structure LruCache : sig
    val cache : Cache.cache
end = struct


(* Mono *)

open Mono

val dummyLoc = ErrorMsg.dummySpan
val stringTyp = (TFfi ("Basis", "string"), dummyLoc)
val optionStringTyp = (TOption stringTyp, dummyLoc)
fun withTyp typ = map (fn exp => (exp, typ))

fun ffiAppCache' (func, index, argTyps) =
    EFfiApp ("Sqlcache", func ^ Int.toString index, argTyps)

fun check (index, keys) =
    ffiAppCache' ("check", index, withTyp stringTyp keys)

fun store (index, keys, value) =
    ffiAppCache' ("store", index, (value, stringTyp) :: withTyp stringTyp keys)

fun flush (index, keys) =
    ffiAppCache' ("flush", index, withTyp optionStringTyp keys)

fun lock (index, write) =
    ffiAppCache' ((if write then "w" else "r") ^ "lock", index, [])


(* Cjr *)

open Print
open Print.PD

fun setupQuery {index, params} =
    let

        val i = Int.toString index

        fun paramRepeat itemi sep =
            let
                fun f n =
                    if n < 0 then ""
                    else if n = 0 then itemi (Int.toString 0)
                    else f (n-1) ^ sep ^ itemi (Int.toString n)
            in
                f (params - 1)
            end

        fun paramRepeatRev itemi sep =
            let
                fun f n =
                    if n < 0 then ""
                    else if n = 0 then itemi (Int.toString 0)
                    else itemi (Int.toString n) ^ sep ^ f (n-1)
            in
                f (params - 1)
            end

        fun paramRepeatInit itemi sep =
            if params = 0 then "" else sep ^ paramRepeat itemi sep

        val typedArgs = paramRepeatInit (fn p => "uw_Basis_string p" ^ p) ", "

        val revArgs = paramRepeatRev (fn p => "p" ^ p) ", "

    in
        Print.box
            [string ("static uw_Sqlcache_Cache cacheStruct" ^ i ^ " = {"),
             newline,
             string "  .lock = PTHREAD_RWLOCK_INITIALIZER,",
             newline,
             string "  .table = NULL,",
             newline,
             string ("  .numKeys = " ^ Int.toString params ^ ","),
             newline,
             string "  .timeInvalid = 0,",
             newline,
             string "  .timeNow = 0};",
             newline,
             string ("static uw_Sqlcache_Cache *cache" ^ i ^ " = &cacheStruct" ^ i ^ ";"),
             newline,
             newline,

             string ("static uw_Basis_string uw_Sqlcache_check" ^ i),
             string ("(uw_context ctx" ^ typedArgs ^ ") {"),
             newline,
             string ("  char *ks[] = {" ^ revArgs ^ "};"),
             newline,
             string ("  uw_Sqlcache_Value *v = uw_Sqlcache_check(ctx, cache" ^ i ^ ", ks);"),
             newline,
             (* If the output is null, it means we had too much recursion, so it's a miss. *)
             string "  if (v && v->output != NULL) {",
             newline,
             string ("    puts(\"SQLCACHE: hit " ^ i ^ ".\");"),
             newline,
             string "    uw_write(ctx, v->output);",
             newline,
             string "    return v->result;",
             newline,
             string "  } else {",
             newline,
             string ("    puts(\"SQLCACHE: miss " ^ i ^ ".\");"),
             newline,
             string "    uw_recordingStart(ctx);",
             newline,
             string "    return NULL;",
             newline,
             string "  }",
             newline,
             string "}",
             newline,
             newline,

             string ("static uw_unit uw_Sqlcache_store" ^ i),
             string ("(uw_context ctx, uw_Basis_string s" ^ typedArgs ^ ") {"),
             newline,
             string ("  char *ks[] = {" ^ revArgs ^ "};"),
             newline,
             string ("  uw_Sqlcache_Value *v = malloc(sizeof(uw_Sqlcache_Value));"),
             newline,
             string "  v->result = strdup(s);",
             newline,
             string "  v->output = uw_recordingRead(ctx);",
             newline,
             string ("  puts(\"SQLCACHE: stored " ^ i ^ ".\");"),
             newline,
             string ("  uw_Sqlcache_store(ctx, cache" ^ i ^ ", ks, v);"),
             newline,
             string "  return uw_unit_v;",
             newline,
             string "}",
             newline,
             newline,

             string ("static uw_unit uw_Sqlcache_flush" ^ i),
             string ("(uw_context ctx" ^ typedArgs ^ ") {"),
             newline,
             string ("  char *ks[] = {" ^ revArgs ^ "};"),
             newline,
             string ("  uw_Sqlcache_flush(ctx, cache" ^ i ^ ", ks);"),
             newline,
             string "  return uw_unit_v;",
             newline,
             string "}",
             newline,
             newline]
    end

val setupGlobal = string "/* No global setup for LRU cache. */"


(* Bundled up. *)

(* For now, use the toy implementation if there are no arguments. *)
fun toyIfNoKeys numKeys implLru implToy args =
    if numKeys args = 0
    then implToy args
    else implLru args

val cache =
    (* let *)
    (*     val {check = toyCheck, *)
    (*          store = toyStore, *)
    (*          flush = toyFlush, *)
    (*          setupQuery = toySetupQuery, *)
    (*          ...} = ToyCache.cache *)
    (* in *)
        (* {check = toyIfNoKeys (length o #2) check toyCheck, *)
        (*  store = toyIfNoKeys (length o #2) store toyStore, *)
        (*  flush = toyIfNoKeys (length o #2) flush toyFlush, *)
    {check = check, store = store, flush = flush, lock = lock,
     setupQuery = setupQuery, setupGlobal = setupGlobal}
    (* end *)

end