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

from collections import defaultdict
import itertools

from odoo import api, fields, models, Command


class Followers(models.Model):
    """ mail_followers holds the data related to the follow mechanism inside
    Odoo. Partners can choose to follow documents (records) of any kind
    that inherits from mail.thread. Following documents allow to receive
    notifications for new messages. A subscription is characterized by:

    :param: res_model: model of the followed objects
    :param: res_id: ID of resource (may be 0 for every objects)
    """
    _name = 'mail.followers'
    _rec_name = 'partner_id'
    _log_access = False
    _description = 'Document Followers'

    # Note. There is no integrity check on model names for performance reasons.
    # However, followers of unlinked models are deleted by models themselves
    # (see 'ir.model' inheritance).
    res_model = fields.Char(
        'Related Document Model Name', required=True, index=True)
    res_id = fields.Many2oneReference(
        'Related Document ID', index=True, help='Id of the followed resource', model_field='res_model')
    partner_id = fields.Many2one(
        'res.partner', string='Related Partner', index=True, ondelete='cascade', required=True)
    subtype_ids = fields.Many2many(
        'mail.message.subtype', string='Subtype',
        help="Message subtypes followed, meaning subtypes that will be pushed onto the user's Wall.")
    name = fields.Char('Name', related='partner_id.name')
    email = fields.Char('Email', related='partner_id.email')
    is_active = fields.Boolean('Is Active', related='partner_id.active')

    def _invalidate_documents(self, vals_list=None):
        """ Invalidate the cache of the documents followed by ``self``.

        Modifying followers change access rights to individual documents. As the
        cache may contain accessible/inaccessible data, one has to refresh it.
        """
        to_invalidate = defaultdict(list)
        for record in (vals_list or [{'res_model': rec.res_model, 'res_id': rec.res_id} for rec in self]):
            if record.get('res_id'):
                to_invalidate[record.get('res_model')].append(record.get('res_id'))

    @api.model_create_multi
    def create(self, vals_list):
        res = super(Followers, self).create(vals_list)
        res._invalidate_documents(vals_list)
        return res

    def write(self, vals):
        if 'res_model' in vals or 'res_id' in vals:
            self._invalidate_documents()
        res = super(Followers, self).write(vals)
        if any(x in vals for x in ['res_model', 'res_id', 'partner_id']):
            self._invalidate_documents()
        return res

    def unlink(self):
        self._invalidate_documents()
        return super(Followers, self).unlink()

    _sql_constraints = [
        ('mail_followers_res_partner_res_model_id_uniq', 'unique(res_model,res_id,partner_id)', 'Error, a partner cannot follow twice the same object.'),
    ]

    # --------------------------------------------------
    # Private tools methods to fetch followers data
    # --------------------------------------------------

    @api.model
    def _get_mail_recipients_follower_status(self, mail_ids):
        """ Get partner mail recipients that follows the related record of the mails.

        Note that followers for message related to discuss.channel are not fetched.

        :param list mail_ids: mail_mail ids
        :return: followers of the related record of the mails limited to the
            recipients of the mails as a set of tuple (model, res_id, partner_id).
        :rtype: set
        """
        self.env['mail.mail'].flush_model(['message_id', 'recipient_ids'])
        self.env['mail.followers'].flush_model(['partner_id', 'res_model', 'res_id'])
        self.env['mail.message'].flush_model(['model', 'res_id'])
        # mail_mail_res_partner_rel is the join table for the m2m recipient_ids field
        self.env.cr.execute("""
            SELECT message.model, message.res_id, mail_partner.res_partner_id
              FROM mail_mail mail        
              JOIN mail_mail_res_partner_rel mail_partner ON mail_partner.mail_mail_id = mail.id
              JOIN mail_message message ON mail.mail_message_id = message.id AND message.model != 'discuss.channel'
              JOIN mail_followers follower ON message.model = follower.res_model 
               AND message.res_id = follower.res_id 
               AND mail_partner.res_partner_id = follower.partner_id
             WHERE mail.id IN %(mail_ids)s
        """, {'mail_ids': tuple(mail_ids)})
        return set(self.env.cr.fetchall())

    def _get_recipient_data(self, records, message_type, subtype_id, pids=None):
        """ Private method allowing to fetch recipients data based on a subtype.
        Purpose of this method is to fetch all data necessary to notify recipients
        in a single query. It fetches data from

         * followers (partners and channels) of records that follow the given
           subtype if records and subtype are set;
         * partners if pids is given;

        :param records: fetch data from followers of ``records`` that follow
          ``subtype_id``;
        :param str message_type: mail.message.message_type in order to allow custom
          behavior depending on it (SMS for example);
        :param int subtype_id: mail.message.subtype to check against followers;
        :param pids: additional set of partner IDs from which to fetch recipient
          data independently from following status;

        :return dict: recipients data based on record.ids if given, else a generic
          '0' key to keep a dict-like return format. Each item is a dict based on
          recipients partner ids formatted like
          {'active': whether partner is active;
           'id': res.partner ID;
           'is_follower': True if linked to a record and if partner is a follower;
           'lang': lang of the partner;
           'groups': groups of the partner's user. If several users exist preference
                is given to internal user, then share users. In case of multiples
                users of same kind groups are unioned;
            'notif': notification type ('inbox' or 'email'). Overrides may change
                this value (e.g. 'sms' in sms module);
            'share': if partner is a customer (no user or share user);
            'ushare': if partner has users, whether all are shared (public or portal);
            'type': summary of partner 'usage' (portal, customer, internal user);
          }
        """
        self.env['mail.followers'].flush_model(['partner_id', 'subtype_ids'])
        self.env['mail.message.subtype'].flush_model(['internal'])
        self.env['res.users'].flush_model(['notification_type', 'active', 'partner_id', 'groups_id'])
        self.env['res.partner'].flush_model(['active', 'partner_share'])
        self.env['res.groups'].flush_model(['users'])
        # if we have records and a subtype: we have to fetch followers, unless being
        # in user notification mode (contact only pids)
        if message_type != 'user_notification' and records and subtype_id:
            query = """
    WITH sub_followers AS (
        SELECT fol.partner_id AS pid,
               fol.id AS fid,
               fol.res_id AS res_id,
               TRUE as is_follower,
               COALESCE(subrel.follow, FALSE) AS subtype_follower,
               COALESCE(subrel.internal, FALSE) AS internal
          FROM mail_followers fol
     LEFT JOIN LATERAL (
            SELECT TRUE AS follow,
                   subtype.internal AS internal
              FROM mail_followers_mail_message_subtype_rel m
         LEFT JOIN mail_message_subtype subtype ON subtype.id = m.mail_message_subtype_id
             WHERE m.mail_followers_id = fol.id AND m.mail_message_subtype_id = %s
            ) subrel ON TRUE
         WHERE fol.res_model = %s
               AND fol.res_id IN %s

     UNION ALL

        SELECT res_partner.id AS pid,
               0 AS fid,
               0 AS res_id,
               FALSE as is_follower,
               FALSE as subtype_follower,
               FALSE as internal
          FROM res_partner
         WHERE res_partner.id = ANY(%s)
    )
    SELECT partner.id as pid,
           partner.active as active,
           partner.lang as lang,
           partner.partner_share as pshare,
           sub_user.uid as uid,
           COALESCE(sub_user.share, FALSE) as ushare,
           COALESCE(sub_user.notification_type, 'email') as notif,
           sub_user.groups as groups,
           sub_followers.res_id as res_id,
           sub_followers.is_follower as _insert_followerslower
      FROM res_partner partner
      JOIN sub_followers ON sub_followers.pid = partner.id
                        AND (sub_followers.internal IS NOT TRUE OR partner.partner_share IS NOT TRUE)
 LEFT JOIN LATERAL (
        SELECT users.id AS uid,
               users.share AS share,
               users.notification_type AS notification_type,
               ARRAY_AGG(groups_rel.gid) FILTER (WHERE groups_rel.gid IS NOT NULL) AS groups
          FROM res_users users
     LEFT JOIN res_groups_users_rel groups_rel ON groups_rel.uid = users.id
         WHERE users.partner_id = partner.id AND users.active
      GROUP BY users.id,
               users.share,
               users.notification_type
      ORDER BY users.share ASC NULLS FIRST, users.id ASC
         FETCH FIRST ROW ONLY
         ) sub_user ON TRUE

     WHERE sub_followers.subtype_follower OR partner.id = ANY(%s)
"""
            params = [subtype_id, records._name, tuple(records.ids), list(pids or []), list(pids or [])]
            self.env.cr.execute(query, tuple(params))
            res = self.env.cr.fetchall()
        # partner_ids and records: no sub query for followers but check for follower status
        elif pids and records:
            params = []
            query = """
    SELECT partner.id as pid,
           partner.active as active,
           partner.lang as lang,
           partner.partner_share as pshare,
           sub_user.uid as uid,
           COALESCE(sub_user.share, FALSE) as ushare,
           COALESCE(sub_user.notification_type, 'email') as notif,
           sub_user.groups as groups,
           ARRAY_AGG(fol.res_id) FILTER (WHERE fol.res_id IS NOT NULL) AS res_ids
      FROM res_partner partner
 LEFT JOIN mail_followers fol ON fol.partner_id = partner.id
                              AND fol.res_model = %s
                              AND fol.res_id IN %s
 LEFT JOIN LATERAL (
        SELECT users.id AS uid,
               users.share AS share,
               users.notification_type AS notification_type,
               ARRAY_AGG(groups_rel.gid) FILTER (WHERE groups_rel.gid IS NOT NULL) AS groups
          FROM res_users users
     LEFT JOIN res_groups_users_rel groups_rel ON groups_rel.uid = users.id
         WHERE users.partner_id = partner.id AND users.active
      GROUP BY users.id,
               users.share,
               users.notification_type
      ORDER BY users.share ASC NULLS FIRST, users.id ASC
         FETCH FIRST ROW ONLY
         ) sub_user ON TRUE

     WHERE partner.id IN %s
  GROUP BY partner.id,
           sub_user.uid,
           sub_user.share,
           sub_user.notification_type,
           sub_user.groups
"""
            params = [records._name, tuple(records.ids), tuple(pids)]
            self.env.cr.execute(query, tuple(params))
            simplified_res = self.env.cr.fetchall()
            # simplified query contains res_ids -> flatten it by making it a list
            # with res_id and add follower status
            res = []
            for item in simplified_res:
                res_ids = item[-1]
                if not res_ids:  # keep res_ids Falsy (global), set as not follower
                    flattened = [list(item) + [False]]
                else:  # generate an entry for each res_id with partner being follower
                    flattened = [list(item[:-1]) + [res_id, True]
                                 for res_id in res_ids]
                res += flattened
        # only partner ids: no follower status involved, fetch only direct recipients information
        elif pids:
            query = """
    SELECT partner.id as pid,
           partner.active as active,
           partner.lang as lang,
           partner.partner_share as pshare,
           sub_user.uid as uid,
           COALESCE(sub_user.share, FALSE) as ushare,
           COALESCE(sub_user.notification_type, 'email') as notif,
           sub_user.groups as groups,
           0 as res_id,
           FALSE as is_follower
      FROM res_partner partner
 LEFT JOIN LATERAL (
        SELECT users.id AS uid,
               users.share AS share,
               users.notification_type AS notification_type,
               ARRAY_AGG(groups_rel.gid) FILTER (WHERE groups_rel.gid IS NOT NULL) AS groups
          FROM res_users users
     LEFT JOIN res_groups_users_rel groups_rel ON groups_rel.uid = users.id
         WHERE users.partner_id = partner.id AND users.active
      GROUP BY users.id,
               users.share,
               users.notification_type
      ORDER BY users.share ASC NULLS FIRST, users.id ASC
         FETCH FIRST ROW ONLY
         ) sub_user ON TRUE

     WHERE partner.id IN %s
  GROUP BY partner.id,
           sub_user.uid,
           sub_user.share,
           sub_user.notification_type,
           sub_user.groups
"""
            params = [tuple(pids)]
            self.env.cr.execute(query, tuple(params))
            res = self.env.cr.fetchall()
        else:
            res = []

        res_ids = records.ids if records else [0]
        doc_infos = dict((res_id, {}) for res_id in res_ids)
        for (partner_id, is_active, lang, pshare, uid, ushare, notif, groups, res_id, is_follower) in res:
            to_update = [res_id] if res_id else res_ids
            for res_id_to_update in to_update:
                # avoid updating already existing information, unnecessary dict update
                if not res_id and partner_id in doc_infos[res_id_to_update]:
                    continue
                follower_data = {
                    'active': is_active,
                    'id': partner_id,
                    'is_follower': is_follower,
                    'lang': lang,
                    'groups': set(groups or []),
                    'notif': notif,
                    'share': pshare,
                    'uid': uid,
                    'ushare': ushare,
                }
                # additional information
                if follower_data['ushare']:  # any type of share user
                    follower_data['type'] = 'portal'
                elif follower_data['share']:  # no user, is share -> customer (partner only)
                    follower_data['type'] = 'customer'
                else:  # has a user not share -> internal user
                    follower_data['type'] = 'user'
                doc_infos[res_id_to_update][partner_id] = follower_data

        return doc_infos

    def _get_subscription_data(self, doc_data, pids, include_pshare=False, include_active=False):
        """ Private method allowing to fetch follower data from several documents of a given model.
        Followers can be filtered given partner IDs and channel IDs.

        :param doc_data: list of pair (res_model, res_ids) that are the documents from which we
          want to have subscription data;
        :param pids: optional partner to filter; if None take all, otherwise limitate to pids
        :param include_pshare: optional join in partner to fetch their share status
        :param include_active: optional join in partner to fetch their active flag

        :return: list of followers data which is a list of tuples containing
          follower ID,
          document ID,
          partner ID,
          followed subtype IDs,
          share status of partner (returned only if include_pshare is True)
          active flag status of partner (returned only if include_active is True)
        """
        self.env['mail.followers'].flush_model(['partner_id', 'res_id', 'res_model', 'subtype_ids'])
        self.env['res.partner'].flush_model(['active', 'partner_share'])
        # base query: fetch followers of given documents
        where_clause = ' OR '.join(['fol.res_model = %s AND fol.res_id IN %s'] * len(doc_data))
        where_params = list(itertools.chain.from_iterable((rm, tuple(rids)) for rm, rids in doc_data))

        # additional: filter on optional pids
        sub_where = []
        if pids:
            sub_where += ["fol.partner_id IN %s"]
            where_params.append(tuple(pids))
        elif pids is not None:
            sub_where += ["fol.partner_id IS NULL"]
        if sub_where:
            where_clause += "AND (%s)" % " OR ".join(sub_where)

        query = """
SELECT fol.id, fol.res_id, fol.partner_id, array_agg(subtype.id)%s%s
FROM mail_followers fol
%s
LEFT JOIN mail_followers_mail_message_subtype_rel fol_rel ON fol_rel.mail_followers_id = fol.id
LEFT JOIN mail_message_subtype subtype ON subtype.id = fol_rel.mail_message_subtype_id
WHERE %s
GROUP BY fol.id%s%s""" % (
            ', partner.partner_share' if include_pshare else '',
            ', partner.active' if include_active else '',
            'LEFT JOIN res_partner partner ON partner.id = fol.partner_id' if (include_pshare or include_active) else '',
            where_clause,
            ', partner.partner_share' if include_pshare else '',
            ', partner.active' if include_active else ''
        )
        self.env.cr.execute(query, tuple(where_params))
        return self.env.cr.fetchall()

    # --------------------------------------------------
    # Private tools methods to generate new subscription
    # --------------------------------------------------

    def _insert_followers(self, res_model, res_ids,
                          partner_ids, subtypes=None,
                          customer_ids=None, check_existing=True, existing_policy='skip'):
        """ Main internal method allowing to create or update followers for documents, given a
        res_model and the document res_ids. This method does not handle access rights. This is the
        role of the caller to ensure there is no security breach.

        :param subtypes: see ``_add_followers``. If not given, default ones are computed.
        :param customer_ids: see ``_add_default_followers``
        :param check_existing: see ``_add_followers``;
        :param existing_policy: see ``_add_followers``;
        """
        sudo_self = self.sudo().with_context(default_partner_id=False)
        if not subtypes:  # no subtypes -> default computation, no force, skip existing
            new, upd = self._add_default_followers(
                res_model, res_ids, partner_ids,
                customer_ids=customer_ids,
                check_existing=check_existing,
                existing_policy=existing_policy)
        else:
            new, upd = self._add_followers(
                res_model, res_ids,
                partner_ids, subtypes,
                check_existing=check_existing,
                existing_policy=existing_policy)
        if new:
            sudo_self.create([
                dict(values, res_id=res_id)
                for res_id, values_list in new.items()
                for values in values_list
            ])
        for fol_id, values in upd.items():
            sudo_self.browse(fol_id).write(values)

    def _add_default_followers(self, res_model, res_ids, partner_ids, customer_ids=None,
                               check_existing=True, existing_policy='skip'):
        """ Shortcut to ``_add_followers`` that computes default subtypes. Existing
        followers are skipped as their subscription is considered as more important
        compared to new default subscription.

        :param customer_ids: optional list of partner ids that are customers. It is used if computing
         default subtype is necessary and allow to avoid the check of partners being customers (no
         user or share user). It is just a matter of saving queries if the info is already known;
        :param check_existing: see ``_add_followers``;
        :param existing_policy: see ``_add_followers``;

        :return: see ``_add_followers``
        """
        if not partner_ids:
            return dict(), dict()

        default, _, external = self.env['mail.message.subtype'].default_subtypes(res_model)
        if partner_ids and customer_ids is None:
            customer_ids = self.env['res.partner'].sudo().search([('id', 'in', partner_ids), ('partner_share', '=', True)]).ids

        p_stypes = dict((pid, external.ids if pid in customer_ids else default.ids) for pid in partner_ids)

        return self._add_followers(res_model, res_ids, partner_ids, p_stypes, check_existing=check_existing, existing_policy=existing_policy)

    def _add_followers(self, res_model, res_ids, partner_ids, subtypes,
                       check_existing=False, existing_policy='skip'):
        """ Internal method that generates values to insert or update followers. Callers have to
        handle the result, for example by making a valid ORM command, inserting or updating directly
        follower records, ... This method returns two main data

         * first one is a dict which keys are res_ids. Value is a list of dict of values valid for
           creating new followers for the related res_id;
         * second one is a dict which keys are follower ids. Value is a dict of values valid for
           updating the related follower record;

        :param subtypes: optional subtypes for new partner followers. This
          is a dict whose keys are partner IDs and value subtype IDs for that
          partner.
        :param channel_subtypes: optional subtypes for new channel followers. This
          is a dict whose keys are channel IDs and value subtype IDs for that
          channel.
        :param check_existing: if True, check for existing followers for given
          documents and handle them according to existing_policy parameter.
          Setting to False allows to save some computation if caller is sure
          there are no conflict for followers;
        :param existing policy: if check_existing, tells what to do with already
          existing followers:

          * skip: simply skip existing followers, do not touch them;
          * force: update existing with given subtypes only;
          * replace: replace existing with new subtypes (like force without old / new follower);
          * update: gives an update dict allowing to add missing subtypes (no subtype removal);
        """
        _res_ids = res_ids or [0]
        data_fols, doc_pids = dict(), dict((i, set()) for i in _res_ids)

        if check_existing and res_ids:
            for fid, rid, pid, sids in self._get_subscription_data([(res_model, res_ids)], partner_ids or None):
                if existing_policy != 'force':
                    if pid:
                        doc_pids[rid].add(pid)
                data_fols[fid] = (rid, pid, sids)

            if existing_policy == 'force':
                self.sudo().browse(data_fols.keys()).unlink()

        new, update = dict(), dict()
        for res_id in _res_ids:
            for partner_id in set(partner_ids or []):
                if partner_id not in doc_pids[res_id]:
                    new.setdefault(res_id, list()).append({
                        'res_model': res_model,
                        'partner_id': partner_id,
                        'subtype_ids': [Command.set(subtypes[partner_id])],
                    })
                elif existing_policy in ('replace', 'update'):
                    fol_id, sids = next(((key, val[2]) for key, val in data_fols.items() if val[0] == res_id and val[1] == partner_id), (False, []))
                    new_sids = set(subtypes[partner_id]) - set(sids)
                    old_sids = set(sids) - set(subtypes[partner_id])
                    update_cmd = []
                    if fol_id and new_sids:
                        update_cmd += [Command.link(sid) for sid in new_sids]
                    if fol_id and old_sids and existing_policy == 'replace':
                        update_cmd += [Command.unlink(sid) for sid in old_sids]
                    if update_cmd:
                        update[fol_id] = {'subtype_ids': update_cmd}

        return new, update

    def _format_for_chatter(self):
        return [{
            'id': follower.id,
            'partner_id': follower.partner_id.id,
            'name': follower.name,
            'display_name': follower.display_name,
            'email': follower.email,
            'is_active': follower.is_active,
            'partner': follower.partner_id.mail_partner_format()[follower.partner_id],
        } for follower in self]
