refactor lookups to separate functions

This allows them to be used separately.

src/bahnhofname.gleam

@@ -86,16 +86,23 @@ fn unpercent(encoded: String) -> String {
   res
 }
 
-fn the_lookup(
+/// Looks up a query in a Map by exact value, no fuzzy matching.
+fn lookup_exact(query: String, lookup: Map(String, String)) -> #(Int, String) {
+  case map.get(lookup, query) {
+    Ok(result) -> #(200, result)
+    _ -> #(404, "??")
+  }
+}
+
+/// Looks up a station by its name, with fuzzy matching.
+fn lookup_by_name(
   query: String,
   stations: Map(String, String),
   ds100s: Map(String, String),
   fuzzy: fn(String) -> List(String)
 ) -> #(Int, String) {
-  case map.get(ds100s, query) {
-    Ok(name) -> #(200, name)
-    _ -> {
   io.println(query)
+
   case map.get(stations, query) {
     Ok(ds100) -> #(200, ds100)
     _ -> {
@@ -117,8 +124,6 @@ fn the_lookup(
     }
   }
 }
-  }
-}
 
 fn lookup_station(
   request: Request(t),
@@ -135,8 +140,16 @@ fn lookup_station(
       200,
       "ds100 → Name: " <> baseurl <> "/NN\n" <> "Name → ds100: " <> baseurl <> "/Nürnberg Hbf",
     )
-    Request(method: Get, path: "/" <> path, ..) ->
-      the_lookup(unpercent(path), stations, ds100s, fuzzy)
+    Request(method: Get, path: "/" <> path, ..) -> {
+      let path = unpercent(path)
+
+      let by_ds100 = lookup_exact(path, ds100s)
+
+      case by_ds100.0 {
+        200 -> by_ds100
+        _ -> lookup_by_name(path, stations, ds100s, fuzzy)
+      }
+    }
     _ -> #(404, "intended usage is e.g. curl " <> baseurl <> "/FF")
   }
   let body = bit_builder.from_string(text)