package api;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import models.DataSourceResult;

import com.google.gson.Gson;

import repositories.ProductsRepository;

// responds to requests made to the /api/products endpoint (e.g. localhost/api/product)
@WebServlet("/api/products")
public class Products extends HttpServlet {
	private static final long serialVersionUID = 1L;
    
	// class level instance of the products data access class
	private repositories.ProductsRepository _repository = null;
    
	// this method is called by the servlet automatically when
	// it starts up
    public void init() throws ServletException {
    		super.init();
    		
    		// ask the server for the full path to the sqlite3 database
    		String path = this.getServletContext().getRealPath("data/sample.db");
    		
    		// pass the path to the database to the repository
    		_repository = new ProductsRepository(path);
    }
	
    /**
     * @see HttpServlet#HttpServlet()
     */
    public Products() {
        super();
        // TODO Auto-generated constructor stub
    }

	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		
		try {

			// get the take and skip parameters that the grid sends off of the request, 
			// setting some default values
			int take = request.getParameter("take") == null ? 5 :
				Integer.parseInt(request.getParameter("take"));
			int skip = request.getParameter("skip") == null ? 0 :
				Integer.parseInt(request.getParameter("skip"));
			
			// create a new DataSourceResult object to send back as the result of this method
			models.DataSourceResult result = new DataSourceResult();
			
			// set the data property to the list of products
			result.setData(_repository.listProducts(skip, take));
			// set the total to the count
			result.setTotal(_repository.getCount());
			
			// create a new Gson object for serializing JSON
			Gson gson = new Gson();
			
			// set the response type to JSON
			response.setContentType("application/json");
			
			// write the DataSourceResult to the response and serialize it
			// to JSON with Gson
			response.getWriter().write(gson.toJson(result));
			
		} catch (Exception e) {
			// if anything goes wrong, send a generic error
			response.sendError(500);
			e.printStackTrace();
		}
	}

	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		
		try {

			// create a new Gson object for writing JSON
			Gson gson = new Gson();
			
			// convert the parameters in the request to a product model object
			models.Product product = parseRequest(request);
			
			// read the type of operation requested off the query string
			String type = request.getQueryString();
		
			switch (type) {
				case "update": {
					// update the product
					_repository.doUpdate(product);
					break;
				}
				case "destroy": {
					// delete the product
					_repository.doDelete(product);
					break;
				}
				case "create": {
					// create a product which returns the newly created it
					// set the id on the product model object
					product.setProductID(_repository.doCreate(product));
					
					// write the product to the response and serliaze as JSON
					response.getWriter().write(gson.toJson(product));
					break;
				}
			}
		
			// set the response type as JSON
			response.setContentType("application/json");
		} catch (Exception e) {
			// throw a generic error
			e.printStackTrace();
			response.sendError(500);
		}
	}
	
	// this private method pulls the parameters out of an HTTP request and
	// attempts to map them into a product model object
	private models.Product parseRequest(HttpServletRequest request) {

		// create a new product model object
		models.Product product = new models.Product();
		
		// TODO: perform server-side validation on fields
		
		// parse the product information off of the request
		
		// product id may or may not be included in the parameters
		product.setProductID(request.getParameter("ProductID").equals("") ? 0 : 
			Integer.parseInt(request.getParameter("ProductID")));
		
		// create a new supplier
		product.setSupplier(new models.Supplier(Integer.parseInt(request.getParameter("Supplier[SupplierID]")), 
				request.getParameter("Supplier[SupplierName]")));
		
		// create a new category
		product.setCategory(new models.Category(Integer.parseInt(request.getParameter("Category[CategoryID]")), 
				request.getParameter("Category[Categoryname]")));
		
		// set the rest of the product fields
		product.setUnitPrice(Float.parseFloat(request.getParameter("UnitPrice")));
		product.setUnitsInStock(Integer.parseInt(request.getParameter("UnitsInStock")));
		product.setDiscontinued(Boolean.parseBoolean(request.getParameter("Discontinued")));
		product.setProductName(request.getParameter("ProductName"));
		
		return product;
	}

}