refactor(api): split MSN provider module

src/api/msn/symbols.rs

@@ -0,0 +1,56 @@
+use std::collections::HashMap;
+use std::sync::OnceLock;
+
+const SYMBOL_IDS_RAW: &str = include_str!("symbol_ids.tsv");
+
+static SYMBOL_IDS: OnceLock<HashMap<&'static str, &'static str>> = OnceLock::new();
+
+fn symbol_ids() -> &'static HashMap<&'static str, &'static str> {
+    SYMBOL_IDS.get_or_init(|| {
+        SYMBOL_IDS_RAW
+            .lines()
+            .filter_map(|line| line.split_once('\t'))
+            .collect()
+    })
+}
+
+pub(crate) fn ticker_from_symbol(symbol: &str) -> Option<String> {
+    let trimmed = symbol.trim();
+    if trimmed.is_empty() {
+        return None;
+    }
+    Some(
+        trimmed
+            .split('.')
+            .next()
+            .unwrap_or(trimmed)
+            .trim()
+            .to_uppercase(),
+    )
+}
+
+pub(crate) fn resolve_msn_id(symbol: &str) -> Option<&'static str> {
+    let ticker = ticker_from_symbol(symbol)?;
+    symbol_ids().get(ticker.as_str()).copied()
+}
+
+pub(crate) fn normalized_symbol(requested: &str, fallback_ticker: &str) -> String {
+    let trimmed = requested.trim().to_uppercase();
+    if trimmed.contains('.') || fallback_ticker.is_empty() {
+        trimmed
+    } else {
+        format!("{}.JK", fallback_ticker.trim().to_uppercase())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::resolve_msn_id;
+
+    #[test]
+    fn resolves_symbol_variants() {
+        assert_eq!(resolve_msn_id("BBCA"), Some("bn91jc"));
+        assert_eq!(resolve_msn_id("bbca.jk"), Some("bn91jc"));
+        assert_eq!(resolve_msn_id("INVALID"), None);
+    }
+}