c['nb_clicks'] / c['nb_mails']) for c in campaign_data])
        for campaign in self:
            campaign.clicks_ratio = mapped_data.get(campaign.id, 0)

    def _compute_statistics(self):
        """ Compute statistics of the mass mailing campaign """
        self.env.cr.execute("""
            SELECT
                c.id as campaign_id,
                COUNT(s.id) AS total,
                COUNT(CASE WHEN s.sent is not null THEN 1 ELSE null END) AS sent,
                COUNT(CASE WHEN s.scheduled is not null AND s.sent is null AND s.exception is null THEN 1 ELSE null END) AS scheduled,
                COUNT(CASE WHEN s.scheduled is not null AND s.sent is null AND s.exception is not null THEN 1 ELSE null END) AS failed,
                COUNT(CASE WHEN s.id is not null AND s.bounced is null THEN 1 ELSE null END) AS delivered,
                COUNT(CASE WHEN s.opened is not null THEN 1 ELSE null END) AS opened,
                COUNT(CASE WHEN s.replied is not null THEN 1 ELSE null END) AS replied ,
                COUNT(CASE WHEN s.bounced is not null THEN 1 ELSE null END) AS bounced
            FROM
                mail_mail_statistics s
            RIGHT JOIN
                mail_mass_mailing_campaign c
                ON (c.id = s.mass_mailing_campaign_id)
            WHERE
                c.id IN %s
            GROUP BY
                c.id
        """, (tuple(self.ids), ))

        for row in self.env.cr.dictfetchall():
            total = row['total'] or 1
            row['delivered'] = row['sent'] - row['bounced']
            row['received_ratio'] = 100.0 * row['delivered'] / total
            row['opened_ratio'] = 100.0 * row['opened'] / total
            row['replied_ratio'] = 100.0 * row['replied'] / total
            row['bounced_ratio'] = 100.0 * row['bounced'] / total
            self.browse(row.pop('campaign_id')).update(row)

    def _compute_total_mailings(self):
        campaign_data = self.env['mail.mass_mailing'].read_group(
            [('mass_mailing_campaign_id', 'in', self.ids)],
            ['mass_mailing_campaign_id'], ['mass_mailing_campaign_id'])
        mapped_data = dict([(c['mass_mailing_campaign_id'][0], c['mass_mailing_campaign_id_count']) for c in campaign_data])
        for campaign in self:
            campaign.total_mailings = mapped_data.get(campaign.id, 0)

    def get_recipients(self, model=None):
        """Return the recipients of a mailing campaign. This is based on the statistics
        build for each mailing. """
        res = dict.fromkeys(self.ids, {})
        for campaign in self:
            domain = [('mass_mailing_campaign_id', '=', campaign.id)]
            if model:
                domain += [('model', '=', model)]
            res[campaign.id] = set(self.env['mail.mail.statistics'].search(domain).mapped('res_id'))
        return res

    @api.model
    def read_group(self, domain, fields, groupby, offset=0, limit=None, orderby=False, lazy=True):
        """ Override read_group to always display all states. """
        if groupby and groupby[0] == "stage_id":
            # Default result structure
            states_read = self.env['mail.mass_mailing.stage'].search_read([], ['name'])
            states = [(state['id'], state['name']) for state in states_read]
            read_group_all_states = [{
                '__context': {'group_by': groupby[1:]},
                '__domain': domain + [('stage_id', '=', state_value)],
                'stage_id': state_value,
                'state_count': 0,
            } for state_value, state_name in states]
            # Get standard results
            read_group_res = super(MassMailingCampaign, self).read_group(domain, fields, groupby, offset=offset, limit=limit, orderby=orderby)
            # Update standard results with default results
            result = []
            for state_value, state_name in states:
                res = filter(lambda x: x['stage_id'] == (state_value, state_name), read_group_res)
                if not res:
                    res = filter(lambda x: x['stage_id'] == state_value, read_group_all_states)
                res[0]['stage_id'] = [state_value, state_name]
                result.append(res[0])
            return result
        else:
            return super(MassMailingCampaign, self).read_group(domain, fields, groupby, offset=offset, limit=limit, orderby=orderby)


class MassMailing(models.Model):
    """ MassMailing models a wave of emails for a mass mailign campaign.
    A mass mailing is an occurence of sending emails. """

    _name = 'mail.mass_mailing'
    _description = 'Mass Mailing'
    # number of periods for tracking mail_mail statistics
    _period_number = 6
    _order = 'sent_date DESC'
    _inherits = {'utm.source': 'source_id'}
    _rec_name = "source_id"

    @api.model
    def default_get(self, fields):
        res = super(MassMailing, self).default_get(fields)
        if 'reply_to_mode' in fields and not 'reply_to_mode' in res and res.get('mailing_model'):
            if res['mailing_model'] in ['res.partner', 'mail.mass_mailing.contact']:
                res['reply_to_mode'] = 'email'
            else:
                res['reply_to_mode'] = 'thread'
        return res

    def _get_mailing_model(self):
        res = []
        for model_name in self.env:
            model = self.env[model_name]
            if hasattr(model, '_mail_mass_mailing') and getattr(model, '_mail_mass_mailing'):
                if getattr(model, 'message_mass_mailing_enabled'):
                    res.append((model._name, model.message_mass_mailing_enabled()))
                else:
                    res.append((model._name, model._mail_mass_mailing))
        res.append(('mail.mass_mailing.contact', _('Mailing List')))
        return res

    # indirections for inheritance
    _mailing_model = lambda self: self._get_mailing_model()

    active = fields.Boolean(default=True)
    email_from = fields.Char(string='From', required=True,
        default=lambda self: self.env['mail.message']._get_default_from())
    create_date = fields.Datetime(string='Creation Date')
    sent_date = fields.Datetime(string='Sent Date', oldname='date', copy=False)
    schedule_date = fields.Datetime(string='Schedule in the Future')
    body_html = fields.Html(string='Body', sanitize_attributes=False)
    attachment_ids = fields.Many2many('ir.attachment', 'mass_mailing_ir_attachments_rel',
        'mass_mailing_id', 'attachment_id', string='Attachments')
    keep_archives = fields.Boolean(string='Keep Archives')
    mass_mailing_campaign_id = fields.Many2one('mail.mass_mailing.campaign', string='Mass Mailing Campaign')
    campaign_id = fields.Many2one('utm.campaign', string='Campaign',
                                  help="This name helps you tracking your different campaign efforts, e.g. Fall_Drive, Christmas_Special")
    source_id = fields.Many2one('utm.source', string='Subject', required=True, ondelete='cascade',
                                help="This is the link source, e.g. Search Engine, another domain, or name of email list")
    medium_id = fields.Many2one('utm.medium', string='Medium',
                                help="This is the delivery method, e.g. Postcard, Email, or Banner Ad", default=lambda self: self.env.ref('utm.utm_medium_email'))
    clicks_ratio = fields.Integer(compute="_compute_clicks_ratio", string="Number of Clicks")
    state = fields.Selection([('draft', 'Draft'), ('in_queue', 'In Queue'), ('sending', 'Sending'), ('done', 'Sent')],
        string='Status', required=True, copy=False, default='draft')
    color = fields.Integer(related='mass_mailing_campaign_id.color', string='Color Index')
    # mailing options
    reply_to_mode = fields.Selection(
        [('thread', 'Followers of leads/applicants'), ('email', 'Specified Email Address')],
        string='Reply-To Mode', required=True)
    reply_to = fields.Char(string='Reply To', help='Preferred Reply-To Address',
        default=lambda self: self.env['mail.message']._get_default_from())
    # recipients
    mailing_model = fields.Selection(selection=_mailing_model, string='Recipients Model', required=True, default='mail.mass_mailing.contact')
    mailing_domain = fields.Char(string='Domain', oldname='domain', default=[])
    contact_list_ids = fields.Many2many('mail.mass_mailing.list', 'mail_mass_mailing_list_rel',
        string='Mailing Lists')
    contact_ab_pc = fields.Integer(string='A/B Testing percentage',
        help='Percentage of the contacts that will be mailed. Recipients will be taken randomly.', default=100)
    # statistics data
    statistics_ids = fields.One2many('mail.mail.statistics', 'mass_mailing_id', string='Emails Statistics')
    total = fields.Integer(compute="_compute_total")
    scheduled = fields.Integer(compute="_compute_statistics")
    failed = fields.Integer(compute="_compute_statistics")
    sent = fields.Integer(compute="_compute_statistics")
    delivered = fields.Integer(compute="_compute_statistics")
    opened = fields.Integer(compute="_compute_statistics")
    replied = fields.Integer(compute="_compute_statistics")
    bounced = fields.Integer(compute="_compute_statistics")
    failed = fields.Integer(compute="_compute_statistics")
    received_ratio = fields.Integer(compute="_compute_statistics", string='Received Ratio')
    opened_ratio = fields.Integer(compute="_compute_statistics", string='Opened Ratio')
    replied_ratio = fields.Integer(compute="_compute_statistics", string='Replied Ratio')
    bounced_ratio = fields.Integer(compute="_compute_statistics", String='Bounced Ratio')
    next_departure = fields.Datetime(compute="_compute_next_departure", string='Next Departure')

    def _compute_total(self):
        for mass_mailing in self:
            mass_mailing.total = len(mass_mailing.sudo().get_recipients())

    def _compute_clicks_ratio(self):
        self.env.cr.execute("""
            SELECT COUNT(DISTINCT(stats.id)) AS nb_mails, COUNT(DISTINCT(clicks.mail_stat_id)) AS nb_clicks, stats.mass_mailing_id AS id
            FROM mail_mail_statistics AS stats
            LEFT OUTER JOIN link_tracker_click AS clicks ON clicks.mail_stat_id = stats.id
            WHERE stats.mass_mailing_id IN %s
            GROUP BY stats.mass_mailing_id
        """, (tuple(self.ids), ))

        mass_mailing_data = self.env.cr.dictfetchall()
        mapped_data = dict([(m['id'], 100 * m['nb_clicks'] / m['nb_mails']) for m in mass_mailing_data])
        for mass_mailing in self:
            mass_mailing.clicks_ratio = mapped_data.get(mass_mailing.id, 0)

    def _compute_statistics(self):
        """ Compute statistics of the mass mailing """
        self.env.cr.execute("""
            SELECT
                m.id as mailing_id,
                COUNT(s.id) AS total,
                COUNT(CASE WHEN s.sent is not null THEN 1 ELSE null END) AS sent,
                COUNT(CASE WHEN s.scheduled is not null AND s.sent is null AND s.exception is null THEN 1 ELSE null END) AS scheduled,
                COUNT(CASE WHEN s.scheduled is not null AND s.sent is null AND s.exception is not null THEN 1 ELSE null END) AS failed,
                COUNT(CASE WHEN s.sent is not null AND s.bounced is null THEN 1 ELSE null END) AS delivered,
                COUNT(CASE WHEN s.opened is not null THEN 1 ELSE null END) AS opened,
                COUNT(CASE WHEN s.replied is not null THEN 1 ELSE null END) AS replied,
                COUNT(CASE WHEN s.bounced is not null THEN 1 ELSE null END) AS bounced,
                COUNT(CASE WHEN s.exception is not null THEN 1 ELSE null END) AS failed
            FROM
                mail_mail_statistics s
            RIGHT JOIN
                mail_mass_mailing m
                ON (m.id = s.mass_mailing_id)
            WHERE
                m.id IN %s
            GROUP BY
                m.id
        """, (tuple(self.ids), ))
        for row in self.env.cr.dictfetchall():
            total = row.pop('total') or 1
            row['received_ratio'] = 100.0 * row['delivered'] / total
            row['opened_ratio'] = 100.0 * row['opened'] / total
            row['replied_ratio'] = 100.0 * row['replied'] / total
            row['bounced_ratio'] = 100.0 * row['bounced'] / total
            self.browse(row.pop('mailing_id')).update(row)

    def _compute_next_departure(self):
        cron_next_call = self.env.ref('mass_mailing.ir_cron_mass_mailing_queue').sudo().nextcall
        for mass_mailing in self:
            schedule_date = mass_mailing.schedule_date
            if schedule_date:
                if datetime.now() > fields.Datetime.from_string(schedule_date):
                    mass_mailing.next_departure = cron_next_call
                else:
                    mass_mailing.next_departure = schedule_date
            else:
                mass_mailing.next_departure = cron_next_call

    @api.onchange('mass_mailing_campaign_id')
    def _onchange_mass_mailing_campaign_id(self):
        if self.mass_mailing_campaign_id:
            dic = {'campaign_id': self.mass_mailing_campaign_id.campaign_id,
                   'source_id': self.mass_mailing_campaign_id.source_id,
                   'medium_id': self.mass_mailing_campaign_id.medium_id}
            self.update(dic)

    @api.onchange('mailing_model', 'contact_list_ids')
    def _onchange_model_and_list(self):
        if self.mailing_model == 'mail.mass_mailing.contact':
            if self.contact_list_ids:
                self.mailing_domain = "[('list_id', 'in', %s), ('opt_out', '=', False)]" % self.contact_list_ids.ids
            else:
                self.mailing_domain = "[('list_id', '=', False)]"
        elif 'opt_out' in self.env[self.mailing_model]._fields:
            self.mailing_domain = "[('opt_out', '=', False)]"
        else:
            self.mailing_domain = []
        self.body_html = "on_change_model_and_list"

    #------------------------------------------------------
    # Technical stuff
    #------------------------------------------------------

    @api.model
    def name_create(self, name):
        """ _rec_name is source_id, creates a utm.source instead """
        mass_mailing = self.create({'name': name})
        return mass_mailing.name_get()[0]

    @api.multi
    def copy(self, default=None):
        self.ensure_one()
        default = dict(default or {},
                       name=_('%s (copy)') % self.name)
        return super(MassMailing, self).copy(default=default)

    @api.model
    def read_group(self, domain, fields, groupby, offset=0, limit=None, orderby=False, lazy=True):
        """ Override read_group to always display all states. """
        if groupby and groupby[0] == "state":
            # Default result structure
            states = [('draft', _('Draft')), ('in_queue', _('In Queue')), ('sending', _('Sending')), ('done', _('Sent'))]
            read_group_all_states = [{
                '__context': {'group_by': groupby[1:]},
                '__domain': domain + [('state', '=', state_value)],
                'state': state_value,
                'state_count': 0,
            } for state_value, state_name in states]
            # Get standard results
            read_group_res = super(MassMailing, self).read_group(domain, fields, groupby, offset=offset, limit=limit, orderby=orderby)
            # Update standard results with default results
            result = []
            for state_value, state_name in states:
                res = filter(lambda x: x['state'] == state_value, read_group_res)
                if not res:
                    res = filter(lambda x: x['state'] == state_value, read_group_all_states)
                res[0]['state'] = [state_value, state_name]
                result.append(res[0])
            return result
        else:
            return super(MassMailing, self).read_group(domain, fields, groupby, offset=offset, limit=limit, orderby=orderby)

    def update_opt_out(self, email, res_ids, value):
        model = self.env[self.mailing_model].with_context(active_test=False)
        if 'opt_out' in model._fields:
            email_fname = 'email_from'
            if 'email' in model._fields:
                email_fname = 'email'
            records = model.search([('id', 'in', res_ids), (email_fname, 'ilike', email)])
            records.write({'opt_out': value})

    #------------------------------------------------------
    # Views & Actions
    #------------------------------------------------------

    @api.multi
    def action_duplicate(self):
        self.ensure_one()
        mass_mailing_copy = self.copy()
        if mass_mailing_copy:
            return {
                'type': 'ir.actions.act_window',
                'view_type': 'form',
                'view_mode': 'form',
                'res_model': 'mail.mass_mailing',
                'res_id': mass_mailing_copy.id,
                'context': self.env.context,
                'flags': {'initial_mode': 'edit'},
            }
        return False

    @api.multi
    def action_test_mailing(self):
        self.ensure_one()
        ctx = dict(self.env.context, default_mass_mailing_id=self.id)
        return {
            'name': _('Test Mailing'),
            'type': 'ir.actions.act_window',
            'view_mode': 'form',
            'res_model': 'mail.mass_mailing.test',
            'target': 'new',
            'context': ctx,
        }

    @api.multi
    def put_in_queue(self):
        self.write({'sent_date': fields.Datetime.now(), 'state': 'in_queue'})

    @api.multi
    def cancel_mass_mailing(self):
        self.write({'state': 'draft'})

    @api.multi
    def retry_failed_mail(self):
        failed_mails = self.env['mail.mail'].search([('mailing_id', 'in', self.ids), ('state', '=', 'exception')])
        failed_mails.mapped('statistics_ids').unlink()
        failed_mails.sudo().unlink()
        self.write({'state': 'in_queue'})

    #------------------------------------------------------
    # Email Sending
    #------------------------------------------------------

    def get_recipients(self):
        if self.mailing_domain:
            domain = safe_eval(self.mailing_domain)
            res_ids = self.env[self.mailing_model].search(domain).ids
        else:
            res_ids = []
            domain = [('id', 'in', res_ids)]

        # randomly choose a fragment
        if self.contact_ab_pc < 100:
            contact_nbr = self.env[self.mailing_model].search_count(domain)
            topick = int(contact_nbr / 100.0 * self.contact_ab_pc)
            if self.mass_mailing_campaign_id and self.mass_mailing_campaign_id.unique_ab_testing:
                already_mailed = self.mass_mailing_campaign_id.get_recipients()[self.mass_mailing_campaign_id.id]
            else:
                already_mailed = set([])
            remaining = set(res_ids).difference(already_mailed)
            if topick > len(remaining):
                topick = len(remaining)
            res_ids = random.sample(remaining, topick)
        return res_ids

    def get_remaining_recipients(self):
        res_ids = self.get_recipients()
        already_mailed = self.env['mail.mail.statistics'].search_read([('model', '=', self.mailing_model),
                                                                     ('res_id', 'in', res_ids),
                                                                     ('mass_mailing_id', '=', self.id)], ['res_id'])
        already_mailed_res_ids = [record['res_id'] for record in already_mailed]
        return list(set(res_ids) - set(already_mailed_res_ids))

    def send_mail(self):
        author_id = self.env.user.partner_id.id
        for mailing in self:
            # instantiate an email composer + send emails
            res_ids = mailing.get_remaining_recipients()
            if not res_ids:
                raise UserError(_('Please select recipients.'))

            # Convert links in absolute URLs before the application of the shortener
            mailing.body_html = self.env['mail.template']._replace_local_links(mailing.body_html)

            composer_values = {
                'author_id': author_id,
                'attachment_ids': [(4, attachment.id) for attachment in mailing.attachment_ids],
                'body': mailing.convert_links()[mailing.id],
                'subject': mailing.name,
                'model': mailing.mailing_model,
                'email_from': mailing.email_from,
                'record_name': False,
                'composition_mode': 'mass_mail',
                'mass_mailing_id': mailing.id,
                'mailing_list_ids': [(4, l.id) for l in mailing.contact_list_ids],
                'no_auto_thread': mailing.reply_to_mode != 'thread',
                'template_id': None,
            }
            if mailing.reply_to_mode == 'email':
                composer_values['reply_to'] = mailing.reply_to

            composer = self.env['mail.compose.message'].with_context(active_ids=res_ids).create(composer_values)
            composer.with_context(active_ids=res_ids).send_mail(auto_commit=True)
            mailing.state = 'done'
        return True

    def convert_links(self):
        res = {}
        for mass_mailing in self:
            utm_mixin = mass_mailing.mass_mailing_campaign_id if mass_mailing.mass_mailing_campaign_id else mass_mailing
            html = mass_mailing.body_html if mass_mailing.body_html else ''

            vals = {'mass_mailing_id': mass_mailing.id}

            if mass_mailing.mass_mailing_campaign_id:
                vals['mass_mailing_campaign_id'] = mass_mailing.mass_mailing_campaign_id.id
            if utm_mixin.campaign_id:
                vals['campaign_id'] = utm_mixin.campaign_id.id
            if utm_mixin.source_id:
                vals['source_id'] = utm_mixin.source_id.id
            if utm_mixin.medium_id:
                vals['medium_id'] = utm_mixin.medium_id.id

            res[mass_mailing.id] = self.env['link.tracker'].convert_links(html, vals, blacklist=['/unsubscribe_from_list'])

        return res

    @api.model
    def _process_mass_mailing_queue(self):
        mass_mailings = self.search([('state', 'in', ('in_queue', 'sending')), '|', ('schedule_date', '<', fields.Datetime.now()), ('schedule_date', '=', False)])
        for mass_mailing in mass_mailings:
            user = mass_mailing.write_uid or self.env.user
            mass_mailing = mass_mailing.with_context(**user.sudo(user=user).context_get())
            if len(mass_mailing.get_remaining_recipients()) > 0:
                mass_mailing.state = 'sending'
                mass_mailing.send_mail()
            else:
                mass_mailing.state = 'done'