initial commit

.gitignore

@@ -0,0 +1 @@
+build/*

src/bahnhofname.gleam

@@ -0,0 +1,98 @@
+import gleam/http/response.{Response}
+import gleam/http/request.{Request}
+import gleam/http.{Get}
+import gleam/bit_builder.{BitBuilder}
+import gleam/erlang/process
+import gleam/io
+import gleam/string
+import gleam/list
+import gleam/map.{Map}
+import gleam/result.{lazy_unwrap}
+import gleam/uri
+import gleam/hackney
+import mist
+
+fn the_lookup(
+  query: String,
+  stations: Map(String, String),
+  ds100s: Map(String, String),
+) -> String {
+  map.get(ds100s, query)
+  |> lazy_unwrap(fn() {
+    io.println(query)
+    map.get(stations, query)
+    |> lazy_unwrap(fn() { "unknown" })
+  })
+}
+
+fn lookup_station(
+  request: Request(t),
+  stations: Map(String, String),
+  ds100s: Map(String, String),
+  baseurl: String,
+) -> Response(BitBuilder) {
+  let #(code, text) = case request {
+    Request(method: Get, path: "/help", ..) -> #(
+      200,
+      "ds100 → Name: " <> baseurl <> "/FF\n" <> "Name → ds100: " <> baseurl <> "/Frankfurt Hbf",
+    )
+    Request(method: Get, path: "/" <> path, ..) -> #(
+      200,
+      the_lookup(string.replace(path, each: "%20", with: " "), stations, ds100s),
+    )
+    _ -> #(404, "intended usage is e.g. curl " <> baseurl <> "/FF")
+  }
+  let body = bit_builder.from_string(text)
+
+  response.new(code)
+  |> response.prepend_header(
+    "x-data-source",
+    "https://data.deutschebahn.com/dataset/data-betriebsstellen.html",
+  )
+  |> response.set_body(body)
+}
+
+fn fetch_data() -> Result(String, hackney.Error) {
+  let assert Ok(uri) =
+    uri.parse(
+      "https://download-data.deutschebahn.com/static/datasets/betriebsstellen/DBNetz-Betriebsstellenverzeichnis-Stand2021-10.csv",
+    )
+  let assert Ok(request) = request.from_uri(uri)
+  let assert Ok(response) = hackney.send(request)
+
+  Ok(response.body)
+}
+
+fn read_csv() -> List(#(String, String)) {
+  // let assert Ok(contents) = file.read(path)
+  let assert Ok(contents) = fetch_data()
+  contents
+  // the file doesn't use quotes, so this is fine
+  |> string.split(on: "\n")
+  |> list.map(fn(a) { string.split(a, on: ";") })
+  |> list.filter_map(fn(fields) {
+    case fields {
+      [_, ds100, name, ..] -> Ok(#(name, ds100))
+      _ -> Error(fields)
+    }
+  })
+}
+
+pub fn main() {
+  let baseurl = "https://bahnhof.name"
+  let stations = read_csv()
+  let stationmap =
+    stations
+    |> map.from_list
+  let ds100map =
+    stations
+    |> list.map(fn(a) { #(a.1, a.0) })
+    |> map.from_list
+
+  let assert Ok(_) = mist.run_service(
+    1234,
+    fn(req) { lookup_station(req, stationmap, ds100map, baseurl) },
+    max_body_limit: 100,
+  )
+  process.sleep_forever()
+}