// See https://github.com/microsoft/TypeScript/issues/29729 for why LiteralUnion
// eslint-disable-next-line @typescript-eslint/naming-convention
type LiteralUnion<T extends U, U = string> = T | (U & { _?: never });

export type Environment = LiteralUnion<'dev' | 'go' | 'next' | 'qa' | 'stage' | 'test'>;
export type EnvironmentValues = Partial<Record<Environment, string>>;

export function getValueForEnvironment(
    values: EnvironmentValues,
    defaultEnvironment: Environment = 'qa',
    hostname: string = window.location.hostname
) {
    const keys = Object.keys(values) as (keyof typeof values)[];
    const key = detectEnvironment(keys, defaultEnvironment, hostname);
    return values[key];
}

function detectEnvironment(
    keys: Environment[],
    defaultEnvironment: Environment,
    hostname: string
): Environment {
    if (isTestEnvironment()) {
        return 'test';
    }

    if (isLocalHost(hostname)) {
        return 'dev';
    }

    for (const key of keys) {
        if (
            hostname.indexOf(`${key}.servicetitan.com`) >= 0 ||
            (key.endsWith('.st.dev') && hostname.indexOf(key) >= 0)
        ) {
            return key;
        }
    }

    return defaultEnvironment;
}

function isLocalHost(hostname: string) {
    return ['localhost', '127.0.0.1', 'app-web'].some(host => hostname.indexOf(host) >= 0);
}

function isTestEnvironment() {
    return process.env.NODE_ENV === 'test';
}