Session.java

package app.sunstreak.yourpisd.net;

import org.jsoup.Connection;
import org.jsoup.HttpStatusException;
import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.jsoup.nodes.FormElement;

import java.io.IOException;
import java.net.SocketTimeoutException;
import java.net.URL;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Locale;
import java.util.Map;

import app.sunstreak.yourpisd.net.data.Student;


public class Session {
    public static final String GRADEBOOK_ROOT = "https://gradebook.pisd.edu/Pinnacle/Gradebook";
    public static final String LOGOFF = GRADEBOOK_ROOT + "/Logon.aspx?Action=Logout";
    public static final String LOGON = GRADEBOOK_ROOT + "/logon.aspx";

    // Example: Sat Sep 03 2016 20:31:32 GMT-0500 (Central Daylight Time)
    public static final SimpleDateFormat FULL_DATE_FORMAT = new SimpleDateFormat("EEE MMM dd yyyy H:mm:ss 'GMT'z", Locale.ENGLISH);

    private final String username;
    private final String password;
    private boolean loggedIn = false;

    private final Map<String, String> cookies = new HashMap<>();
    private Date expiration;

    List<Student> students = new ArrayList<>();
    public int studentIndex = 0;
    public boolean MULTIPLE_STUDENTS;

    public static Session createSession(String username, String password) {
        return new Session(username, password);
    }

    private Session(String username, String password) {
        this.username = username;
        this.password = password;
    }

    public String getUsername() {
        return username;
    }

    public String getPassword() {
        return password;
    }

    /**
     * Loads a GET request from a specified path and query info
     * @param path the path (beginning with a forward slash).
     * @param params parameter information to pass as query.
     * @return the body string, or null if error occurs.
     * @throws IOException
     */
    public String request(String path, Map<String, String> params) throws IOException {
        if (checkExpiration() != 1)
            return null;

        Connection conn = Jsoup.connect(Session.GRADEBOOK_ROOT + path)
                .timeout(60000).cookies(getCookies());
        if (params != null)
            conn.data(params);

        try {
            Connection.Response resp = conn.execute();
            return resp.body();
        } catch (HttpStatusException e) {
            e.printStackTrace();
            return null;
        }

    }

    public List<Student> getStudents() {
        return students;
    }

    public Map<String, String> getCookies() {
        return cookies;
    }

    public Student getCurrentStudent() {
        return students.get(studentIndex);
    }

    /**
     * Checks the expiration of the current session
     * @return the status code (1 for good, -1 for bad password, -2 for server error).
     * @throws IOException
     */
    public int checkExpiration() throws IOException {
        if (Jsoup.connect(GRADEBOOK_ROOT + "/InternetViewer/GradeSummary.aspx").cookies(cookies)
                .timeout(60000).execute().url().toExternalForm().equalsIgnoreCase(LOGON)) {
            int status = login();
            if (status <= 0)
                return status;
        }
        return 1;
    }


    /**
     * This function logs in the student/ parent with their current credentials to Gradebook Pinnacle.
     * It then records session IDs and expiration time via cookies.
     * Precondition: username and password are both defined.
     *
     * @return a status code (1 for no error, -1 for bad password, and -2 for server error.)
     * @throws IOException if an I/O error occurs while connecting to server.
     */
    public int login() throws IOException {
        final URL LOAD_URL = new URL(LOGON);
        final String USERNAME_FIELD = "ctl00$ContentPlaceHolder$Username";
        final String PASSWORD_FIELD = "ctl00$ContentPlaceHolder$Password";

        try {
            // Submitting form data.
            Document html = Jsoup.parse(LOAD_URL, 60000);
            FormElement form = (FormElement) html.getElementsByTag("form").get(0);
            Connection conn = form.submit();

            // Find username and password field.
            Connection.KeyVal usernameField = null;
            Connection.KeyVal passwordField = null;
            for (Connection.KeyVal field : conn.request().data())
                if (field.key().equals(USERNAME_FIELD))
                    usernameField = field;
                else if (field.key().equals(PASSWORD_FIELD))
                    passwordField = field;

            if (usernameField == null) {
                System.err.println("EXPECTED: Form field for username.");
                return -2;
            }

            if (passwordField == null) {
                System.err.println("EXPECTED: Form field for password.");
                return -2;
            }

            // Submit username and password
            usernameField.value(username);
            passwordField.value(password);
            Connection.Response resp = conn.timeout(60000).execute();

            if (resp.url().equals(LOAD_URL))
                return -1;
            else {
                cookies.putAll(resp.cookies());
                updateExpirationDate();

                students.addAll(Parser.parseStudents(this, resp.body()));
                MULTIPLE_STUDENTS = students.size() > 1;

                loggedIn = true;
                return 1;
            }
        } catch (SocketTimeoutException e) {
            e.printStackTrace();
            return -2;
        }
    }

    /**
     * Updates expiration dates for the current session.
     */
    public void updateExpirationDate() {
        try {
            if (cookies.containsKey("SessionReminder"))
                expiration = FULL_DATE_FORMAT.parse(cookies.get("SessionReminder"));
        } catch (ParseException e) {
            System.err.println("Unable to parse expiration time-stamp");
            e.printStackTrace();
        }
    }

    /**
     * Logs out the user from their account, and resets cookies.
     * @return true if we successfully logged out, false for an error.
     */
    public boolean logout() {
        try {
            boolean success = Jsoup.connect(LOGOFF).timeout(60000).cookies(cookies).execute()
                    .statusCode() == 200;
            cookies.clear();
            return success;
        } catch (IOException e) {
            return false;
        }
    }
}