#!/bin/sh
# SPDX-License-Identifier: MIT
# Meshname DNS Controller - Decentralized .ygg domain resolution
#
# Copyright (C) 2026 CyberMind.fr

. /lib/functions.sh
. /usr/share/libubox/jshn.sh

CONFIG="meshname-dns"
LIB_DIR="/usr/lib/meshname-dns"
STATE_DIR="/var/lib/meshname-dns"
HOSTS_FILE="/tmp/hosts/meshname"
DOMAINS_FILE="$STATE_DIR/domains.json"
LOCAL_FILE="$STATE_DIR/local.json"
LOG_TAG="meshname-dns"

# Source libraries
[ -f "$LIB_DIR/announcer.sh" ] && . "$LIB_DIR/announcer.sh"
[ -f "$LIB_DIR/resolver.sh" ] && . "$LIB_DIR/resolver.sh"

usage() {
	cat <<'EOF'
Usage: meshnamectl <command> [options]

Commands:
  announce <name> [port]        Announce service as <name>.ygg
  revoke <name>                 Stop announcing service
  resolve <name>.ygg            Resolve domain to IPv6
  list                          List known .ygg domains
  sync                          Force sync with mesh peers
  status                        Show meshname DNS status
  daemon                        Run sync daemon (internal)

Examples:
  meshnamectl announce myapp 8080    # Announces myapp.ygg -> local Ygg IPv6
  meshnamectl resolve peer.ygg       # Returns peer's Ygg IPv6
  meshnamectl list                   # Shows all known .ygg domains

Configuration: /etc/config/meshname-dns
EOF
}

log_info() { logger -t "$LOG_TAG" "$*"; echo "[INFO] $*"; }
log_warn() { logger -t "$LOG_TAG" -p warning "$*"; echo "[WARN] $*" >&2; }
log_error() { logger -t "$LOG_TAG" -p err "$*"; echo "[ERROR] $*" >&2; }

uci_get() { uci -q get "${CONFIG}.$1"; }
uci_set() { uci set "${CONFIG}.$1=$2"; }

# Get local Yggdrasil IPv6 address
get_ygg_ipv6() {
	# Try tun0 first (standard Yggdrasil interface)
	local ipv6=$(ip -6 addr show tun0 2>/dev/null | grep -oP '(?<=inet6 )2[0-9a-f:]+(?=/)')

	# If not found, try any interface with 200: prefix
	if [ -z "$ipv6" ]; then
		ipv6=$(ip -6 addr show 2>/dev/null | grep -oP '(?<=inet6 )2[0-9a-f][0-9a-f]:[0-9a-f:]+(?=/)' | head -1)
	fi

	echo "$ipv6"
}

# Initialize state files
init_state() {
	mkdir -p "$STATE_DIR"
	mkdir -p "$(dirname "$HOSTS_FILE")"

	[ -f "$DOMAINS_FILE" ] || echo '{}' > "$DOMAINS_FILE"
	[ -f "$LOCAL_FILE" ] || echo '{}' > "$LOCAL_FILE"
	[ -f "$HOSTS_FILE" ] || touch "$HOSTS_FILE"
}

# Load configuration
load_config() {
	enabled=$(uci_get main.enabled)
	auto_announce=$(uci_get main.auto_announce)
	sync_interval=$(uci_get main.sync_interval)
	hosts_file=$(uci_get main.hosts_file)

	resolver_enabled=$(uci_get resolver.enabled)
	cache_ttl=$(uci_get resolver.cache_ttl)

	gossip_enabled=$(uci_get gossip.enabled)
	announce_priority=$(uci_get gossip.announce_priority)

	[ -z "$sync_interval" ] && sync_interval=60
	[ -z "$cache_ttl" ] && cache_ttl=300
	[ -z "$announce_priority" ] && announce_priority=50
	[ -n "$hosts_file" ] && HOSTS_FILE="$hosts_file"
}

# =============================================================================
# STATUS
# =============================================================================

cmd_status() {
	init_state
	load_config

	local ygg_ipv6=$(get_ygg_ipv6)
	local local_count=0
	local domain_count=0

	if [ -f "$LOCAL_FILE" ] && [ -s "$LOCAL_FILE" ]; then
		local_count=$(jsonfilter -i "$LOCAL_FILE" -e '@' 2>/dev/null | grep -c '"name"' || echo 0)
	fi

	if [ -f "$DOMAINS_FILE" ] && [ -s "$DOMAINS_FILE" ]; then
		domain_count=$(jsonfilter -i "$DOMAINS_FILE" -e '@' 2>/dev/null | grep -c '"ipv6"' || echo 0)
	fi

	echo "=== Meshname DNS Status ==="
	echo ""
	echo "Enabled: $([ "$enabled" = "1" ] && echo "Yes" || echo "No")"
	echo "Yggdrasil IPv6: ${ygg_ipv6:-not available}"
	echo "Sync Interval: ${sync_interval}s"
	echo ""
	echo "=== Services ==="
	echo "Local Announced: $local_count"
	echo "Known Domains: $domain_count"
	echo ""
	echo "=== Files ==="
	echo "Hosts File: $HOSTS_FILE"
	[ -f "$HOSTS_FILE" ] && echo "Hosts Entries: $(wc -l < "$HOSTS_FILE")"

	if [ -f "$STATE_DIR/last_sync" ]; then
		echo "Last Sync: $(cat "$STATE_DIR/last_sync")"
	fi
}

# =============================================================================
# ANNOUNCE
# =============================================================================

cmd_announce() {
	local name="$1"
	local port="${2:-0}"

	[ -z "$name" ] && {
		echo "Usage: meshnamectl announce <name> [port]"
		echo "Example: meshnamectl announce myservice 8080"
		exit 1
	}

	# Strip .ygg suffix if present
	name="${name%.ygg}"

	init_state
	load_config

	local ygg_ipv6=$(get_ygg_ipv6)
	[ -z "$ygg_ipv6" ] && {
		log_error "Yggdrasil IPv6 not available. Is Yggdrasil running?"
		exit 1
	}

	local fqdn="${name}.ygg"
	local timestamp=$(date +%s)

	log_info "Announcing $fqdn -> $ygg_ipv6 (port: $port)"

	# Store locally
	local tmp_file="/tmp/meshname_local_$$.json"
	if [ -s "$LOCAL_FILE" ] && [ "$(cat "$LOCAL_FILE")" != "{}" ]; then
		# Update existing entry or add new
		python3 -c "
import json, sys
name, ipv6, port, ts = sys.argv[1:5]
try:
    with open('$LOCAL_FILE') as f:
        data = json.load(f)
except:
    data = {}
data[name] = {'name': name, 'fqdn': name + '.ygg', 'ipv6': ipv6, 'port': int(port), 'timestamp': int(ts)}
with open('$tmp_file', 'w') as f:
    json.dump(data, f, indent=2)
" "$name" "$ygg_ipv6" "$port" "$timestamp"
	else
		python3 -c "
import json, sys
name, ipv6, port, ts = sys.argv[1:5]
data = {name: {'name': name, 'fqdn': name + '.ygg', 'ipv6': ipv6, 'port': int(port), 'timestamp': int(ts)}}
with open('$tmp_file', 'w') as f:
    json.dump(data, f, indent=2)
" "$name" "$ygg_ipv6" "$port" "$timestamp"
	fi
	mv "$tmp_file" "$LOCAL_FILE"

	# Update local hosts file
	update_hosts_entry "$fqdn" "$ygg_ipv6"

	# Broadcast via gossip
	if [ "$gossip_enabled" = "1" ]; then
		broadcast_announce "$name" "$fqdn" "$ygg_ipv6" "$port"
	fi

	log_info "Announced $fqdn"
}

# =============================================================================
# REVOKE
# =============================================================================

cmd_revoke() {
	local name="$1"

	[ -z "$name" ] && {
		echo "Usage: meshnamectl revoke <name>"
		exit 1
	}

	# Strip .ygg suffix if present
	name="${name%.ygg}"

	init_state
	load_config

	local fqdn="${name}.ygg"

	log_info "Revoking $fqdn"

	# Remove from local file
	if [ -f "$LOCAL_FILE" ]; then
		python3 -c "
import json, sys
name = sys.argv[1]
try:
    with open('$LOCAL_FILE') as f:
        data = json.load(f)
    if name in data:
        del data[name]
        with open('$LOCAL_FILE', 'w') as f:
            json.dump(data, f, indent=2)
        print('Removed:', name)
except Exception as e:
    print('Error:', e)
" "$name"
	fi

	# Remove from hosts file
	remove_hosts_entry "$fqdn"

	# Broadcast revocation via gossip (with empty IPv6)
	if [ "$gossip_enabled" = "1" ]; then
		broadcast_revoke "$name" "$fqdn"
	fi

	log_info "Revoked $fqdn"
}

# =============================================================================
# RESOLVE
# =============================================================================

cmd_resolve() {
	local domain="$1"

	[ -z "$domain" ] && {
		echo "Usage: meshnamectl resolve <name>.ygg"
		exit 1
	}

	# Add .ygg suffix if not present
	echo "$domain" | grep -q '\.ygg$' || domain="${domain}.ygg"

	init_state

	# Check hosts file first
	local ipv6=$(grep -w "$domain" "$HOSTS_FILE" 2>/dev/null | awk '{print $1}')

	if [ -n "$ipv6" ]; then
		echo "$ipv6"
		return 0
	fi

	# Check domains cache
	local name="${domain%.ygg}"
	if [ -f "$DOMAINS_FILE" ]; then
		ipv6=$(python3 -c "
import json, sys
name = sys.argv[1]
try:
    with open('$DOMAINS_FILE') as f:
        data = json.load(f)
    if name in data:
        print(data[name].get('ipv6', ''))
except:
    pass
" "$name")

		if [ -n "$ipv6" ]; then
			echo "$ipv6"
			return 0
		fi
	fi

	log_error "Cannot resolve $domain"
	return 1
}

# =============================================================================
# LIST
# =============================================================================

cmd_list() {
	init_state

	echo "=== Local Services ==="
	if [ -f "$LOCAL_FILE" ] && [ -s "$LOCAL_FILE" ] && [ "$(cat "$LOCAL_FILE")" != "{}" ]; then
		python3 -c "
import json
try:
    with open('$LOCAL_FILE') as f:
        data = json.load(f)
    for name, info in data.items():
        port = info.get('port', 0)
        port_str = f' (port {port})' if port > 0 else ''
        print(f\"  {info['fqdn']} -> {info['ipv6']}{port_str}\")
except:
    print('  (none)')
"
	else
		echo "  (none)"
	fi

	echo ""
	echo "=== Known Domains ==="
	if [ -f "$DOMAINS_FILE" ] && [ -s "$DOMAINS_FILE" ] && [ "$(cat "$DOMAINS_FILE")" != "{}" ]; then
		python3 -c "
import json
try:
    with open('$DOMAINS_FILE') as f:
        data = json.load(f)
    for name, info in data.items():
        origin = info.get('origin', 'unknown')[:16]
        print(f\"  {info['fqdn']} -> {info['ipv6']} (from {origin})\")
except:
    print('  (none)')
"
	else
		echo "  (none)"
	fi

	echo ""
	echo "=== Hosts File ($HOSTS_FILE) ==="
	if [ -f "$HOSTS_FILE" ] && [ -s "$HOSTS_FILE" ]; then
		sed 's/^/  /' "$HOSTS_FILE"
	else
		echo "  (empty)"
	fi
}

# =============================================================================
# SYNC
# =============================================================================

cmd_sync() {
	init_state
	load_config

	log_info "Syncing with mesh peers..."

	# Re-announce all local services
	if [ -f "$LOCAL_FILE" ] && [ "$gossip_enabled" = "1" ]; then
		python3 -c "
import json
try:
    with open('$LOCAL_FILE') as f:
        data = json.load(f)
    for name, info in data.items():
        print(f\"{name}|{info['fqdn']}|{info['ipv6']}|{info.get('port', 0)}\")
except:
    pass
" | while IFS='|' read -r name fqdn ipv6 port; do
			[ -n "$name" ] && broadcast_announce "$name" "$fqdn" "$ipv6" "$port"
		done
	fi

	# Regenerate hosts file from domains cache
	regenerate_hosts

	date -Iseconds > "$STATE_DIR/last_sync"
	log_info "Sync complete"
}

# =============================================================================
# DAEMON
# =============================================================================

cmd_daemon() {
	load_config

	[ "$enabled" = "1" ] || {
		log_error "Meshname DNS is disabled"
		exit 1
	}

	log_info "Starting Meshname DNS daemon (interval: ${sync_interval}s)..."

	# Initial sync
	cmd_sync 2>&1 | while read -r line; do
		logger -t "$LOG_TAG" "$line"
	done

	# Periodic sync loop
	while true; do
		sleep "$sync_interval"

		cmd_sync 2>&1 | while read -r line; do
			logger -t "$LOG_TAG" "$line"
		done
	done
}

# =============================================================================
# HELPER FUNCTIONS
# =============================================================================

# Update a single entry in hosts file
update_hosts_entry() {
	local fqdn="$1"
	local ipv6="$2"

	[ -z "$fqdn" ] || [ -z "$ipv6" ] && return 1

	# Remove existing entry if present
	sed -i "/ ${fqdn}$/d" "$HOSTS_FILE" 2>/dev/null

	# Add new entry
	echo "$ipv6 $fqdn" >> "$HOSTS_FILE"

	# Signal dnsmasq to reload
	killall -HUP dnsmasq 2>/dev/null
}

# Remove entry from hosts file
remove_hosts_entry() {
	local fqdn="$1"

	sed -i "/ ${fqdn}$/d" "$HOSTS_FILE" 2>/dev/null
	killall -HUP dnsmasq 2>/dev/null
}

# Regenerate entire hosts file from caches
regenerate_hosts() {
	local tmp_hosts="/tmp/meshname_hosts_$$.tmp"
	: > "$tmp_hosts"

	# Add local services
	if [ -f "$LOCAL_FILE" ]; then
		python3 -c "
import json
try:
    with open('$LOCAL_FILE') as f:
        data = json.load(f)
    for name, info in data.items():
        print(f\"{info['ipv6']} {info['fqdn']}\")
except:
    pass
" >> "$tmp_hosts"
	fi

	# Add remote domains
	if [ -f "$DOMAINS_FILE" ]; then
		python3 -c "
import json
try:
    with open('$DOMAINS_FILE') as f:
        data = json.load(f)
    for name, info in data.items():
        print(f\"{info['ipv6']} {info['fqdn']}\")
except:
    pass
" >> "$tmp_hosts"
	fi

	# Deduplicate and sort
	sort -u "$tmp_hosts" > "$HOSTS_FILE"
	rm -f "$tmp_hosts"

	# Signal dnsmasq
	killall -HUP dnsmasq 2>/dev/null
}

# Broadcast announcement via gossip
broadcast_announce() {
	local name="$1"
	local fqdn="$2"
	local ipv6="$3"
	local port="${4:-0}"

	# Use mirrornet gossip if available
	if [ -f /usr/lib/mirrornet/gossip.sh ]; then
		. /usr/lib/mirrornet/gossip.sh

		local data="{\"name\":\"$name\",\"fqdn\":\"$fqdn\",\"ipv6\":\"$ipv6\",\"port\":$port,\"type\":\"announce\"}"
		gossip_broadcast "meshname_announce" "$data" "$announce_priority"
	fi
}

# Broadcast revocation via gossip
broadcast_revoke() {
	local name="$1"
	local fqdn="$2"

	if [ -f /usr/lib/mirrornet/gossip.sh ]; then
		. /usr/lib/mirrornet/gossip.sh

		local data="{\"name\":\"$name\",\"fqdn\":\"$fqdn\",\"ipv6\":\"\",\"type\":\"revoke\"}"
		gossip_broadcast "meshname_announce" "$data" "$announce_priority"
	fi
}

# =============================================================================
# MAIN
# =============================================================================

case "$1" in
	status)
		cmd_status
		;;
	announce)
		cmd_announce "$2" "$3"
		;;
	revoke)
		cmd_revoke "$2"
		;;
	resolve)
		cmd_resolve "$2"
		;;
	list)
		cmd_list
		;;
	sync)
		cmd_sync
		;;
	daemon)
		cmd_daemon
		;;
	-h|--help|help)
		usage
		;;
	*)
		usage
		exit 1
		;;
esac