type t =
  | VUnit
  | VInt of int
  | VBool of bool
  | VString of string
  | VTuple of t list
  | VRecord of string * (string * t) list
  | VCollection of t Delta_runtime.Pure_map.t

let rec to_string value =
  match value with
  | VUnit -> "unit"
  | VInt number -> string_of_int number
  | VBool true -> "true"
  | VBool false -> "false"
  | VString text -> Printf.sprintf "%S" text
  | VTuple items -> "(tuple " ^ Util.join " " (List.map to_string items) ^ ")"
  | VRecord (name, fields) ->
      Printf.sprintf "(record:%s %s)" name
        (Util.join " " (List.map (fun (label, field) -> "(" ^ label ^ " " ^ to_string field ^ ")") fields))
  | VCollection map ->
      let entries =
        List.map (fun (key, item) -> Printf.sprintf "(%d %s)" key (to_string item))
          (Delta_runtime.Pure_map.bindings map)
      in
      "(collection " ^ Util.join " " entries ^ ")"

let collection_of_list entries =
  List.fold_left
    (fun map (key, value) ->
      if Delta_runtime.Pure_map.mem key map then
        Diagnostic.error Location.none "duplicate key %d in the initial input" key;
      Delta_runtime.Pure_map.add key value map)
    Delta_runtime.Pure_map.empty entries

let collection_to_list map = Delta_runtime.Pure_map.bindings map

let rec equal (left : t) (right : t) =
  match (left, right) with
  | VUnit, VUnit -> true
  | VInt a, VInt b -> a = b
  | VBool a, VBool b -> a = b
  | VString a, VString b -> a = b
  | VTuple a, VTuple b -> List.length a = List.length b && List.for_all2 equal a b
  | VRecord (name_a, fields_a), VRecord (name_b, fields_b) ->
      name_a = name_b
      && List.length fields_a = List.length fields_b
      && List.for_all2 (fun (label_a, value_a) (label_b, value_b) -> label_a = label_b && equal value_a value_b) fields_a fields_b
  | VCollection map_a, VCollection map_b -> Delta_runtime.Pure_map.equal equal map_a map_b
  | _ -> false

let field record label =
  match record with
  | VRecord (_, fields) -> Util.assoc_opt label fields
  | _ -> None

let is_collection = function VCollection _ -> true | _ -> false