Kotlin Word Count Challenge

Readme.txt

As the purpose is to provide insights about messages entered by a real person, it was assumed that any symbol that doesn't belong to the alphabet or to the numerical system doesn't give meaningful information. So, this filter was included in the solution.

Full project can be found here: https://github.com/caroltr/word-count-challenge

Extensions.kt

fun Map<String, Int>.orderDescendingByValue(): Map<String, Int> {
    return this.toList().sortedByDescending { it.second }.toMap()
}

Main.kt

fun main() {
    val controller = MessageController()

    val input = listOf("I love summer.", "My family loves to hike in the summer.")
    val frequency = controller.countWords(input)
    val frequencyOrdered = frequency?.orderDescendingByValue()

    print(frequencyOrdered?.toList())
}

MessageController.kt

class MessageController {
    fun countWords(messages: List<String>): Map<String, Int>? {
        return if (messages.isEmpty()) null else  {
            val allMessages: String = messages.joinToString(" ")
            allMessages.split(" ")
                .groupingBy { getPlainWord(it) }
                .eachCount()
        }
    }

    private fun getPlainWord(word: String): String {
        return word.toLowerCase().filter { it.isLetterOrDigit() }
    }
}