/** Purpose: Adds, creates, displays and searches the XMl database file.
 *  Created by: Stanley Hao
 *  Created on: December 9, 2018
 */

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import nu.xom.*;

public class ManageData
{
	static Element cars = new Element("cars");
	static Document carsDoc = new Document(cars);
	static File existingFile = new File("carDatabase.txt");

	//Adds an entry to the existing file, if no file exists, creates a new file.
	public static void addCar(String name, String brand, String modelYear)
	{

		//If there is already a file.
		if(existingFile.exists() && !existingFile.isDirectory())
		{

			//Structures file into XML format and adds a car entry with it's sub-elements.
			Builder builder = new Builder();
			try
			{
				carsDoc = builder.build(existingFile);

				Element cars = carsDoc.getRootElement();
				Element car = new Element("car");
				Element model = new Element("model");
				Element carBrand = new Element("brand");
				Element year = new Element("year");

				//Sets the value of each element.
				car.appendChild(name);
				model.appendChild(name);
				carBrand.appendChild(brand);
				year.appendChild(modelYear);

				//Structures the elements into parent and child elements.
				cars.appendChild(car);
				car.appendChild(model);
				car.appendChild(carBrand);
				car.appendChild(year);
			}
			catch(ValidityException e)
			{
				System.out.println("Error: " + e);
			}
			catch(ParsingException e)
			{
				System.out.println("Error: " + e);
			}
			catch(IOException e)
			{
				System.out.println("Error: " + e);
			}
		}

		//If there isn't a pre-existing file, creates a new file and adds a car entry with its sub-elements.
		else
		{
			Element car = new Element("car");
			Element model = new Element("model");
			Element carBrand = new Element("brand");
			Element year = new Element("year");

			//Sets the value of each element.
			car.appendChild(name);
			model.appendChild(name);
			carBrand.appendChild(brand);
			year.appendChild(modelYear);

			//Structures the elements into parent and child elements.
			cars.appendChild(car);
			car.appendChild(model);
			car.appendChild(carBrand);
			car.appendChild(year);
		}

		//Creates a new database file and fills it with XML data.
		try
		{
			FileWriter databaseFile = new FileWriter("carDatabase.txt");
			BufferedWriter writer = new BufferedWriter(databaseFile);
			writer.write(carsDoc.toXML());
			writer.close();
		}

		catch(IOException e)
		{
				System.out.println("Error: " + e);
		}

	}

	//Displays all the data in the database in a list with each element and their sub-elements.
	public static void showData()
	{

		//Structures existing file into recognizable XML format.
		Builder builder = new Builder();
		try
		{
			carsDoc = builder.build(existingFile);
		}
		catch (ValidityException e)
		{
			System.out.println("Error: " + e);
		}
		catch (ParsingException e)
		{
			System.out.println("Error: " + e);
		}
		catch (IOException e)
		{
			System.out.println("Error: " + e + " \nPlease create a database to display!");
		}

		//Sets variables to root element and list of elements in database.
		Element cars = carsDoc.getRootElement();
		Elements carList = cars.getChildElements();

		//Displays the list of entries.
		for(int i = 0; i < carList.size(); i++)
		{
			System.out.println(carList.get(i).getFirstChildElement("model").getValue() + ": ");
			System.out.println("Brand: " + carList.get(i).getFirstChildElement("brand").getValue());
			System.out.println("Model Year: " + carList.get(i).getFirstChildElement("year").getValue() + "\n");
		}

		/*try
		  {
		   Serializer serializer = new Serializer(System.out);
		   serializer.setIndent(4);
		   serializer.setMaxLength(64);
		   serializer.write(carsDoc);
		  }

		catch (IOException ex)
		  {
		   System.err.println(ex);
		  }*/
	}

	//Searches the database for a specific car, then displays said element if it exists.
	public static void searchData(String query)
	{

		//Structures existing file into recognizable XML format.
		Builder builder = new Builder();
		try
		{
			carsDoc = builder.build(existingFile);
		}

		catch(ValidityException e)
		{
			System.out.println("Error: " + e);
		}

		catch(ParsingException e)
		{
			System.out.println("Error: " + e);
		}

		catch(IOException e)
		{
			System.out.println("Error: " + e);
		}

		//Sets variables to root element and list of elements in database.
		Element cars = carsDoc.getRootElement();
		Elements carList = cars.getChildElements();

		//Searches database and displays all entries that have the same model name as the search query.
		for(int i = 0; i < carList.size(); i++)
		{

			//Displays the vehicle's model name followed by it's brand name and model year.
			if(carList.get(i).getFirstChildElement("model").getValue().equalsIgnoreCase(query))
			{
				System.out.println(carList.get(i).getFirstChildElement("model").getValue() + ": ");
				System.out.println("Brand: " + carList.get(i).getFirstChildElement("brand").getValue());
				System.out.println("Model Year: " + carList.get(i).getFirstChildElement("year").getValue() + "\n");
			}
			else
			{
				//Displays after the entire database is searched and nothing matches.
				if(i == carList.size() - 1)
				{
					System.out.println("The item you searched does not exist.");
				}
			}
		}

	}
}