package httpapi

import (
	"context"
	"net/http"
	"time"

	"evobgp/internal/nodedispatch"
	"evobgp/internal/store"
	"evobgp/internal/telemetry"
)

func (s *Server) loadTelemetry(ctx context.Context, tenant string, speakers []*store.Speaker) ([]speakerBGPLive, map[string]map[string]any, error) {
	ctx, cancel := context.WithTimeout(ctx, 2*time.Second)
	defer cancel()
	snapshots, err := s.store.ListTelemetry(ctx, tenant)
	if err != nil {
		return nil, nil, err
	}
	views, statuses := hydrateTelemetry(speakers, snapshots, time.Now(), telemetry.ConfigFromEnv().StaleAfter)
	return views, statuses, nil
}

// snapshotObservation uses control-plane receipt time, never the remote clock.
func snapshotObservation(o store.TelemetryObservation, now time.Time, staleAfter time.Duration, invalid string) liveObservation {
	v := liveObservation{ObservedAt: liveTime(o.ObservedAt), ReceivedAt: liveTime(o.ReceivedAt), LastSuccessAt: liveTime(o.LastSuccessAt), Source: o.Source, Quality: "unknown"}
	if !o.ReceivedAt.IsZero() {
		v.ExpiresAt = liveTime(o.ReceivedAt.Add(staleAfter))
	}
	if v.Source == "" {
		v.Source = "none"
	}
	switch {
	case invalid != "":
		v.ErrorCode = invalid
	case o.ReceivedAt.IsZero():
		v.ErrorCode = "not_polled"
	case o.ReceivedAt.After(now) || now.Sub(o.ReceivedAt) > staleAfter:
		v.Quality, v.ErrorCode = "stale", "snapshot_expired"
	case o.Error != "":
		v.Quality, v.ErrorCode = "unreachable", liveErrorCode(o.Error)
		if !o.LastSuccessAt.IsZero() {
			v.Quality = "stale"
		}
	default:
		v.Quality = "ok"
	}
	return v
}

func hydrateTelemetry(speakers []*store.Speaker, snapshots []store.TelemetrySnapshot, now time.Time, staleAfter time.Duration) ([]speakerBGPLive, map[string]map[string]any) {
	byID := make(map[string]*store.Speaker, len(speakers))
	for _, sp := range speakers {
		if sp != nil {
			byID[sp.ID] = sp
		}
	}
	grouped := make(map[string][]store.TelemetrySnapshot)
	for _, snapshot := range snapshots {
		if snapshot.SpeakerID != "" && byID[snapshot.SpeakerID] == nil {
			continue
		}
		if snapshot.SpeakerID == "" && snapshot.Kind != "local_bird" {
			continue
		}
		grouped[snapshot.SpeakerID] = append(grouped[snapshot.SpeakerID], snapshot)
	}
	views := make([]speakerBGPLive, 0, len(speakers)+1)
	statuses := make(map[string]map[string]any, len(speakers))
	appendView := func(id string, sp *store.Speaker) {
		view := speakerBGPLive{SpeakerID: id, Label: speakerDisplayLabel(sp)}
		if sp == nil {
			view.Label = "CP (local)"
		}
		var health *agentHealthPoll
		rows := grouped[id]
		// A restarted local collector may leave an expired authority behind.
		// Only simultaneously current authorities conflict; never prefer one
		// of two current BIRD nodes arbitrarily.
		if len(rows) > 1 {
			current := make([]store.TelemetrySnapshot, 0, len(rows))
			for _, row := range rows {
				if row.Kind == "local_bird" && row.ConfigFingerprint == store.TelemetrySpeakerFingerprint(sp) && !row.BGP.ReceivedAt.IsZero() && !row.BGP.ReceivedAt.After(now) && now.Sub(row.BGP.ReceivedAt) <= staleAfter {
					current = append(current, row)
				}
			}
			if len(current) > 0 {
				rows = current
			}
		}
		if len(rows) > 1 {
			view.Error = "ambiguous telemetry authorities"
			view.ObservationOverride = &liveObservation{Source: "none", Quality: "unknown", ErrorCode: "ambiguous_authority"}
		} else if len(rows) == 1 {
			row := rows[0]
			invalid := ""
			if row.ConfigFingerprint != store.TelemetrySpeakerFingerprint(sp) {
				invalid = "configuration_changed"
			}
			bgp := snapshotObservation(row.BGP.TelemetryObservation, now, staleAfter, invalid)
			view.ObservationOverride = &bgp
			view.Polled = !row.BGP.ReceivedAt.IsZero()
			view.ObservedAt, view.ReceivedAt, view.LastSuccessAt, view.Source = row.BGP.ObservedAt, row.BGP.ReceivedAt, row.BGP.LastSuccessAt, row.BGP.Source
			if bgp.Quality == "ok" {
				view.Sessions = row.BGP.Sessions
			} else {
				view.Error = bgp.ErrorCode
			}
			if row.Kind == "remote_agent" {
				h := snapshotObservation(row.Health.TelemetryObservation, now, staleAfter, invalid)
				result := nodedispatch.AgentHealthResult{OK: row.Health.OK && h.Quality == "ok", Error: row.Health.Error, LastSyncAt: row.Health.LastSyncAt, LastAppliedRevisionID: row.Health.LastAppliedRevisionID}
				if h.Quality != "ok" {
					result.Error = h.ErrorCode
				}
				if h.Quality == "ok" && !result.OK {
					h.Quality, h.ErrorCode = "unreachable", "reported_unhealthy"
				}
				health = &agentHealthPoll{result: result, observationOverride: &h}
			}
		}
		views = append(views, view)
		if sp != nil {
			statuses[id] = speakerLiveStatusWithPoll(sp, view, health)
		}
	}
	for _, sp := range speakers {
		if sp != nil {
			appendView(sp.ID, sp)
		}
	}
	if len(grouped[""]) > 0 {
		appendView("", nil)
	}
	return views, statuses
}

func (s *Server) handleTelemetryRefresh(w http.ResponseWriter, r *http.Request) {
	a, ok := authFromContext(r.Context())
	if !ok {
		writeProblem(w, http.StatusUnauthorized, "Unauthorized", "missing auth")
		return
	}
	if !s.requirePerm(w, a, "bgp:network:read") {
		return
	}
	ctx, cancel := context.WithTimeout(r.Context(), 2*time.Second)
	defer cancel()
	requested, err := s.store.RequestTelemetryRefresh(ctx, a.TenantID, 10*time.Second)
	if err != nil {
		writeProblem(w, http.StatusServiceUnavailable, "Service Unavailable", "telemetry refresh unavailable")
		return
	}
	writeJSON(w, http.StatusAccepted, map[string]any{"requested": requested})
}