Restructuring, prepare for room, Discord support

src/utils.rs

@@ -0,0 +1,47 @@
+use wana_kana::{ConvertJapanese, IsJapaneseStr};
+
+pub fn get_starting_mora(word: &str) -> String {
+    if word.is_empty() {
+        return String::from("");
+    }
+    let word = word.to_hiragana();
+    let mut iter = word.chars();
+    let starting_char = iter.next().unwrap();
+    let second_char = iter.next().unwrap();
+    match second_char {
+        'ゃ' | 'ゅ' | 'ょ' => format!("{starting_char}{second_char}"),
+        _ => starting_char.to_string(),
+    }
+}
+
+// Trim off lengtheners and non-kana that are irrelevant to shiritori
+// TODO: Use slices
+fn trim_irrelevant_chars(word: &str) -> String {
+    let mut iter = word.chars().rev().peekable();
+    while let Some(c) = iter.peek() {
+        if *c == 'ー' || !c.to_string().is_kana() {
+            iter.next();
+        } else {
+            break;
+        }
+    }
+    iter.rev().collect()
+}
+
+// Get final mora, which could be multiple chars e.g. しゃ
+// TODO: Use slices
+pub fn get_final_mora(word: &str) -> String {
+    let word = trim_irrelevant_chars(word).to_hiragana();
+    if word.is_empty() {
+        return String::from("");
+    }
+    let mut iter = word.chars().rev();
+    let final_char = iter.next().unwrap();
+    match final_char {
+        'ゃ' | 'ゅ' | 'ょ' => format!("{}{final_char}", match iter.next() {
+            Some(c) => c.to_string(),
+            None => String::from(""),
+        }),
+        _ => final_char.to_string(),
+    }
+}