(* This file is part of the Catala compiler, a specification language for tax
   and social benefits computation rules. Copyright (C) 2020 Inria,
   contributors: Denis Merigoux <denis.merigoux@inria.fr>, Emile Rolley
   <emile.rolley@tuta.io>

   Licensed under the Apache License, Version 2.0 (the "License"); you may not
   use this file except in compliance with the License. You may obtain a copy of
   the License at

   http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
   WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
   License for the specific language governing permissions and limitations under
   the License. *)

module Cli = Utils.Cli
module Errors = Utils.Errors
module Pos = Utils.Pos

(** Associates a {!type: Cli.backend_lang} with its string represtation. *)
let languages = [ ("en", Cli.En); ("fr", Cli.Fr); ("pl", Cli.Pl) ]

(** Associates a file extension with its corresponding {!type: Cli.backend_lang}
    string representation. *)
let extensions =
  [ (".catala_fr", "fr"); (".catala_en", "en"); (".catala_pl", "pl") ]

(** Entry function for the executable. Returns a negative number in case of
    error. Usage: [driver source_file options]*)
let driver source_file (options : Cli.options) : int =
  try
    Cli.set_option_globals options;
    Cli.debug_print "Reading files...";
    let filename = ref "" in
    (match source_file with
    | Pos.FileName f -> filename := f
    | Contents c -> Cli.contents := c);
    (match options.max_prec_digits with
    | None -> ()
    | Some i -> Cli.max_prec_digits := i);
    let l =
      match options.language with
      | Some l -> l
      | None -> (
        (* Try to infer the language from the intput file extension. *)
        let ext = Filename.extension !filename in
        if ext = "" then
          Errors.raise_error
            "No file extension found for the file '%s'. (Try to add one or to \
             specify the -l flag)"
            !filename;
        try List.assoc ext extensions with Not_found -> ext)
    in
    let language =
      try List.assoc l languages
      with Not_found ->
        Errors.raise_error
          "The selected language (%s) is not supported by Catala" l
    in
    Cli.locale_lang := language;
    let backend = options.backend in
    let backend =
      match Cli.catala_backend_option_of_string backend with
      | Some b -> b
      | None ->
        Errors.raise_error
          "The selected backend (%s) is not supported by Catala" backend
    in
    let prgm =
      Surface.Parser_driver.parse_top_level_file source_file language
    in
    let prgm = Surface.Fill_positions.fill_pos_with_legislative_info prgm in
    match backend with
    | Cli.Makefile ->
      let backend_extensions_list = [ ".tex" ] in
      let source_file =
        match source_file with
        | FileName f -> f
        | Contents _ ->
          Errors.raise_error
            "The Makefile backend does not work if the input is not a file"
      in
      let output_file =
        match options.output_file with
        | Some f -> f
        | None -> Filename.remove_extension source_file ^ ".d"
      in
      Cli.debug_print "Writing list of dependencies to %s..." output_file;
      let oc = open_out output_file in
      Printf.fprintf oc "%s:\\\n%s\n%s:"
        (String.concat "\\\n"
           (output_file
           :: List.map
                (fun ext -> Filename.remove_extension source_file ^ ext)
                backend_extensions_list))
        (String.concat "\\\n" prgm.program_source_files)
        (String.concat "\\\n" prgm.program_source_files);
      0
    | Cli.Latex | Cli.Html ->
      let source_file =
        match source_file with
        | FileName f -> f
        | Contents _ ->
          Errors.raise_error
            "The literate programming backends do not work if the input is not \
             a file"
      in
      Cli.debug_print "Weaving literate program into %s"
        (match backend with
        | Cli.Latex -> "LaTeX"
        | Cli.Html -> "HTML"
        | _ -> assert false (* should not happen *));
      let output_file =
        match options.output_file with
        | Some f -> f
        | None -> (
          Filename.remove_extension source_file
          ^
          match backend with
          | Cli.Latex -> ".tex"
          | Cli.Html -> ".html"
          | _ -> assert false
          (* should not happen *))
      in
      let oc = open_out output_file in
      let weave_output =
        match backend with
        | Cli.Latex -> Literate.Latex.ast_to_latex language
        | Cli.Html -> Literate.Html.ast_to_html language
        | _ -> assert false
        (* should not happen *)
      in
      Cli.debug_print "Writing to %s" output_file;
      let fmt = Format.formatter_of_out_channel oc in
      if options.wrap_weaved_output then
        match backend with
        | Cli.Latex ->
          Literate.Latex.wrap_latex prgm.Surface.Ast.program_source_files
            language fmt (fun fmt -> weave_output fmt prgm)
        | Cli.Html ->
          Literate.Html.wrap_html prgm.Surface.Ast.program_source_files language
            fmt (fun fmt -> weave_output fmt prgm)
        | _ -> assert false (* should not happen *)
      else weave_output fmt prgm;
      close_out oc;
      0
    | _ -> (
      Cli.debug_print "Name resolution...";
      let ctxt = Surface.Name_resolution.form_context prgm in
      let scope_uid =
        match (options.ex_scope, backend) with
        | None, Cli.Interpret ->
          Errors.raise_error "No scope was provided for execution."
        | None, _ ->
          snd
            (try Desugared.Ast.IdentMap.choose ctxt.scope_idmap
             with Not_found ->
               Errors.raise_error "There isn't any scope inside the program.")
        | Some name, _ -> (
          match Desugared.Ast.IdentMap.find_opt name ctxt.scope_idmap with
          | None ->
            Errors.raise_error "There is no scope \"%s\" inside the program."
              name
          | Some uid -> uid)
      in
      Cli.debug_print "Desugaring...";
      let prgm = Surface.Desugaring.desugar_program ctxt prgm in
      Cli.debug_print "Collecting rules...";
      let prgm = Desugared.Desugared_to_scope.translate_program prgm in
      if backend = Cli.Scopelang then begin
        let fmt, at_end =
          match options.output_file with
          | Some f ->
            let oc = open_out f in
            (Format.formatter_of_out_channel oc, fun _ -> close_out oc)
          | None -> (Format.std_formatter, fun _ -> ())
        in
        if Option.is_some options.ex_scope then
          Format.fprintf fmt "%a\n"
            (Scopelang.Print.format_scope ~debug:options.debug)
            ( scope_uid,
              Scopelang.Ast.ScopeMap.find scope_uid prgm.program_scopes )
        else
          Format.fprintf fmt "%a\n"
            (Scopelang.Print.format_program ~debug:options.debug)
            prgm;
        at_end ();
        exit 0
      end;
      Cli.debug_print "Translating to default calculus...";
      let prgm, type_ordering =
        Scopelang.Scope_to_dcalc.translate_program prgm
      in
      let prgm =
        if options.optimize then begin
          Cli.debug_print "Optimizing default calculus...";
          Dcalc.Optimizations.optimize_program prgm
        end
        else prgm
      in
      let prgrm_dcalc_expr =
        Bindlib.unbox (Dcalc.Ast.build_whole_program_expr prgm scope_uid)
      in
      if backend = Cli.Dcalc then begin
        let fmt, at_end =
          match options.output_file with
          | Some f ->
            let oc = open_out f in
            (Format.formatter_of_out_channel oc, fun _ -> close_out oc)
          | None -> (Format.std_formatter, fun _ -> ())
        in
        if Option.is_some options.ex_scope then
          Format.fprintf fmt "%a\n"
            (Dcalc.Print.format_scope ~debug:options.debug prgm.decl_ctx)
            ( scope_uid,
              Option.get
                (Dcalc.Ast.fold_left_scope_defs ~init:None
                   ~f:(fun acc scope_def _ ->
                     if
                       Dcalc.Ast.ScopeName.compare scope_def.scope_name
                         scope_uid
                       = 0
                     then Some scope_def.scope_body
                     else acc)
                   prgm.scopes) )
        else
          Format.fprintf fmt "%a\n"
            (Dcalc.Print.format_expr prgm.decl_ctx)
            prgrm_dcalc_expr;
        at_end ();
        exit 0
      end;
      Cli.debug_print "Typechecking...";
      let _typ = Dcalc.Typing.infer_type prgm.decl_ctx prgrm_dcalc_expr in
      (* Cli.debug_format "Typechecking results :@\n%a" (Dcalc.Print.format_typ
         prgm.decl_ctx) typ; *)
      match backend with
      | Cli.Typecheck ->
        (* That's it! *)
        Cli.result_print "Typechecking successful!";
        0
      | Cli.Proof ->
        let vcs =
          Verification.Conditions.generate_verification_conditions prgm
            (match options.ex_scope with
            | None -> None
            | Some _ -> Some scope_uid)
        in
        Verification.Solver.solve_vc prgm.decl_ctx vcs;
        0
      | Cli.Interpret ->
        Cli.debug_print "Starting interpretation...";
        let results =
          Dcalc.Interpreter.interpret_program prgm.decl_ctx prgrm_dcalc_expr
        in
        let out_regex = Re.Pcre.regexp "\\_out$" in
        let results =
          List.map
            (fun ((v1, v1_pos), e1) ->
              let v1 =
                Re.Pcre.substitute ~rex:out_regex ~subst:(fun _ -> "") v1
              in
              ((v1, v1_pos), e1))
            results
        in
        let results =
          List.sort
            (fun ((v1, _), _) ((v2, _), _) -> String.compare v1 v2)
            results
        in
        Cli.debug_print "End of interpretation";
        Cli.result_print "Computation successful!%s"
          (if List.length results > 0 then " Results:" else "");
        List.iter
          (fun ((var, _), result) ->
            Cli.result_format "@[<hov 2>%s@ =@ %a@]" var
              (Dcalc.Print.format_expr prgm.decl_ctx)
              result)
          results;
        0
      | Cli.OCaml | Cli.Python | Cli.Lcalc | Cli.Scalc ->
        Cli.debug_print "Compiling program into lambda calculus...";
        let prgm =
          if options.avoid_exceptions then
            Lcalc.Compile_without_exceptions.translate_program prgm
          else Lcalc.Compile_with_exceptions.translate_program prgm
        in
        let prgm =
          if options.optimize then begin
            Cli.debug_print "Optimizing lambda calculus...";
            Lcalc.Optimizations.optimize_program prgm
          end
          else prgm
        in
        let prgm =
          if options.closure_conversion then (
            Cli.debug_print "Performing closure conversion...";
            let prgm = Lcalc.Closure_conversion.closure_conversion prgm in
            let prgm = Bindlib.unbox prgm in
            prgm)
          else prgm
        in
        if backend = Cli.Lcalc then begin
          let fmt, at_end =
            match options.output_file with
            | Some f ->
              let oc = open_out f in
              (Format.formatter_of_out_channel oc, fun _ -> close_out oc)
            | None -> (Format.std_formatter, fun _ -> ())
          in
          if Option.is_some options.ex_scope then
            Format.fprintf fmt "%a\n"
              (Lcalc.Print.format_scope ~debug:options.debug prgm.decl_ctx)
              ( scope_uid,
                Option.get
                  (Dcalc.Ast.fold_left_scope_defs ~init:None
                     ~f:(fun acc scope_def _ ->
                       if
                         Dcalc.Ast.ScopeName.compare scope_def.scope_name
                           scope_uid
                         = 0
                       then Some scope_def.scope_body
                       else acc)
                     prgm.scopes) )
          else
            ignore
              (Dcalc.Ast.fold_left_scope_defs ~init:0
                 ~f:(fun i scope_def _ ->
                   Format.fprintf fmt "%s%a"
                     (if i = 0 then "" else "\n")
                     (Lcalc.Print.format_scope prgm.decl_ctx)
                     (scope_uid, scope_def.scope_body);
                   i + 1)
                 prgm.scopes);
          at_end ();
          exit 0
        end;
        let source_file =
          match source_file with
          | FileName f -> f
          | Contents _ ->
            Errors.raise_error
              "This backend does not work if the input is not a file"
        in
        let new_output_file (extension : string) : string =
          match options.output_file with
          | Some f -> f
          | None -> Filename.remove_extension source_file ^ extension
        in
        (match backend with
        | Cli.OCaml ->
          let output_file = new_output_file ".ml" in
          Cli.debug_print "Writing to %s..." output_file;
          let oc = open_out output_file in
          let fmt = Format.formatter_of_out_channel oc in
          Cli.debug_print "Compiling program into OCaml...";
          Lcalc.To_ocaml.format_program fmt prgm type_ordering;
          close_out oc
        | Cli.Python | Cli.Scalc ->
          let prgm = Scalc.Compile_from_lambda.translate_program prgm in
          if backend = Cli.Scalc then begin
            let fmt, at_end =
              match options.output_file with
              | Some f ->
                let oc = open_out f in
                (Format.formatter_of_out_channel oc, fun _ -> close_out oc)
              | None -> (Format.std_formatter, fun _ -> ())
            in
            if Option.is_some options.ex_scope then
              Format.fprintf fmt "%a\n"
                (Scalc.Print.format_scope ~debug:options.debug prgm.decl_ctx)
                (let body =
                   List.find
                     (fun body -> body.Scalc.Ast.scope_body_name = scope_uid)
                     prgm.scopes
                 in
                 body)
            else
              Format.fprintf fmt "%a\n"
                (Format.pp_print_list
                   ~pp_sep:(fun fmt () -> Format.fprintf fmt "\n\n")
                   (fun fmt scope ->
                     (Scalc.Print.format_scope prgm.decl_ctx) fmt scope))
                prgm.scopes;
            at_end ();
            exit 0
          end;
          let output_file = new_output_file ".py" in
          Cli.debug_print "Compiling program into Python...";
          Cli.debug_print "Writing to %s..." output_file;
          let oc = open_out output_file in
          let fmt = Format.formatter_of_out_channel oc in
          Scalc.To_python.format_program fmt prgm type_ordering;
          close_out oc
        | _ -> assert false (* should not happen *));
        0
      | _ -> assert false
      (* should not happen *))
  with
  | Errors.StructuredError (msg, pos) ->
    Cli.error_print "%s" (Errors.print_structured_error msg pos);
    -1
  | Sys_error msg ->
    Cli.error_print "System error: %s" msg;
    -1

let main () =
  let return_code =
    Cmdliner.Cmd.eval'
      (Cmdliner.Cmd.v Cli.info (Cli.catala_t (fun f -> driver (FileName f))))
  in
  exit return_code