import java.util.*;

public class Template {
    private final String companyName;
    private final Set<String> templates = new HashSet<>();

    public Template(String companyName, String... templates) {
        this.companyName = companyName;
        Arrays.stream(templates).forEach(this.templates::add);
    }

    public List<String> formatFor(String name) {
        List<String> emailAddresses = new ArrayList<>();

        for(String template : templates) {
            String[] firstAndLastNameOfTemplate = parseFirstAndLastNameFromTemplate(template);

            if (firstAndLastNameOfTemplate.length == 1) {
                emailAddresses.add(formatForOnlyFirstName(name, template));
            }
            else if (firstAndLastNameOfTemplate.length == 2){
                emailAddresses.add(formatFirstAndSecondName(name, template));
            }
            else {
                throw new RuntimeException("Unknown format for template");
            }
        }

        return emailAddresses;
    }

    private String formatFirstAndSecondName(String name, String template) {
        String firstName = name.split(" ")[0];
        String lastName = name.split(" ")[1];
        String domain = getDomainFrom(template);


        if (templateUsesFirstLetterOfFirstName(template) && templateUsesFirstLetterOfLastName(template)) {
            return firstName.charAt(0) + "." + lastName.charAt(0) + "@" + domain;
        }
        else if (templateUsesFirstLetterOfFirstName(template)) {
            return firstName.charAt(0) + "." + lastName + "@" + domain;
        }
        else if (templateUsesFirstLetterOfLastName(template)) {
            return firstName + "." + lastName.charAt(0) + "@" + domain;
        }
        else {
            return firstName + "." + lastName + "@" + domain;
        }
    }

    private String[] parseFirstAndLastNameFromTemplate(String template) {
        String namePartOfTemplate = template.split("@")[0];
        return namePartOfTemplate.split("\\.");
    }

    private boolean templateUsesFirstLetterOfFirstName(String template) {
        String[] firstAndLastNameOfTemplate = parseFirstAndLastNameFromTemplate(template);
        return firstAndLastNameOfTemplate[0].length() == 1;
    }

    private boolean templateUsesFirstLetterOfLastName(String template) {
        String[] firstAndLastNameOfTemplate = parseFirstAndLastNameFromTemplate(template);
        return firstAndLastNameOfTemplate[1].length() == 1;
    }

    private String formatForOnlyFirstName(String name, String template) {
        //only first name
        String firstName = name.split(" ")[0];
        String domain = getDomainFrom(template);
        return firstName + "@" + domain;
    }

    private String getDomainFrom(String template) {
        String[] emailAddress = template.split("@");
        return emailAddress[1];
    }
}












import org.junit.Test;

import java.util.List;

import static org.hamcrest.MatcherAssert.assertThat;
import static org.hamcrest.core.IsCollectionContaining.hasItems;
import static org.hamcrest.core.IsEqual.equalTo;

public class TemplateTest {

    private final String name = "phil cummins";

    @Test
    public void given_a_template_with_first_name_name_into_email_address() {
        Template template = new Template("Alphasights", "david@alphasights.com");

        List<String> emailAddresses = template.formatFor(name);
        assertThat(emailAddresses.size(), equalTo(1));
        assertThat(emailAddresses.get(0), equalTo("phil@alphasights.com"));
    }

    @Test
    public void given_a_template_with_first_and_second_name_into_email_address() {
        Template template = new Template("Stripe", "patrick.collison@stripe.com");

        List<String> emailAddresses = template.formatFor(name);
        assertThat(emailAddresses.get(0), equalTo("phil.cummins@stripe.com"));
    }

    @Test
    public void given_a_template_with_one_letter_of_first_name_and_last_name_into_email_address() {
        Template template = new Template("Apple", "s.jobs@apple.com");

        List<String> emailAddresses = template.formatFor(name);
        assertThat(emailAddresses.get(0), equalTo("p.cummins@apple.com"));
    }

    @Test
    public void given_a_template_with_first_name_and_one_letter_of_last_name_into_email_address() {
        Template template = new Template("Google", "larry.p@google.com");

        List<String> emailAddresses = template.formatFor(name);
        assertThat(emailAddresses.get(0), equalTo("phil.c@google.com"));
    }

    @Test
    public void given_a_template_with_first_letter_of_both_first_and_last_name_into_email_addresses() {
        Template template = new Template("Heroku", "a.b@heroku.com");

        List<String> emailAddresses = template.formatFor(name);
        assertThat(emailAddresses.get(0), equalTo("p.c@heroku.com"));
    }

    @Test
    public void given_multiple_templates_into_email_addresses() {
        Template template = new Template("Google", "s.bring@google.com", "larry.p@google.com");
        List<String> emailAddresses = template.formatFor(name);
        assertThat(emailAddresses, hasItems("p.cummins@google.com", "phil.c@google.com"));
    }

}