From 46169ec3eb38e177cafd7faf6338d36c6a9e3971 Mon Sep 17 00:00:00 2001
From: Rutger Broekhoff
Date: Thu, 27 Nov 2025 23:35:08 +0100
Subject: Whatever all of this is

---
 lib/ledger.ml | 192 +++++++++++++++++++++++++++++++++++++++++-----------------
 1 file changed, 137 insertions(+), 55 deletions(-)

(limited to 'lib/ledger.ml')

diff --git a/lib/ledger.ml b/lib/ledger.ml
index 84a0146..7805179 100644
--- a/lib/ledger.ml
+++ b/lib/ledger.ml
@@ -1,7 +1,5 @@
 open Prelude
 
-type account_type = Asset | Equity | Liability | Expense | Income
-
 type tx_type =
   | Interest_tx
   | Online_banking_tx
@@ -14,11 +12,10 @@ type tx_type =
   | Direct_debit_tx
   | Periodic_tx
 
-type iban_tag = Account_tag | Counterparty_iban_tag
-[@@deriving compare, sexp_of]
+type iban_tag = Account_tag | Counterparty_iban_tag [@@deriving compare, sexp]
 
 type unit_tag = Filed_tag | Google_pay_tag | Auto_round_savings_tag
-[@@deriving compare, sexp_of]
+[@@deriving compare, sexp]
 
 type string_tag =
   | Desc_tag
@@ -32,7 +29,7 @@ type string_tag =
   | Terminal_tag
   | Card_seq_no_tag
   | Savings_account_tag
-[@@deriving compare, sexp_of]
+[@@deriving compare, sexp]
 
 module Label = struct
   type 'a t =
@@ -62,29 +59,41 @@ end
 module Labels = struct
   include Dmap.Make (Label)
 
-  let sexp_of_t m =
-    Sexp.List
-      (bindings m
-      |> List.map ~f:(function
-           | Binding (Iban_label tag, iban) ->
-               Sexp.List
-                 [
-                   Sexp.Atom "Iban_label";
-                   [%sexp_of: iban_tag] tag;
-                   [%sexp_of: Iban.t] iban;
-                 ]
-           | Binding (String_label tag, s) ->
-               Sexp.List
-                 [
-                   Sexp.Atom "String_label";
-                   [%sexp_of: string_tag] tag;
-                   Sexp.Atom s;
-                 ]
-           | Binding (Timestamp_label, ts) ->
-               Sexp.List
-                 [ Sexp.Atom "Timestamp_label"; [%sexp_of: Time_ns_unix.t] ts ]
-           | Binding (Unit_label tag, ()) ->
-               Sexp.List [ Sexp.Atom "Unit_label"; [%sexp_of: unit_tag] tag ]))
+  let sexp_of_binding = function
+    | Binding (Iban_label tag, iban) ->
+        Sexp.List
+          [
+            Sexp.Atom "iban"; [%sexp_of: iban_tag] tag; [%sexp_of: Iban.t] iban;
+          ]
+    | Binding (String_label tag, s) ->
+        Sexp.List
+          [ Sexp.Atom "string"; [%sexp_of: string_tag] tag; Sexp.Atom s ]
+    | Binding (Timestamp_label, ts) ->
+        Sexp.List [ Sexp.Atom "timestamp"; [%sexp_of: Time_ns_unix.t] ts ]
+    | Binding (Unit_label tag, ()) ->
+        Sexp.List [ Sexp.Atom "unit"; [%sexp_of: unit_tag] tag ]
+
+  let binding_of_sexp sexp =
+    match sexp with
+    | Sexp.List [ Sexp.Atom "iban"; tag_sexp; iban_sexp ] ->
+        Binding
+          ( Iban_label ([%of_sexp: iban_tag] tag_sexp),
+            [%of_sexp: Iban.t] iban_sexp )
+    | Sexp.List [ Sexp.Atom "string"; tag_sexp; Sexp.Atom s ] ->
+        Binding (String_label ([%of_sexp: string_tag] tag_sexp), s)
+    | Sexp.List [ Sexp.Atom "timestamp"; ts_sexp ] ->
+        Binding (Timestamp_label, [%of_sexp: Time_ns_unix.t] ts_sexp)
+    | Sexp.List [ Sexp.Atom "unit"; tag_sexp ] ->
+        Binding (Unit_label ([%of_sexp: unit_tag] tag_sexp), ())
+    | _ -> of_sexp_error "Labels.binding_of_sexp: invalid binding" sexp
+
+  let sexp_of_t m = Sexp.List (bindings m |> List.map ~f:sexp_of_binding)
+
+  let t_of_sexp sexp =
+    match sexp with
+    | Sexp.List labels ->
+        Sequence.(of_list labels >>| binding_of_sexp |> to_seq) |> of_seq
+    | Sexp.Atom _ -> of_sexp_error "Labels.t_of_sexp: list needed" sexp
 end
 
 module Money : sig
@@ -92,27 +101,33 @@ module Money : sig
 
   val equal : t -> t -> bool
   val compare : t -> t -> int
-  val of_z : Z.t -> t
-  val to_z : t -> Z.t
+  val of_bigint : Bigint.t -> t
+  val to_bigint : t -> Bigint.t
   val ( + ) : t -> t -> t
   val ( - ) : t -> t -> t
+  val ( = ) : t -> t -> bool
+  val ( ~$ ) : int -> t
   val sexp_of_t : t -> Sexp.t
 end = struct
-  type t = Z.t [@@deriving sexp_of]
-
-  let equal = Z.equal
-  let compare = Z.compare
-  let of_z = Fn.id
-  let to_z = Fn.id
-  let ( + ) x y = Z.(x + y)
-  let ( - ) x y = Z.(x - y)
-end
+  type t = Bigint.t [@@deriving sexp_of]
 
-type scalar = Amount of Money.t | Rate of Z.t
-[@@deriving equal, compare, sexp_of]
+  let equal = Bigint.equal
+  let compare = Bigint.compare
+  let of_bigint = Fn.id
+  let to_bigint = Fn.id
+  let ( + ) x y = Bigint.(x + y)
+  let ( - ) x y = Bigint.(x - y)
+  let ( = ) = equal
+  let ( ~$ ) = Fn.compose of_bigint Bigint.of_int
+end
 
 type commodity_id = string
-(* TODO: consider making this UUID *) [@@deriving sexp]
+(* TODO: consider making this UUID *) [@@deriving equal, compare, sexp]
+
+type scalar =
+  | Amount of Money.t
+  | Rate of { in_primary_commodity : Money.t; rate : Bigdecimal.t }
+[@@deriving equal, compare, sexp_of]
 
 module Account_id = struct
   type t = string list [@@deriving sexp, compare]
@@ -135,13 +150,18 @@ type bal_assert = {
 
 module Account_id_map = Map.Make (Account_id)
 
+module Debit_credit = struct
+  type t = Debit | Credit [@@deriving string, sexp_of]
+
+  let opposite = function Debit -> Credit | Credit -> Debit
+end
+
 module Tx : sig
   (* Private because we only want to allow constructing balanced transactions. *)
   type t = private {
     cleared : Date.t option;
     commodity_id : commodity_id;
-    debit : scalar Account_id_map.t;
-    credit : scalar Account_id_map.t;
+    entries : (Debit_credit.t * scalar * Money.t option) Account_id_map.t;
     labels : Labels.t;
   }
 
@@ -150,8 +170,7 @@ module Tx : sig
   val make :
     cleared:Date.t option ->
     commodity_id:commodity_id ->
-    debit:scalar Account_id_map.t ->
-    credit:scalar Account_id_map.t ->
+    entries:(Debit_credit.t * scalar * Money.t option) Account_id_map.t ->
     labels:Labels.t ->
     (t, error) result
 
@@ -160,23 +179,86 @@ end = struct
   type t = {
     cleared : Date.t option;
     commodity_id : commodity_id;
-    debit : scalar Account_id_map.t;
-    credit : scalar Account_id_map.t;
+    entries : (Debit_credit.t * scalar * Money.t option) Account_id_map.t;
     labels : Labels.t;
   }
   [@@deriving sexp_of]
 
   type error = Unbalanced
 
-  (* TODO: check if debits and credits are balanced *)
-  let is_balanced _debits _credits = true
+  let is_balanced entries =
+    Map.fold entries
+      ~init:Money.(~$0, ~$0)
+      ~f:(fun ~key:_ ~data:(type_, scalar, _oassert) (ds, cs) ->
+        let m =
+          match scalar with
+          | Amount m -> m
+          | Rate { in_primary_commodity = m; _ } -> m
+        in
+        match type_ with
+        | Debit_credit.Debit -> Money.(ds + m, cs)
+        | Debit_credit.Credit -> Money.(ds, cs + m))
+    |> fun (ds, cs) -> Money.(ds = cs)
 
-  let make ~cleared ~commodity_id ~debit ~credit ~labels =
-    if not (is_balanced debit credit) then Error Unbalanced
-    else Ok { cleared; commodity_id; debit; credit; labels }
+  let make ~cleared ~commodity_id ~entries ~labels =
+    if not (is_balanced entries) then Error Unbalanced
+    else Ok { cleared; commodity_id; entries; labels }
 end
 
-type item = Tx_item of Tx.t | Bal_assert_item of bal_assert
+type item =
+  | Tx_item of Tx.t
+  | Bal_assert_item of bal_assert (*| Account_decl_item of account_decl*)
 [@@deriving sexp_of]
 
 type t = item list [@@deriving sexp_of]
+
+module Account = struct
+  type global_type = Asset | Equity | Liability | Expense | Income
+  [@@deriving compare, sexp]
+
+  type asset
+  type global
+
+  type 'a subcategory =
+    | Asset : asset subcategory option -> global subcategory
+    | Checking : asset subcategory
+
+  type 'a t = Sub of ('a, 'a t) category String.Map.t
+
+  let world : global t =
+    Sub
+      (String.Map.of_alist_exn [ ("Assets", Asset (Some (
+           String.Map.of_alist_exn [
+             ("Checking", Checking)
+           ]
+         ))) ])
+end
+
+(*
+module World = struct
+  type t = (commodity_id * Money.t) Account_id_map.t
+
+  let empty : t = Account_id_map.empty
+
+  let apply_tx_entry_base aid primary_commodity debit_credit scalar =
+    let amount = Scalar.to_amount ~commodity:primary_commodity scalar in
+    Map.update aid ~f:(function
+          | None -> 
+
+            (*
+  let assert_bal aid sc world =
+
+  let apply_tx_entry aid (dc, sc, oassert) world = *)
+
+  let apply_tx (tx : Tx.t) world =
+    Map.fold tx.entries ~init:world ~f:(fun ~key:account_id ~data:(type_, scalar, _oassert) world ->
+        
+
+      )
+
+  let apply : item -> t -> t = function
+    | Tx_item tx -> apply_tx tx
+    | Bal_assert_item ba -> apply_ba ba
+end *)
+
+let make = Fn.id
-- 
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