(*****************************************************************************)
(*                                                                           *)
(* Open Source License                                                       *)
(* Copyright (c) 2018 Dynamic Ledger Solutions, Inc. <contact@tezos.com>     *)
(* Copyright (c) 2018 Nomadic Labs. <contact@nomadic-labs.com>               *)
(*                                                                           *)
(* Permission is hereby granted, free of charge, to any person obtaining a   *)
(* copy of this software and associated documentation files (the "Software"),*)
(* to deal in the Software without restriction, including without limitation *)
(* the rights to use, copy, modify, merge, publish, distribute, sublicense,  *)
(* and/or sell copies of the Software, and to permit persons to whom the     *)
(* Software is furnished to do so, subject to the following conditions:      *)
(*                                                                           *)
(* The above copyright notice and this permission notice shall be included   *)
(* in all copies or substantial portions of the Software.                    *)
(*                                                                           *)
(* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR*)
(* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,  *)
(* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL   *)
(* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER*)
(* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING   *)
(* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER       *)
(* DEALINGS IN THE SOFTWARE.                                                 *)
(*                                                                           *)
(*****************************************************************************)

open Error_monad
open Micheline

type 'a parsing_result = 'a * error list

let compare compare (aa, ael) (ba, bel) =
  Compare.or_else (compare aa ba) (fun () ->
      (* FIXME: we need error comparison *)
      Stdlib.compare ael bel)

type point = {point : int; byte : int; line : int; column : int}

let point_zero = {point = 0; byte = 0; line = 0; column = 0}

let point_encoding =
  let open Data_encoding in
  conv
    (fun {line; column; point; byte} -> (line, column, point, byte))
    (fun (line, column, point, byte) -> {line; column; point; byte})
    (obj4
       (req "line" uint16)
       (req "column" uint16)
       (req "point" uint16)
       (req "byte" uint16))

type location = {start : point; stop : point}

let location_zero = {start = point_zero; stop = point_zero}

let location_encoding =
  let open Data_encoding in
  conv
    (fun {start; stop} -> (start, stop))
    (fun (start, stop) -> {start; stop})
    (obj2 (req "start" point_encoding) (req "stop" point_encoding))

type token_value =
  | String of string
  | Bytes of string
  | Int of string
  | Ident of string
  | Annot of string
  | Comment of string
  | Eol_comment of string
  | Semi
  | Open_paren
  | Close_paren
  | Open_brace
  | Close_brace

let token_value_encoding =
  let open Data_encoding in
  union
    [
      case
        (Tag 0)
        ~title:"String"
        (obj1 (req "string" string))
        (function String s -> Some s | _ -> None)
        (fun s -> String s);
      case
        (Tag 1)
        ~title:"Int"
        (obj1 (req "int" string))
        (function Int s -> Some s | _ -> None)
        (fun s -> Int s);
      case
        (Tag 2)
        ~title:"Annot"
        (obj1 (req "annot" string))
        (function Annot s -> Some s | _ -> None)
        (fun s -> Annot s);
      case
        (Tag 3)
        ~title:"Comment"
        (obj2 (req "comment" string) (dft "end_of_line" bool false))
        (function
          | Comment s -> Some (s, false)
          | Eol_comment s -> Some (s, true)
          | _ -> None)
        (function s, false -> Comment s | s, true -> Eol_comment s);
      case
        (Tag 4)
        ~title:"Punctuation"
        (obj1
           (req
              "punctuation"
              (string_enum
                 [
                   ("(", Open_paren);
                   (")", Close_paren);
                   ("{", Open_brace);
                   ("}", Close_brace);
                   (";", Semi);
                 ])))
        (fun t -> Some t)
        (fun t -> t);
      case
        (Tag 5)
        ~title:"Bytes"
        (obj1 (req "bytes" string))
        (function Bytes s -> Some s | _ -> None)
        (fun s -> Bytes s);
      case
        (Tag 6)
        ~title:"Ident"
        (obj1 (req "ident" string))
        (function Ident s -> Some s | _ -> None)
        (fun s -> Ident s);
    ]

type token = {token : token_value; loc : location}

let max_annot_length = 255

type error += Invalid_utf8_sequence of point * string

type error += Unexpected_character of point * string

type error += Undefined_escape_sequence of point * string

type error += Missing_break_after_number of point

type error += Unterminated_string of location

type error += Unterminated_integer of location

type error += Invalid_hex_bytes of location

type error += Unterminated_comment of location

type error += Annotation_length of location

let tokenize source =
  let decoder = Uutf.decoder ~encoding:`UTF_8 (`String source) in
  let here () =
    {
      point = Uutf.decoder_count decoder;
      byte = Uutf.decoder_byte_count decoder;
      line = Uutf.decoder_line decoder;
      column = Uutf.decoder_col decoder;
    }
  in
  let tok start stop token = {loc = {start; stop}; token} in
  let stack = ref [] in
  let errors = ref [] in
  let rec next () =
    match !stack with
    | charloc :: charlocs ->
        stack := charlocs ;
        charloc
    | [] -> (
        let loc = here () in
        match Uutf.decode decoder with
        | `Await -> assert false
        | `Malformed s ->
            errors := Invalid_utf8_sequence (loc, s) :: !errors ;
            next ()
        | (`Uchar _ | `End) as other -> (other, loc))
  in
  let back charloc = stack := charloc :: !stack in
  let uchar_to_char c =
    if Uchar.is_char c then Some (Uchar.to_char c) else None
  in
  let allowed_ident_char c =
    match uchar_to_char c with
    | Some ('a' .. 'z' | 'A' .. 'Z' | '_' | '0' .. '9') -> true
    | Some _ | None -> false
  in
  let allowed_annot_char c =
    match uchar_to_char c with
    | Some ('a' .. 'z' | 'A' .. 'Z' | '_' | '.' | '%' | '@' | '0' .. '9') ->
        true
    | Some _ | None -> false
  in
  let rec skip acc =
    match next () with
    | `End, _ -> List.rev acc
    | `Uchar c, start -> (
        match uchar_to_char c with
        | Some ('a' .. 'z' | 'A' .. 'Z' | '_') ->
            ident acc start (fun s _ -> Ident s)
        | Some ('@' | ':' | '$' | '&' | '%' | '!' | '?') ->
            annot acc start (fun str stop ->
                if String.length str > max_annot_length then
                  errors := Annotation_length {start; stop} :: !errors ;
                Annot str)
        | Some '-' -> (
            match next () with
            | `End, stop ->
                errors := Unterminated_integer {start; stop} :: !errors ;
                List.rev acc
            | (`Uchar c, stop) as first -> (
                match uchar_to_char c with
                | Some '0' -> base acc start
                | Some '1' .. '9' -> integer acc start
                | Some _ | None ->
                    errors := Unterminated_integer {start; stop} :: !errors ;
                    back first ;
                    skip acc))
        | Some '0' -> base acc start
        | Some '1' .. '9' -> integer acc start
        | Some (' ' | '\n') -> skip acc
        | Some ';' -> skip (tok start (here ()) Semi :: acc)
        | Some '{' -> skip (tok start (here ()) Open_brace :: acc)
        | Some '}' -> skip (tok start (here ()) Close_brace :: acc)
        | Some '(' -> skip (tok start (here ()) Open_paren :: acc)
        | Some ')' -> skip (tok start (here ()) Close_paren :: acc)
        | Some '"' -> string acc [] start
        | Some '#' -> eol_comment acc start
        | Some '/' -> (
            match next () with
            | `Uchar c, _ when Uchar.equal c (Uchar.of_char '*') ->
                comment acc start 0
            | ((`Uchar _ | `End), _) as charloc ->
                errors := Unexpected_character (start, "/") :: !errors ;
                back charloc ;
                skip acc)
        | Some _ | None ->
            let byte = Uutf.decoder_byte_count decoder in
            let s = String.sub source start.byte (byte - start.byte) in
            errors := Unexpected_character (start, s) :: !errors ;
            skip acc)
  and base acc start =
    match next () with
    | (`Uchar c, stop) as charloc -> (
        match uchar_to_char c with
        | Some '0' .. '9' -> integer acc start
        | Some 'x' -> bytes acc start
        | Some ('a' .. 'w' | 'y' | 'z' | 'A' .. 'Z' | '_') ->
            errors := Missing_break_after_number stop :: !errors ;
            back charloc ;
            skip (tok start stop (Int "0") :: acc)
        | Some _ | None ->
            back charloc ;
            skip (tok start stop (Int "0") :: acc))
    | (_, stop) as other ->
        back other ;
        skip (tok start stop (Int "0") :: acc)
  and integer acc start =
    let tok stop =
      let value = String.sub source start.byte (stop.byte - start.byte) in
      tok start stop (Int value)
    in
    match next () with
    | (`Uchar c, stop) as charloc -> (
        let missing_break () =
          errors := Missing_break_after_number stop :: !errors ;
          back charloc ;
          skip (tok stop :: acc)
        in
        match Uchar.to_char c with
        | '0' .. '9' -> integer acc start
        | 'a' .. 'z' | 'A' .. 'Z' | '_' -> missing_break ()
        | _ ->
            back charloc ;
            skip (tok stop :: acc))
    | (`End, stop) as other ->
        back other ;
        skip (tok stop :: acc)
  and bytes acc start =
    let tok stop =
      let value = String.sub source start.byte (stop.byte - start.byte) in
      tok start stop (Bytes value)
    in
    match next () with
    | (`Uchar c, stop) as charloc -> (
        let missing_break () =
          errors := Missing_break_after_number stop :: !errors ;
          back charloc ;
          skip (tok stop :: acc)
        in
        match Uchar.to_char c with
        | '0' .. '9' | 'a' .. 'f' | 'A' .. 'F' -> bytes acc start
        | 'g' .. 'z' | 'G' .. 'Z' -> missing_break ()
        | _ ->
            back charloc ;
            skip (tok stop :: acc))
    | (`End, stop) as other ->
        back other ;
        skip (tok stop :: acc)
  and string acc sacc start =
    let tok () =
      tok start (here ()) (String (String.concat "" (List.rev sacc)))
    in
    match next () with
    | `End, stop ->
        errors := Unterminated_string {start; stop} :: !errors ;
        skip (tok () :: acc)
    | `Uchar c, stop -> (
        match uchar_to_char c with
        | Some '"' -> skip (tok () :: acc)
        | Some ('\n' | '\r') ->
            errors := Unterminated_string {start; stop} :: !errors ;
            skip (tok () :: acc)
        | Some '\\' -> (
            match next () with
            | `End, stop ->
                errors := Unterminated_string {start; stop} :: !errors ;
                skip (tok () :: acc)
            | `Uchar c, loc -> (
                match uchar_to_char c with
                | Some '"' -> string acc ("\"" :: sacc) start
                | Some 'r' -> string acc ("\r" :: sacc) start
                | Some 'n' -> string acc ("\n" :: sacc) start
                | Some 't' -> string acc ("\t" :: sacc) start
                | Some 'b' -> string acc ("\b" :: sacc) start
                | Some '\\' -> string acc ("\\" :: sacc) start
                | Some _ | None ->
                    let byte = Uutf.decoder_byte_count decoder in
                    let s = String.sub source loc.byte (byte - loc.byte) in
                    errors := Undefined_escape_sequence (loc, s) :: !errors ;
                    string acc sacc start))
        | Some _ | None ->
            let byte = Uutf.decoder_byte_count decoder in
            let s = String.sub source stop.byte (byte - stop.byte) in
            string acc (s :: sacc) start)
  and generic_ident allow_char acc start (ret : string -> point -> token_value)
      =
    let tok stop =
      let name = String.sub source start.byte (stop.byte - start.byte) in
      tok start stop (ret name stop)
    in
    match next () with
    | (`Uchar c, stop) as charloc ->
        if allow_char c then generic_ident allow_char acc start ret
        else (
          back charloc ;
          skip (tok stop :: acc))
    | (_, stop) as other ->
        back other ;
        skip (tok stop :: acc)
  and ident acc start ret = generic_ident allowed_ident_char acc start ret
  and annot acc start ret = generic_ident allowed_annot_char acc start ret
  and comment acc start lvl =
    match next () with
    | `End, stop ->
        errors := Unterminated_comment {start; stop} :: !errors ;
        let text = String.sub source start.byte (stop.byte - start.byte) in
        skip (tok start stop (Comment text) :: acc)
    | `Uchar c, _ -> (
        match uchar_to_char c with
        | Some '*' -> (
            match next () with
            | `Uchar c, _ when Uchar.equal c (Uchar.of_char '/') ->
                if lvl = 0 then
                  let stop = here () in
                  let text =
                    String.sub source start.byte (stop.byte - start.byte)
                  in
                  skip (tok start stop (Comment text) :: acc)
                else comment acc start (lvl - 1)
            | other ->
                back other ;
                comment acc start lvl)
        | Some '/' -> (
            match next () with
            | `Uchar c, _ when Uchar.equal c (Uchar.of_char '*') ->
                comment acc start (lvl + 1)
            | other ->
                back other ;
                comment acc start lvl)
        | Some _ | None -> comment acc start lvl)
  and eol_comment acc start =
    let tok stop =
      let text = String.sub source start.byte (stop.byte - start.byte) in
      tok start stop (Eol_comment text)
    in
    match next () with
    | `Uchar c, stop -> (
        match uchar_to_char c with
        | Some '\n' -> skip (tok stop :: acc)
        | Some _ | None -> eol_comment acc start)
    | (_, stop) as other ->
        back other ;
        skip (tok stop :: acc)
  in
  let tokens = skip [] in
  (tokens, List.rev !errors)

type node = (location, string) Micheline.node

(* Beginning of a sequence of consecutive primitives *)
let min_point : node list -> point = function
  | [] -> point_zero
  | Int ({start; _}, _) :: _
  | String ({start; _}, _) :: _
  | Bytes ({start; _}, _) :: _
  | Prim ({start; _}, _, _, _) :: _
  | Seq ({start; _}, _) :: _ ->
      start

(* End of a sequence of consecutive primitives *)
let rec max_point : node list -> point = function
  | [] -> point_zero
  | _ :: (_ :: _ as rest) -> max_point rest
  | [Int ({stop; _}, _)]
  | [String ({stop; _}, _)]
  | [Bytes ({stop; _}, _)]
  | [Prim ({stop; _}, _, _, _)]
  | [Seq ({stop; _}, _)] ->
      stop

(* An item in the parser's state stack.
   Not every value of type [mode list] is a valid parsing context.
   It must respect the following additional invariants.
   - a state stack always ends in [Toplevel _],
   - [Toplevel _] does not appear anywhere else,
   - [Unwrapped _] cannot appear directly on top of [Wrapped _],
   - [Wrapped _] cannot appear directly on top of [Sequence _],
   - [Wrapped _] cannot appear directly on top of [Sequence _]. *)
type mode =
  | Toplevel of node list
  | Expression of node option
  | Sequence of token * node list
  | Unwrapped of location * string * node list * string list
  | Wrapped of token * string * node list * string list

(* Enter a new parsing state. *)
let push_mode mode stack = mode :: stack

(* Leave a parsing state. *)
let pop_mode = function [] -> assert false | _ :: rest -> rest

(* Usually after a [pop_mode], jump back into the previous parsing
   state, injecting the current reduction (insert the just parsed item
   of a sequence or argument of a primitive application). *)
let fill_mode result = function
  | [] -> assert false
  | Expression _ :: _ :: _ -> assert false
  | [Expression (Some _)] -> assert false
  | Toplevel _ :: _ :: _ -> assert false
  | [Expression None] -> [Expression (Some result)]
  | [Toplevel exprs] -> [Toplevel (result :: exprs)]
  | Sequence (token, exprs) :: rest -> Sequence (token, result :: exprs) :: rest
  | Wrapped (token, name, exprs, annot) :: rest ->
      Wrapped (token, name, result :: exprs, annot) :: rest
  | Unwrapped (start, name, exprs, annot) :: rest ->
      Unwrapped (start, name, result :: exprs, annot) :: rest

type error += Unclosed of token

type error += Unexpected of token

type error += Extra of token

type error += Misaligned of node

type error += Empty

let rec annots = function
  | {token = Annot annot; _} :: rest ->
      let annots, rest = annots rest in
      (annot :: annots, rest)
  | rest -> ([], rest)

let rec parse ?(check = true) errors tokens stack =
  (* Two steps:
     - 1. parse without checking indentation [parse]
     - 2. check indentation [check] (inlined in 1) *)
  match (stack, tokens) with
  (* Start by preventing all absurd cases, so now the pattern
     matching exhaustivity can tell us that we treater all
     possible tokens for all possible valid states. *)
  | [], _
  | [Wrapped _], _
  | [Unwrapped _], _
  | Unwrapped _ :: Unwrapped _ :: _, _
  | Unwrapped _ :: Wrapped _ :: _, _
  | Toplevel _ :: _ :: _, _
  | Expression _ :: _ :: _, _ ->
      assert false
  (* Return *)
  | Expression (Some result) :: _, [] -> ([result], List.rev errors)
  | Expression (Some _) :: _, token :: rem ->
      let errors = Unexpected token :: errors in
      parse ~check errors rem (* skip *) stack
  | Expression None :: _, [] ->
      let errors = Empty :: errors in
      let ghost = {start = point_zero; stop = point_zero} in
      ([Seq (ghost, [])], List.rev errors)
  | [Toplevel [(Seq (_, exprs) as expr)]], [] ->
      let errors =
        if check then do_check ~toplevel:false errors expr else errors
      in
      (exprs, List.rev errors)
  | [Toplevel exprs], [] ->
      let exprs = List.rev exprs in
      let loc = {start = min_point exprs; stop = max_point exprs} in
      let expr = Seq (loc, exprs) in
      let errors =
        if check then do_check ~toplevel:true errors expr else errors
      in
      (exprs, List.rev errors)
  (* Ignore comments *)
  | _, {token = Eol_comment _ | Comment _; _} :: rest ->
      parse ~check errors rest stack
  | ( (Expression None | Sequence _ | Toplevel _) :: _,
      ({token = Int _ | String _ | Bytes _; _} as token)
      :: {token = Eol_comment _ | Comment _; _}
      :: rest )
  | ( (Wrapped _ | Unwrapped _) :: _,
      ({token = Open_paren; _} as token)
      :: {token = Eol_comment _ | Comment _; _}
      :: rest ) ->
      parse ~check errors (token :: rest) stack
  (* Erroneous states *)
  | ( (Wrapped _ | Unwrapped _) :: _,
      ({token = Open_paren; _} as token)
      :: {token = Open_paren | Open_brace; _}
      :: rem )
  | ( Unwrapped _ :: Expression _ :: _,
      ({token = Semi | Close_brace | Close_paren; _} as token) :: rem )
  | ( Expression None :: _,
      ({token = Semi | Close_brace | Close_paren | Open_paren; _} as token)
      :: rem ) ->
      let errors = Unexpected token :: errors in
      parse ~check errors rem (* skip *) stack
  | ( (Sequence _ | Toplevel _) :: _,
      ({token = Semi; _} as valid) :: ({token = Semi; _} as token) :: rem ) ->
      let errors = Extra token :: errors in
      parse ~check errors (* skip *) (valid :: rem) stack
  | ( (Wrapped _ | Unwrapped _) :: _,
      {token = Open_paren; _}
      :: ({token = Int _ | String _ | Bytes _ | Annot _ | Close_paren; _} as
         token)
      :: rem )
  | ( (Expression None | Sequence _ | Toplevel _) :: _,
      {token = Int _ | String _ | Bytes _; _}
      :: ({
            token =
              ( Ident _ | Int _ | String _ | Bytes _ | Annot _ | Close_paren
              | Open_paren | Open_brace );
            _;
          } as token)
      :: rem )
  | ( Unwrapped (_, _, _, _) :: Toplevel _ :: _,
      ({token = Close_brace; _} as token) :: rem )
  | Unwrapped (_, _, _, _) :: _, ({token = Close_paren; _} as token) :: rem
  | [Toplevel _], ({token = Close_paren; _} as token) :: rem
  | [Toplevel _], ({token = Open_paren; _} as token) :: rem
  | [Toplevel _], ({token = Close_brace; _} as token) :: rem
  | Sequence _ :: _, ({token = Open_paren; _} as token) :: rem
  | Sequence _ :: _, ({token = Close_paren; _} as token) :: rem
  | ( (Wrapped _ | Unwrapped _) :: _,
      ({token = Open_paren; _} as token)
      :: (({token = Close_brace | Semi; _} :: _ | []) as rem) )
  | _, ({token = Annot _; _} as token) :: rem ->
      let errors = Unexpected token :: errors in
      parse ~check errors rem (* skip *) stack
  | Wrapped (token, _, _, _) :: _, ([] | {token = Close_brace | Semi; _} :: _)
    ->
      let errors = Unclosed token :: errors in
      let fake = {token with token = Close_paren} in
      let tokens = (* insert *) fake :: tokens in
      parse ~check errors tokens stack
  | (Sequence (token, _) :: _ | Unwrapped _ :: Sequence (token, _) :: _), [] ->
      let errors = Unclosed token :: errors in
      let fake = {token with token = Close_brace} in
      let tokens = (* insert *) fake :: tokens in
      parse ~check errors tokens stack
  (* Valid states *)
  | ( (Toplevel _ | Sequence (_, _)) :: _,
      {token = Ident name; loc} :: ({token = Annot _; _} :: _ as rest) ) ->
      let annots, rest = annots rest in
      let mode = Unwrapped (loc, name, [], annots) in
      parse ~check errors rest (push_mode mode stack)
  | ( (Expression None | Toplevel _ | Sequence (_, _)) :: _,
      {token = Ident name; loc} :: rest ) ->
      let mode = Unwrapped (loc, name, [], []) in
      parse ~check errors rest (push_mode mode stack)
  | (Unwrapped _ | Wrapped _) :: _, {token = Int value; loc} :: rest
  | ( (Expression None | Sequence _ | Toplevel _) :: _,
      {token = Int value; loc}
      :: (([] | {token = Semi | Close_brace; _} :: _) as rest) ) ->
      let expr : node = Int (loc, Z.of_string value) in
      let errors =
        if check then do_check ~toplevel:false errors expr else errors
      in
      parse ~check errors rest (fill_mode expr stack)
  | (Unwrapped _ | Wrapped _) :: _, {token = String contents; loc} :: rest
  | ( (Expression None | Sequence _ | Toplevel _) :: _,
      {token = String contents; loc}
      :: (([] | {token = Semi | Close_brace; _} :: _) as rest) ) ->
      let expr : node = String (loc, contents) in
      let errors =
        if check then do_check ~toplevel:false errors expr else errors
      in
      parse ~check errors rest (fill_mode expr stack)
  | (Unwrapped _ | Wrapped _) :: _, {token = Bytes contents; loc} :: rest
  | ( (Expression None | Sequence _ | Toplevel _) :: _,
      {token = Bytes contents; loc}
      :: (([] | {token = Semi | Close_brace; _} :: _) as rest) ) ->
      let errors, bytes =
        match
          Hex.to_bytes
            (`Hex (String.sub contents 2 (String.length contents - 2)))
        with
        | None -> (Invalid_hex_bytes loc :: errors, Bytes.empty)
        | Some bytes -> (errors, bytes)
      in
      let expr : node = Bytes (loc, bytes) in
      let errors =
        if check then do_check ~toplevel:false errors expr else errors
      in
      parse ~check errors rest (fill_mode expr stack)
  | ( Sequence ({loc = {start; _}; _}, exprs) :: _,
      {token = Close_brace; loc = {stop; _}} :: rest ) ->
      let exprs = List.rev exprs in
      let expr = Micheline.Seq ({start; stop}, exprs) in
      let errors =
        if check then do_check ~toplevel:false errors expr else errors
      in
      parse ~check errors rest (fill_mode expr (pop_mode stack))
  | (Sequence _ | Toplevel _) :: _, {token = Semi; _} :: rest ->
      parse ~check errors rest stack
  | ( Unwrapped ({start; stop}, name, exprs, annot) :: Expression _ :: _,
      ([] as rest) )
  | ( Unwrapped ({start; stop}, name, exprs, annot) :: Toplevel _ :: _,
      (({token = Semi; _} :: _ | []) as rest) )
  | ( Unwrapped ({start; stop}, name, exprs, annot) :: Sequence _ :: _,
      ({token = Close_brace | Semi; _} :: _ as rest) )
  | ( Wrapped ({loc = {start; stop}; _}, name, exprs, annot) :: _,
      {token = Close_paren; _} :: rest ) ->
      let exprs = List.rev exprs in
      let stop = if exprs = [] then stop else max_point exprs in
      let expr = Micheline.Prim ({start; stop}, name, exprs, annot) in
      let errors =
        if check then do_check ~toplevel:false errors expr else errors
      in
      parse ~check errors rest (fill_mode expr (pop_mode stack))
  | ( (Wrapped _ | Unwrapped _) :: _,
      ({token = Open_paren; _} as token)
      :: {token = Ident name; _}
      :: ({token = Annot _; _} :: _ as rest) ) ->
      let annots, rest = annots rest in
      let mode = Wrapped (token, name, [], annots) in
      parse ~check errors rest (push_mode mode stack)
  | ( (Wrapped _ | Unwrapped _) :: _,
      ({token = Open_paren; _} as token) :: {token = Ident name; _} :: rest ) ->
      let mode = Wrapped (token, name, [], []) in
      parse ~check errors rest (push_mode mode stack)
  | (Wrapped _ | Unwrapped _) :: _, {token = Ident name; loc} :: rest ->
      let expr = Micheline.Prim (loc, name, [], []) in
      let errors =
        if check then do_check ~toplevel:false errors expr else errors
      in
      parse ~check errors rest (fill_mode expr stack)
  | ( (Wrapped _ | Unwrapped _ | Toplevel _ | Sequence _ | Expression None) :: _,
      ({token = Open_brace; _} as token) :: rest ) ->
      let mode = Sequence (token, []) in
      parse ~check errors rest (push_mode mode stack)

(* indentation checker *)
and do_check ?(toplevel = false) errors = function
  | Seq ({start; stop}, []) as expr ->
      if start.column >= stop.column then Misaligned expr :: errors else errors
  | ( Prim ({start; stop}, _, first :: rest, _)
    | Seq ({start; stop}, first :: rest) ) as expr ->
      let {column = first_column; line = first_line; _} = min_point [first] in
      if start.column >= stop.column then Misaligned expr :: errors
      else if (not toplevel) && start.column >= first_column then
        Misaligned expr :: errors
      else
        (* In a sequence or in the arguments of a primitive, we
           require all items to be aligned, but we relax the rule to
           allow consecutive items to be written on the same line. *)
        let rec in_line_or_aligned prev_start_line errors = function
          | [] -> errors
          | expr :: rest ->
              let {column; line = start_line; _} = min_point [expr] in
              let {line = stop_line; _} = max_point [expr] in
              let errors =
                if stop_line <> prev_start_line && column <> first_column then
                  Misaligned expr :: errors
                else errors
              in
              in_line_or_aligned start_line errors rest
        in
        in_line_or_aligned first_line errors rest
  | Prim (_, _, [], _) | String _ | Int _ | Bytes _ -> errors

let parse_expression ?check tokens =
  let result =
    match tokens with
    | ({token = Open_paren; _} as token)
      :: {token = Ident name; _}
      :: {token = Annot annot; _}
      :: rest ->
        let annots, rest = annots rest in
        let mode = Wrapped (token, name, [], annot :: annots) in
        parse ?check [] rest [mode; Expression None]
    | ({token = Open_paren; _} as token) :: {token = Ident name; _} :: rest ->
        let mode = Wrapped (token, name, [], []) in
        parse ?check [] rest [mode; Expression None]
    | _ -> parse ?check [] tokens [Expression None]
  in
  match result with [single], errors -> (single, errors) | _ -> assert false

let parse_toplevel ?check tokens = parse ?check [] tokens [Toplevel []]

let print_point ppf {line; column; _} =
  Format.fprintf ppf "At line %d character %d" line column

let print_token_kind ppf = function
  | Open_paren | Close_paren -> Format.fprintf ppf "parenthesis"
  | Open_brace | Close_brace -> Format.fprintf ppf "curly brace"
  | String _ -> Format.fprintf ppf "string constant"
  | Bytes _ -> Format.fprintf ppf "bytes constant"
  | Int _ -> Format.fprintf ppf "integer constant"
  | Ident _ -> Format.fprintf ppf "identifier"
  | Annot _ -> Format.fprintf ppf "annotation"
  | Comment _ | Eol_comment _ -> Format.fprintf ppf "comment"
  | Semi -> Format.fprintf ppf "semi colon"

let print_location ppf loc =
  if loc.start.line = loc.stop.line then
    if loc.start.column = loc.stop.column then
      Format.fprintf
        ppf
        "At line %d character %d"
        loc.start.line
        loc.start.column
    else
      Format.fprintf
        ppf
        "At line %d characters %d to %d"
        loc.start.line
        loc.start.column
        loc.stop.column
  else
    Format.fprintf
      ppf
      "From line %d character %d to line %d character %d"
      loc.start.line
      loc.start.column
      loc.stop.line
      loc.stop.column

let no_parsing_error (ast, errors) =
  match errors with [] -> Ok ast | errors -> Error errors

let () =
  register_error_kind
    `Permanent
    ~id:"micheline.parse_error.invalid_utf8_sequence"
    ~title:"Micheline parser error: invalid UTF-8 sequence"
    ~description:
      "While parsing a piece of Micheline source, a sequence of bytes that is \
       not valid UTF-8 was encountered."
    ~pp:(fun ppf (point, str) ->
      Format.fprintf ppf "%a, invalid UTF-8 sequence %S" print_point point str)
    Data_encoding.(obj2 (req "point" point_encoding) (req "sequence" string))
    (function
      | Invalid_utf8_sequence (point, str) -> Some (point, str) | _ -> None)
    (fun (point, str) -> Invalid_utf8_sequence (point, str)) ;
  register_error_kind
    `Permanent
    ~id:"micheline.parse_error.unexpected_character"
    ~title:"Micheline parser error: unexpected character"
    ~description:
      "While parsing a piece of Micheline source, an unexpected character was \
       encountered."
    ~pp:(fun ppf (point, str) ->
      Format.fprintf ppf "%a, unexpected character %s" print_point point str)
    Data_encoding.(obj2 (req "point" point_encoding) (req "character" string))
    (function
      | Unexpected_character (point, str) -> Some (point, str) | _ -> None)
    (fun (point, str) -> Unexpected_character (point, str)) ;
  register_error_kind
    `Permanent
    ~id:"micheline.parse_error.undefined_escape_sequence"
    ~title:"Micheline parser error: undefined escape sequence"
    ~description:
      "While parsing a piece of Micheline source, an unexpected escape \
       sequence was encountered in a string."
    ~pp:(fun ppf (point, str) ->
      Format.fprintf
        ppf
        "%a, undefined escape sequence \"%s\""
        print_point
        point
        str)
    Data_encoding.(obj2 (req "point" point_encoding) (req "sequence" string))
    (function
      | Undefined_escape_sequence (point, str) -> Some (point, str) | _ -> None)
    (fun (point, str) -> Undefined_escape_sequence (point, str)) ;
  register_error_kind
    `Permanent
    ~id:"micheline.parse_error.missing_break_after_number"
    ~title:"Micheline parser error: missing break after number"
    ~description:
      "While parsing a piece of Micheline source, a number was not visually \
       separated from its follower token, leading to misreadability."
    ~pp:(fun ppf point ->
      Format.fprintf ppf "%a, missing break after number" print_point point)
    Data_encoding.(obj1 (req "point" point_encoding))
    (function Missing_break_after_number point -> Some point | _ -> None)
    (fun point -> Missing_break_after_number point) ;
  register_error_kind
    `Permanent
    ~id:"micheline.parse_error.unterminated_string"
    ~title:"Micheline parser error: unterminated string"
    ~description:
      "While parsing a piece of Micheline source, a string was not terminated."
    ~pp:(fun ppf loc ->
      Format.fprintf ppf "%a, unterminated string" print_location loc)
    Data_encoding.(obj1 (req "location" location_encoding))
    (function Unterminated_string loc -> Some loc | _ -> None)
    (fun loc -> Unterminated_string loc) ;
  register_error_kind
    `Permanent
    ~id:"micheline.parse_error.unterminated_integer"
    ~title:"Micheline parser error: unterminated integer"
    ~description:
      "While parsing a piece of Micheline source, an integer was not \
       terminated."
    ~pp:(fun ppf loc ->
      Format.fprintf ppf "%a, unterminated integer" print_location loc)
    Data_encoding.(obj1 (req "location" location_encoding))
    (function Unterminated_integer loc -> Some loc | _ -> None)
    (fun loc -> Unterminated_integer loc) ;
  register_error_kind
    `Permanent
    ~id:"micheline.parse_error.invalid_hex_bytes"
    ~title:"Micheline parser error: invalid hex bytes"
    ~description:
      "While parsing a piece of Micheline source, a byte sequence (0x...) was \
       not valid as a hex byte."
    ~pp:(fun ppf loc ->
      Format.fprintf ppf "%a, invalid hex bytes" print_location loc)
    Data_encoding.(obj1 (req "location" location_encoding))
    (function Invalid_hex_bytes loc -> Some loc | _ -> None)
    (fun loc -> Invalid_hex_bytes loc) ;
  register_error_kind
    `Permanent
    ~id:"micheline.parse_error.unterminated_comment"
    ~title:"Micheline parser error: unterminated comment"
    ~description:
      "While parsing a piece of Micheline source, a commentX was not \
       terminated."
    ~pp:(fun ppf loc ->
      Format.fprintf ppf "%a, unterminated comment" print_location loc)
    Data_encoding.(obj1 (req "location" location_encoding))
    (function Unterminated_comment loc -> Some loc | _ -> None)
    (fun loc -> Unterminated_comment loc) ;
  register_error_kind
    `Permanent
    ~id:"micheline.parse_error.annotation_exceeds_max_length"
    ~title:"Micheline parser error: annotation exceeds max length"
    ~description:
      (Format.sprintf
         "While parsing a piece of Micheline source, an annotation exceeded \
          the maximum length (%d)."
         max_annot_length)
    ~pp:(fun ppf loc ->
      Format.fprintf
        ppf
        "%a, annotation exceeded maximum length (%d chars)"
        print_location
        loc
        max_annot_length)
    Data_encoding.(obj1 (req "location" location_encoding))
    (function Annotation_length loc -> Some loc | _ -> None)
    (fun loc -> Annotation_length loc) ;
  register_error_kind
    `Permanent
    ~id:"micheline.parse_error.unclosed_token"
    ~title:"Micheline parser error: unclosed token"
    ~description:
      "While parsing a piece of Micheline source, a parenthesis or a brace was \
       unclosed."
    ~pp:(fun ppf (loc, token) ->
      Format.fprintf
        ppf
        "%a, unclosed %a"
        print_location
        loc
        print_token_kind
        token)
    Data_encoding.(
      obj2 (req "location" location_encoding) (req "token" token_value_encoding))
    (function Unclosed {loc; token} -> Some (loc, token) | _ -> None)
    (fun (loc, token) -> Unclosed {loc; token}) ;
  register_error_kind
    `Permanent
    ~id:"micheline.parse_error.unexpected_token"
    ~title:"Micheline parser error: unexpected token"
    ~description:
      "While parsing a piece of Micheline source, an unexpected token was \
       encountered."
    ~pp:(fun ppf (loc, token) ->
      Format.fprintf
        ppf
        "%a, unexpected %a"
        print_location
        loc
        print_token_kind
        token)
    Data_encoding.(
      obj2 (req "location" location_encoding) (req "token" token_value_encoding))
    (function Unexpected {loc; token} -> Some (loc, token) | _ -> None)
    (fun (loc, token) -> Unexpected {loc; token}) ;
  register_error_kind
    `Permanent
    ~id:"micheline.parse_error.extra_token"
    ~title:"Micheline parser error: extra token"
    ~description:
      "While parsing a piece of Micheline source, an extra semi colon or \
       parenthesis was encountered."
    ~pp:(fun ppf (loc, token) ->
      Format.fprintf
        ppf
        "%a, extra %a"
        print_location
        loc
        print_token_kind
        token)
    Data_encoding.(
      obj2 (req "location" location_encoding) (req "token" token_value_encoding))
    (function Extra {loc; token} -> Some (loc, token) | _ -> None)
    (fun (loc, token) -> Extra {loc; token}) ;
  (* [Misaligned] is registered in the encoding module to break a dependency
     cycle *)
  register_error_kind
    `Permanent
    ~id:"micheline.parse_error.empty_expression"
    ~title:"Micheline parser error: empty_expression"
    ~description:
      "Tried to interpret an empty piece or Micheline source as a single \
       expression."
    ~pp:(fun ppf () -> Format.fprintf ppf "empty expression")
    Data_encoding.empty
    (function Empty -> Some () | _ -> None)
    (fun () -> Empty)

(* helper functions for the encoding *)

let check_annot s =
  String.length s <= max_annot_length
  &&
  match tokenize s with
  | [{token = Annot s'; _}], [] (* no errors *) -> String.equal s s'
  | _ -> false