June 2018 Update

Task/Simple-database/Kotlin/simple-database.kotlin

@@ -0,0 +1,110 @@
+// version 1.2.31
+
+import java.text.SimpleDateFormat
+import java.util.Date
+import java.io.File
+import java.io.IOException
+
+val file = File("simdb.csv")
+
+class Item(
+    val name: String,
+    val date: String,
+    val category: String
+) : Comparable<Item> {
+
+    override fun compareTo(other: Item) = date.compareTo(other.date)
+
+    override fun toString() = "$name, $date, $category"
+}
+
+fun addItem(input: Array<String>) {
+    if (input.size < 2) {
+        printUsage()
+        return
+    }
+    val sdf = SimpleDateFormat("yyyy-MM-dd HH:mm:ss")
+    val date = sdf.format(Date())
+    val cat = if (input.size == 3) input[2] else "none"
+    store(Item(input[1], date, cat))
+}
+
+fun printLatest(a: Array<String>) {
+    val db = load()
+    if (db.isEmpty()) {
+        println("No entries in database.")
+        return
+    }
+    // no need to sort db as items are added chronologically
+    if (a.size == 2) {
+        var found = false
+        for (item in db.reversed()) {
+            if (item.category == a[1]) {
+                println(item)
+                found = true
+                break
+            }
+        }
+        if (!found) println("There are no items for category '${a[1]}'")
+    }
+    else println(db[db.lastIndex])
+}
+
+fun printAll() {
+    val db = load()
+    if (db.isEmpty()) {
+        println("No entries in database.")
+        return
+    }
+    // no need to sort db as items are added chronologically
+    for (item in db) println(item)
+}
+
+fun load(): MutableList<Item> {
+    val db = mutableListOf<Item>()
+    try {
+        file.forEachLine { line ->
+            val item = line.split(", ")
+            db.add(Item(item[0], item[1], item[2]))
+        }
+    }
+    catch (e: IOException) {
+        println(e)
+        System.exit(1)
+    }
+    return db
+}
+
+fun store(item: Item) {
+    try {
+        file.appendText("$item\n")
+    }
+    catch (e: IOException) {
+        println(e)
+    }
+}
+
+fun printUsage() {
+    println("""
+        |Usage:
+        |  simdb cmd [categoryName]
+        |  add     add item, followed by optional category
+        |  latest  print last added item(s), followed by optional category
+        |  all     print all
+        |  For instance: add "some item name" "some category name"
+    """.trimMargin())
+}
+
+fun main(args: Array<String>) {
+    if (args.size !in 1..3) {
+        printUsage()
+        return
+    }
+    file.createNewFile()  // create file if it doesn't already exist
+    when (args[0].toLowerCase()) {
+        "add"    -> addItem(args)
+        "latest" -> printLatest(args)
+        "all"    -> printAll()
+        else     -> printUsage()
+    }
+}