CosmicClash/server/api/admission.go

package api

import (
	"strings"
	"sync/atomic"
)

// AdmissionController decides whether a classified public operation may
// start. Implementations must be safe for concurrent requests.
type AdmissionController interface {
	Allow(operation string) bool
}

// AdmissionGate is the operator-controlled overload gate for new matchmaking
// work. Degraded mode is deliberately narrow: existing matches can continue
// to report results and clients can still use read/recovery/event endpoints.
type AdmissionGate struct {
	degraded atomic.Bool
}

func NewAdmissionGate(degraded bool) *AdmissionGate {
	gate := &AdmissionGate{}
	gate.degraded.Store(degraded)
	return gate
}

func (g *AdmissionGate) SetDegraded(value bool) {
	if g != nil {
		g.degraded.Store(value)
	}
}

func (g *AdmissionGate) Degraded() bool {
	return g != nil && g.degraded.Load()
}

func (g *AdmissionGate) Allow(operation string) bool {
	if !g.Degraded() {
		return true
	}
	switch operation {
	case "login", "queue", "proposal", "allocation":
		return false
	default:
		return true
	}
}

func admissionOperation(path, method string) string {
	if method == "GET" || method == "HEAD" || method == "OPTIONS" {
		return ""
	}
	path = strings.TrimSuffix(path, "/")
	switch {
	case path == "/v1/session/steam" || path == "/api/v1/session/steam":
		return "login"
	case path == "/v1/queue" || path == "/api/v1/queue/tickets":
		return "queue"
	case underPath(path, "/v1/queue/") || underPath(path, "/api/v1/queue/tickets/"):
		return "queue"
	case underPath(path, "/v1/proposals/") || underPath(path, "/api/v1/proposals/"):
		return "proposal"
	default:
		return ""
	}
}

func underPath(path, prefix string) bool {
	return strings.HasPrefix(path, prefix) && len(path) > len(prefix)
}