package server

import "sync/atomic"

// HandlerStats aggregates the per-transport counters plus the engine's own
// view. It is the "what is this thing doing right now" summary the admin API
// and the health endpoint read.
type HandlerStats struct {
	// Queries is every query the server accepted across all transports.
	Queries uint64 `json:"queries"`
	// Blocked is queries answered by a blocklist rule.
	Blocked uint64 `json:"blocked"`
	// Cached is queries answered from the cache.
	Cached uint64 `json:"cached"`
	// Errors is queries answered with SERVFAIL, dropped or malformed.
	Errors uint64 `json:"errors"`
	// Dropped is queries answered with silence.
	Dropped uint64 `json:"dropped"`
	// Inflight is the current in-flight count.
	Inflight int64 `json:"inflight"`
}

// ByTransport returns a per-transport breakdown for the UI's transport tab.
func (s *Server) ByTransport() map[string]TransportStats {
	out := map[string]TransportStats{}
	for _, t := range []string{"udp", "tcp", "dot", "doh"} {
		ts := TransportStats{Transport: t}
		ts.Queries = s.load(t, "queries")
		ts.Blocked = s.load(t, "blocked")
		ts.Cached = s.load(t, "cached")
		ts.Errors = s.load(t, "errors")
		ts.Truncated = s.load(t, "truncated")
		ts.Sent = s.load(t, "sent")
		out[t] = ts
	}
	return out
}

func (s *Server) load(transport, field string) uint64 {
	v, ok := s.counters.Load(transport + "." + field)
	if !ok {
		return 0
	}
	return v.(*atomic.Uint64).Load()
}

// TransportStats is a per-transport counter set.
type TransportStats struct {
	Transport string `json:"transport"`
	Queries   uint64 `json:"queries"`
	Blocked   uint64 `json:"blocked"`
	Cached    uint64 `json:"cached"`
	Errors    uint64 `json:"errors"`
	Truncated uint64 `json:"truncated"`
	Sent      uint64 `json:"sent"`
}