open Printf ;;
open Interp_ast ;;
open Interp ;;
open Interp_lib ;;

open Big_int ;;

let lit_to_string = function
 | L_unit -> "unit"
 | L_zero -> "bitzero"
 | L_one -> "bitone"
 | L_true -> "true"
 | L_false -> "false"
 | L_num n -> string_of_big_int n
 | L_hex s -> s
 | L_bin s -> s
 | L_undef -> "undefined"
 | L_string s -> "\"" ^ s ^ "\""
;;

let id_to_string = function
  | Id s | DeIid s -> s
;;

let rec val_to_string = function
 | V_boxref n -> sprintf "boxref %d" n
 | V_lit l -> sprintf "literal %s" (lit_to_string l)
 | V_tuple l ->
     let repr = String.concat ", " (List.map val_to_string l) in
     sprintf "tuple (%s)" repr
 | V_list l ->
     let repr = String.concat "; " (List.map val_to_string l) in
     sprintf "list [%s]" repr
 | V_vector (first_index, inc, l) ->
     let order = if inc then "little-endian" else "big-endian" in
     let repr = String.concat "; " (List.map val_to_string l) in
     sprintf "vector [%s] (%s, from %s)" repr order (string_of_big_int first_index)
 | V_record l ->
     let pp (id, value) = sprintf "%s = %s" (id_to_string id) (val_to_string value) in
     let repr = String.concat "; " (List.map  pp l) in
     sprintf "record {%s}" repr
 | V_ctor (id, value) ->
     sprintf "constructor %s %s" (id_to_string id) (val_to_string value)
;;

let rec env_to_string = function
  | [] -> ""
  | [id,v] -> sprintf "%s |-> %s" (id_to_string id) (val_to_string v)
  | (id,v)::env -> sprintf "%s |-> %s, %s" (id_to_string id) (val_to_string v) (env_to_string env)

let rec stack_to_string = function
  | Top -> "Top"
  | Frame(id,exp,env,mem,s) ->
    sprintf "(Frame of %s, e, (%s), m, %s)" (id_to_string id) (env_to_string env) (stack_to_string s)
;;  


let reg_to_string = function Reg (id,_) | SubReg (id,_,_) -> id_to_string id ;;
let sub_to_string = function None -> "" | Some (x, y) -> sprintf " (%s, %s)"
  (string_of_big_int x) (string_of_big_int y)
let act_to_string = function
 | Read_reg (reg, sub) ->
     sprintf "read_reg %s%s" (reg_to_string reg) (sub_to_string sub)
 | Write_reg (reg, sub, value) ->
     sprintf "write_reg %s%s = %s" (reg_to_string reg) (sub_to_string sub)
     (val_to_string value)
 | Read_mem (id, args, sub) ->
     sprintf "read_mem %s(%s)%s" (id_to_string id) (val_to_string args)
     (sub_to_string sub)
 | Write_mem (id, args, sub, value) ->
     sprintf "write_mem %s(%s)%s = %s" (id_to_string id) (val_to_string args)
     (sub_to_string sub) (val_to_string value)
 | Call_extern (name, arg) ->
     sprintf "extern call %s applied to %s" name (val_to_string arg)
;;

module Reg = struct
  include Map.Make(struct type t = id let compare = compare end)
end ;;

module Mem = struct
  include Map.Make(struct
    type t = (id * big_int)
    let compare (i1, v1) (i2, v2) =
      match compare i1 i2 with
      | 0 -> compare_big_int v1 v2
      | n -> n
    end)
end ;;

let slice v = function
  | None -> v
  | Some (n, m) -> slice_vector v n m
;;

let vconcat v v' = vec_concat (V_tuple [v; v']) ;;

let perform_action ((reg, mem) as env) = function
 | Read_reg ((Reg (id, _) | SubReg (id, _, _)), sub) ->
     slice (Reg.find id reg) sub, env
 | Read_mem (id, V_lit(L_num n), sub) ->
     slice (Mem.find (id, n) mem) sub, env
 | Write_reg ((Reg (id, _) | SubReg (id, _, _)), None, value) ->
     V_lit L_unit, (Reg.add id value reg, mem)
 | Write_reg ((Reg (id, _) | SubReg (id, _, _)), Some (start, stop), value) ->
     (* XXX if updating a single element, wrap value into a vector -
      * should the typechecker do that coercion for us automatically? *)
     let value = if eq_big_int start stop then V_vector (zero_big_int, true, [value]) else value in
     let old_val = Reg.find id reg in
     let new_val = fupdate_vector_slice old_val value start stop in
     V_lit L_unit, (Reg.add id new_val reg, mem)
 | Write_mem (id, V_lit(L_num n), None, value) ->
     V_lit L_unit, (reg, Mem.add (id, n) value mem)
 (* multi-byte accesses to memory *)
 (* XXX this doesn't deal with endianess at all, and it seems broken in tests *)
 | Read_mem (id, V_tuple [V_lit(L_num n); V_lit(L_num size)], sub) ->
     let rec fetch k acc =
       if eq_big_int k size then slice acc sub else
         let slice = Mem.find (id, add_big_int n k) mem in
         fetch (succ_big_int k) (vconcat acc slice)
     in
     fetch zero_big_int (V_vector (zero_big_int, true, [])), env
 (* XXX no support for multi-byte slice write at the moment - not hard to add,
  * but we need a function basic read/write first since slice access involves
  * read, fupdate, write. *)
 | Write_mem (id, V_tuple [V_lit(L_num n); V_lit(L_num size)], None, value) ->
     (* assumes smallest unit of memory is 8 bit *)
     let byte_size = 8 in
     let rec update k mem =
       if eq_big_int k size then mem else
         let slice = slice_vector value
           (mult_int_big_int byte_size k)
           (mult_int_big_int byte_size (succ_big_int k)) in
         let mem' = Mem.add (id, add_big_int n k) slice mem in
         update (succ_big_int k) mem'
     in V_lit L_unit, (reg, update zero_big_int mem)
 (* This case probably never happens in the POWER spec anyway *)
 | Write_mem (id, V_lit(L_num n), Some (start, stop), value) ->
     (* XXX if updating a single element, wrap value into a vector -
      * should the typechecker do that coercion for us automatically? *)
     let value = if eq_big_int start stop then V_vector (zero_big_int, true, [value]) else value in
     let old_val = Mem.find (id, n) mem in
     let new_val = fupdate_vector_slice old_val value start stop in
     V_lit L_unit, (reg, Mem.add (id, n) new_val mem)
 | Call_extern (name, arg) -> eval_external name arg, env
 | _ -> assert false
;;


let run (name, test) =
  let rec loop env = function
  | Value v -> eprintf "%s: returned %s\n" name (val_to_string v)
  | Action (a, s) ->
      eprintf "%s: suspended on action %s\n" name (act_to_string a);
      (*eprintf "%s: suspended on action %s, with stack %s\n" name (act_to_string a) (stack_to_string s);*)
      let return, env' = perform_action env a in
      eprintf "%s: action returned %s\n" name (val_to_string return);
      loop env' (resume test s return)
  | Error e -> eprintf "%s: error: %s\n" name e in
  let entry = E_app((Id "main"), [E_lit L_unit]) in
  eprintf "%s: starting\n" name;
  try
    Printexc.record_backtrace true;
    loop (Reg.empty, Mem.empty) (interp test entry)
  with e ->
    let trace = Printexc.get_backtrace () in
    eprintf "%s: interpretor error %s\n%s\n" name (Printexc.to_string e) trace
;;