#!/bin/bash


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

    # Default values
    local DEFAULT_SERVER_URL="http://127.0.0.1:8080"
    local DEFAULT_LISTEN_ADDR="127.0.0.1:8080"
    local DEFAULT_METRICS_LISTEN_ADDR="127.0.0.1:9090"
    local DEFAULT_GRPC_LISTEN_ADDR="127.0.0.1:50443"
    local DEFAULT_GRPC_ALLOW_INSECURE="false"
    local DEFAULT_DB_TYPE="sqlite3"
    local DEFAULT_DB_PATH="/var/lib/headscale/db.sqlite"
    local DEFAULT_UNIX_SOCKET="/var/run/headscale/headscale.sock"
    local DEFAULT_UNIX_SOCKET_PERMISSION="0770"

    # 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

    # Function to replace or use default value
    replace_or_default() {
        local var_name=$1
        local default_value=$2
        local line=$3
        local var_value
        eval var_value=\$$var_name
        if [ -z "$var_value" ]; then
            var_value=$default_value
        fi
        echo ${line/\$\{$var_name\}/$var_value}
    }

    # Read the template and replace variables with defaults if not set
    while IFS= read -r line || [[ -n "$line" ]]; do
        line=$(replace_or_default "SERVER_URL" "$DEFAULT_SERVER_URL" "$line")
        line=$(replace_or_default "LISTEN_ADDR" "$DEFAULT_LISTEN_ADDR" "$line")
        line=$(replace_or_default "METRICS_LISTEN_ADDR" "$DEFAULT_METRICS_LISTEN_ADDR" "$line")
        line=$(replace_or_default "GRPC_LISTEN_ADDR" "$DEFAULT_GRPC_LISTEN_ADDR" "$line")
        line=$(replace_or_default "GRPC_ALLOW_INSECURE" "$DEFAULT_GRPC_ALLOW_INSECURE" "$line")
        line=$(replace_or_default "DB_TYPE" "$DEFAULT_DB_TYPE" "$line")
        line=$(replace_or_default "DB_PATH" "$DEFAULT_DB_PATH" "$line")
        line=$(replace_or_default "UNIX_SOCKET" "$DEFAULT_UNIX_SOCKET" "$line")
        line=$(replace_or_default "UNIX_SOCKET_PERMISSION" "$DEFAULT_UNIX_SOCKET_PERMISSION" "$line")
        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