// svxdr — live-data daemon for SvxPortal (nodelist + proxy + astmeta + xlink)
// Copyright (C) 2026 SA7AUX (Björn)
// SPDX-License-Identifier: AGPL-3.0-or-later
//
// This program is free software: you can redistribute it and/or modify it under
// the terms of the GNU Affero General Public License as published by the Free
// Software Foundation, either version 3 of the License, or (at your option) any
// later version. See the LICENSE file for details.

package nodelist

// Monitor Nodes, the simple way: read ONE reflector /status endpoint that
// already carries the whole picture (local nodes + every trunk with its nodes)
// and reshape it into {local, trunks:[{name,host,nodes}]}. No recursive crawl.
//
// Which URL is read is per-box config MONITOR_STATUS_URL (falls back to
// REFLECTOR_STATUS_URL):
//   hub box    → https://<master-reflector>/geu/status/   (the master's full view)
//   bridge box → http://127.0.0.1:8080/status              (its own reflector)

import (
	"encoding/json"
	"io"
	"net/http"
	"regexp"
	"sort"
	"strconv"
	"strings"
	"sync"
	"time"

	"svxportal/svxdr/statusnorm"
)

var monitorStatusURL = env("MONITOR_STATUS_URL", reflectorURL)

// monitorInterval is how often REMOTE status reads (a Monitor->Nodes URL or a
// trunk_status topology URL that points at another server) run. Gentle by default
// so a shared hub is never hammered; override via svxdr.json nodelist.monitor_interval.
// A LOCAL read (127.0.0.1) is free and refreshes fast — see localReadInterval.
var monitorInterval = 60 * time.Second

// localReadInterval: reading our OWN reflector costs nothing, so do it often.
var localReadInterval = 5 * time.Second

// isLocalURL reports whether a status URL points at this host (loopback). Local
// reads may be frequent; remote reads must be throttled to monitorInterval.
func isLocalURL(u string) bool {
	return strings.Contains(u, "127.0.0.1") || strings.Contains(u, "localhost") || strings.Contains(u, "[::1]")
}

// readInterval picks the fast (local) or gentle (remote) cadence for a URL.
func readInterval(u string) time.Duration {
	if isLocalURL(u) {
		return localReadInterval
	}
	return monitorInterval
}

type monNode struct {
	Callsign  string `json:"callsign"`
	TG        string `json:"tg,omitempty"`
	NodeClass string `json:"nodeClass,omitempty"`
	Mode      string `json:"mode,omitempty"`
	Talker    bool   `json:"talker,omitempty"`
}

// uniquifyNames makes every node name in the view unique WITHOUT ever touching the
// Local (top-level) nodes — those are the reflector's own map keys, exactly what the
// Reflector clients view shows, so renaming them would make the two views disagree.
// Only trunk/satellite array nodes (which have no key and never appear in Reflector
// clients) are numbered, and only enough to stay clear of every name already taken
// (Local keys + earlier array nodes): SA7AUX -> SA7AUX-1, SA7AUX-2, …
func uniquifyNames(out *monStatus) {
	taken := map[string]bool{}
	for _, n := range out.Local { // canonical, never renamed
		taken[n.Callsign] = true
	}
	next := map[string]int{}
	for i := range out.Trunks {
		for j := range out.Trunks[i].Nodes {
			base := out.Trunks[i].Nodes[j].Callsign
			if !taken[base] {
				taken[base] = true
				continue
			}
			for {
				next[base]++
				cand := base + "-" + strconv.Itoa(next[base])
				if !taken[cand] {
					taken[cand] = true
					out.Trunks[i].Nodes[j].Callsign = cand
					break
				}
			}
		}
	}
}

type monTrunk struct {
	Name      string    `json:"name"`
	Host      string    `json:"host,omitempty"`
	Connected bool      `json:"connected"`
	Nodes     []monNode `json:"nodes"`
}

type monStatus struct {
	Local     []monNode  `json:"local"`
	Trunks    []monTrunk `json:"trunks"`
	Source    string     `json:"source"`
	UpdatedAt string     `json:"updated_at"`
}

var monState = struct {
	mu   sync.RWMutex
	data monStatus
}{}

// rawNode is one node as it appears either as a value in the top-level "nodes"
// object (keyed by callsign) or as an item in a trunk's "nodes" array.
type rawNode struct {
	Callsign     string        `json:"callsign"`
	SW           string        `json:"sw"`
	TG           json.Number   `json:"tg"`
	NodeClass    string        `json:"nodeClass"`
	RestrictedTG bool          `json:"restrictedTG"`
	IsTalker     bool          `json:"isTalker"`
	System       string        `json:"system"`    // per-node link/type from the data (e.g. "DMR", "DMR/YSF", "DMR/Hytera")
	Reflector    string        `json:"Reflector"` // which reflector this node is on (master status carries it)
	MonitoredTGs []json.Number `json:"monitoredTGs"`
	Links        []struct {
		LocalTg json.Number `json:"localTg"`
	} `json:"links"`
}

// masterReflectorName picks a label for the monitored master's own nodes purely
// from the DATA (the Reflector field the nodes report) — no dependency on the
// local conf format, so every box derives it the same way.
func masterReflectorName(nodes map[string]json.RawMessage) string {
	count := map[string]int{}
	for _, raw := range nodes {
		var r struct {
			Reflector string `json:"Reflector"`
		}
		if json.Unmarshal(raw, &r) == nil && strings.TrimSpace(r.Reflector) != "" {
			count[r.Reflector]++
		}
	}
	best, n := "", 0
	for k, c := range count {
		if c > n {
			best, n = k, c
		}
	}
	return best
}

// monModeOf: real type from the software string (svx nodes carry no "mode").
func monModeOf(sw string) string {
	s := strings.ToLower(sw)
	switch {
	case strings.Contains(s, "chan_pbx"):
		return "PBX"
	case strings.Contains(s, "chan_svx_sat"):
		return "AllStar"
	case strings.Contains(s, "chan_svx"):
		return "AllStar"
	case strings.Contains(s, "svxlink"):
		return "SVX"
	case strings.Contains(s, "mmdvm"), strings.Contains(s, "brandmeister"), strings.Contains(s, "dmr"):
		return "DMR"
	case strings.Contains(s, "ysf"):
		return "YSF"
	case strings.Contains(s, "nxdn"):
		return "NXDN"
	case strings.Contains(s, "m17"):
		return "M17"
	case sw != "":
		return sw
	default:
		return ""
	}
}

// A bridge node just links systems together (chan_svx asterisk, a DMR/trunk
// bridge, or an -AC/-DMR/-T suffix) — not a real user/radio client, so we never
// show it. chan_svx_sat IS a real AllStar node over the satellite trunk and is
// kept. Mirrors the TG Monitor's isBridge so both views show only real users.
var bridgeSuffix = regexp.MustCompile(`(?i)-(AC|DMR|T)$`)

func isBridgeNode(callsign, sw, nodeClass string) bool {
	s := strings.ToLower(sw)
	// AllStar radio-network peers ARE shown — the links to svx/dmr/ysf/nxdn/m17
	// are exactly what the user wants visible under their node/trunk. chan_svx and
	// chan_svx_sat both count. Only pure non-radio infrastructure stays hidden.
	if strings.Contains(s, "chan_svx") || strings.Contains(s, "chan_pbx") { // chan_svx + chan_svx_sat + chan_pbx_svx (PBX)
		return false
	}
	nc := strings.ToLower(nodeClass)
	switch nc {
	case "dmr", "ysf", "nxdn", "m17":
		return false // radio-network peer — show
	case "xlx", "mumble", "stream", "echolink", "sip", "zello":
		return true // non-radio / D-Star infra — hide
	}
	// sw-based radio bridges (DMR_/YSF_/NXDN_/M17_Bridge) → show; the remaining
	// "*bridge" (XLX_/Mumble_/Janus Bridge) is non-radio infra → hide.
	if strings.Contains(s, "dmr") || strings.Contains(s, "ysf") ||
		strings.Contains(s, "nxdn") || strings.Contains(s, "m17") {
		return false
	}
	if strings.Contains(s, "bridge") {
		return true
	}
	// pure infrastructure gateway callsigns are never real peers.
	u := strings.ToUpper(callsign)
	if strings.HasPrefix(u, "SIP") || strings.HasPrefix(u, "DCS") ||
		strings.HasPrefix(u, "XLX") || strings.Contains(u, "MUMBLE") {
		return true
	}
	return false // default: show (real users + radio peers)
}

func toMonNode(callsign string, raw json.RawMessage) (monNode, bool) {
	var r rawNode
	_ = json.Unmarshal(raw, &r)
	// Display name = the node's KEY (its registered identity — exactly what the
	// Reflector clients view shows via the /status map key), so the two views can
	// never disagree on a name. Trunk/satellite array nodes have no key -> use the
	// callsign field (which statusnorm may have set to the per-TG group name).
	cs := callsign
	if cs == "" {
		cs = r.Callsign
	}
	// A configured node (in nodes[]) is an intentional own node — always show it,
	// even if its nodeClass would otherwise read as infra (e.g. a DMR gateway as
	// "Stream"). Everything else keeps the bridge/infra filter.
	if !isConfiguredName(cs) && isBridgeNode(cs, r.SW, r.NodeClass) {
		return monNode{}, false // bridge, not a real user — hide it
	}
	// TG: the node's own tg, else its first monitored/linked TG.
	tg := ""
	if s := r.TG.String(); s != "" && s != "0" {
		tg = s
	} else if len(r.MonitoredTGs) > 0 {
		tg = r.MonitoredTGs[0].String()
	} else if len(r.Links) > 0 {
		tg = r.Links[0].LocalTg.String()
	}
	if r.RestrictedTG && tg != "" {
		tg = "*" + tg
	}
	// Per-TG name: several sat nodes share ONE reflector login (KT4ROY-ASL), so
	// under a trunk they'd all show that same callsign. If svxdr.json configures a
	// per-TG via for this node's TG, show THAT (KT4ROY-ASL1..4) — the trunk's own
	// name is unaffected. One place (svxdr.json) drives it.
	// Type/mode, in priority order (no hardcoding of any mode):
	//   1) config nodes[].mode (explicit override, keyed by display name)
	//   2) the node's own "system" field from the data (DMR, DMR/YSF, DMR/Hytera…)
	//   3) type derived from the software string
	mode := modeForName(cs)
	if mode == "" {
		mode = r.System
	}
	if mode == "" {
		mode = monModeOf(r.SW)
	}
	return monNode{Callsign: cs, TG: tg, NodeClass: r.NodeClass, Mode: mode, Talker: r.IsTalker}, true
}

// ownLocalNodes reads OUR OWN reflector (reflectorURL) and returns its top-level
// nodes — the ones genuinely local to THIS server. Used to keep Local accurate
// when MONITOR_STATUS_URL points at a foreign master.
func ownLocalNodes(client *http.Client) ([]monNode, bool) {
	resp, err := client.Get(reflectorURL)
	if err != nil {
		return nil, false
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusOK {
		return nil, false
	}
	var raw struct {
		Nodes map[string]json.RawMessage `json:"nodes"`
	}
	if json.NewDecoder(resp.Body).Decode(&raw) != nil {
		return nil, false
	}
	var out []monNode
	for cs, rn := range raw.Nodes {
		if mn, ok := toMonNode(cs, rn); ok {
			out = append(out, mn)
		}
	}
	return out, true
}

func buildMonitor(client *http.Client, generated string) (monStatus, bool) {
	resp, err := client.Get(monitorStatusURL)
	if err != nil {
		return monStatus{}, false
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusOK {
		return monStatus{}, false
	}
	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return monStatus{}, false
	}
	// Normalize at ingest: sat-login node callsigns -> per-TG name. Covers the
	// case where monitorStatusURL is a foreign master (e.g. a hub box reads a foreign master
	// where its satellite nodes federate in). A local read via the proxy is already
	// normalized; re-normalizing is a harmless no-op.
	body = statusnorm.Normalize(body, renameSatNode)
	var raw struct {
		Nodes  map[string]json.RawMessage `json:"nodes"`
		Trunks map[string]struct {
			Host      string            `json:"host"`
			Connected bool              `json:"connected"`
			Nodes     []json.RawMessage `json:"nodes"`
		} `json:"trunks"`
		// Satellite trunks (chan_svx_sat): each id (e.g. KT4ROY-ASL) carries N
		// AllStar nodes. They live here, NOT in top-level nodes, so Monitor→Nodes
		// must read them too or the sat nodes are invisible.
		Satellites map[string]struct {
			Authenticated bool              `json:"authenticated"`
			Nodes         []json.RawMessage `json:"nodes"`
		} `json:"satellites"`
	}
	if json.Unmarshal(body, &raw) != nil {
		return monStatus{}, false
	}

	out := monStatus{Source: monitorStatusURL, UpdatedAt: generated}

	// Local = only OUR reflector's own nodes. Whenever MONITOR_STATUS_URL is a
	// REMOTE master (not our own reflector), ALWAYS split: read our OWN reflector for
	// the local set and put the master's own top-level nodes under a section instead.
	// This must behave the SAME on every box regardless of its svxreflector.conf
	// dialect — so the split is decided purely by "is the master remote", and the
	// section label is derived from the DATA (masterReflectorName) when the conf
	// doesn't name the uplink trunk. No per-box special cases.
	doSplit := reflectorURL != monitorStatusURL
	masterLabel := ""
	if doSplit {
		if masterLabel = masterReflectorName(raw.Nodes); masterLabel == "" {
			masterLabel = "uplink"
		}
	}
	selfCalls := map[string]bool{}
	if doSplit {
		if selfNodes, ok := ownLocalNodes(client); ok {
			for _, mn := range selfNodes {
				out.Local = append(out.Local, mn)
				selfCalls[strings.ToUpper(mn.Callsign)] = true
			}
		}
	}

	var foreignTop []monNode
	for cs, rn := range raw.Nodes {
		mn, ok := toMonNode(cs, rn)
		if !ok {
			continue
		}
		if !doSplit {
			out.Local = append(out.Local, mn)
		} else if !selfCalls[strings.ToUpper(mn.Callsign)] {
			foreignTop = append(foreignTop, mn) // the master's own node → its trunk section
		}
	}
	sort.Slice(out.Local, func(i, j int) bool { return out.Local[i].Callsign < out.Local[j].Callsign })

	// The master's own nodes become one trunk section (we reach it over a trunk).
	if len(foreignTop) > 0 {
		sort.Slice(foreignTop, func(i, j int) bool { return foreignTop[i].Callsign < foreignTop[j].Callsign })
		out.Trunks = append(out.Trunks, monTrunk{Name: masterLabel, Connected: true, Nodes: foreignTop})
	}

	for name, t := range raw.Trunks {
		mt := monTrunk{Name: name, Host: t.Host, Connected: t.Connected}
		for _, rn := range t.Nodes {
			if mn, ok := toMonNode("", rn); ok {
				mt.Nodes = append(mt.Nodes, mn)
			}
		}
		sort.Slice(mt.Nodes, func(i, j int) bool { return mt.Nodes[i].Callsign < mt.Nodes[j].Callsign })
		out.Trunks = append(out.Trunks, mt)
	}

	// Satellite trunks: one section per satellite id (KT4ROY-ASL), its AllStar
	// nodes (KT4ROY-ASL1..4 via toMonNode's per-TG rename) shown under it.
	for id, s := range raw.Satellites {
		mt := monTrunk{Name: id, Connected: s.Authenticated}
		for _, rn := range s.Nodes {
			if mn, ok := toMonNode("", rn); ok {
				mt.Nodes = append(mt.Nodes, mn)
			}
		}
		sort.Slice(mt.Nodes, func(i, j int) bool { return mt.Nodes[i].Callsign < mt.Nodes[j].Callsign })
		out.Trunks = append(out.Trunks, mt)
	}
	// Connected trunks first, then by name — stable, tidy sections.
	sort.Slice(out.Trunks, func(i, j int) bool {
		if out.Trunks[i].Connected != out.Trunks[j].Connected {
			return out.Trunks[i].Connected
		}
		return out.Trunks[i].Name < out.Trunks[j].Name
	})
	// Make every node name unique across the whole view (backend, before the web).
	uniquifyNames(&out)
	return out, true
}

func monitorNodesStart(mux *http.ServeMux) {
	client := &http.Client{Timeout: 12 * time.Second}

	refresh := func() {
		// stamp with a wall-clock time computed off the request (Date.now is
		// unavailable in workflow scripts, but this is normal server code).
		if next, ok := buildMonitor(client, time.Now().UTC().Format(time.RFC3339)); ok {
			monState.mu.Lock()
			monState.data = next
			monState.mu.Unlock()
		}
	}
	refresh()
	go func() {
		// Local reflector reads are free (fast); a remote master URL is throttled.
		t := time.NewTicker(readInterval(monitorStatusURL))
		defer t.Stop()
		for range t.C {
			refresh()
		}
	}()

	mux.HandleFunc("/api/monitor-nodes", func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "application/json; charset=utf-8")
		monState.mu.RLock()
		b, _ := json.Marshal(monState.data)
		monState.mu.RUnlock()
		writeMaybeGzip(w, r, b)
	})
}