import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.Scanner;


/**
 * This example demonstrates how to create a trigger based on File Upload event using the server API.
 */
public class CreateTriggerExample {

    private static final BufferedReader CONSOLE_READER = new BufferedReader(new InputStreamReader(System.in));

    private static final String LOGIN_URL_TEMPLATE = "http://%s:%s/rest/management/login";
    private static final String LOGOUT_URL_TEMPLATE = "http://%s:%s/rest/management/logout";
    private static final String ADD_TRIGGER_URL_TEMPLATE = "http://%s:%s/rest/management/triggers/%s";

    private static final String LOGIN_TEMPLATE = "{\"username\":\"%s\", \"password\":\"%s\"}";

    private static final String TRIGGER_TEMPLATE = "{\"name\":\"%s\","
                                                   + "\"description\":\"%s\","
                                                   + "\"eventType\":\"%s\","
                                                   + "\"expressionString\":\"%s\","
                                                   + "\"contexts\":[%s],"
                                                   + "\"allowErrorEvent\":false,"
                                                   + "\"enabled\":true}";

    private static final String ACTION_TEMPLATE = "{\"actionClass\":\"%s\","
                                                  + "\"parametersMap\":{\"%s\":\"%s\"}}";

    private static final String CHARSET = "UTF-8";

    private final String host;
    private final int port;
    private final String username;
    private final String password;
    private final String domainName;
    private String sessionId;

    /**
     * Collects information about the account.
     *
     * @param args command line arguments
     *
     * @throws Exception if an error occurs
     */
    public static void main(String[] args)
            throws Exception {
        showExampleTitle();
        CreateTriggerExample example = createExample();
        example.execute();
    }

    /**
     * Shows example title.
     */
    private static void showExampleTitle() {
        System.out.println(
                "This example demonstrates how to create a trigger based on File Upload event using the server API.");
        System.out.println();
    }

    /**
     * Creates an example instance.
     *
     * @return an example instance
     *
     * @throws Exception if an error occurs
     */
    private static CreateTriggerExample createExample()
            throws Exception {
        String host = getParameter("Enter server REST host: ");
        int port = Integer.parseInt(getParameter("Enter server REST port: "));
        String username = getParameter("Enter username: ");
        String password = getParameter("Enter password: ");
        String domainName = getParameter("Enter domain name: ");

        return new CreateTriggerExample(host, port, username, password, domainName);
    }

    /**
     * Support method. Shows prompt on console and reads user response.
     *
     * @param prompt prompt string
     *
     * @return user response
     *
     * @throws Exception if an I/O error occurs
     */
    private static String getParameter(String prompt)
            throws Exception {
        System.out.print(prompt);
        return CONSOLE_READER.readLine();
    }

    /**
     * Constructs example.
     *
     * @param host       server REST host
     * @param port       server REST port
     * @param username   server username
     * @param password   server password
     * @param domainName domain name
     */
    public CreateTriggerExample(String host,
                                int port,
                                String username,
                                String password,
                                String domainName) {
        this.host = host;
        this.port = port;
        this.username = username;
        this.password = password;
        this.domainName = domainName;
    }

    /**
     * Creates domain and adds to server.
     */
    public void execute() {
        try {
            login();

            String triggerString = createTriggerString();
            addTrigger(triggerString);

            logout();

            System.out.println("Event service updated successfully!");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * Performs server management login.
     *
     * @throws Exception if an error occurs
     */
    private void login()
            throws Exception {
        URL url = new URL(String.format(LOGIN_URL_TEMPLATE, this.host, this.port));
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();

        try {
            connection.setDoOutput(true);
            connection.setRequestMethod("POST");
            connection.setRequestProperty("Content-Type", "application/json");

            String authenticationString = String.format(LOGIN_TEMPLATE, this.username, this.password);
            byte[] authenticationData = authenticationString.getBytes(CHARSET);

            connection.setRequestProperty("Content-Length", Integer.toString(authenticationData.length));

            OutputStream out = connection.getOutputStream();
            out.write(authenticationData);
            out.close();

            assertRequestSucceeded(connection);

            String cookie = connection.getHeaderField("Set-Cookie");
            this.sessionId = new Scanner(cookie).useDelimiter(";").next();
        } finally {
            connection.disconnect();
        }
    }

    /**
     * Performs server management logout.
     *
     * @throws Exception if an error occurs
     */
    private void logout()
            throws Exception {
        URL url = new URL(String.format(LOGOUT_URL_TEMPLATE, this.host, this.port));
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();

        try {
            connection.setDoOutput(true);
            connection.setRequestMethod("POST");
            connection.setRequestProperty("Cookie", this.sessionId);
        } finally {
            connection.disconnect();
        }
    }

    /**
     * Adds a trigger to the domain.
     *
     * @param triggerString the trigger string
     *
     * @throws Exception if an error occurs
     */
    private void addTrigger(String triggerString)
            throws Exception {
        URL url = new URL(String.format(ADD_TRIGGER_URL_TEMPLATE, this.host, this.port, this.domainName));
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();

        try {
            connection.setDoOutput(true);
            connection.setRequestMethod("POST");
            connection.setRequestProperty("Cookie", this.sessionId);
            connection.setRequestProperty("Content-Type", "application/json");

            byte[] data = triggerString.getBytes(CHARSET);

            connection.setRequestProperty("Content-Length", Integer.toString(data.length));

            OutputStream out = connection.getOutputStream();
            out.write(data);
            out.close();

            assertRequestSucceeded(connection);
        } finally {
            connection.disconnect();
        }
    }

    /**
     * Asserts that request was successful.
     *
     * @param connection target connection
     *
     * @throws Exception if an error occurs
     */
    private void assertRequestSucceeded(HttpURLConnection connection)
            throws Exception {
        int code = connection.getResponseCode();
        if (code < 200 || code >= 300) {
            throw new Exception(String.format("HTTP request error. Response code: %d", code));
        }
    }

    /**
     * Creates a trigger string.
     *
     * @return a trigger string
     */
    private String createTriggerString() {
        String triggerName = "Test trigger";
        String triggerDescription = "A trigger example.";
        String eventClass = "com.jscape.inet.mft.transport.events.FileUploadEvent";
        String expression = "((Success = true) AND (Name = \\\"test.txt\\\"))";
        String actionData = createActionString();

        return String.format(TRIGGER_TEMPLATE,
                             triggerName,
                             triggerDescription,
                             eventClass,
                             expression,
                             actionData);
    }

    /**
     * Creates an action string.
     *
     * @return an action string
     */
    private String createActionString() {
        String actionClass = "com.jscape.inet.mft.workflow.actions.SystemOutAction";
        String messageParameterName = "Message";
        String messageParameterValue = "File %Name% is successfully uploaded.";

        return String.format(ACTION_TEMPLATE,
                             actionClass,
                             messageParameterName,
                             messageParameterValue);
    }

}
