#!/bin/bash

MAX_INSTANCES=2

# Start SNMP daemon instances for testing
# Usage: start_snmpd_instances [count] [base_port] [directory]
start_snmpd_instances() {
    local count="${1:-2}"
    local base_port="${2:-10160}"
    local dir="${3:-/tmp/snmpd_port}"
    
    mkdir -p "$dir"
    
    for i in $(seq 1 "$count"); do
        local port=$((base_port + i))
        local conf="$dir/snmpd_$i.conf"
        
        cat > "$conf" << EOF
agentaddress udp:127.0.0.1:$port
rocommunity public
createUser testuser SHA "authpass123456" AES "privpass123456"
rwuser testuser priv
sysLocation "Test device $i"
sysContact "test@test.com"
sysName "device-$i"
EOF

        snmpd -C -c "$conf" \
              -p "$dir/snmpd_$i.pid" \
              -Lf "$dir/snmpd_$i.log" \
              -I -smux
    done
    
    echo "Started $count snmpd instances on ports $((base_port+1))-$((base_port+count))"
    echo "snmpwalk -v3 -u testuser -A authpass123456 -a SHA -X privpass123456 -x AES -l authPriv 127.0.0.1:$((base_port+1)) 1.3.6.1.2.1.1"
    echo "snmpwalk -v2c -c public 127.0.0.1:$((base_port+1)) 1.3.6.1.2.1.1"
}

# Start SNMP daemon instances with unique users/passwords for each instance
# Usage: start_snmpd_instances_unique [count] [base_port] [directory]
start_snmpd_instances_unique() {
    local count="${1:-2}"
    local base_port="${2:-10160}"
    local dir="${3:-/tmp/snmpd_port}"
    
    mkdir -p "$dir"
    
    # Mark this as unique mode for status display
    touch "$dir/unique_mode"
    
    for i in $(seq 1 "$count"); do
        local port=$((base_port + i))
        local conf="$dir/snmpd_$i.conf"
        local user="usersingle"
        local authpass="authpass$i"
        local privpass="privpass$i"
        
        cat > "$conf" << EOF
agentaddress udp:127.0.0.1:$port
rocommunity public
createUser $user MD5 "$authpass" DES "$privpass"
rwuser $user priv
sysLocation "Test device $i"
sysContact "test@test.com"
sysName "device-$i"
EOF

        snmpd -C -c "$conf" \
              -p "$dir/snmpd_$i.pid" \
              -Lf "$dir/snmpd_$i.log" \
              -I -smux
    done
    
    echo "Started $count snmpd instances on ports $((base_port+1))-$((base_port+count))"
    echo ""
    echo "Unique credentials for each instance:"
    for i in $(seq 1 "$count"); do
        local port=$((base_port + i))
        local user="usersingle"
        local authpass="authpass$i"
        local privpass="privpass$i"
        echo "Instance $i (port $port): snmpwalk -v3 -u $user -A $authpass -a MD5 -X $privpass -x DES -l authPriv 127.0.0.1:$port 1.3.6.1.2.1.1"
    done
    echo "or for SNMPv2c:"
    echo "  snmpwalk -v2c -c public 127.0.0.1:$((base_port+1)) 1.3.6.1.2.1.1"
}

# Start SNMP daemon instances with unique users AND passwords for each instance
# Usage: start_snmpd_instances_unique_users [count] [base_port] [directory]
start_snmpd_instances_unique_users() {
    local count="${1:-2}"
    local base_port="${2:-10160}"
    local dir="${3:-/tmp/snmpd_port}"
    
    mkdir -p "$dir"
    
    # Mark this as unique mode for status display
    touch "$dir/unique_mode"
    touch "$dir/unique_users_mode"
    
    for i in $(seq 1 "$count"); do
        local port=$((base_port + i))
        local conf="$dir/snmpd_$i.conf"
        local user="user$i"
        local authpass="authpass$i"
        local privpass="privpass$i"
        
        cat > "$conf" << EOF
agentaddress udp:127.0.0.1:$port
rocommunity public
createUser $user MD5 "$authpass" DES "$privpass"
rwuser $user priv
sysLocation "Test device $i"
sysContact "test@test.com"
sysName "device-$i"
EOF

        snmpd -C -c "$conf" \
              -p "$dir/snmpd_$i.pid" \
              -Lf "$dir/snmpd_$i.log" \
              -I -smux
    done
    
    echo "Started $count snmpd instances on ports $((base_port+1))-$((base_port+count))"
    echo ""
    echo "Unique users and credentials for each instance:"
    for i in $(seq 1 "$count"); do
        local port=$((base_port + i))
        local user="user$i"
        local authpass="authpass$i"
        local privpass="privpass$i"
        echo "Instance $i (port $port): snmpwalk -v3 -u $user -A $authpass -a MD5 -X $privpass -x DES -l authPriv 127.0.0.1:$port 1.3.6.1.2.1.1"
    done
    echo "or for SNMPv2c:"
    echo "  snmpwalk -v2c -c public 127.0.0.1:$((base_port+1)) 1.3.6.1.2.1.1"
}

# Stop SNMP daemon instances
# Usage: stop_snmpd_instances [directory]
stop_snmpd_instances() {
    local dir="${1:-/tmp/snmpd_port}"
    
    if [ ! -d "$dir" ]; then
        echo "Directory $dir does not exist"
        return 1
    fi
    
    local count=0
    for pidfile in "$dir"/snmpd_*.pid; do
        if [ -f "$pidfile" ]; then
            local pid=$(cat "$pidfile")
            if kill "$pid" 2>/dev/null; then
                echo "Stopped snmpd process $pid"
                ((count++))
            fi
        fi
    done
    
    # Clean up files
    rm -f "$dir"/snmpd_*.conf "$dir"/snmpd_*.pid "$dir"/snmpd_*.log
    rm -f "$dir/unique_mode" "$dir/unique_users_mode"
    
    echo "Stopped $count snmpd instances"
    return 0
}

# Show status of SNMP daemon instances
# Usage: status_snmpd_instances [directory]
status_snmpd_instances() {
    local dir="${1:-/tmp/snmpd_port}"
    
    if [ ! -d "$dir" ]; then
        echo "Directory $dir does not exist"
        return 1
    fi
    
    echo "SNMP Daemon Instances Status:"
    echo "================================"
    echo "Directory: $dir"
    echo ""
    
    local running=0
    local stopped=0
    
    for pidfile in "$dir"/snmpd_*.pid; do
        if [ -f "$pidfile" ]; then
            local pid=$(cat "$pidfile")
            local num=$(basename "$pidfile" .pid | sed 's/snmpd_//')
            local logfile="$dir/snmpd_$num.log"
            
            if kill -0 "$pid" 2>/dev/null; then
                echo "✓ Instance $num (PID: $pid) - RUNNING"
                ((running++))
                
                # Show credentials for unique mode
                if [ -f "$dir/unique_users_mode" ]; then
                    echo "  Credentials: user${num}/authpass${num}/privpass${num}"
                    echo "  snmpwalk command: snmpwalk -v3 -u user${num} -A authpass${num} -a MD5 -X privpass${num} -x DES -l authPriv 127.0.0.1:$((10160 + num)) 1.3.6.1.2.1.1"
                elif [ -f "$dir/unique_mode" ]; then
                    echo "  Credentials: usersingle/authpass${num}/privpass${num}"
                    echo "  snmpwalk command: snmpwalk -v3 -u usersingle -A authpass${num} -a MD5 -X privpass${num} -x DES -l authPriv 127.0.0.1:$((10160 + num)) 1.3.6.1.2.1.1"
                fi
            else
                echo "✗ Instance $num (PID: $pid) - STOPPED"
                ((stopped++))
            fi
            
            if [ -f "$logfile" ]; then
                echo "  Log: $logfile"
            fi
        fi
    done
    
    # Calculate port range and total count for summary
    local total_instances=0
    local min_port=""
    local max_port=""
    
    for pidfile in "$dir"/snmpd_*.pid; do
        if [ -f "$pidfile" ]; then
            local num=$(basename "$pidfile" .pid | sed 's/snmpd_//')
            local conf="$dir/snmpd_$num.conf"
            
            if [ -f "$conf" ]; then
                local port=$(grep "agentaddress" "$conf" | sed 's/.*:\([0-9]*\).*/\1/')
                if [ -n "$port" ]; then
                    if [ -z "$min_port" ] || [ "$port" -lt "$min_port" ]; then
                        min_port="$port"
                    fi
                    if [ -z "$max_port" ] || [ "$port" -gt "$max_port" ]; then
                        max_port="$port"
                    fi
                fi
            fi
            ((total_instances++))
        fi
    done
    
    echo ""
    echo "Summary: $running running, $stopped stopped"
    
    if [ $total_instances -gt 0 ]; then
        echo "Total instances: $total_instances"
        if [ -n "$min_port" ] && [ -n "$max_port" ]; then
            echo "Port range: $min_port-$max_port"
        fi
    fi
  
    echo ""
    echo "Usage: $0 {start|stop|status|unique|unique-users} [options]"
    echo "  start [count] [base_port] [directory]         # Same credentials for all instances"
    echo "  unique [count] [base_port] [directory]        # Same username, unique passwords per instance"
    echo "  unique-users [count] [base_port] [directory]  # Unique username and passwords per instance"
    echo "  stop [directory]"
    echo "  status [directory]"
    echo ""

    if [ $running -eq 0 ] && [ -z "$(ls "$dir"/snmpd_*.pid 2>/dev/null)" ]; then
        echo "No instances found"
        return 1
    fi
    
    if [ -f "$dir/unique_users_mode" ]; then
        echo "Example snmpwalk commands (UNIQUE USERS MODE - different username and credentials per instance):"
        echo "  Instance 1: snmpwalk -v3 -u user1 -A authpass1 -a MD5 -X privpass1 -x DES -l authPriv 127.0.0.1:10161 1.3.6.1.2.1.1"
        echo "  Instance 2: snmpwalk -v3 -u user2 -A authpass2 -a MD5 -X privpass2 -x DES -l authPriv 127.0.0.1:10162 1.3.6.1.2.1.1"
        echo "  Instance N: snmpwalk -v3 -u userN -A authpassN -a MD5 -X privpassN -x DES -l authPriv 127.0.0.1:PORT 1.3.6.1.2.1.1"
    elif [ -f "$dir/unique_mode" ]; then
        echo "Example snmpwalk commands (UNIQUE MODE - different credentials per instance):"
        echo "  Instance 1: snmpwalk -v3 -u usersingle -A authpass1 -a MD5 -X privpass1 -x DES -l authPriv 127.0.0.1:10161 1.3.6.1.2.1.1"
        echo "  Instance 2: snmpwalk -v3 -u usersingle -A authpass2 -a MD5 -X privpass2 -x DES -l authPriv 127.0.0.1:10162 1.3.6.1.2.1.1"
        echo "  Instance N: snmpwalk -v3 -u usersingle -A authpassN -a MD5 -X privpassN -x DES -l authPriv 127.0.0.1:PORT 1.3.6.1.2.1.1"
    else
        echo "Example snmpwalk command (STANDARD MODE - same credentials for all instances):"
        echo "  snmpwalk -v3 -u testuser -A authpass123456 -a SHA -X privpass123456 -x AES -l authPriv 127.0.0.1:10161 1.3.6.1.2.1.1"
    fi

    echo "or for SNMPv2c:"
    echo "  snmpwalk -v2c -c public 127.0.0.1:10161 1.3.6.1.2.1.1"
    echo ""

    return 0
}

# Main
case "${1:-status}" in
    start)
        start_snmpd_instances "${2:-$MAX_INSTANCES}" "${3:-10160}" "${4:-/tmp/snmpd_port}"
        ;;
    unique)
        start_snmpd_instances_unique "${2:-$MAX_INSTANCES}" "${3:-10160}" "${4:-/tmp/snmpd_port}"
        ;;
    unique-users)
        start_snmpd_instances_unique_users "${2:-$MAX_INSTANCES}" "${3:-10160}" "${4:-/tmp/snmpd_port}"
        ;;
    stop)
        stop_snmpd_instances "${2:-/tmp/snmpd_port}"
        ;;
    status)
        status_snmpd_instances "${2:-/tmp/snmpd_port}"
        ;;
    *)
        echo "Usage: $0 {start|stop|status|unique|unique-users} [options]"
        echo "  start [count] [base_port] [directory]         # Same credentials for all instances"
        echo "  unique [count] [base_port] [directory]        # Same username, unique passwords per instance"
        echo "  unique-users [count] [base_port] [directory]  # Unique username and passwords per instance"
        echo "  stop [directory]"
        echo "  status [directory]"
        exit 1
        ;;
esac