module Make (Storage : Management.Physical.S) = struct
  module Ops = Manipulation.Make(Storage)

  type error =
    | ParseError        of string
    | ManipulationError of Manipulation.error
    | RelationNotFound  of string

  let sexp_of_error e =
    let open Sexplib.Sexp in
    match e with
    | ParseError s        -> List [Atom "parse-error";        Atom s]
    | ManipulationError e -> Manipulation.sexp_of_error e
    | RelationNotFound s  -> List [Atom "relation-not-found"; Atom s]

  let ( let* ) = Result.bind

  let wrap_manip r = Result.map_error (fun e -> ManipulationError e) r

  let get_rel db name =
    Ops.get_relation db ~name
    |> Option.to_result ~none:(RelationNotFound name)

  let convert_cardinality : Ast.cardinality_spec -> Conventions.Cardinality.t = function
    | Ast.Finite n          -> Conventions.Cardinality.Finite n
    | Ast.AlephZero         -> Conventions.Cardinality.AlephZero
    | Ast.Continuum         -> Conventions.Cardinality.Continuum
    | Ast.ConstrainedFinite -> Conventions.Cardinality.ConstrainedFinite

  let execute
      (storage : Storage.t)
      (db : Management.Database.t)
      (stmt : Ast.statement)
    : (Management.Database.t * string, error) result =
    match stmt with
    | Ast.CreateDatabase name ->
      let* db = Ops.create_database storage ~name |> wrap_manip in
      Ok (db, "Database created: " ^ name)

    | Ast.CreateRelation { name; schema = schema_pairs } ->
      let schema =
        List.fold_left (fun s (attr, dom) -> Schema.add attr dom s) Schema.empty schema_pairs
      in
      let* (db, _) = Ops.create_relation storage db ~name ~schema |> wrap_manip in
      Ok (db, "Relation created: " ^ name)

    | Ast.RetractRelation name ->
      let* db = Ops.retract_relation storage db ~name |> wrap_manip in
      Ok (db, "Relation retracted: " ^ name)

    | Ast.ClearRelation name ->
      let* rel    = get_rel db name in
      let* (db, _) = Ops.clear_relation storage db rel |> wrap_manip in
      Ok (db, "Relation cleared: " ^ name)

    | Ast.RegisterDomain { name; cardinality } ->
      let domain = Domain.make
        ~name
        ~generator:(fun _ -> Generator.Error "not enumerable via DDL")
        ~membership_criteria:(fun _ -> true)
        ~cardinality:(convert_cardinality cardinality)
        ~compare:Stdlib.compare
      in
      let* db = Ops.register_domain storage db domain |> wrap_manip in
      Ok (db, "Domain registered: " ^ name)
end

module Memory = Make(Management.Physical.Memory)