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

    @api.model
    def _record_usage(self, subscription, metric_code, quantity, period_start, period_end, idem=None):
        """Upsert one aggregated usage row. Same idempotency key updates in place (no double-count)."""
        metric = self.env['fusion.billing.metric'].search([('code', '=', metric_code)], limit=1)
        if not metric:
            raise ValueError("Unknown metric code: %s" % metric_code)
        vals = {
            'subscription_id': subscription.id,
            'metric_id': metric.id,
            'period_start': period_start,
            'period_end': period_end,
            'quantity': quantity,
            'idempotency_key': idem,
        }
        if idem:
            existing = self.search([('idempotency_key', '=', idem)], limit=1)
            if existing:
                existing.write({'quantity': quantity})
                return existing
        return self.create(vals)

    @api.model
    def _cron_rate_open_periods(self):
        """Hourly cron: for every active charge, aggregate usage and upsert overage lines
        on all in-progress subscriptions whose next invoice date is set."""
        Charge = self.env['fusion.billing.charge'].search([('active', '=', True)])
        SaleOrder = self.env['sale.order']
        for charge in Charge:
            subs = SaleOrder.search([
                ('is_subscription', '=', True),
                ('subscription_state', '=', '3_progress'),
                ('plan_id.name', '!=', False),
            ])
            for sub in subs:
                if not sub.next_invoice_date:
                    continue
                period_end = fields.Datetime.to_datetime(sub.next_invoice_date)
                period_start = period_end.replace(day=1)
                sub._fc_rate_usage(charge, period_start, period_end)

    @api.model
    def _aggregate(self, subscription, metric, period_start, period_end):
        """Aggregate stored usage for a subscription+metric within [period_start, period_end)
        using the metric's aggregation function."""
        rows = self.search([
            ('subscription_id', '=', subscription.id),
            ('metric_id', '=', metric.id),
            ('period_start', '>=', period_start),
            ('period_end', '<=', period_end),
        ])
        qtys = rows.mapped('quantity')
        if not qtys:
            return 0.0
        agg = metric.aggregation
        if agg == 'sum':
            return sum(qtys)
        if agg == 'max':
            return max(qtys)
        if agg == 'last':
            return rows.sorted('period_start')[-1].quantity
        if agg == 'unique_count':
            return float(len(set(qtys)))
        return sum(qtys)