#!/bin/bash
set -e

INTERFACE_FILE="/config/interface.conf"
WHITELIST_FILE="/config/whitelist.conf"
NETWORK_FILE="/config/network.conf"
DHCPD_CONF="/etc/dhcp/dhcpd.conf"

if [ ! -f "$INTERFACE_FILE" ]; then
    echo "Error: Interface configuration file not found: $INTERFACE_FILE"
    exit 1
fi

if [ ! -f "$WHITELIST_FILE" ]; then
    echo "Error: Whitelist configuration file not found: $WHITELIST_FILE"
    exit 1
fi

INTERFACE=$(cat "$INTERFACE_FILE" | tr -d '\n\r ')
echo "Using interface: $INTERFACE"

# Wait for interface to be available
for i in {1..30}; do
    if ip link show "$INTERFACE" &>/dev/null; then
        break
    fi
    echo "Waiting for interface $INTERFACE..."
    sleep 1
done

if ! ip link show "$INTERFACE" &>/dev/null; then
    echo "Error: Interface $INTERFACE not found"
    exit 1
fi

# Load network configuration if available
if [ -f "$NETWORK_FILE" ]; then
    echo "Loading network configuration from $NETWORK_FILE"
    source "$NETWORK_FILE"
else
    echo "No network configuration file found, using defaults"
fi

# Set defaults for unset variables
RANGE_START_OFFSET=${RANGE_START_OFFSET:-10}
RANGE_END_OFFSET=${RANGE_END_OFFSET:-100}
LEASE_TIME=${LEASE_TIME:-43200}
MAX_LEASE_TIME=${MAX_LEASE_TIME:-86400}

# Get interface IP and network info
INTERFACE_IP=$(ip -4 addr show "$INTERFACE" | grep "inet " | awk '{print $2}' | cut -d'/' -f1)
INTERFACE_CIDR=$(ip -4 addr show "$INTERFACE" | grep "inet " | awk '{print $2}' | cut -d'/' -f2)

# Check if subnet is manually configured
if [ -n "$SUBNET" ] && [ -n "$NETMASK" ]; then
    echo "Using manual network configuration: $SUBNET/$NETMASK"
    INTERFACE_NETWORK="$SUBNET"
    # Calculate broadcast from subnet and netmask
    if [ "$NETMASK" = "255.255.255.0" ]; then
        BROADCAST="${SUBNET%.*}.255"
    elif [ "$NETMASK" = "255.255.0.0" ]; then
        BROADCAST="${SUBNET%.*.*}.255.255"
    elif [ "$NETMASK" = "255.0.0.0" ]; then
        BROADCAST="${SUBNET%.*.*.*}.255.255.255"
    else
        BROADCAST="${SUBNET%.*}.255"
    fi
else
    echo "Auto-detecting network configuration from interface"
    # For test environment, handle Docker's internal network properly
    if [ "$INTERFACE" = "eth0" ] && [ -n "$INTERFACE_IP" ]; then
        # Extract network base from the actual IP
        INTERFACE_NETWORK=$(echo "$INTERFACE_IP" | sed 's/\.[0-9]*$/\.0/')
    else
        # Fallback for physical interfaces
        INTERFACE_NETWORK=$(ip -4 addr show "$INTERFACE" | grep "inet " | awk '{print $2}' | cut -d'/' -f1 | sed 's/\.[0-9]*$/\.0/')
    fi

    # Convert CIDR to netmask and calculate broadcast
    case $INTERFACE_CIDR in
        24) 
            NETMASK="255.255.255.0"
            BROADCAST="${INTERFACE_NETWORK%.*}.255"
            ;;
        16) 
            NETMASK="255.255.0.0"
            BROADCAST="${INTERFACE_NETWORK%.*.*}.255.255"
            ;;
        8)  
            NETMASK="255.0.0.0"
            BROADCAST="${INTERFACE_NETWORK%.*.*.*}.255.255.255"
            ;;
        *)  
            NETMASK="255.255.255.0"
            BROADCAST="${INTERFACE_NETWORK%.*}.255"
            ;;
    esac
fi

echo "Interface IP: $INTERFACE_IP"
echo "Network: $INTERFACE_NETWORK/$NETMASK"
echo "DHCP Range: ${INTERFACE_NETWORK%.*}.$RANGE_START_OFFSET - ${INTERFACE_NETWORK%.*}.$RANGE_END_OFFSET"
echo "Lease Time: $LEASE_TIME seconds"

# Generate dhcpd.conf from template
cp /etc/dhcp/dhcpd.conf.template "$DHCPD_CONF"

# Generate host entries for whitelisted MACs
HOST_ENTRIES=""
HOST_NUM=1
echo "Reading whitelist from $WHITELIST_FILE"

# Check if file exists and is readable
if [ ! -f "$WHITELIST_FILE" ]; then
    echo "ERROR: Whitelist file does not exist!"
    exit 1
fi

if [ ! -r "$WHITELIST_FILE" ]; then
    echo "ERROR: Whitelist file is not readable!"
    exit 1
fi

echo "File size: $(stat -c%s "$WHITELIST_FILE") bytes"
echo "File contents (hex dump):"
hexdump -C "$WHITELIST_FILE" | head -5
echo "File contents (raw):"
cat "$WHITELIST_FILE"
echo ""
echo "--- Processing MACs ---"

# Read file line by line without subshell
while IFS= read -r MAC || [ -n "$MAC" ]; do
    # Remove any whitespace, carriage returns, and convert to lowercase
    ORIG_MAC="$MAC"
    MAC=$(echo "$MAC" | tr -d '\r\n\t ' | tr '[:upper:]' '[:lower:]')
    echo "Processing: original='$ORIG_MAC' cleaned='$MAC'"
    
    if [ -n "$MAC" ]; then
        # Generate IP based on host number (starting from .10)
        LAST_OCTET=$((10 + HOST_NUM - 1))
        HOST_IP="${INTERFACE_NETWORK%.*}.$LAST_OCTET"
        NEW_ENTRY="
host client$HOST_NUM {
    hardware ethernet $MAC;
    fixed-address $HOST_IP;
}"
        HOST_ENTRIES="${HOST_ENTRIES}${NEW_ENTRY}"
        echo "Added whitelist entry: $MAC -> $HOST_IP"
        HOST_NUM=$((HOST_NUM + 1))
    fi
done < "$WHITELIST_FILE"

if [ -z "$HOST_ENTRIES" ]; then
    echo "Warning: No MAC addresses found in whitelist!"
else
    echo "Total whitelisted MACs: $((HOST_NUM - 1))"
fi

# Replace placeholders in config
sed -i "s#__SUBNET__#$INTERFACE_NETWORK#g" "$DHCPD_CONF"
sed -i "s#__NETMASK__#$NETMASK#g" "$DHCPD_CONF"
sed -i "s#__RANGE_START__#${INTERFACE_NETWORK%.*}.$RANGE_START_OFFSET#g" "$DHCPD_CONF"
sed -i "s#__RANGE_END__#${INTERFACE_NETWORK%.*}.$RANGE_END_OFFSET#g" "$DHCPD_CONF"
sed -i "s#__BROADCAST__#$BROADCAST#g" "$DHCPD_CONF"
sed -i "s#__LEASE_TIME__#$LEASE_TIME#g" "$DHCPD_CONF"
sed -i "s#__MAX_LEASE_TIME__#$MAX_LEASE_TIME#g" "$DHCPD_CONF"
# Use a different approach for multiline HOST_ENTRIES
awk -v entries="$HOST_ENTRIES" '{gsub(/__HOST_ENTRIES__/, entries); print}' "$DHCPD_CONF" > "$DHCPD_CONF.tmp" && mv "$DHCPD_CONF.tmp" "$DHCPD_CONF"

echo "Starting DHCP server on interface $INTERFACE..."
echo "Configuration:"
cat "$DHCPD_CONF"

# Start DHCP server
exec dhcpd -4 -f -d -cf "$DHCPD_CONF" "$INTERFACE"