package org.expeditee.auth.account;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.security.KeyStoreException;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.security.cert.CertificateException;
import java.sql.SQLException;
import java.util.Base64;
import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Properties;
import java.util.Scanner;

import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.AddressException;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;

import org.expeditee.auth.AuthenticatorBrowser;
import org.expeditee.auth.mail.Mail;
import org.expeditee.auth.mail.Mail.MailEntry;
import org.expeditee.auth.tags.AuthenticationTag;
import org.expeditee.encryption.CryptographyConstants;
import org.expeditee.gui.DisplayController;
import org.expeditee.gui.Frame;
import org.expeditee.gui.FrameIO;
import org.expeditee.gui.MessageBay;
import org.expeditee.items.Text;
import org.expeditee.settings.UserSettings;
import org.expeditee.settings.identity.passwordrecovery.Colleagues;
import org.expeditee.settings.identity.secrets.KeyList;
import org.expeditee.stats.Formatter;

import com.codahale.shamir.Scheme;

public class Password implements CryptographyConstants {
	/**
	 * Changes the recorded password for a user in the key store; given the username signaling whose password to change, along with the existing and new password.
	 */
	public static void changePassword(Map<AuthenticationTag, String> userdata) throws NoSuchAlgorithmException, KeyStoreException, FileNotFoundException, CertificateException, IOException, ClassNotFoundException, SQLException {
		String username = userdata.get(AuthenticationTag.Username);
		String password = userdata.get(AuthenticationTag.Password);
		String newpassword = userdata.get(AuthenticationTag.NewPassword);

		final SecretKey key = AuthenticatorBrowser.getInstance().getSecretKey(username, password);
		if (key == null) {
			MessageBay.errorMessage("The username + existing password combination was incorrect.");
		} else {
			AuthenticatorBrowser.getInstance().putKey(username, newpassword, key);
			MessageBay.displayMessage("Password changed successfully.");
			DisplayController.setCurrentFrame(FrameIO.LoadFrame("multiuser1"), true);
		}
	}

	/**
	 * Generates a intergalaictic number for a specified user and emails that number using the specified email.
	 * @param userData
	 */
	public static void generateAndDeliverIntergalacticNumber(Map<AuthenticationTag, String> userData) {
		String username = userData.get(AuthenticationTag.Username);
		String email = userData.get(AuthenticationTag.Email);
		try {
			// Generate message text.
			String intergalacticNumber = AuthenticatorBrowser.getInstance().newIntergalacticNumber(username, email);
			String nl = System.getProperty("line.separator");
			StringBuilder sb = new StringBuilder();
			sb.append("You are receiving this email because someone is attempting to reset your Expeditee password." + nl);
			sb.append("If you did not make this request then no action is required." + nl);
			sb.append("If it was you who made this request, the following string of characters is your intergalactic number: " + intergalacticNumber + nl);
			
			sendEmail(email, sb);		
		} catch (KeyStoreException | NoSuchAlgorithmException | CertificateException | ClassNotFoundException
				| IOException | SQLException | MessagingException e) {
			e.printStackTrace();
		}
	}
	
	/**
	 * Confirms that the specified intergalaictic number matches the one of file for the specified username.
	 * Passing this test it then alerts the users pw colleagues through a one-off secure Expeditee message.
	 * @param tags
	 */
	public static void confirmIntergalacticNumberAndAlertTrustedUsers(Map<AuthenticationTag, String> tags) {
		// Confirm intergalactic numbers match
		String username = tags.get(AuthenticationTag.Username);
		String intergalacticNumber = tags.get(AuthenticationTag.IntergalacticNumber);
		boolean match = false;
		try {
			match = AuthenticatorBrowser.getInstance().confirmIntergalaticNumber(username, intergalacticNumber);
		} catch (NoSuchAlgorithmException | KeyStoreException | CertificateException | ClassNotFoundException
				| IOException | SQLException e) {
			e.printStackTrace();
			return;
		}
		if (!match) {
			MessageBay.errorMessage("The provided identity number does not match the one stored on file.");
			return;
		}
		
		// Get colleagues to distribute messages too.
		String[] colleagues = getPasswordColleaguesFromUsername(username);
		// 	Send secure message to colleague one
		String colleagueOne = colleagues[0];
		String time = Formatter.getDateTime();
		String topic = "Password Recovery for " + username;
		String message = "Your colleague " + username + " would like you to help them recover access to their account.";
		Map<String, String> options = new HashMap<String, String>();
		options.put("Provide assistance", "AuthEmailPasswordShare " + username); 
		MailEntry mail = new MailEntry(time, username, colleagueOne, topic, message, options);
		Mail.sendOneOffMail(mail, colleagueOne, Base64.getDecoder().decode(intergalacticNumber));
		
		//	Send secure message to colleague two
		String colleagueTwo = colleagues[1];
		Mail.sendOneOffMail(mail, colleagueTwo, Base64.getDecoder().decode(intergalacticNumber));
		
		String nl = System.getProperty("line.separator");
		StringBuilder sb = new StringBuilder();
		sb.append("You are receiving this email because one of your Expeditee contacts has sent you a one-off secure message." + nl);
		sb.append("When you log into Expeditee and check your mail it will be there waiting for you." + nl);
		sb.append("You will need the following key to read this message: " + nl);
		sb.append(intergalacticNumber);
		try {
			//	Send email with key to colleague one
			String colleagueOneEmail = colleagues[2];
			sendEmail(colleagueOneEmail, sb);
			//	Send email with key to colleague two
			String colleagueTwoEmail = colleagues[3];
			sendEmail(colleagueTwoEmail, sb);
			
			MessageBay.displayMessage("Identity confirmed.  Your trusted contacts have been notified via one-off secure Expeditee message.  "
					+ "You will recieve an email message with a password share from each once they have completed their part of the process.  Enter them below.");
		} catch (MessagingException e) {
			e.printStackTrace();
		}		
	}
	
	private static String[] getPasswordColleaguesFromUsername(String username) {
		Path credentialsFilePath = Paths.get(FrameIO.PROFILE_PATH).resolve(username).resolve("pwcolleagues.inf");
		String fileName = null;
		if (credentialsFilePath.toFile().exists()) {
			try (Scanner in = new Scanner(credentialsFilePath)) {
				fileName = in.nextLine();
			} catch (IOException e) {
				MessageBay.errorMessage("Unable to find trusted users contact frame for specified user, are they registered on this computer?");
				return null;
			}
		} else {
			MessageBay.errorMessage("Unable to find trusted users contact frame for specified user, are they registered on this computer?");
			return null;
		}
		
		int number = Integer.parseInt(fileName.replace(".exp", ""));
		Frame pwColleagueFrame = FrameIO.LoadFrame(username + number, FrameIO.PROFILE_PATH);
		Collection<Text> textItems = pwColleagueFrame.getTextItems();
		textItems.removeIf(text -> !text.getText().startsWith("User_"));
		
		String[] ret = new String[4];
		Iterator<Text> it = textItems.iterator();
		while(it.hasNext()) {
			String content = it.next().getText().toLowerCase().trim();
			if (content.contains("user_one:")) {
				ret[0] = content.replace("user_one:", "").trim();
			} else if (content.contains("user_two:")) {
				ret[1] = content.replace("user_two:", "").trim();
			}
		}
				
		// find colleague one email
		Path credentialsDirectoryPath = UserSettings.PublicAndPrivateResources 
				? Paths.get(FrameIO.PARENT_FOLDER).resolve("resources-" + username)
				: Paths.get(FrameIO.PARENT_FOLDER);
		credentialsDirectoryPath = credentialsDirectoryPath.resolve("contacts").resolve(ret[0] + "-credentials");
		try (Scanner in = new Scanner(credentialsDirectoryPath.resolve("credentials.inf").toFile())) {
			int parseInt = Integer.parseInt(in.nextLine().replace(".exp", ""));
			Frame frame = FrameIO.LoadFrame(ret[0] + "-credentials" + parseInt, credentialsDirectoryPath.toAbsolutePath().getParent().toString() + File.separator);
			textItems = frame.getTextItems();
			textItems.removeIf(text -> !text.getText().startsWith("Email:"));
			ret[2] = textItems.iterator().next().getText().replace("Email:", "").trim();
		} catch (FileNotFoundException e) {
			MessageBay.errorMessage("You do not appear to have contact with your nominated password colleague: " + ret[0]);
			return null;
		}
		
		
		// find colleague two email
		credentialsDirectoryPath = UserSettings.PublicAndPrivateResources 
				? Paths.get(FrameIO.PARENT_FOLDER).resolve("resources-" + username)
				: Paths.get(FrameIO.PARENT_FOLDER);
		credentialsDirectoryPath = credentialsDirectoryPath.resolve("contacts").resolve(ret[1] + "-credentials");
		try (Scanner in = new Scanner(credentialsDirectoryPath.resolve("credentials.inf").toFile())) {
			int parseInt = Integer.parseInt(in.nextLine().replace(".exp", ""));
			Frame frame = FrameIO.LoadFrame(ret[1] + "-credentials" + parseInt, credentialsDirectoryPath.toAbsolutePath().getParent().toString() + File.separator);
			textItems = frame.getTextItems();
			textItems.removeIf(text -> !text.getText().startsWith("Email:"));
			ret[3] = textItems.iterator().next().getText().replace("Email:", "").trim();
		} catch (FileNotFoundException e) {
			MessageBay.errorMessage("You do not appear to have contact with your nominated password colleague: " + ret[1]);
			return null;
		}
		
		return ret;
	}
	

	public static void sendEmail(String email, StringBuilder sb) throws MessagingException, AddressException {
		// Establish properties for email.
		Properties properties = System.getProperties();
		properties.setProperty("mail.transport.protocol", "smtp");
		properties.setProperty("mail.smtp.host", "smtp.gmail.com");
		properties.setProperty("mail.smtp.port", "465");
		properties.setProperty("mail.smtp.starttls.enable", "true");
		properties.setProperty("mail.smtp.auth", "true");
		properties.setProperty("mail.smtp.debug", "true");
		properties.setProperty("mail.smtp.auth", "true");
		properties.setProperty("mail.smtp.socketFactory.port", "465");
		properties.setProperty("mail.smtp.socketFactory.class", "javax.net.ssl.SSLSocketFactory");
		properties.setProperty("mail.smtp.socketFactory.fallback", "false");
		
		Session session = Session.getDefaultInstance(properties, new javax.mail.Authenticator() {
			@Override
			protected PasswordAuthentication getPasswordAuthentication() {
				//return new PasswordAuthentication("noreply.expeditee", "intergalacticnumber");
				return new PasswordAuthentication("noreply.expeditee", "exped!tee");
			};
		});
		
		// construct email message
		final MimeMessage message = new MimeMessage(session);
		message.setFrom(new InternetAddress("noreply@expeditee.com"));
		message.addRecipient(Message.RecipientType.TO, new InternetAddress(email));
		message.setSubject("Expeditee Password Recovery");
		message.setText(sb.toString());
		
		// send email message
		Transport.send(message);
	}

	public static void setPWColleagues(String colleagueOne, String colleagueTwo) {
		// Get needed text items.
		Frame pwRecoveryFrame = FrameIO.LoadFrame(UserSettings.UserName.get() + AuthenticatorBrowser.PASSWORD_RECOVERY_FRAME);
		Collection<Text> textItems = pwRecoveryFrame.getTextItems();
		textItems.removeIf(t -> !t.getText().toLowerCase().startsWith("user_"));
		
		// Find colleague one and two text items.  Set appropriate values.
		Iterator<Text> it = textItems.iterator();
		while (it.hasNext()) {
			Text text = it.next();
			if (text.getText().toLowerCase().startsWith("user_one:")) {
				text.setText("User_one: " + colleagueOne);
				Colleagues.User_One.set(colleagueOne);
			} else if (text.getText().toLowerCase().startsWith("user_two:")) {
				text.setText("User_two:" + colleagueTwo);
				Colleagues.User_Two.set(colleagueTwo);
			}
		}
		FrameIO.ForceSaveFrame(pwRecoveryFrame);
		
		// Key to split and distribute
		String fullKey = KeyList.PersonalKey.get().getData().get(0);
		byte[] keyBytes = Base64.getDecoder().decode(fullKey);
		
		// Initialise Shamir
		int totalShares = 2;
		int requiredShares = 2;
		Scheme scheme = new Scheme(new SecureRandom(), totalShares, requiredShares);
		
		// Create shares
		Map<Integer, byte[]> shares = scheme.split(keyBytes);
		String colleagueOneShare = Base64.getEncoder().encodeToString(shares.get(1));
		String colleagueTwoShare = Base64.getEncoder().encodeToString(shares.get(2));
		
		// Distribute share zero to colleague one
		String time = org.expeditee.stats.Formatter.getDateTime();
		String sender = UserSettings.UserName.get();
		String topic = "Please help me secure my Expeditee account.";
		String message = "Run the below action to store a secret key that will help me recover access to my account should I ever loose it.";
		Map<String, String> options = new HashMap<String, String>();
		options.put("Store Secret Key for " + sender, "AuthAddSecretKey " + sender + "PersonalKeyShare " + colleagueOneShare);
		MailEntry mail = new MailEntry(time, sender, colleagueOne, topic, message, options);
		Mail.sendMail(mail, colleagueOne);
		
		// Distribute share one to colleague two
		options = new HashMap<String, String>();
		options.put("Store Secret Key for " + sender, "AuthAddSecretKey " + sender + "PersonalKeyShare " + colleagueTwoShare);
		mail = new MailEntry(time, sender, colleagueTwo, topic, message, options);
		Mail.sendMail(mail, colleagueTwo);
		
		MessageBay.displayMessage("You PW Colleagues have been set to " + colleagueOne + " and " + colleagueTwo + ".  "
				+ "They have been sent a Expeditee mail that they can use to store a share of your secret key.");
	}

	public static void emailPasswordShare(String colleagueName) {
		Path credentialsDirectoryPath = Paths.get(FrameIO.CONTACTS_PATH).resolve(colleagueName + "-credentials");
		String colleagueEmail = null;
		try (Scanner in = new Scanner(credentialsDirectoryPath.resolve("credentials.inf").toFile())) {
			int parseInt = Integer.parseInt(in.nextLine().replace(".exp", ""));
			Frame frame = FrameIO.LoadFrame(colleagueName + "-credentials" + parseInt, credentialsDirectoryPath.toAbsolutePath().getParent().toString() + File.separator);
			Collection<Text> textItems = frame.getTextItems();
			textItems.removeIf(text -> !text.getText().startsWith("Email:"));
			colleagueEmail = textItems.iterator().next().getText().replace("Email:", "").trim();
		} catch (FileNotFoundException e) {
			MessageBay.errorMessage("You do not appear to have contact with: " + colleagueName);
			return;
		}
		
		Frame secretsFrame = FrameIO.LoadFrame(UserSettings.UserName.get() + AuthenticatorBrowser.SECRETS_FRAME);
		Collection<Text> textItems = secretsFrame.getTextItems();
		textItems.removeIf(text -> !text.getText().toLowerCase().equals(colleagueName + "personalkeyshare"));
		String key = textItems.iterator().next().getData().get(0);
		
		String nl = System.getProperty("line.separator");
		StringBuilder sb = new StringBuilder();
		sb.append("In responce to your request for assistance regaining access to your Expeditee account, your colleague " + UserSettings.UserName.get() + " has provided you with the following key share:" + nl);
		sb.append(key + nl);
		
		try {
			sendEmail(colleagueEmail, sb);
			MessageBay.displayMessage("Your share of " + colleagueName + "'s password has been sent to their public email address.");
		} catch (MessagingException e) {
			MessageBay.errorMessage("An error occured sending a email to your colleage " + colleagueName + " with the email " + colleagueEmail);
		}
	}

	public static void regainAccountAccess(Map<AuthenticationTag, String> userData) {
		// Store shares in map
		Map<Integer, byte[]> contributingParts = new HashMap<Integer, byte[]>();
		contributingParts.put(1, Base64.getDecoder().decode(userData.get(AuthenticationTag.PasswordSliceOne)));
		contributingParts.put(2, Base64.getDecoder().decode(userData.get(AuthenticationTag.PasswordSliceTwo)));
		
		// initialise shamir
		int totalShares = 2;
		int requiredShares = 2;
		Scheme scheme = new Scheme(new SecureRandom(), totalShares, requiredShares);
		
		// perform joining
		byte[] join = scheme.join(contributingParts);
		
		try {
			// TODO: YIKES!  We can currently change anyone's password!
			AuthenticatorBrowser.getInstance().putKey(userData.get(AuthenticationTag.Username), userData.get(AuthenticationTag.NewPassword), new SecretKeySpec(join, SymmetricAlgorithm));
		} catch (KeyStoreException | NoSuchAlgorithmException | CertificateException | ClassNotFoundException
				| IOException | SQLException e) {
			e.printStackTrace();
		}
		
		MessageBay.displayMessage("Your new password has been set.");
	}
}