from odoo import api, models


class HelpdeskTicket(models.Model):
    _inherit = "helpdesk.ticket"

    @api.depends("team_id")
    def _compute_user_id(self):
        """Recompute the assigned user whenever the team changes.

        Delegates to :meth:`_define_user_id` so that, when a team is set or
        changed, the assigned user is realigned with that team (replaced by
        the team leader if the current user does not belong to the team).
        """
        for ticket in self:
            ticket.user_id = self._define_user_id(
                ticket.team_id,
                ticket.user_id,
            )

    @api.model_create_multi
    def create(self, vals_list):
        """Auto-assign team, project and user for portal-created tickets.

        When a ticket is created without an explicit team but with a partner,
        the partner's linked user is looked up and, if that user has a default
        helpdesk team configured, the ticket is routed accordingly:

        * ``team_id`` is set to the user's default helpdesk team.
        * ``project_id`` is set to the team's default project, if any.
        * ``user_id`` is set to the team leader (via :meth:`_define_user_id`).

        Tickets that already have a team, that have no partner, or whose
        partner has no linked user / no default team are left untouched.
        """
        for vals in vals_list:
            if not vals.get("team_id") and vals.get("partner_id"):
                # Find the user who creates the ticket
                partner = self.env["res.partner"].browse(vals.get("partner_id"))
                if not partner:
                    continue
                # A partner may have no linked user (e.g. a plain contact)
                user = partner.user_ids[:1]
                if not user:
                    continue

                # Get its default team_id
                team = user.default_helpdesk_ticket_team_id
                if not team:
                    continue

                vals["team_id"] = team.id

                # Set the linked project
                if team.default_project_id:
                    vals["project_id"] = team.default_project_id.id

                # Set the user_id to which the ticket is assigned
                user_id = self._define_user_id(team, None)
                if user_id:
                    vals["user_id"] = user_id.id
        return super().create(vals_list)

    def _define_user_id(self, team_id=None, ticket_user_id=None):
        """Determine which user should be assigned to a ticket for a team.

        Decides whether the current ticket user must be kept or replaced by
        the helpdesk team leader (``team_id.user_id``), according to the
        following rules:

        * No team             -> keep ``ticket_user_id`` unchanged.
        * No current user     -> use the team leader.
        * User not in team    -> replace with the team leader.
        * User is a team member-> keep ``ticket_user_id`` unchanged.

        :param team_id: the ``helpdesk.ticket.team`` record (or falsy).
        :param ticket_user_id: the currently assigned ``res.users`` (or falsy).
        :return: the ``res.users`` record that should be assigned (possibly an
            empty recordset when the team has no leader and the current user
            is not a member of the team).
        """
        if not team_id:
            # If no team, return the current ticket_user_id
            return ticket_user_id

        if not ticket_user_id:
            # If no current user, fall back to the team leader (may be empty).
            return team_id.user_id

        if ticket_user_id not in team_id.user_ids:
            # If the current user is not a team member, replace it with the
            # team leader (may be empty).
            return team_id.user_id

        # Otherwise the current user is a valid team member: keep it unchanged.
        return ticket_user_id