# -*- coding: utf-8 -*-
# Copyright 2026 Nexa Systems Inc.
# License OPL-1
from odoo import fields, models


class FusionBillingUsage(models.Model):
    """Aggregated usage rollup for a (subscription, metric, period).

    Aggregate-push model: apps send periodic counters (not raw events). The
    ``idempotency_key`` makes re-sent counters safe — they never double-count.
    A pre-invoice cron sums these and feeds billable quantity onto the subscription.

    NOTE (Odoo 19, verified): the subscription is a ``sale.order`` with
    ``is_subscription=True`` — there is no ``sale.subscription`` model. See spec §5.2.
    """

    _name = "fusion.billing.usage"
    _description = "Fusion Billing — Aggregated Usage (period rollup)"
    _order = "period_start desc"

    subscription_id = fields.Many2one(
        "sale.order", required=True, ondelete="cascade", index=True,
        string="Subscription", domain=[("is_subscription", "=", True)],
    )
    metric_id = fields.Many2one(
        "fusion.billing.metric", required=True, ondelete="restrict", index=True,
    )
    period_start = fields.Datetime(required=True)
    period_end = fields.Datetime(required=True)
    quantity = fields.Float(default=0.0)
    source = fields.Char(default="push")
    idempotency_key = fields.Char(
        index=True, help="Dedupe key so re-sent counters never double-count.",
    )

    _idempotency_uniq = models.Constraint(
        "unique(idempotency_key)", "Usage idempotency key must be unique.",
    )