#!/bin/sh
# SecuBox DNS Master - BIND Zone Management
# Manages DNS zones and records for BIND server

VERSION="1.0.0"
CONFIG="dns-master"
BIND_DIR="/etc/bind"
ZONES_DIR="/etc/bind/zones"
NAMED_CONF="/etc/bind/named.conf"

# Colors
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
CYAN='\033[0;36m'
NC='\033[0m'

log() { echo -e "${GREEN}[DNS]${NC} $1"; }
warn() { echo -e "${YELLOW}[WARN]${NC} $1"; }
error() { echo -e "${RED}[ERROR]${NC} $1"; }

uci_get() { uci -q get ${CONFIG}.$1; }

# ============================================================================
# Status
# ============================================================================

cmd_status() {
    echo ""
    echo "========================================"
    echo "  SecuBox DNS Master v$VERSION"
    echo "========================================"
    echo ""

    # BIND status
    if pgrep named >/dev/null 2>&1; then
        local pid=$(pgrep named | head -1)
        echo -e "  BIND Status:  ${GREEN}Running${NC} (PID: $pid)"
    else
        echo -e "  BIND Status:  ${RED}Stopped${NC}"
    fi

    # Zone count
    local zone_count=$(ls -1 "$ZONES_DIR"/*.zone 2>/dev/null | wc -l)
    echo "  Zones:        $zone_count"

    # Total records
    local record_count=0
    for zone in "$ZONES_DIR"/*.zone; do
        [ -f "$zone" ] || continue
        local cnt=$(grep -cE "^\s*[^;].*\s+IN\s+" "$zone" 2>/dev/null || echo 0)
        record_count=$((record_count + cnt))
    done
    echo "  Records:      $record_count"

    echo ""
    echo "  Zones Directory: $ZONES_DIR"
    echo "  Config File:     $NAMED_CONF"
    echo ""
}

cmd_status_json() {
    local running=0
    local pid=""
    pgrep named >/dev/null 2>&1 && { running=1; pid=$(pgrep named | head -1); }

    local zone_count=$(ls -1 "$ZONES_DIR"/*.zone 2>/dev/null | wc -l)
    local record_count=0
    for zone in "$ZONES_DIR"/*.zone; do
        [ -f "$zone" ] || continue
        local cnt=$(grep -cE "^\s*[^;].*\s+IN\s+" "$zone" 2>/dev/null || echo 0)
        record_count=$((record_count + cnt))
    done

    local default_ttl=$(uci_get main.default_ttl)
    default_ttl="${default_ttl:-300}"

    cat << EOF
{
    "running": $([ "$running" = "1" ] && echo true || echo false),
    "pid": "$pid",
    "zones": $zone_count,
    "records": $record_count,
    "default_ttl": $default_ttl,
    "zones_dir": "$ZONES_DIR",
    "bind_dir": "$BIND_DIR"
}
EOF
}

# ============================================================================
# Zone Management
# ============================================================================

cmd_zone_list() {
    echo "Zones:"
    echo ""
    for zone_file in "$ZONES_DIR"/*.zone; do
        [ -f "$zone_file" ] || continue
        local name=$(basename "$zone_file" .zone)
        local records=$(grep -cE "^\s*[^;].*\s+IN\s+" "$zone_file" 2>/dev/null || echo 0)
        local serial=$(grep -oE '[0-9]{10}' "$zone_file" | head -1)
        echo "  $name ($records records, serial: $serial)"
    done
}

cmd_zone_list_json() {
    local zones=""
    local first=1

    for zone_file in "$ZONES_DIR"/*.zone; do
        [ -f "$zone_file" ] || continue
        local name=$(basename "$zone_file" .zone)
        local records=$(grep -cE "^\s*[^;].*\s+IN\s+" "$zone_file" 2>/dev/null || echo 0)
        local serial=$(grep -oE '[0-9]{10}' "$zone_file" | head -1)
        local mtime=$(stat -c %Y "$zone_file" 2>/dev/null || echo 0)

        # Check zone validity
        local valid=1
        named-checkzone "$name" "$zone_file" >/dev/null 2>&1 || valid=0

        [ $first -eq 0 ] && zones="$zones,"
        zones="$zones{\"name\":\"$name\",\"file\":\"$zone_file\",\"records\":$records,\"serial\":\"$serial\",\"valid\":$([ $valid -eq 1 ] && echo true || echo false),\"mtime\":$mtime}"
        first=0
    done

    echo "{\"zones\":[$zones]}"
}

cmd_zone_show() {
    local zone="$1"
    [ -z "$zone" ] && { error "Usage: dnsmaster zone-show <zone>"; return 1; }

    local zone_file="$ZONES_DIR/${zone}.zone"
    [ -f "$zone_file" ] || { error "Zone file not found: $zone_file"; return 1; }

    echo "Zone: $zone"
    echo "File: $zone_file"
    echo ""
    cat "$zone_file"
}

cmd_zone_add() {
    local zone="$1"
    [ -z "$zone" ] && { error "Usage: dnsmaster zone-add <zone>"; return 1; }

    local zone_file="$ZONES_DIR/${zone}.zone"
    [ -f "$zone_file" ] && { error "Zone already exists"; return 1; }

    local serial=$(date +%Y%m%d01)
    local ttl=$(uci_get main.default_ttl)
    ttl="${ttl:-300}"

    cat > "$zone_file" << EOF
\$TTL $ttl
@       IN      SOA     ns1.${zone}. admin.${zone}. (
                        $serial      ; Serial
                        3600         ; Refresh
                        600          ; Retry
                        604800       ; Expire
                        $ttl )       ; Negative TTL

; Nameservers
@       IN      NS      ns1.${zone}.

; A records
@       IN      A       127.0.0.1
ns1     IN      A       127.0.0.1
EOF

    log "Created zone: $zone"
    log "Edit $zone_file to add records"
}

# ============================================================================
# Record Management
# ============================================================================

cmd_records_json() {
    local zone="$1"
    [ -z "$zone" ] && { echo '{"error":"Zone required"}'; return 1; }

    local zone_file="$ZONES_DIR/${zone}.zone"
    [ -f "$zone_file" ] || { echo '{"error":"Zone not found"}'; return 1; }

    local records=""
    local first=1

    # Parse zone file for records
    # Match: name [ttl] IN type value
    while IFS= read -r line; do
        # Skip comments and empty lines
        echo "$line" | grep -qE '^\s*(;|$)' && continue
        # Skip SOA and control directives
        echo "$line" | grep -qE '^\$|SOA' && continue

        # Parse record line
        local name type value ttl
        if echo "$line" | grep -qE '\s+IN\s+'; then
            name=$(echo "$line" | awk '{print $1}')
            # Check if TTL is present
            if echo "$line" | grep -qE '^[^[:space:]]+\s+[0-9]+\s+IN\s+'; then
                ttl=$(echo "$line" | awk '{print $2}')
                type=$(echo "$line" | awk '{print $4}')
                value=$(echo "$line" | cut -d' ' -f5-)
            else
                ttl=""
                type=$(echo "$line" | awk '{print $3}')
                value=$(echo "$line" | cut -d' ' -f4-)
            fi

            # Clean value (remove trailing comments)
            value=$(echo "$value" | sed 's/\s*;.*//')

            # Skip NS records for now (handled separately)
            [ "$type" = "NS" ] && continue

            [ $first -eq 0 ] && records="$records,"
            # Escape quotes in value
            value=$(echo "$value" | sed 's/"/\\"/g')
            records="$records{\"name\":\"$name\",\"type\":\"$type\",\"value\":\"$value\",\"ttl\":\"$ttl\"}"
            first=0
        fi
    done < "$zone_file"

    echo "{\"zone\":\"$zone\",\"records\":[$records]}"
}

cmd_record_add() {
    local zone="$1"
    local type="$2"
    local name="$3"
    local value="$4"
    local ttl="${5:-}"

    [ -z "$zone" ] || [ -z "$type" ] || [ -z "$name" ] || [ -z "$value" ] && {
        error "Usage: dnsmaster record-add <zone> <type> <name> <value> [ttl]"
        return 1
    }

    local zone_file="$ZONES_DIR/${zone}.zone"
    [ -f "$zone_file" ] || { error "Zone not found"; return 1; }

    # Bump serial
    bump_serial "$zone_file"

    # Format record line
    local record
    if [ -n "$ttl" ]; then
        record="$name\t$ttl\tIN\t$type\t$value"
    else
        record="$name\t\tIN\t$type\t$value"
    fi

    # Append record to zone file
    echo -e "$record" >> "$zone_file"

    log "Added $type record: $name -> $value"

    # Reload BIND
    cmd_reload
}

cmd_record_del() {
    local zone="$1"
    local type="$2"
    local name="$3"
    local value="$4"

    [ -z "$zone" ] || [ -z "$type" ] || [ -z "$name" ] && {
        error "Usage: dnsmaster record-del <zone> <type> <name> [value]"
        return 1
    }

    local zone_file="$ZONES_DIR/${zone}.zone"
    [ -f "$zone_file" ] || { error "Zone not found"; return 1; }

    # Backup first
    cp "$zone_file" "${zone_file}.bak"

    # Bump serial
    bump_serial "$zone_file"

    # Delete matching record(s)
    if [ -n "$value" ]; then
        # Match specific value
        sed -i "/^${name}[[:space:]].*IN[[:space:]]*${type}[[:space:]]*${value}/d" "$zone_file"
    else
        # Match any value for this name/type
        sed -i "/^${name}[[:space:]].*IN[[:space:]]*${type}/d" "$zone_file"
    fi

    log "Deleted $type record for $name"

    # Reload BIND
    cmd_reload
}

bump_serial() {
    local zone_file="$1"
    local today=$(date +%Y%m%d)
    local current_serial=$(grep -oE '[0-9]{10}' "$zone_file" | head -1)

    local new_serial
    local serial_date=$(echo "$current_serial" | cut -c1-8)
    if [ "$serial_date" = "$today" ]; then
        # Same day, increment counter
        local counter=$(echo "$current_serial" | cut -c9-10)
        # Remove leading zero and increment
        counter=$(expr "$counter" + 1 2>/dev/null || echo 1)
        new_serial="${today}$(printf '%02d' $counter)"
    else
        # New day, reset counter
        new_serial="${today}01"
    fi

    sed -i "s/$current_serial/$new_serial/" "$zone_file"
}

# ============================================================================
# BIND Control
# ============================================================================

cmd_reload() {
    log "Reloading BIND..."
    rndc reload 2>/dev/null || {
        warn "rndc reload failed, trying service restart"
        /etc/init.d/named restart 2>/dev/null || /etc/init.d/bind restart 2>/dev/null
    }
    log "BIND reloaded"
}

cmd_check() {
    local zone="$1"

    if [ -n "$zone" ]; then
        local zone_file="$ZONES_DIR/${zone}.zone"
        [ -f "$zone_file" ] || { error "Zone not found"; return 1; }

        log "Checking zone: $zone"
        named-checkzone "$zone" "$zone_file"
        return $?
    else
        # Check all zones
        local errors=0
        for zone_file in "$ZONES_DIR"/*.zone; do
            [ -f "$zone_file" ] || continue
            local name=$(basename "$zone_file" .zone)
            if named-checkzone "$name" "$zone_file" >/dev/null 2>&1; then
                echo -e "${GREEN}OK${NC}    $name"
            else
                echo -e "${RED}ERROR${NC} $name"
                errors=$((errors + 1))
            fi
        done
        return $errors
    fi
}

cmd_logs() {
    local lines="${1:-50}"
    logread -l "$lines" 2>/dev/null | grep -i "named\|bind" || \
        tail -n "$lines" /var/log/messages 2>/dev/null | grep -i "named\|bind" || \
        echo "No BIND logs found"
}

cmd_backup() {
    local zone="$1"
    local backup_dir="/srv/dns-master/backups"
    local timestamp=$(date +%Y%m%d-%H%M%S)

    mkdir -p "$backup_dir"

    if [ -n "$zone" ]; then
        local zone_file="$ZONES_DIR/${zone}.zone"
        [ -f "$zone_file" ] || { error "Zone not found"; return 1; }
        cp "$zone_file" "$backup_dir/${zone}-${timestamp}.zone"
        log "Backed up: $zone -> $backup_dir/${zone}-${timestamp}.zone"
    else
        # Backup all zones
        for zone_file in "$ZONES_DIR"/*.zone; do
            [ -f "$zone_file" ] || continue
            local name=$(basename "$zone_file" .zone)
            cp "$zone_file" "$backup_dir/${name}-${timestamp}.zone"
        done
        log "Backed up all zones to $backup_dir"
    fi
}

# ============================================================================
# Help
# ============================================================================

show_help() {
    cat << EOF
SecuBox DNS Master v$VERSION

Usage: dnsmaster <command> [options]

Status:
  status              Show BIND server status
  status-json         Status in JSON format

Zones:
  zone-list           List all zones
  zone-list-json      List zones in JSON format
  zone-show <zone>    Show zone file contents
  zone-add <zone>     Create new zone

Records:
  records-json <zone>                       Get records as JSON
  record-add <zone> <type> <name> <value> [ttl]
  record-del <zone> <type> <name> [value]

Control:
  reload              Reload BIND configuration
  check [zone]        Validate zone file(s)
  logs [lines]        View BIND logs
  backup [zone]       Backup zone file(s)

Examples:
  dnsmaster zone-list
  dnsmaster record-add secubox.in A www 192.168.1.100
  dnsmaster record-add secubox.in MX @ "10 mail.secubox.in."
  dnsmaster record-del secubox.in A www
  dnsmaster check secubox.in

EOF
}

# ============================================================================
# Main
# ============================================================================

case "${1:-}" in
    status)           shift; cmd_status "$@" ;;
    status-json)      shift; cmd_status_json "$@" ;;
    zone-list)        shift; cmd_zone_list "$@" ;;
    zone-list-json)   shift; cmd_zone_list_json "$@" ;;
    zone-show)        shift; cmd_zone_show "$@" ;;
    zone-add)         shift; cmd_zone_add "$@" ;;
    records-json)     shift; cmd_records_json "$@" ;;
    record-add)       shift; cmd_record_add "$@" ;;
    record-del)       shift; cmd_record_del "$@" ;;
    reload)           shift; cmd_reload "$@" ;;
    check)            shift; cmd_check "$@" ;;
    logs)             shift; cmd_logs "$@" ;;
    backup)           shift; cmd_backup "$@" ;;
    help|--help|-h|'') show_help ;;
    *)                error "Unknown command: $1"; show_help >&2; exit 1 ;;
esac

exit 0