#!/bin/bash

replace_config_values() {
    local config_template="/etc/headscale/config-example.yaml"
    local config_output="/etc/headscale/config.yaml"

    # Check if the output config file already exists
    if [[ -f "$config_output" ]]; then
        echo "$config_output already exists."
        return 0
    fi

    # Ensure the template file exists
    if [[ ! -f "$config_template" ]]; then
        echo "Template file $config_template not found."
        return 1
    fi

    # Read the template and replace variables
    while IFS= read -r line || [[ -n "$line" ]]; do
        while [[ "$line" =~ \$\{([a-zA-Z_][a-zA-Z_0-9]*)\} ]]; do
            var_name=${BASH_REMATCH[1]}
            var_value=$(eval echo "\$$var_name")
            line=${line//\$\{$var_name\}/$var_value}
        done
        echo "$line"
    done < "$config_template" > "$config_output"

    echo "Config file generated at $config_output"
}

# Run the function to replace variables and start headscale
replace_config_values
headscale