package com.mousetech.gourmetj.utils;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.List;

import org.apache.commons.lang3.StringUtils;
import org.primefaces.model.DefaultStreamedContent;
import org.primefaces.model.StreamedContent;
import org.primefaces.util.SerializableSupplier;
import com.mousetech.gourmetj.ShopIngredient;

/**
 * Construct a Primefaces file output content for an ingredient
 * list in YAML format.
 * @see ShoppingListBean
 * 
 * @author timh
 * @since Jan 15, 2022
 */

public class YamlShoppingList {

	/**
	 * Create "file" to download in YAML format
	 * @param ingredientList Ingredient list to format
	 * @return Http response for file download
	 */
	public static StreamedContent createDownload(
			List<ShopIngredient> ingredientList) {
	    StreamedContent file;
		
		
		ByteArrayOutputStream ary = new ByteArrayOutputStream();
		PrintWriter wtr = new PrintWriter(ary);
		wtr.println("---");
		formatContent(wtr, ingredientList);
		wtr.close();

		InputStream airy = new ByteArrayInputStream(ary.toByteArray());
		file = DefaultStreamedContent.
				builder().contentEncoding("text/text")
					.name("shopping_list.yml")
                    .stream(() -> airy)
                    .build();
		
		return file;
	}

	/**
	 * Output line items in the ingredient list with topics for
	 * each Shopping Category.
	 * 
	 * @param wtr            Output Writer
	 * @param ingredientList Ingredient list to output.
	 */
	private static void formatContent(PrintWriter wtr,
			List<ShopIngredient> ingredientList) {
		String oldShopcat = null;
		for (ShopIngredient ing : ingredientList) {
			String newShopcat = ing.getShopCat();
			if (StringUtils.isBlank(newShopcat)) {
				newShopcat = "Unassigned";
			}
			if ( ing.isInPantry()) {
				// Don't put pantry items in list.
				continue;
			}
			if (!StringUtils.equals(newShopcat, oldShopcat)) {
				wtr.println(newShopcat + ":");
				oldShopcat = newShopcat;
			}
			wtr.print("  -  ");
			String displa = ing.getDisplayAmount();
			wtr.print(displa);
			if (!displa.isBlank()) {
				wtr.print(' ');
			}
			String unit = ing.getUnit();
			if (StringUtils.isNotBlank(unit)) {
				wtr.print(unit);
				wtr.print(' ');
			}
			wtr.println(ing.getItem());
		}
	}

}