fun morseDecode(communication: String): List<String> {
if (communication.isEmpty()) return emptyList()
if (communication.containsInvalidCharacters()) return emptyList()
return decode(communication, with = morseTree)
}
fun decode(
communication: String,
with: MorseTreeOrBranch
): List<String> {
val characterToDecode = communication[0]
val restOfTheCommunication = communication.substring(1)
return when (characterToDecode) {
'.' -> decodeDotChar(with, restOfTheCommunication)
'_' -> decodeDashChar(with, restOfTheCommunication)
'?' -> decodeDotChar(with, restOfTheCommunication)
.plus(decodeDashChar(with, restOfTheCommunication))
else -> emptyList()
}
}
fun decodeDashChar(
with: MorseTreeOrBranch,
restOfTheCommunication: String
): List<String> {
val children = with.dash.children
return if (restOfTheCommunication.isNotEmpty() && children != null) {
decode(restOfTheCommunication, children)
} else {
listOf(with.dash.value)
}
}
fun decodeDotChar(
with: MorseTreeOrBranch,
restOfTheCommunication: String
): List<String> {
val children = with.dot.children
return if (restOfTheCommunication.isNotEmpty() && children != null) {
decode(restOfTheCommunication, children)
} else {
listOf(with.dot.value)
}
}
val morseTree: MorseTree = MorseTree(
dot = MorseNode(
value = "E",
children = MorseBranch(
dot = MorseNode(
value = "I",
children = MorseBranch(
dot = MorseNode(
value = "S",
children = MorseBranch(
dot = MorseNode(
value = "H",
children = null
),
dash = MorseNode(
value = "V",
children = null
)
)
),
dash = MorseNode(
value = "U",
children = MorseBranch(
dot = MorseNode(
value = "F",
children = null
),
dash = MorseNode(
value = "Ü",
children = null
)
)
)
)
),
dash = MorseNode(
value = "A",
children = MorseBranch(
dot = MorseNode(
value = "R",
children = MorseBranch(
dot = MorseNode(
value = "L",
children = null
),
dash = MorseNode(
value = "Ä",
children = null
)
)
),
dash = MorseNode(
value = "W",
children = MorseBranch(
dot = MorseNode(
value = "P",
children = null
),
dash = MorseNode(
value = "J",
children = null
)
)
)
)
)
)
),
dash = MorseNode(
value = "T",
children = MorseBranch(
dot = MorseNode(
value = "N",
children = MorseBranch(
dot = MorseNode(
value = "D",
children = MorseBranch(
dot = MorseNode(
value = "B",
children = null
),
dash = MorseNode(
value = "X",
children = null
)
)
),
dash = MorseNode(
value = "K",
children = MorseBranch(
dot = MorseNode(
value = "C",
children = null
),
dash = MorseNode(
value = "Y",
children = null
)
)
)
)
),
dash = MorseNode(
value = "M",
children = MorseBranch(
dot = MorseNode(
value = "G",
children = MorseBranch(
dot = MorseNode(
value = "Z",
children = null
),
dash = MorseNode(
value = "Q",
children = null
)
)
),
dash = MorseNode(
value = "O",
children = MorseBranch(
dot = MorseNode(
value = "Ö",
children = null
),
dash = MorseNode(
value = "CH",
children = null
)
)
)
)
)
)
)
)
data class MorseTree(
override val dot: MorseNode,
override val dash: MorseNode
) : MorseTreeOrBranch
data class MorseNode(
val value: String,
val children: MorseBranch?
)
data class MorseBranch(
override val dot: MorseNode,
override val dash: MorseNode
) : MorseTreeOrBranch
/**
* Would've preferred to use Union Types (not in kotlin sadly), or just an
* Either class, but... KISS
*/
interface MorseTreeOrBranch {
val dot: MorseNode
val dash: MorseNode
}
fun String.containsInvalidCharacters(): Boolean {
return !all {
it == '_' || it == '.' || it == '?'
}
}
