New code implementation

Java/src/main/java/com/gildedrose/GildedRose.java

@@ -1,78 +1,212 @@
 package com.gildedrose;
 
 class GildedRose {
+
+    private static final String BACKSTAGE_PASSES_TO_A_TAFKAL_80_ETC_CONCERT = "Backstage passes to a TAFKAL80ETC concert";
+    private static final String AGED_BRIE = "Aged Brie";
+    private static final String SULFURAS_HAND_OF_RAGNAROS = "Sulfuras, Hand of Ragnaros";
+    private static final String CONJURED_MANA_CAKE = "Conjured Mana Cake";
+    private static final int MAX_QUALITY = 50;
+
     Item[] items;
 
+    /**
+     * Creates a new GildedRose {@link GildedRose}
+     * @param items The items of the {@link GildedRose} rose
+     */
     public GildedRose(Item[] items) {
         this.items = items;
     }
 
+    /**
+     * Updates the quality of every item in the list
+     */
     public void updateQuality() {
-        for (int i = 0; i < items.length; i++) {
-            if (!items[i].name.equals("Aged Brie")
-                    && !items[i].name.equals("Backstage passes to a TAFKAL80ETC concert")) {
-                if (items[i].quality > 0) {
-                    if (items[i].name.equals("Conjured Mana Cake")) {
-                        if (items[i].quality > 1) {
-                            items[i].quality -= 2;
-                        } else {
-                            items[i].quality = 0;
-                        }
-                    } else {
-                        if (!items[i].name.equals("Sulfuras, Hand of Ragnaros")) {
-                            items[i].quality = items[i].quality - 1;
-                        }
-                    }
-                }
-            } else {
-                if (items[i].quality < 50) {
-                    items[i].quality = items[i].quality + 1;
-
-                    if (items[i].name.equals("Backstage passes to a TAFKAL80ETC concert")) {
-                        if (items[i].sellIn < 11) {
-                            if (items[i].quality < 50) {
-                                items[i].quality = items[i].quality + 1;
-                            }
-                        }
-
-                        if (items[i].sellIn < 6) {
-                            if (items[i].quality < 50) {
-                                items[i].quality = items[i].quality + 1;
-                            }
-                        }
-                    }
-                }
-            }
-
-            if (!items[i].name.equals("Sulfuras, Hand of Ragnaros")) {
-                items[i].sellIn = items[i].sellIn - 1;
-            }
-
-            if (items[i].sellIn < 0) {
-                if (!items[i].name.equals("Aged Brie")) {
-                    if (!items[i].name.equals("Backstage passes to a TAFKAL80ETC concert")) {
-                        if (items[i].quality > 0) {
-                            if (items[i].name.equals("Conjured Mana Cake")) {
-                                if (items[i].quality > 1) {
-                                    items[i].quality -= 2;
-                                } else {
-                                    items[i].quality = 0;
-                                }
-                            } else {
-                                if (!items[i].name.equals("Sulfuras, Hand of Ragnaros")) {
-                                    items[i].quality = items[i].quality - 1;
-                                }
-                            }
-                        }
-                    } else {
-                        items[i].quality = 0;
-                    }
-                } else {
-                    if (items[i].quality < 50) {
-                        items[i].quality = items[i].quality + 1;
-                    }
-                }
+        for (Item item : items) {
+            switch (item.name) {
+                case BACKSTAGE_PASSES_TO_A_TAFKAL_80_ETC_CONCERT:
+                    processBackstage(item);
+                    break;
+                case AGED_BRIE:
+                    processAgeBrie(item);
+                    break;
+                case SULFURAS_HAND_OF_RAGNAROS:
+                    continue;
+                case CONJURED_MANA_CAKE:
+                    processConjured(item);
+                    break;
+                default:
+                    processGeneral(item);
             }
+            commonEndProcess(item);
         }
     }
+
+    /**
+     * Decreases the quality of a general item
+     * 1 decrease within the exiry date: item.sellIn >0
+     * 2 decrease after it expires: item.sellIn <= 0
+     * Never decreases after 0. Quality never below 0
+     *
+     * @param item Item {@link Item}
+     */
+    private void processGeneral(Item item) {
+        decreaseQualityConditionally1X(item);
+    }
+
+    /**
+     * Decreases the quality of a conjured item
+     * 2 decrease within the exiry date: item.sellIn >0
+     * 4 decrease after it expires: item.sellIn <= 0
+     * Never decreases after 0. Quality never below 0
+     *
+     * @param item Item {@link Item}
+     */
+    private void processConjured(Item item) {
+        decreaseQualityConditionally2X(item);
+    }
+
+    /**
+     * Increases the quality of a Age Brie item
+     * 1 increase within the exiry date: item.sellIn >0
+     * 2 increase after it expires: item.sellIn <= 0
+     * Never increases after 50. Quality never over 50
+     *
+     * @param item Item {@link Item}
+     */
+    private void processAgeBrie(Item item) {
+        if (item.sellIn > 0) {
+            increaseQualityConditionally1X(item);
+        } else {
+            increaseQualityConditionally2X(item);
+        }
+    }
+
+    /**
+     * Increases the quality of a Backstage Ticket item
+     * 1 increase if there are still more than 10 days to go
+     * 2 increase if there are still between 10 days (inclusive) and 5 (exclusive) to go
+     * 3 increase if there are still between 5 days (inclusive) and 0 (exclusive) to go
+     * Quality is set to 0 once the concert is done and the ticket has expired
+     * Quality never below zero.
+     *
+     * @param item Item {@link Item}
+     */
+    private void processBackstage(Item item) {
+        if (item.sellIn > 10) {
+            increaseQualityConditionally1X(item);
+        } else if (item.sellIn > 5) {
+            increaseQualityConditionally2X(item);
+        } else if (item.sellIn > 0) {
+            increaseQuality3X(item);
+        } else {
+            item.quality = 0;
+        }
+    }
+
+    /**
+     * Auxiliary method to perform the conditional quality increase by one fold.
+     * It calls a common method which receives 1 as a fold parameter.
+     *
+     * @param item Item {@link Item}
+     */
+    private void increaseQualityConditionally1X(Item item) {
+        item.quality = getQualityIncrease(item.quality, 1);
+    }
+
+    /**
+     * Auxiliary method to perform the conditional quality increase by two fold.
+     * It calls a common method which receives 2 as a fold parameter.
+     *
+     * @param item Item {@link Item}
+     */
+    private void increaseQualityConditionally2X(Item item) {
+        item.quality = getQualityIncrease(item.quality, 2);
+    }
+
+    /**
+     * Auxiliary method to perform the conditional quality increase by three fold.
+     * It calls a common method which receives 3 as a fold parameter.
+     *
+     * @param item Item {@link Item}
+     */
+    private void increaseQuality3X(Item item) {
+        item.quality = getQualityIncrease(item.quality, 3);
+    }
+
+    /**
+     * Auxiliary method to perform the conditional quality decrease by one fold.
+     * It calls a common method which receives 1 as a fold parameter.
+     *
+     * @param item Item {@link Item}
+     */
+    private void decreaseQualityConditionally1X(Item item) {
+        decreaseQualityByFold(item, 1);
+    }
+
+    /**
+     * Auxiliary method to perform the conditional quality decrease by two fold.
+     * It calls a common method which receives 2 as a fold parameter.
+     *
+     * @param item Item {@link Item}
+     */
+    private void decreaseQualityConditionally2X(Item item) {
+        decreaseQualityByFold(item, 2);
+    }
+
+    /**
+     * Support method for conditional quality decrease
+     * It performs a conditional decrease by the fold.
+     * Within the expiry date means an attempt to decrease 1 * fold: sellIn > 0 => 1 * fold
+     * Outside the expiry date means an attempt to decrease 2 * fold: sellIn <=0 => 2 * fold
+     *
+     * @param item Item {@link Item}
+     * @param fold Fold numbrt
+     */
+    private void decreaseQualityByFold(Item item, int fold) {
+        if (item.sellIn > 0) {
+            item.quality = decreaseQualityConditionally(item.quality, fold);
+        } else {
+            item.quality = decreaseQualityConditionally(item.quality, fold * 2);
+        }
+    }
+
+    /**
+     * Calculates the new quality value in a conditional way
+     * The returned value is never zero.
+     *
+     * @param quality   The value of the quality
+     * @param decrement The decrement value
+     * @return New quality value
+     */
+    private int decreaseQualityConditionally(int quality, int decrement) {
+        if (quality >= decrement) {
+            return quality - decrement;
+        }
+        return 0;
+    }
+
+    /**
+     * Calculates the new quality value in a conditional way.
+     * The returned value is never greater than the maximum quality.
+     *
+     * @param quality   The value of the quality
+     * @param increment The decrement value
+     * @return New quality value
+     */
+    private int getQualityIncrease(int quality, int increment) {
+        if (quality <= MAX_QUALITY - increment) {
+            return quality + increment;
+        }
+        return MAX_QUALITY;
+    }
+
+    /**
+     * Decreases the sellIn.
+     *
+     * @param item Item {@link Item}
+     */
+    private void commonEndProcess(Item item) {
+        item.sellIn--;
+    }
 }