refactor lookups to separate functions

This allows them to be used separately.

src/bahnhofname.gleam

@@ -86,35 +86,40 @@ 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)
     _ -> {
-      io.println(query)
-      case map.get(stations, query) {
-        Ok(ds100) -> #(200, ds100)
-        _ -> {
-          let results = fuzzy(query)
-            |> list.filter_map(fn (res) { map.get(ds100s, string.uppercase(res)) })
-          case results {
-            // results -> {
-            //   let names = results
-            //     |> list.map (fn (res) {
-            //     map.get(ds100s, string.uppercase(res))
-            //     |> result.map(fn(a) { "/" <> a })
-            //     |> result.unwrap("/")})
-            //   #(200, string.join(names, "\n"))
-            // }
-            [res] -> #(302, res)
-            [res, ..] -> #(302, res)
-            _ -> #(404, "??")
-          }
-        }
+      let results = fuzzy(query)
+        |> list.filter_map(fn (res) { map.get(ds100s, string.uppercase(res)) })
+      case results {
+        // results -> {
+        //   let names = results
+        //     |> list.map (fn (res) {
+        //     map.get(ds100s, string.uppercase(res))
+        //     |> result.map(fn(a) { "/" <> a })
+        //     |> result.unwrap("/")})
+        //   #(200, string.join(names, "\n"))
+        // }
+        [res] -> #(302, res)
+        [res, ..] -> #(302, res)
+        _ -> #(404, "??")
       }
     }
   }
@@ -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)