// COMP28112 Exercise 22 - Dainius Varanauskas

package uk.ac.manchester.cs.comp28112.lab2;

import java.io.IOException;

import org.apache.commons.httpclient.methods.PutMethod;
import org.apache.commons.httpclient.methods.RequestEntity;
import org.apache.commons.httpclient.methods.StringRequestEntity;

import org.apache.commons.httpclient.*;
import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.HttpStatus;
import org.apache.commons.httpclient.methods.GetMethod;

// Client Class to book a hotel and a band.
public class Client {

	// Client fields.
	private static String my_username = "8dv141";
	private static String my_password = "TiLQGq";
	private static PutMethod putMethodHotel = new PutMethod("http://jewel.cs.man.ac.uk:3010/queue/enqueue");
	private static PutMethod putMethodBand = new PutMethod("http://jewel.cs.man.ac.uk:3020/queue/enqueue");

	// Main
	public static void main(String[] args) {

	  // Manual cancel request.
    if (args.length > 0 && args[0].equals("Cancel")) {
			System.out.println("---------------| Canceling Hotel |---------------");
      String request_id = Long.toString(System.currentTimeMillis());                    // Generate a request id.
      cancel_slot(my_username, my_password, Integer.parseInt(args[1]), putMethodHotel); // Cancel Hotel booking.
			System.out.println("---------------| Canceling Bands |---------------");
      request_id = Long.toString(System.currentTimeMillis());                           // Generate a request id.
      cancel_slot(my_username, my_password, Integer.parseInt(args[1]), putMethodBand);  // Cancel Band booking.
      System.exit(1);																																		// Exit program.
    }

	  // Attempt to reserve the slot id for band. Continue until output is a non-negative result.
	  // If the result is negative, reset slot id and make hotel look for a new one.
	  int my_slot_id = -1;
    do {
      // Cancel the slot booked by the hotel if the slot id is positive.
      if (my_slot_id > 0) {
				System.out.println("---------------| Canceling Hotel |---------------");
        String request_id = Long.toString(System.currentTimeMillis());                  // Generate a request id.
        cancel_slot(my_username, my_password, my_slot_id, putMethodHotel);							// Cancel Hotel booking.
      }
	    // Attempt to reserve the slot id for hotel. Continue until output is a non-negative result.
      do {
        // Find the earliest slot id. Continue until a valid (positive) slot id is found.
				System.out.println("-------------| Looking for slot id |-------------");
	      while (my_slot_id < 0) {
        my_slot_id = find_slot_id(get_availability_list(my_username, my_password, putMethodHotel),
                                  get_availability_list(my_username, my_password, putMethodBand));
        }
        // Reset put methods to build different requests using XMLStrings.
        reset_putMethods();
				System.out.println("---------------| Reserving Hotel |---------------");
      } while (reserve_slot(my_username, my_password, 0, putMethodHotel) != 0);
			System.out.println("---------------| Reserving Bands |---------------");
	  } while (reserve_slot(my_username, my_password, my_slot_id, putMethodBand) != 0); 	// TODO :: WHILE IS NOT LOOPING CAUSE THE return value is not properly returned.
  } // main

	// Reset the putMethod objects.
	private static void reset_putMethods() {
	  putMethodHotel = new PutMethod("http://jewel.cs.man.ac.uk:3010/queue/enqueue");
	  putMethodBand = new PutMethod("http://jewel.cs.man.ac.uk:3020/queue/enqueue");
	} // reset_putMethods

	// Check if input string contains value.
	private static void check_for_null(String string, String method) {
		if (string == null) {																											// Check if input string is null.
			System.err.println("Resulting string in " + method + " was null.");			// Print what method it originated from.
			System.exit(1);                                                         // Exit the program.
		}
	} // check_for_null

	// Build a uri using given username and password.
	private static String msg_uri_builder(String msg_uri, String username, String password) {
		return msg_uri += "?username=" + username + "&password=" + password;
	} // msg_uri_builder

	// Cancel a slot for an event.
	private static int cancel_slot(String username, String password, int slot_id, PutMethod putMethod) {
	  String request_id = Long.toString(System.currentTimeMillis());            // Generate a request id.
	  String xmlString = cancelation(request_id, username, password, slot_id);	// Build a cancelation XML string.
		Pair <String, Integer> response = send_message(xmlString, putMethod);     // Send a cancel request and get a response.
		String msg_uri = response.getKey();																				// Get the response body.
		msg_uri = msg_uri_builder(msg_uri, username, password);                   // Build a string with username and password.
		String response_msg_cancelation = get_message(msg_uri);	                  // Request a cancel response message.
		return response.getValue();                                               // Return response code.
	} // cancel_slot

	// Build a cancel request in XML.
	private static String cancelation(String request_id, String username, String password, int slot_id) {
	  String xmlString = null;																								  // Create a string to hold XML.
		try {
			xmlString = XMLRequest.Cancel(request_id, username, password, slot_id); // Build the reservation request.
		} catch (Exception e) {
			System.err.println("Failed to build XML string.");											// Catch exceptions.
			e.printStackTrace();
		}
		check_for_null(xmlString, "cancelation");																	// Check for error.
		return xmlString;
	}

  // Reserve a slot for an event.
  private static int reserve_slot(String username, String password, int slot_id, PutMethod putMethod) {
	  String request_id = Long.toString(System.currentTimeMillis());            // Generate a request id.
    String xmlString = reservation(request_id, username, password, slot_id);	// Build a reservation XML string.
		Pair <String, Integer> response = send_message(xmlString, putMethod);     // Send a reservation request and get a response.
		String msg_uri = response.getKey();																				// Get the response body.
		msg_uri = msg_uri_builder(msg_uri, username, password);                   // Build a string with username and password.
		String response_msg_reservation = get_message(msg_uri);	                  // Request a reservation response message.
		return response.getValue();                                              	// Return response code.
  } // reserve_slot

  // Build a reservation request in XML.
  private static String reservation(String request_id, String username, String password, int slot_id) {
    String xmlString = null;																								        // Create a string to hold XML.
		try {
			xmlString = XMLRequest.Reservation(request_id, username, password, slot_id);  // Build the reservation request.
		} catch (Exception e) {
			System.err.println("Failed to build XML string.");											      // Catch exceptions.
			e.printStackTrace();
		}
		check_for_null(xmlString, "reservation");																      	// Check for error.
		return xmlString;
  } // reservation

  // Find the earliest matching slot id.
  private static int find_slot_id(int[] availableHotels, int[]availableBands) {
    for (int i = 0; i < availableHotels.length; i++) {                        // Poly. search O(n^2)
      for (int j = 0; j < availableBands.length; j++) {
        if (availableHotels[i] == availableBands[j]) {
          System.out.println("Found slot: " + availableHotels[i]);
          return availableHotels[i];
        }
      }
    }
    System.out.println("No slot found. Retrying.");
    return -1;                                                                // Return negative value if no slot found.
  } // find_slot_id

  private static int[] get_availability_list(String username, String password, PutMethod putMethod) {
	  String request_id = Long.toString(System.currentTimeMillis());            // Generate a request id.
    String xmlString = availability(request_id, username, password);          // Build an availability XML string.
		Pair <String, Integer> response = send_message(xmlString, putMethod);     // Send a availability request and get a response.
		String msg_uri = response.getKey();																				// Get the response body.
		msg_uri = msg_uri_builder(msg_uri, username, password);                   // Build a string with username and password.
		String response_msg_availability = get_message(msg_uri);	                // Request an availability response message.
		return availability_parser(response_msg_availability);                    // Get and return the availability list as a list of integers.
  } // get_availability_list

	// Build an availability request in XML.
	private static String availability(String request_id, String username, String password) {
		String xmlString = null;																									// Create a string to hold XML.
		try {
			xmlString = XMLRequest.Availability(request_id, username, password);		// Build the availability request.
		} catch (Exception e) {
			System.err.println("Failed to build XML string.");											// Catch exceptions.
			e.printStackTrace();
		}
		check_for_null(xmlString, "availability");																// Check for error.
		return xmlString;																													// Return result.
	} // availability

	// Parse the availability list.
	private static int[] availability_parser(String availability) {
		String[] digits = availability.replaceAll("\\[|\\]|\\s", "").split(",");  // Split the string into set of substrings with only numbers.
		int[] availableHotels = new int[digits.length];														// Create a list for numbers.
		for (int i = 0; i < digits.length; i++) {																  // Parse each digit.
			try {
				availableHotels[i] = Integer.parseInt(digits[i]);
			} catch (Exception err) {
				System.out.println("Digits array length: " + digits.length);					// Catch exceptions.
				System.out.println("Error whilst parsing availability list");
				err.printStackTrace();
			}
		}
		return availableHotels;																								    // Return the list.
	} // availability_parser

	// Send a message to the server.
	private static Pair<String, Integer> send_message(String xmlString, PutMethod putMethod) {
		String msg_uri = null;																										// Create message to return.
		RequestEntity entity = new StringRequestEntity(xmlString);								// Set the request's entity (body).
		putMethod.setRequestEntity(entity);
		putMethod.addRequestHeader("Content-Type", "application/xml");						// Set the put method's headers
		putMethod.addRequestHeader("Accept", "application/xml");
		HttpClient client = new HttpClient();																			// Create a client and the execute the put method.
		int responseCode = -1;																										// Initialise the temporary values.
		int delay = 3000; 																												// n second delay (1000 = 1s).
		long p_time = System.currentTimeMillis();																	// Set previous time.
		long c_time = System.currentTimeMillis();																	// Set current time.
		do {
			if (c_time - p_time > delay) {																					// If delta between times exceeds delay, execute request.
				try {
					responseCode = client.executeMethod(putMethod);											// Get reseponse code.
					if (responseCode == HttpStatus.SC_OK) {															// Check the response code and react accordingly.
						System.out.println("Message uri: " + Response.getMsgURI(putMethod.getResponseBodyAsString()));
						msg_uri = Response.getMsgURI(putMethod.getResponseBodyAsString());
					} else if (responseCode == HttpStatus.SC_CONFLICT) {
						System.out.println("Message uri: " + Response.getMsgURI(putMethod.getResponseBodyAsString()));
						System.out.println("Error: Slot is not free");
						System.out.println("Error code:" + responseCode);
						System.out.println("Error message:" + putMethod.getResponseBodyAsString());
					} else if (responseCode == HttpStatus.SC_UNAUTHORIZED) {
						System.out.println("Message uri: " + Response.getMsgURI(putMethod.getResponseBodyAsString()));
						System.out.println("Error: request requires authorisation");
						System.out.println("Error code:" + responseCode);
						System.out.println("Error message:" + putMethod.getResponseBodyAsString());
					} else if (responseCode == HttpStatus.SC_FORBIDDEN) {
						System.out.println("Message uri: " + Response.getMsgURI(putMethod.getResponseBodyAsString()));
						System.out.println("Error: request forbidden");
						System.out.println("Error code:" + responseCode);
						System.out.println("Error message:" + putMethod.getResponseBodyAsString());
					} else if (responseCode == 510) {
						System.out.println("Message uri: " + Response.getMsgURI(putMethod.getResponseBodyAsString()));
						System.out.println("Error: Invalid request");
						System.out.println("Error code:" + responseCode);
						System.out.println("Error message:" + putMethod.getResponseBodyAsString());
					} else if (responseCode == HttpStatus.SC_NOT_FOUND) {
						System.out.println("Message uri: " + Response.getMsgURI(putMethod.getResponseBodyAsString()));
						System.out.println("Error: Not found");
						System.out.println("Error code:" + responseCode);
						System.out.println("Error message:" + putMethod.getResponseBodyAsString());
					} else {
						System.out.println("Error code:" + responseCode);
						System.out.println("Error message:" + putMethod.getResponseBodyAsString());
					}
				} catch (HttpException e) {																						// Catch exceptions.
					e.printStackTrace();
				} catch (IOException e) {
					e.printStackTrace();
				} catch (ParseException e) {
					e.printStackTrace();
				}
				p_time = c_time;																											// Set previous time to current (previous).
			}
			c_time = System.currentTimeMillis();																		// Advance the current time to present (current).
		} while (responseCode != HttpStatus.SC_OK);																// If the code is 200 (OK) continue.
		check_for_null(msg_uri, "send_message");																	// Check for error.
		return new Pair<String, Integer>(msg_uri, responseCode);									// Return the URI of the received msg.
	} // send_message

	// Get a response from the server.
	private static Pair<String, Integer> get_message(String msg_uri) {
		int responseCode = -1;																									  // Initialise the temporary values.
		int delay = 3000; 																											  // n second delay (1000 = 1s).
		long p_time = System.currentTimeMillis();																  // Set previous time.
		long c_time = System.currentTimeMillis();																  // Set current time.
		String responseBody = null;																							  // Response string containing the result.
		do {
			if (c_time - p_time > delay) {																				  // If delta between times exceeds delay, execute request.
				try {
					GetMethod getMethod = null;																				  // Create a get method.
					getMethod = new GetMethod(msg_uri);
					getMethod.addRequestHeader("Content-Type", "application/xml");		  // Setup get method.
					getMethod.addRequestHeader("Accept", "application/xml");
					HttpClient client = new HttpClient();															  // Create a client and the execute the method.
					responseCode = client.executeMethod(getMethod);
					if (responseCode == HttpStatus.SC_OK) {														  // Check the response code and react accordingly.
						Response response = Response.parseGetResponse(getMethod.getResponseBodyAsString());
						responseBody = response.toString();											          // Save the responsebody from response.
						System.out.println("Response type: " + response.getResponseType());
						System.out.println(response.toString());
					} else if (responseCode == HttpStatus.SC_CONFLICT) {
						System.out.println("Slot is not free: " + responseCode);
						System.out.println("Error message: " + getMethod.getResponseBodyAsString());
					} else if (responseCode == HttpStatus.SC_NOT_FOUND){
						System.out.println("Message not found: " + responseCode);
						System.out.println("Error message: " + getMethod.getResponseBodyAsString());
					} else if (responseCode == HttpStatus.SC_UNAUTHORIZED) {
						System.out.println("Invalid username/password to retrieve message: " + responseCode);
						System.out.println("Error message: " + getMethod.getResponseBodyAsString());
					} else {
						System.out.println("Error code: " + responseCode);
						System.out.println("Error message: " + getMethod.getResponseBodyAsString());
					}
				} catch (Exception err) {																						  // Catch exceptions.
					System.out.println("Usage: 'java ClientRecMsg msg_uri'");
					err.printStackTrace();
				}
				p_time = c_time;																										  // Set previous time to current (previous).
			}
			c_time = System.currentTimeMillis();																	  // Advance the current time to present (current).
		} while (responseCode != HttpStatus.SC_OK);															  // If the code is 200 (OK) continue.
		check_for_null(responseBody, "request_message");												  // Check for error.
		return new Pair<String, Integer>(responseBody, response);									// Return response body string.
	} // get_message
} // Client