#!/bin/bash

# Define paths and variables
CONFIG_FILE="/var/lib/cosmos/cosmos.config.json"
USER=$(whoami)
HOSTNAME=$(hostname)
OUTPUT_FILE="/home/$USER/internal_hosts-$HOSTNAME.conf"
REMOTE_SERVER="sdb-share"
REMOTE_PATH="/etc/dnsmasq.d/"

# Function to get IP address of an interface
get_interface_ip() {
    local interface=$1
    ip -4 addr show "$interface" 2>/dev/null | grep -oP '(?<=inet\s)\d+(\.\d+){3}' | head -n 1
}

# Prefer tailscale0, fallback to eth0
LOCAL_IP=$(get_interface_ip "tailscale0")
if [[ -z "$LOCAL_IP" ]]; then
    LOCAL_IP=$(get_interface_ip "eth0")
fi

# Ensure we have a valid IP address
if [[ -z "$LOCAL_IP" ]]; then
    echo "No valid IP address found for tailscale0 or eth0."
    exit 1
fi

# Check if configuration file exists
if [[ ! -f "$CONFIG_FILE" ]]; then
    echo "Configuration file not found: $CONFIG_FILE"
    exit 1
fi

# Clear or create the output file
> "$OUTPUT_FILE"

# Extract *.internal routes (only enabled ones) and write in dnsmasq format
jq -r '.HTTPConfig.ProxyConfig.Routes[]? 
       | select(type == "object" and (.Host | test("\\.home$")) and ((.Disabled // false) | not)) 
       | .Host' "$CONFIG_FILE" | while read -r host; do
    echo "address=/$host/$LOCAL_IP" >> "$OUTPUT_FILE"
done

# Generate checksums
LOCAL_CHECKSUM=$(sha256sum "$OUTPUT_FILE" | awk '{print $1}')
REMOTE_CHECKSUM=$(ssh guy@$REMOTE_SERVER "sha256sum $REMOTE_PATH/$(basename $OUTPUT_FILE) 2>/dev/null" | awk '{print $1}')

# Compare checksums and sync if different
if [[ "$LOCAL_CHECKSUM" != "$REMOTE_CHECKSUM" ]]; then
    # Sync the file to the remote server using rsync
    if rsync -avz "$OUTPUT_FILE" "guy@$REMOTE_SERVER:$REMOTE_PATH"; then
        echo "File updated and synced to $REMOTE_SERVER:$REMOTE_PATH"

        # Restart dnsmasq service on the remote server
        if ssh guy@$REMOTE_SERVER sudo /bin/systemctl restart dnsmasq.service; then
            echo "dnsmasq service restarted successfully on $REMOTE_SERVER"
        else
            echo "Failed to restart dnsmasq service on $REMOTE_SERVER"
            exit 1
        fi

    else
        echo "Failed to sync file to $REMOTE_SERVER:$REMOTE_PATH"
        exit 1
    fi
else
    echo "No changes detected - skipping sync"
fi