[@@@warning "-30"]

exception TODO of string

open Region

module In = AST

module SMap = Utils.String.Map

module Out =
  struct
    type type_name = string
    type variable  = string

    type ast = {
      types        : type_decl list;
      storage      : typed_var;
      operations   : typed_var;
      declarations : decl list;
      prev         : In.t;
    }

   and typed_var = {name: variable; ty: type_expr}
   and type_decl = {name: variable; ty: type_expr}

   and decl = {name: variable; ty: type_expr; value: expr}

   and type_expr =
     Prod     of type_expr list
   | Sum      of (type_name * type_expr) list
   | Record   of (type_name * type_expr) list
   | TypeApp  of type_name * type_expr list
   | Function of {args: type_expr list; ret: type_expr}
   | Ref      of type_expr
   | Unit
   | Int
   | TODO

   and expr =
     App      of {operator: operator; arguments: expr list}
   | Variable of variable
   | Constant of constant
   | Lambda   of lambda

   and lambda = {
     parameters   : type_expr SMap.t;
     declarations : decl list;
     instructions : instr list;
     result       : expr
   }

   and operator = Add | Sub | Lt | Gt | Function of string

   and constant =
     Unit
   | Int of Z.t

   and instr =
     Assignment    of { name: variable; value: expr }
   | While         of { condition: expr; body: instr list }
   | ForCollection of { list: expr; key: variable;
                        value: variable option;
                        body: instr list }
   | If            of { condition: expr; ifso: instr list; ifnot: instr list }
   | Match         of { expr: expr; cases: (pattern * instr list) list }
   | DropUnit      of expr       (* expr returns unit, drop the result. *)
   | Fail          of { expr: expr }
   | Null

   and pattern =
     PVar    of variable
   | PWild
   | PInt    of Z.t
   | PBytes  of MBytes.t
   | PString of string
   | PUnit
   | PFalse
   | PTrue
   | PNone
   | PSome   of pattern
   | Cons    of pattern * pattern
   | PTuple  of pattern list
  end

let map f l = List.(rev_map f l |> rev)

(* TODO: check that List.to_seq, SMap.of_seq are not broken
   (i.e. check that they are tail-recursive) *)

let append_map f l = map f l |>  List.flatten

let append l = List.(rev l |> rev_append)

let list_to_map l = l |> List.to_seq |> SMap.of_seq  (* Why lazy ? *)

let fold_map f a l =
  let f (acc, l) elem =
    let acc', elem' = f acc elem
    in acc', (elem' :: l) in
  let last_acc, last_l = List.fold_left f (a, []) l
  in last_acc, List.rev last_l

(* Simplify the AST *)

let s_nsepseq : ('a,'sep) Utils.nsepseq -> 'a list =
  fun (first, rest) -> first :: (map snd rest)

let s_sepseq : ('a,'sep) Utils.sepseq -> 'a list =
  function
    None         -> []
  | Some nsepseq -> s_nsepseq nsepseq

let s_name ({value=name; region}: string reg) =
  ignore region; name

let rec s_cartesian {value=sequence; region} : Out.type_expr =
  let () = ignore region in
  Prod (map s_type_expr (s_nsepseq sequence))

and s_sum_type {value=sequence; region} : Out.type_expr =
  let () = ignore region in
  let _todo = sequence in
(*  Sum (map s_type_expr (s_nsepseq sequence)) *)
  TODO

and s_record_type {value=(kwd_record, field_decls, kwd_end); region} : Out.type_expr =
  let () = ignore (kwd_record,region,kwd_end) in
  let _todo = (* s_field_decls *) field_decls in
  TODO

and s_type_app {value=node; region} : Out.type_expr =
  let () = ignore region in
  let _todo = node in
  TODO
  (* let type_name, type_tuple = node in *)
  (* s_var        type_name; *)
  (* s_type_tuple type_tuple *)

and s_par_type {value=node; region} : Out.type_expr =
  let () = ignore region in
  let _todo = node in
  TODO

and s_var {region; value=lexeme} : Out.type_expr =
  let () = ignore region in
  let _todo = lexeme in
  TODO

(*  let lpar, type_expr, rpar = node in
  s_token     lpar "(";
  s_type_expr type_expr;
  s_token     rpar ")"*)

and s_type_expr : In.type_expr -> Out.type_expr = function
  Prod    cartesian   -> s_cartesian   cartesian
| Sum     sum_type    -> s_sum_type    sum_type
| Record  record_type -> s_record_type record_type
| TypeApp type_app    -> s_type_app    type_app
| ParType par_type    -> s_par_type    par_type
| TAlias  type_alias  -> s_var         type_alias


let s_type_decl In.{value={kwd_type;name;kwd_is;type_expr;terminator}; region} : Out.type_decl =
  let () = ignore (kwd_type,kwd_is,terminator,region) in
  Out.{ name = s_name name; ty = s_type_expr type_expr }

let s_storage_decl In.{value={kwd_storage; store_type; terminator}; region} : Out.typed_var =
  let () = ignore (kwd_storage,terminator,region) in
  Out.{ name = "storage"; ty = s_type_expr store_type }

let s_operations_decl In.{value={kwd_operations;op_type;terminator}; region} : Out.typed_var =
  let () = ignore (kwd_operations,terminator,region) in
  Out.{ name = "operations"; ty = s_type_expr op_type }

let s_expr : In.expr -> Out.expr = function
  | _ -> raise (TODO "simplify expressions")

let s_case : In.case -> Out.pattern * (Out.instr list) = function
  | _ -> raise (TODO "simplify pattern matching cases")

let s_const_decl In.{value; region} : Out.decl =
  let In.{kwd_const; name; colon;
          const_type; equal; init; terminator} = value in
  let () = ignore (kwd_const,colon,equal,terminator,region) in
  Out.{name  = s_name name;
       ty    = s_type_expr const_type;
       value = s_expr init}

let s_param_const {value=(kwd_const,variable,colon,type_expr); region} : string * Out.type_expr =
  let () = ignore (kwd_const,colon,region) in
  s_name variable, s_type_expr type_expr

let s_param_var {value=(kwd_var,variable,colon,type_expr); region} : string * Out.type_expr =
  let () = ignore (kwd_var,colon,region) in
  s_name variable, s_type_expr type_expr

let s_param_decl : In.param_decl -> string * Out.type_expr = function
    ParamConst p ->  s_param_const p
  | ParamVar p ->    s_param_var p

let s_parameters ({value=(lpar,param_decl,rpar);region} : In.parameters) : (string * Out.type_expr) list =
  let () = ignore (lpar,rpar,region) in
  let l = (s_nsepseq param_decl) in
  map s_param_decl l

let rec s_var_decl {value; region} : Out.decl =
  let In.{kwd_var; name; colon;
          var_type; ass; init; terminator} = value in
  let () = ignore (kwd_var, colon, ass, terminator, region) in
  Out.{name  = s_name name;
       ty    = s_type_expr var_type;
       value = s_expr init}

and s_local_decl : In.local_decl -> Out.decl = function
  LocalLam   decl -> s_lambda_decl decl
| LocalConst decl -> s_const_decl  decl
| LocalVar   decl -> s_var_decl    decl

and s_instructions ({value=sequence; region} : In.instructions) : Out.instr list =
  let () = ignore region in
  append_map s_instruction (s_nsepseq sequence)

and s_instruction : In.instruction -> Out.instr list = function
  Single instr -> s_single_instr instr
|  Block block -> (s_block block)

and s_conditional In.{kwd_if;test;kwd_then;ifso;kwd_else;ifnot} : Out.instr =
  let () = ignore (kwd_if,kwd_then,kwd_else) in
  If { condition = s_expr test; ifso = s_instruction ifso; ifnot = s_instruction ifnot }

and s_match_instr In.{kwd_match;expr;kwd_with;lead_vbar;cases;kwd_end} : Out.instr =
  let {value=cases;region} = cases in
  let () = ignore (kwd_match,kwd_with,lead_vbar,kwd_end,region) in
  Match { expr = s_expr expr; cases = map s_case (s_nsepseq cases) }

and s_ass_instr {value=(variable,ass,expr); region} : Out.instr =
  let () = ignore (ass,region) in
  Assignment { name = s_name variable; value = s_expr expr }

and s_while_loop {value=(kwd_while, expr, block); region} : Out.instr list =
  let () = ignore (kwd_while,region) in
  [While {condition = s_expr expr; body = s_block block}]

and s_for_loop : In.for_loop -> Out.instr list = function
  ForInt     for_int     -> s_for_int     for_int
| ForCollect for_collect -> s_for_collect for_collect

and s_for_int ({value={kwd_for;ass;down;kwd_to;bound;step;block}; region} : In.for_int reg) : Out.instr list =
  let {value=(variable,ass_kwd,expr);region = ass_region} = ass in
  let () = ignore (kwd_for,ass_region,ass_kwd,kwd_to,region) in
  let name = s_name variable in
  let condition, operator = match down with Some kwd_down -> ignore kwd_down; Out.Gt, Out.Sub
                                          | None          ->                  Out.Lt, Out.Add in
  let step = s_step step
  in [
      Assignment { name; value = s_expr expr };
      (* TODO: lift the declaration of the variable *)
      While {
          condition = App { operator = condition;
                            arguments = [Variable name; s_expr bound] };
          body = List.append (s_block block)
                        [Out.Assignment { name;
                                        value = App { operator;
                                                      arguments = [Variable name; step]}}]
        }
    ]

and s_for_collect ({value={kwd_for;var;bind_to;kwd_in;expr;block}; _} : In.for_collect reg) : Out.instr list =
  let () = ignore (kwd_for,kwd_in) in
  [
    Out.ForCollection {
        list = s_expr expr;
        key = s_name var;
        value = s_bind_to bind_to;
        body = s_block block
      }
  ]

and s_step : (In.kwd_step * In.expr) option -> Out.expr = function
  Some (kwd_step, expr) -> let () = ignore (kwd_step) in s_expr expr
| None -> Constant (Int Z.one)

and s_bind_to : (In.arrow * In.variable) option -> Out.variable option = function
    Some (arrow, variable) ->
    let () = ignore arrow in Some (s_name variable)
| None -> None

and s_loop : In.loop -> Out.instr list = function
    While while_loop -> s_while_loop while_loop
  | For     for_loop -> s_for_loop for_loop

and s_fun_call {value=(fun_name, arguments); region} : Out.expr =
  let () = ignore region in
  App { operator = Function (s_name fun_name); arguments = s_arguments arguments }

and s_arguments {value=(lpar, sequence, rpar); region} =
  let () = ignore (lpar, rpar, region) in
  map s_expr (s_nsepseq sequence);

and s_fail ((kwd_fail, expr) : (In.kwd_fail * In.expr)) : Out.instr =
  ignore kwd_fail; Fail {expr = s_expr expr}

and s_single_instr : In.single_instr -> Out.instr list = function
  Cond     {value; _} -> [s_conditional value]
| Match    {value; _} -> [s_match_instr value]
| Ass      instr      -> [s_ass_instr instr]
| Loop     loop       -> s_loop loop
| ProcCall fun_call   -> [DropUnit (s_fun_call fun_call)]
| Null     kwd_null   -> let () = ignore (kwd_null) in
                         []
| Fail     {value; _} -> [s_fail value]

and s_block In.{value={opening;instr;terminator;close}; _} : Out.instr list =
  let () = ignore (opening,terminator,close) in
  s_instructions instr

and s_fun_decl In.{value={kwd_function;name;param;colon;ret_type;kwd_is;local_decls;block;kwd_with;return;terminator}; region} : Out.decl =
  let () = ignore (kwd_function,colon,kwd_is,kwd_with,terminator,region) in
  Out.{
      name = s_name name;
      ty = Function { args = map snd (s_parameters param); ret = s_type_expr ret_type };
      value = Lambda {
                  parameters   = s_parameters param |> list_to_map;
                  declarations = map s_local_decl local_decls;
                  instructions = s_block block;
                  result       = s_expr return
                }
  }

and s_proc_decl In.{value={kwd_procedure;name;param;kwd_is;local_decls;block;terminator}; region} =
  let () = ignore (kwd_procedure,kwd_is,terminator,region) in
  Out.{
      name = s_name name;
      ty = Function { args = map snd (s_parameters param); ret = Unit };
      value = Lambda {
                  parameters   = s_parameters param |> list_to_map;
                  declarations = map s_local_decl local_decls;
                  instructions = s_block block;
                  result       = Out.Constant Out.Unit
                }
  }

and s_lambda_decl : In.lambda_decl -> Out.decl = function
  FunDecl   fun_decl -> s_fun_decl fun_decl
| ProcDecl proc_decl -> s_proc_decl proc_decl
| EntryDecl entry_decl -> failwith "TODO"

let s_main_block (block: In.block reg) : Out.decl =
  Out.{
      name = "main";
      ty = Function { args = []; ret = Unit };
      value = Lambda {
                  parameters   = SMap.empty;
                  declarations = [];
                  instructions = s_block block;
                  result       = Out.Constant Out.Unit
                }
  }

let s_ast (ast : In.ast) : Out.ast =
  let In.{types;constants;storage;operations;lambdas;block;eof} = ast in
  let () = ignore (eof) in
  Out.{
      types        = map s_type_decl types;
      storage      = s_storage_decl storage;
      operations   = s_operations_decl operations;
      declarations = List.flatten [(map s_const_decl  constants);
                                   (map s_lambda_decl lambdas);
                                   [s_main_block block]];
      prev         = ast
  }





(* let s_token region lexeme = *)
(*   printf "%s: %s\n"(compact region) lexeme *)

(* and s_var {region; value=lexeme} = *)
(*   printf "%s: Ident \"%s\"\n" (compact region) lexeme *)

(* and s_constr {region; value=lexeme} = *)
(*   printf "%s: Constr \"%s\"\n" *)
(*          (compact region) lexeme *)

(* and s_string {region; value=lexeme} = *)
(*   printf "%s: String \"%s\"\n" *)
(*          (compact region) lexeme *)

(* and s_bytes {region; value = lexeme, abstract} = *)
(*   printf "%s: Bytes (\"%s\", \"0x%s\")\n" *)
(*          (compact region) lexeme *)
(*          (MBytes.to_hex abstract |> Hex.to_string) *)

(* and s_int {region; value = lexeme, abstract} = *)
(*   printf "%s: Int (\"%s\", %s)\n" *)
(*          (compact region) lexeme *)
(*          (Z.to_string abstract) *)

(* and s_cartesian {value=sequence; _} = *)
(*   s_nsepseq "*" s_type_expr sequence *)

(* and s_variant {value=node; _} = *)
(*   let constr, kwd_of, cartesian = node in *)
(*   s_constr    constr; *)
(*   s_token     kwd_of "of"; *)
(*   s_cartesian cartesian *)

(* and s_field_decls sequence = *)
(*   s_nsepseq ";" s_field_decl sequence *)

(* and s_field_decl {value=node; _} = *)
(*   let var, colon, type_expr = node in *)
(*   s_var       var; *)
(*   s_token     colon ":"; *)
(*   s_type_expr type_expr *)

(* and s_type_tuple {value=node; _} = *)
(*   let lpar, sequence, rpar = node in *)
(*   s_token lpar "("; *)
(*   s_nsepseq "," s_var sequence; *)
(*   s_token rpar ")" *)


(* and s_parameters {value=node; _} = *)
(*   let lpar, sequence, rpar = node in *)
(*   s_token lpar "("; *)
(*   s_nsepseq ";" s_param_decl sequence; *)
(*   s_token rpar ")" *)

(* and s_param_decl = function *)
(*   ParamConst param_const -> s_param_const param_const *)
(* | ParamVar   param_var   -> s_param_var   param_var *)

(* and s_region_cases {value=sequence; _} = *)
(*   s_nsepseq "|" s_case sequence *)

(* and s_case {value=node; _} = *)
(*   let pattern, arrow, instruction = node in *)
(*   s_pattern pattern; *)
(*   s_token arrow "->"; *)
(*   s_instruction instruction *)

(* and s_expr = function *)
(*   Or {value = expr1, bool_or, expr2; _} -> *)
(*     s_expr expr1; s_token bool_or "||"; s_expr expr2 *)
(* | And {value = expr1, bool_and, expr2; _} -> *)
(*     s_expr expr1; s_token bool_and "&&"; s_expr expr2 *)
(* | Lt {value = expr1, lt, expr2; _} -> *)
(*     s_expr expr1; s_token lt "<"; s_expr expr2 *)
(* | Leq {value = expr1, leq, expr2; _} -> *)
(*     s_expr expr1; s_token leq "<="; s_expr expr2 *)
(* | Gt {value = expr1, gt, expr2; _} -> *)
(*     s_expr expr1; s_token gt ">"; s_expr expr2 *)
(* | Geq {value = expr1, geq, expr2; _} -> *)
(*     s_expr expr1; s_token geq ">="; s_expr expr2 *)
(* | Equal {value = expr1, equal, expr2; _} -> *)
(*     s_expr expr1; s_token equal "="; s_expr expr2 *)
(* | Neq {value = expr1, neq, expr2; _} -> *)
(*     s_expr expr1; s_token neq "=/="; s_expr expr2 *)
(* | Cat {value = expr1, cat, expr2; _} -> *)
(*     s_expr expr1; s_token cat "^"; s_expr expr2 *)
(* | Cons {value = expr1, cons, expr2; _} -> *)
(*     s_expr expr1; s_token cons "<:"; s_expr expr2 *)
(* | Add {value = expr1, add, expr2; _} -> *)
(*     s_expr expr1; s_token add "+"; s_expr expr2 *)
(* | Sub {value = expr1, sub, expr2; _} -> *)
(*     s_expr expr1; s_token sub "-"; s_expr expr2 *)
(* | Mult {value = expr1, mult, expr2; _} -> *)
(*     s_expr expr1; s_token mult "*"; s_expr expr2 *)
(* | Div {value = expr1, div, expr2; _} -> *)
(*     s_expr expr1; s_token div "/"; s_expr expr2 *)
(* | Mod {value = expr1, kwd_mod, expr2; _} -> *)
(*     s_expr expr1; s_token kwd_mod "mod"; s_expr expr2 *)
(* | Neg {value = minus, expr; _} -> *)
(*     s_token minus "-"; s_expr expr *)
(* | Not {value = kwd_not, expr; _} -> *)
(*     s_token kwd_not "not"; s_expr expr *)
(* | Int i            -> s_int i *)
(* | Var var          -> s_var var *)
(* | String s         -> s_string s *)
(* | Bytes b          -> s_bytes b *)
(* | False region     -> s_token region "False" *)
(* | True region      -> s_token region "True" *)
(* | Unit region      -> s_token region "Unit" *)
(* | Tuple tuple      -> s_tuple tuple *)
(* | List list        -> s_list list *)
(* | EmptyList elist  -> s_empty_list elist *)
(* | Set set          -> s_set set *)
(* | EmptySet eset    -> s_empty_set eset *)
(* | NoneExpr nexpr   -> s_none_expr nexpr *)
(* | FunCall fun_call -> s_fun_call fun_call *)
(* | ConstrApp capp   -> s_constr_app capp *)
(* | SomeApp sapp     -> s_some_app sapp *)
(* | MapLookUp lookup -> s_map_lookup lookup *)
(* | ParExpr pexpr    -> s_par_expr pexpr *)

(* and s_list {value=node; _} = *)
(*   let lbra, sequence, rbra = node in *)
(*   s_token lbra "["; *)
(*   s_nsepseq "," s_expr sequence; *)
(*   s_token rbra "]" *)

(* and s_empty_list {value=node; _} = *)
(*   let lpar, (lbracket, rbracket, colon, type_expr), rpar = node in *)
(*   s_token     lpar "("; *)
(*   s_token     lbracket "["; *)
(*   s_token     rbracket "]"; *)
(*   s_token     colon ":"; *)
(*   s_type_expr type_expr; *)
(*   s_token     rpar ")" *)

(* and s_set {value=node; _} = *)
(*   let lbrace, sequence, rbrace = node in *)
(*   s_token lbrace "{"; *)
(*   s_nsepseq "," s_expr sequence; *)
(*   s_token rbrace "}" *)

(* and s_empty_set {value=node; _} = *)
(*   let lpar, (lbrace, rbrace, colon, type_expr), rpar = node in *)
(*   s_token     lpar "("; *)
(*   s_token     lbrace "{"; *)
(*   s_token     rbrace "}"; *)
(*   s_token     colon ":"; *)
(*   s_type_expr type_expr; *)
(*   s_token     rpar ")" *)

(* and s_none_expr {value=node; _} = *)
(*   let lpar, (c_None, colon, type_expr), rpar = node in *)
(*   s_token     lpar "("; *)
(*   s_token     c_None "None"; *)
(*   s_token     colon ":"; *)
(*   s_type_expr type_expr; *)
(*   s_token     rpar ")" *)

(* and s_constr_app {value=node; _} = *)
(*   let constr, arguments = node in *)
(*   s_constr constr; *)
(*   s_tuple  arguments *)

(* and s_some_app {value=node; _} = *)
(*   let c_Some, arguments = node in *)
(*   s_token c_Some "Some"; *)
(*   s_tuple arguments *)

(* and s_map_lookup {value=node; _} = *)
(*   let {value = lbracket, expr, rbracket; _} = node.index in *)
(*   s_var   node.map_name; *)
(*   s_token node.selector "."; *)
(*   s_token lbracket "["; *)
(*   s_expr  expr; *)
(*   s_token rbracket "]" *)

(* and s_par_expr {value=node; _} = *)
(*   let lpar, expr, rpar = node in *)
(*   s_token lpar "("; *)
(*   s_expr  expr; *)
(*   s_token rpar ")" *)

(* and s_pattern {value=sequence; _} = *)
(*   s_nsepseq "<:" s_core_pattern sequence *)

(* and s_core_pattern = function *)
(*   PVar var      -> s_var var *)
(* | PWild wild    -> s_token wild "_" *)
(* | PInt i        -> s_int i *)
(* | PBytes b      -> s_bytes b *)
(* | PString s     -> s_string s *)
(* | PUnit region  -> s_token region "Unit" *)
(* | PFalse region -> s_token region "False" *)
(* | PTrue region  -> s_token region "True" *)
(* | PNone region  -> s_token region "None" *)
(* | PSome psome   -> s_psome psome *)
(* | PList pattern -> s_list_pattern pattern *)
(* | PTuple ptuple -> s_ptuple ptuple *)

(* and s_psome {value=node; _} = *)
(*   let c_Some, patterns = node in *)
(*   s_token    c_Some "Some"; *)
(*   s_patterns patterns *)

(* and s_patterns {value=node; _} = *)
(*   let lpar, core_pattern, rpar = node in *)
(*   s_token lpar "("; *)
(*   s_core_pattern core_pattern; *)
(*   s_token rpar ")" *)

(* and s_list_pattern = function *)
(*   Sugar sugar -> s_sugar sugar *)
(* | Raw     raw -> s_raw raw *)

(* and s_sugar {value=node; _} = *)
(*   let lbracket, sequence, rbracket = node in *)
(*   s_token lbracket "["; *)
(*   s_sepseq "," s_core_pattern sequence; *)
(*   s_token rbracket "]" *)

(* and s_raw {value=node; _} = *)
(*   let lpar, (core_pattern, cons, pattern), rpar = node in *)
(*   s_token        lpar "("; *)
(*   s_core_pattern core_pattern; *)
(*   s_token        cons "<:"; *)
(*   s_pattern      pattern; *)
(*   s_token        rpar ")" *)

(* and s_ptuple {value=node; _} = *)
(*   let lpar, sequence, rpar = node in *)
(*   s_token lpar "("; *)
(*   s_nsepseq "," s_core_pattern sequence; *)
(*   s_token rpar ")" *)

(* and s_terminator = function *)
(*   Some semi -> s_token semi ";" *)
(* | None -> () *)