1 files changed, 49 insertions, 0 deletions
diff --git a/lib/operation.ml b/lib/operation.ml
new file mode 100644
index 0000000..1fb1dd5
--- /dev/null
+++ b/lib/operation.ml
@@ -0,0 +1,49 @@
+module TransactionType = struct
+  type t =
+    | Credit
+    | Debit
+
+  let t =
+    let encode = function
+      | Credit -> "credit"
+      | Debit -> "debit"
+    in
+    let decode = function
+      | "credit" -> Ok Credit
+      | "debit" -> Ok Debit
+      | _ -> Error "Invalid transaction type"
+    in
+    Caqti_type.(enum ~encode ~decode "transaction_type")
+  ;;
+end
+
+type t =
+  | Transaction of
+      { transaction_type : TransactionType.t
+      ; value : int
+      ; description : string
+      }
+  | Balance of { client_id : int }
+
+type transaction =
+  { id : int
+  ; client_id : int
+  ; value : int
+  ; transaction_type : TransactionType.t
+  ; description : string
+  ; created_at : Ptime.t
+  }
+
+let decoder =
+  let open Utils.Decoder in
+  let open Syntax in
+  let transaction_type_decoder =
+    literal "c" *> return TransactionType.Credit
+    <|> literal "d" *> return TransactionType.Debit
+  in
+  (fun value transaction_type description ->
+    Transaction { value; description; transaction_type })
+  <$> ("valor" <: int)
+  <*> ("tipo" <: transaction_type_decoder)
+  <*> ("descricao" <: string)
+;;