refactor: wrap the bad request in invite function to make maintainable

src/app/error.gleam

@@ -1,4 +1,6 @@
+import gleam/io
 import gleam/pgo
+import gleam/result
 import zeptomail.{type ApiError}
 
 pub type AppError {
@@ -11,3 +13,23 @@ pub type AppError {
   DatabaseError(pgo.QueryError)
   ApiError(ApiError)
 }
+
+pub fn map_bad_request(r: Result(a, b)) -> Result(a, AppError) {
+  r
+  |> result.map_error(fn(error) {
+    io.debug(error)
+    case error {
+      _ -> BadRequest
+    }
+  })
+}
+
+pub fn try_bad_request(
+  result: Result(a, e1),
+  apply fun: fn(a) -> Result(b, e2),
+) -> Result(b, AppError) {
+  case result {
+    Ok(x) -> map_bad_request(fun(x))
+    Error(_) -> Error(BadRequest)
+  }
+}

src/app/routes/user_routes.gleam

@@ -12,6 +12,7 @@ import app/models/user.{
 import app/pages
 import app/pages/layout.{layout}
 import app/web.{type Context, Context, bids_cookie, uid_cookie}
+import gleam/function
 import gleam/http.{Http}
 import gleam/http/cookie
 import gleam/http/response
@@ -345,30 +346,22 @@ pub fn post_invite(req: Request, ctx: Context) {
   let email_validator = valid.string_is_email("Not email")
 
   let result = {
-    use user_email <- result.try(
-      list.key_find(form.values, "email")
-      |> result.map_error(fn(_) { error.BadRequest }),
-    )
+    use user_email <-
+      error.try_bad_request(
+        list.key_find(form.values, "email"),
+        email_validator,
+      )
+      |> function.curry2(result.try)
 
-    use _valid <- result.try(
-      email_validator(user_email)
-      |> result.map_error(fn(err) {
-        io.debug(err)
-        error.BadRequest
-      }),
-    )
+    use user_id <-
+      error.try_bad_request(
+        result.map(get_user_by_email(user_email, ctx.db), fn(u) { u.id }),
+        uuid.cast,
+      )
+      |> function.curry2(result.try)
 
     use board_id <- result.try(
-      list.key_find(form.values, "board")
-      |> result.map_error(fn(_) { error.BadRequest }),
-    )
-
-    use user_id <- result.try(
-      get_user_by_email(user_email, ctx.db)
-      |> result.map(fn(user) {
-        uuid.cast(user.id) |> result.map_error(fn(_) { error.BadRequest })
-      })
-      |> result.flatten,
+      error.map_bad_request(list.key_find(form.values, "board")),
     )
 
     use _ <- result.try(validate_board_user(user_id, ctx.db))