package main

// Presence & speed derivation — mirrors lib/presence.js. See that file
// for the signal model (per-server user counters, per-node inbound
// counters, AnyTLS observations; 3-minute window; server-level activity
// attributed to the customer's nodes on that server).

import "time"

const PresenceWindowMs = 180000
const SpeedStaleMs = 150000

func parseISOMsOr0(value *string) int64 {
	if value == nil {
		return 0
	}
	ms, ok := ParseISOMs(*value)
	if !ok {
		return 0
	}
	return ms
}

func CustomerOnline(customer *Customer, nowMs int64) bool {
	ms := parseISOMsOr0(customer.LastOnlineAt)
	return ms > 0 && nowMs-ms <= PresenceWindowMs
}

func CustomerSpeedBps(customer *Customer, nowMs int64) (float64, float64) {
	var up, down float64
	for _, slot := range customer.ServerUsage {
		if slot == nil || slot.SpeedAt == nil {
			continue
		}
		if nowMs-parseISOMsOr0(slot.SpeedAt) > SpeedStaleMs {
			continue
		}
		if slot.SpeedUpBps != nil {
			up += *slot.SpeedUpBps
		}
		if slot.SpeedDownBps != nil {
			down += *slot.SpeedDownBps
		}
	}
	return up, down
}

func NodeSpeedBps(node *Node, nowMs int64) (float64, float64) {
	if node.SpeedAt == nil || nowMs-parseISOMsOr0(node.SpeedAt) > SpeedStaleMs {
		return 0, 0
	}
	var up, down float64
	if node.SpeedUpBps != nil {
		up = *node.SpeedUpBps
	}
	if node.SpeedDownBps != nil {
		down = *node.SpeedDownBps
	}
	return up, down
}

// NodeOnlineCustomerIds mirrors nodeOnlineCustomerIds in lib/presence.js.
func NodeOnlineCustomerIds(d *Data, node *Node, nowMs int64) []string {
	out := []string{}
	for _, nc := range d.NodeClients {
		if nc.NodeID != node.ID || nc.Status != "active" {
			continue
		}
		customer := findCustomer(d, nc.CustomerID)
		if customer == nil {
			continue
		}
		var ms int64
		if slot := customer.ServerUsage["srv:"+node.ServerID]; slot != nil && slot.LastActiveAt != nil {
			ms = parseISOMsOr0(slot.LastActiveAt)
		} else {
			ms = parseISOMsOr0(customer.LastOnlineAt)
		}
		if ms > 0 && nowMs-ms <= PresenceWindowMs {
			out = append(out, customer.ID)
		}
	}
	return out
}

func CountOnlineCustomers(d *Data, now time.Time) int {
	count := 0
	for _, customer := range d.Customers {
		if CustomerOnline(customer, now.UnixMilli()) {
			count++
		}
	}
	return count
}