P3121 Lider Alexandr task-1

src/main/java/ru/ifmo/cet/javabasics/BottleSong.java

@@ -31,13 +31,81 @@
  * Нужно ограничить возможность взятия бутылок натуральным число не более 99 бутылок за раз.
  */
 public class BottleSong {
+    private final int drunk;
+
+    private final String[] numbersUpTo19 = {
+            "",
+            "one",
+            "two",
+            "three",
+            "four",
+            "five",
+            "six",
+            "seven",
+            "eight",
+            "nine",
+            "ten",
+            "eleven",
+            "twelve",
+            "thirteen",
+            "fourteen",
+            "fifteen",
+            "sixteen",
+            "seventeen",
+            "eighteen",
+            "nineteen"
+    };
+
+    private final String[] tensNumbers = {
+            "",
+            "ten",
+            "twenty",
+            "thirty",
+            "forty",
+            "fifty",
+            "sixty",
+            "seventy",
+            "eighty",
+            "ninety"
+    };
+
+    private String transform(int number) {
+        if (number < 20) {
+            return numbersUpTo19[number];
+        }
+        else if (number % 10 == 0) {
+            return tensNumbers[number / 10];
+        }
+        else {
+            return tensNumbers[number / 10] + " " + numbersUpTo19[number % 10];
+        }
+    }
+
+    private String checkIfOne(int number){
+        return number == 1 ? " bottle": " bottles";
+    }
 
     public BottleSong(int bottleTakenAtOnce) {
-        //TODO
+        drunk = bottleTakenAtOnce;
     }
 
     public String getBottleSongLyrics() {
-        //TODO
-        throw new UnsupportedOperationException();
+        if (drunk > 99 || drunk <= 0) {
+            throw new IllegalArgumentException();
+        }
+
+        int counter;
+        StringBuilder res = new StringBuilder();
+        for (counter = 99; counter > drunk; counter -= drunk) {
+            res.append(counter + " bottles of beer on the wall, " + counter + " bottles of beer.\n");
+            res.append("Take " + transform(drunk) + " down and pass around, " + (counter - drunk) + checkIfOne(counter - drunk) + " of beer on the wall.\n");
+        }
+
+        res.append(counter + checkIfOne(counter) + " of beer on the wall, " + counter + checkIfOne(counter) + " of beer.\n");
+        res.append("Take " + transform(counter) + " down and pass around, no more bottles of beer on the wall.\n");
+        res.append("No more bottles of beer on the wall, no more bottles of beer.\nGo to the store and buy some more, 99 bottles of beer on the wall.\n");
+
+        return res.toString();
     }
+
 }