import static org.junit.Assert.*;

import org.junit.Test;

public class GildedRoseTest {

  private GildedRose app;

	@Test
	public void at_the_end_of_each_day_our_system_lowers_both_values_for_every_item() {
		givenItemWithSellinAndQuality("foo", 10, 10);
		whenWeUpdateTheQuality();
		thenItemBecomes("foo", 9, 9);
	}

	@Test
	public void the_Quality_of_an_item_is_never_negative() throws Exception {
		givenItemWithSellinAndQuality("foo", 10, 0);
		whenWeUpdateTheQuality();
		thenItemBecomes("foo", 9, 0);
	}
	
	@Test
	public void once_the_sell_by_date_has_passed_Quality_degrades_twice_as_fast() throws Exception {
		givenItemWithSellinAndQuality("foo", 0, 10);
		whenWeUpdateTheQuality();
		thenItemBecomes("foo", -1, 8);
	}

	@Test
	public void once_the_sell_by_date_has_passed_Quality_degrades_twice_as_fast_2() throws Exception {
		givenItemWithSellinAndQuality("foo", 0, 1);
		whenWeUpdateTheQuality();
		thenItemBecomes("foo", -1, 0);
	}

	@Test
	public void Aged_Brie__actually_increases_in_Quality_the_older_it_gets() throws Exception {
		givenItemWithSellinAndQuality("Aged Brie", 10, 10);
		whenWeUpdateTheQuality();
		thenItemBecomes("Aged Brie", 9, 11);
	}
	
	@Test
	public void the_Quality_of_an_item_is_never_more_than_50() throws Exception {
		givenItemWithSellinAndQuality("Aged Brie", 10, 50);
		whenWeUpdateTheQuality();
		thenItemBecomes("Aged Brie", 9, 50);		 
	}
	
	@Test
	public void Sulfuras_being_a_legendary_item_never_has_to_be_sold_or_decreases_in_Quality() throws Exception {
		String sulfuras = "Sulfuras, Hand of Ragnaros";
		givenItemWithSellinAndQuality(sulfuras, 10, 80);
		whenWeUpdateTheQuality();
		thenItemBecomes(sulfuras, 10, 80);		 		 
	}

	@Test
	public void backstage_passes_increases_in_Quality_as_its_SellIn_value_approaches() throws Exception {
		backstagePassQuality(20, 10, 11);
		backstagePassQuality(11, 10, 11);
		backstagePassQuality(10, 10, 12);
		backstagePassQuality(9, 10, 12);
		backstagePassQuality(6, 10, 12);
		backstagePassQuality(5, 10, 13);
		backstagePassQuality(4, 10, 13);
		backstagePassQuality(1, 10, 13);
		backstagePassQuality(0, 10, 0);
		backstagePassQuality(-1, 10, 0);
		
		backstagePassQuality(20, 50, 50);
		backstagePassQuality(9, 50, 50);
		backstagePassQuality(3, 50, 50);
	}

	private void backstagePassQuality(int sellIn, int startQuality, int expectedQuality) {
		String backstagePass = "Backstage passes to a TAFKAL80ETC concert";
		givenItemWithSellinAndQuality(backstagePass, sellIn, startQuality );
		whenWeUpdateTheQuality();
		assertEquals("quality for sellIn " + sellIn, expectedQuality, app.items(0).quality);	 
		assertEquals("new sellIn for old sellIn " + sellIn, sellIn - 1, app.items(0).sellIn);	 
	}

	private void whenWeUpdateTheQuality() {
		app.updateQuality();
	}
	
	private void givenItemWithSellinAndQuality(String name, int sellIn, int quality) {
		Item[] items = new Item[] { new Item(name, sellIn, quality) };
		app = new GildedRose(items);
	}
	
	private void thenItemBecomes(String name, int sellIn, int quality) {
		assertEquals(name, app.items(0).name);
		assertEquals("sellIn", sellIn, app.items(0).sellIn);
		assertEquals("quality", quality, app.items(0).quality);
	}
}