split messages up based on state, refactored backend to decouple states more

shared/src/player.gleam

@@ -5,12 +5,12 @@ pub type Player {
   Player(name: String, id: Int, score: Int)
 }
 
-pub fn serialize(player: Player) -> List(#(String, json.Json)) {
-  [
+pub fn serialize(player: Player) -> json.Json {
+  json.object([
     #("name", json.string(player.name)),
     #("id", json.int(player.id)),
     #("score", json.int(player.score)),
-  ]
+  ])
 }
 
 pub fn decoder() -> decode.Decoder(Player) {

shared/src/session.gleam

@@ -1,30 +1,37 @@
+import gleam/dict
 import gleam/dynamic/decode
+import gleam/int
 import gleam/json
 import gleam/list
 import player
 
 pub type Session {
-  Session(id: String, host_user_id: Int, players: List(player.Player))
+  Session(id: String, host_user_id: Int, players: dict.Dict(Int, player.Player))
 }
 
 pub fn serialize(session: Session) -> json.Json {
   json.object([
     #("id", json.string(session.id)),
     #("host_user_id", json.int(session.host_user_id)),
-    #(
-      "players",
-      json.array(
-        list.map(session.players, fn(p) { player.serialize(p) }),
-        of: json.object,
-      ),
-    ),
+    #("players", json.dict(session.players, int.to_string, player.serialize)),
   ])
 }
 
 pub fn decoder() -> decode.Decoder(Session) {
   use id <- decode.field("id", decode.string)
   use host_user_id <- decode.field("host_user_id", decode.int)
-  use players <- decode.field("players", decode.list(player.decoder()))
+  use players <- decode.field(
+    "players",
+    decode.dict(decode.string, player.decoder()),
+  )
+
+  let players =
+    dict.to_list(players)
+    |> list.map(fn(entry) {
+      let assert Ok(key) = int.parse(entry.0)
+      #(key, entry.1)
+    })
+    |> dict.from_list
 
   decode.success(Session(id:, host_user_id:, players:))
 }