package envoy.client.data;

import java.io.*;
import java.util.*;

import javafx.collections.*;

import envoy.client.net.WriteProxy;
import envoy.data.*;
import envoy.data.Message.MessageStatus;
import envoy.event.MessageStatusChange;

/**
 * Represents a chat between two {@link User}s
 * as a list of {@link Message} objects.
 *
 * @author Maximilian Käfer
 * @author Leon Hofmeister
 * @author Kai S. K. Engelbart
 * @since Envoy Client v0.1-alpha
 */
public class Chat implements Serializable {

	protected transient ObservableList<Message> messages = FXCollections.observableArrayList();

	protected int		unreadAmount;
	protected boolean	disabled;

	protected final Contact recipient;

	/**
	 * Stores the last time an {@link envoy.event.IsTyping} event has been sent.
	 */
	protected transient long lastWritingEvent;

	private static final long serialVersionUID = 2L;

	/**
	 * Provides the list of messages that the recipient receives.
	 * <p>
	 * Saves the Messages in the corresponding chat at that Point.
	 *
	 * @param recipient the user who receives the messages
	 * @since Envoy Client v0.1-alpha
	 */
	public Chat(Contact recipient) { this.recipient = recipient; }

	private void readObject(ObjectInputStream stream) throws ClassNotFoundException, IOException {
		stream.defaultReadObject();
		messages = FXCollections.observableList((List<Message>) stream.readObject());
	}

	private void writeObject(ObjectOutputStream stream) throws IOException {
		stream.defaultWriteObject();
		stream.writeObject(new ArrayList<>(messages));
	}

	@Override
	public String toString() {
		return String.format(
			"%s[recipient=%s,messages=%d,disabled=%b]",
			getClass().getSimpleName(),
			recipient,
			messages.size(),
			disabled
		);
	}

	/**
	 * Generates a hash code based on the recipient.
	 *
	 * @since Envoy Client v0.1-beta
	 */
	@Override
	public int hashCode() { return Objects.hash(recipient); }

	/**
	 * Tests equality to another object based on the recipient.
	 *
	 * @since Envoy Client v0.1-beta
	 */
	@Override
	public boolean equals(Object obj) {
		if (this == obj) return true;
		if (!(obj instanceof Chat)) return false;
		final var other = (Chat) obj;
		return Objects.equals(recipient, other.recipient);
	}

	/**
	 * Sets the status of all chat messages received from the recipient to
	 * {@code READ} starting from the bottom and stopping once a read message is
	 * found.
	 *
	 * @param writeProxy the write proxy instance used to notify the server about
	 *                   the message status changes
	 * @since Envoy Client v0.3-alpha
	 */
	public void read(WriteProxy writeProxy) {
		for (int i = messages.size() - 1; i >= 0; --i) {
			final var m = messages.get(i);
			if (m.getSenderID() == recipient.getID())
				if (m.getStatus() == MessageStatus.READ)
					break;
				else {
					m.setStatus(MessageStatus.READ);
					writeProxy.writeMessageStatusChange(new MessageStatusChange(m));
				}
		}
		unreadAmount = 0;
	}

	/**
	 * @return {@code true} if the newest message received in the chat doesn't have
	 *         the status {@code READ}
	 * @since Envoy Client v0.3-alpha
	 */
	public boolean isUnread() { return !messages.isEmpty() && messages.get(messages.size() - 1).getStatus() != MessageStatus.READ; }

	/**
	 * Inserts a message at the correct place according to its creation date.
	 *
	 * @param message the message to insert
	 * @since Envoy Client v0.1-beta
	 */
	public void insert(Message message) {
		for (int i = messages.size() - 1; i >= 0; --i)
			if (message.getCreationDate().isAfter(messages.get(i).getCreationDate())) {
				messages.add(i + 1, message);
				return;
			}
		messages.add(0, message);
	}

	/**
	 * Removes the message with the given ID.
	 *
	 * @param messageID the ID of the message to remove
	 * @return whether the message has been found and removed
	 * @since Envoy Client v0.3-beta
	 */
	public boolean remove(long messageID) { return messages.removeIf(m -> m.getID() == messageID); }

	/**
	 * Increments the amount of unread messages.
	 *
	 * @since Envoy Client v0.1-beta
	 */
	public void incrementUnreadAmount() { ++unreadAmount; }

	/**
	 * @return the amount of unread messages in this chat
	 * @since Envoy Client v0.1-beta
	 */
	public int getUnreadAmount() { return unreadAmount; }

	/**
	 * @return all messages in the current chat
	 * @since Envoy Client v0.1-beta
	 */
	public ObservableList<Message> getMessages() { return messages; }

	/**
	 * @return the recipient of a message
	 * @since Envoy Client v0.1-alpha
	 */
	public Contact getRecipient() { return recipient; }

	/**
	 * @return the last known time a {@link envoy.event.IsTyping} event has been
	 *         sent
	 * @since Envoy Client v0.2-beta
	 */
	public long getLastWritingEvent() { return lastWritingEvent; }

	/**
	 * Sets the {@code lastWritingEvent} to {@code System#currentTimeMillis()}.
	 *
	 * @since Envoy Client v0.2-beta
	 */
	public void lastWritingEventWasNow() { lastWritingEvent = System.currentTimeMillis(); }

	/**
	 * Determines whether messages can be sent in this chat. Should be {@code true}
	 * i.e. for chats whose recipient deleted this client as a contact.
	 *
	 * @return whether this chat has been disabled
	 * @since Envoy Client v0.3-beta
	 */
	public boolean isDisabled() { return disabled; }

	/**
	 * Determines whether messages can be sent in this chat. Should be true i.e. for
	 * chats whose recipient deleted this client as a contact.
	 *
	 * @param disabled whether this chat should be disabled
	 * @since Envoy Client v0.3-beta
	 */
	public void setDisabled(boolean disabled) { this.disabled = disabled; }
}