Config Layer — Properties and ConfigReader

# Dev Environment Configuration
base.url=http://localhost:8080/api/v1
auth.username=testuser
auth.password=testpass123
auth.token.url=http://localhost:8080/auth/token

# Timeouts (milliseconds)
connection.timeout=5000
response.timeout=10000

# Feature flags
retry.enabled=true
retry.count=2
logging.enabled=true

# Staging Environment Configuration
base.url=https://staging-api.company.com/api/v1
auth.username=qa_staging
auth.password=stg_secure_456
auth.token.url=https://staging-api.company.com/auth/token

# Timeouts (milliseconds)
connection.timeout=10000
response.timeout=30000

# Feature flags
retry.enabled=true
retry.count=3
logging.enabled=false

package com.company.api.config;

import java.io.InputStream;
import java.util.Properties;

public class ConfigReader {

    private static final Properties properties = new Properties();
    private static boolean loaded = false;

    private ConfigReader() {
        // prevent instantiation — all methods are static
    }

    public static void loadConfig() {
        if (loaded) return;

        String env = System.getProperty("env", "dev");
        String filename = "config/" + env + ".properties";

        try (InputStream is = ConfigReader.class.getClassLoader()
                .getResourceAsStream(filename)) {
            if (is == null) {
                throw new RuntimeException(
                    "Config file not found: " + filename
                    + ". Available: dev.properties, staging.properties, prod.properties"
                );
            }
            properties.load(is);
            loaded = true;
            System.out.println("[ConfigReader] Loaded config: " + filename);
        } catch (Exception e) {
            throw new RuntimeException("Failed to load config: " + filename, e);
        }
    }

    public static String getBaseUrl() {
        loadConfig();
        return properties.getProperty("base.url");
    }

    public static String getUsername() {
        loadConfig();
        return properties.getProperty("auth.username");
    }

    public static String getPassword() {
        loadConfig();
        return properties.getProperty("auth.password");
    }

    public static String getTokenUrl() {
        loadConfig();
        return properties.getProperty("auth.token.url");
    }

    public static int getConnectionTimeout() {
        loadConfig();
        return Integer.parseInt(
            properties.getProperty("connection.timeout", "5000")
        );
    }

    public static int getResponseTimeout() {
        loadConfig();
        return Integer.parseInt(
            properties.getProperty("response.timeout", "10000")
        );
    }

    public static boolean isRetryEnabled() {
        loadConfig();
        return Boolean.parseBoolean(
            properties.getProperty("retry.enabled", "false")
        );
    }

    public static int getRetryCount() {
        loadConfig();
        return Integer.parseInt(
            properties.getProperty("retry.count", "1")
        );
    }

    public static String get(String key) {
        loadConfig();
        return properties.getProperty(key);
    }
}