Initial

app/src/main/java/net/mezimmah/wkt9/keypad/Keypad.kt

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+package net.mezimmah.wkt9.keypad
+
+import net.mezimmah.wkt9.exception.MissingLetterCode
+import java.lang.StringBuilder
+
+class Keypad(
+    private val keyCodeMapping: KeyCodeMapping,
+    private val letterLayout: Map<Key, List<Char>>
+) {
+    private lateinit var letterKeyMap: Map<Char, Key>
+    private lateinit var keyIsLetterMap: Map<Key, Boolean>
+    private var emojiCodes = mapOf(
+        "❤️" to "143278",
+        "\uD83D\uDE18" to "15477"
+    )
+
+    init {
+        initKeyMaps(letterLayout)
+    }
+
+    fun getKey(keyCode: Int): Key? {
+        return keyCodeMapping.key(keyCode)
+    }
+
+    fun getCharacter(key: Key, idx: Int): Char {
+        val chars = letterLayout[key]!!
+        val length = chars.size
+        val wrappedIdx = idx % (length - 1) + 1
+        return chars[wrappedIdx]
+    }
+
+    fun getDigit(key: Key): Char? {
+        val letters = letterLayout[key] ?: return null
+        return if (letters.isNotEmpty() && letters[0].isDigit()) letters[0] else null
+    }
+
+    fun getCodeForWord(word: String): String {
+        if (emojiCodes.keys.contains(word)) return emojiCodes[word]!!
+
+        val builder = StringBuilder()
+
+        for (letter in word) {
+            val code = codeForLetter(letter) ?: throw MissingLetterCode("No code found for '$letter'")
+
+            builder.append(code)
+        }
+
+        return builder.toString()
+    }
+
+    private fun codeForLetter(letter: Char): Char? {
+        return letterKeyMap[letter]?.code
+    }
+
+    private fun initKeyMaps(layout: Map<Key, List<Char>>): Map<Char, Key> {
+        val letterKeyMap = HashMap<Char, Key>()
+        val keyIsLetterMap = HashMap<Key, Boolean>()
+
+        this.letterKeyMap = letterKeyMap
+        this.keyIsLetterMap = keyIsLetterMap
+
+        for ((key, characters) in layout) {
+            for (char in characters) {
+                letterKeyMap[char] = key
+
+                if (!KeyLayout.nonAlphaNumeric.contains(char)) {
+                    letterKeyMap[char.uppercaseChar()] = key
+                    keyIsLetterMap[key] = true
+                } else if (keyIsLetterMap[key] == null) keyIsLetterMap[key] = false
+            }
+        }
+
+        return letterKeyMap
+    }
+}