From 78c4241c617269189ba777bea7f647ee44679498 Mon Sep 17 00:00:00 2001
From: ksetoue <karoline.kimiko@gmail.com>
Date: Tue, 30 Nov 2021 02:22:56 -0300
Subject: [PATCH 1/3] :sparkles: add: queue implementation using arrays

---
 .../kotlin/datastructures/queues/Queue.kt     | 74 +++++++++++++++++++
 1 file changed, 74 insertions(+)
 create mode 100644 src/main/kotlin/datastructures/queues/Queue.kt

diff --git a/src/main/kotlin/datastructures/queues/Queue.kt b/src/main/kotlin/datastructures/queues/Queue.kt
new file mode 100644
index 0000000..2a3ca32
--- /dev/null
+++ b/src/main/kotlin/datastructures/queues/Queue.kt
@@ -0,0 +1,74 @@
+package datastructures
+
+const val DEFAULT_CAPACITY = 10
+
+/**
+ * This is an implementation of a Queue
+ * that uses an array as primary structure
+ *
+ * A queue data structure functions the same as a real world queue. The elements
+ * that are added first are the first to be removed. New elements are added to
+ * the back/rear of the queue.
+ */
+class Queue (size: Int?) {
+
+    private val maxCapacity = size ?: DEFAULT_CAPACITY
+
+    private var itemsCount = 0
+
+    private val queue = IntArray(maxCapacity)
+
+    private var last = -1
+
+    private var first = 0
+
+    /**
+     * @param value is an integer that will be inserted into the queue
+     * @returns false if the queue is full and true if the item was inserted
+     */
+    fun enqueue(value: Int): Boolean {
+        if (isFull()) return false
+
+        itemsCount++
+
+        last = (last + 1) % maxCapacity
+        queue[last] = value
+
+        return true
+    }
+
+    /**
+     * @returns the first item inserted into the queue, and null if it's empty
+     */
+    fun dequeue(): Int? {
+        if (isEmpty()) {
+            return null
+        }
+
+        val itemToReturn = queue[first]
+        first = (first + 1) % maxCapacity
+
+        itemsCount--
+
+        return itemToReturn
+    }
+
+    /**
+     * @returns the first item inserted into the queue as string
+     */
+    fun peekFirst(): String = queue[first].toString()
+
+    /**
+     * @returns the last item inserted into the queue as string
+     */
+    fun peekLast(): String = queue[last].toString()
+
+    /**
+     * @returns the amount of itens inside the queue
+     */
+    fun getSize(): Int = itemsCount
+
+    private fun isFull(): Boolean = itemsCount == maxCapacity
+
+    private fun isEmpty(): Boolean = itemsCount == 0
+}
\ No newline at end of file

From b0ee9a82f480235ba4f186eea42a006f576cba7b Mon Sep 17 00:00:00 2001
From: ksetoue <karoline.kimiko@gmail.com>
Date: Tue, 30 Nov 2021 02:23:28 -0300
Subject: [PATCH 2/3] :white_check_mark: add unit test for queue

---
 .../kotlin/datastructures/queues/QueueTest.kt | 59 +++++++++++++++++++
 1 file changed, 59 insertions(+)
 create mode 100644 src/test/kotlin/datastructures/queues/QueueTest.kt

diff --git a/src/test/kotlin/datastructures/queues/QueueTest.kt b/src/test/kotlin/datastructures/queues/QueueTest.kt
new file mode 100644
index 0000000..0b728c4
--- /dev/null
+++ b/src/test/kotlin/datastructures/queues/QueueTest.kt
@@ -0,0 +1,59 @@
+package datastructures.queues
+import org.assertj.core.api.Assertions.assertThat
+import datastructures.Queue
+
+import org.junit.Test
+
+internal class QueueTest {
+
+    @Test
+    fun `#enqueue must return true queue is not full`() {
+        val valueToInsert = 1
+
+        val newQueue = Queue(10)
+        val returnedValue = newQueue.enqueue(valueToInsert)
+
+        assertThat(returnedValue).isTrue()
+    }
+
+    @Test
+    fun `#enqueue must return false queue is full`() {
+        val valueToInsert = 20
+        val queueSize = 4
+        val newQueue = Queue(queueSize)
+
+        for(i in 0 until queueSize + 1) {
+            newQueue.enqueue(i)
+        }
+
+        val returnedValue = newQueue.enqueue(valueToInsert)
+
+        assertThat(returnedValue).isFalse()
+    }
+
+    @Test
+    fun `#dequeue must return null when queue is empty`() {
+        val queueSize = 2
+        val newQueue = Queue(queueSize)
+
+        val returnedValue = newQueue.dequeue()
+
+        assertThat(returnedValue).isNull()
+    }
+
+    @Test
+    fun `#dequeue must return a value when queue is not empty`() {
+        val valueToInsert = 20
+        val queueSize = 4
+        val newQueue = Queue(queueSize)
+
+        for(i in 0 until queueSize + 1) {
+            newQueue.enqueue(i)
+        }
+
+        val returnedValue = newQueue.dequeue()
+
+        assertThat(returnedValue).isNotNull()
+        assertThat(returnedValue).isEqualTo(0)
+    }
+}
\ No newline at end of file

From e98fe3c93e90d00d93bf561a07b31ddfed8ef7e7 Mon Sep 17 00:00:00 2001
From: ksetoue <karoline.kimiko@gmail.com>
Date: Tue, 30 Nov 2021 02:24:27 -0300
Subject: [PATCH 3/3] :heavy_plus_sign: add junit package

---
 build.gradle | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/build.gradle b/build.gradle
index a301a3b..e543d5c 100644
--- a/build.gradle
+++ b/build.gradle
@@ -14,6 +14,8 @@ repositories {
 
 dependencies {
     implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8"
+    implementation 'org.assertj:assertj-core:3.21.0'
+
     testCompile group: 'junit', name: 'junit', version: '4.12'
 }