(** All the types used in the spreadsheet. *)

let u = UTF8.from_utf8string

exception Error

type cell = Cell.t

type ident = UTF8.t

type _ dataFormat =
  | Date:   DataType.Num.t dataFormat   (* Date *)
  | Number: DataType.Num.t dataFormat   (* Number *)
  | String: DataType.String.t dataFormat(* String  *)
  | Bool:   DataType.Bool.t dataFormat  (* Boolean *)

type numericType =
  | Date
  | Number

let get_numeric_type: DataType.Num.t dataFormat -> numericType = function
  | Date -> Date
  | Number -> Number

type 'a types =
  | Num  : DataType.Num.t dataFormat * DataType.Num.t -> DataType.Num.t types    (** A number *)
  | Str  : DataType.String.t -> DataType.String.t types         (** A string *)
  | Bool : DataType.Bool.t -> DataType.Bool.t types             (** A boolean *)

let number n = Num (Number, n)
let string s = Str s
let date d = Num (Date, d)
let boolean b = Bool b


type 'a returnType =
  | Num  : DataType.Num.t dataFormat option -> DataType.Num.t returnType    (** A number *)
  | Str  : DataType.String.t returnType                         (** A string *)
  | Bool : DataType.Bool.t returnType                           (** A boolean *)


let f_num: DataType.Num.t returnType  = Num None
let f_date: DataType.Num.t returnType = Num (Some Date)
let f_number: DataType.Num.t returnType = Num (Some Number)
let f_string: DataType.String.t returnType = Str
let f_bool: DataType.Bool.t returnType = Bool

type refs =
  | Cell of cell                                      (** A cell *)
  | Range of cell * cell                              (** An area of cells *)

type expression =
  | Value : 'a types -> expression                    (** A direct value *)
  | Ref : refs -> expression                          (** A reference to another cell *)
  | Call : ident * expression list -> expression      (** A call to a function *)
  | Expression : expression -> expression             (** An expression *)

(** Result from a computation *)
type result =
  | Result : 'a types -> result
  | Error : exn -> result

module DataFormat = struct

  type formats = F : 'a dataFormat -> formats [@@unboxed]

  let priority: type a. a dataFormat -> int = function
    | Date   -> 1
    | Number -> 0
    | String -> 0
    | Bool   -> 0

  let collect_format: DataType.Num.t dataFormat -> formats -> DataType.Num.t dataFormat = begin
  fun dataFormat -> function
    | F Date -> Date
    | _ -> dataFormat
  end

  let guess_format_result: type a. a returnType -> (unit -> formats list) -> a dataFormat =
    fun return params -> begin match return with
    | Str -> String
    | Bool -> Bool
    | Num (Some x) -> x
    | Num None -> List.fold_left collect_format Number (params ())
  end

  let default_value_for: type a. a dataFormat -> a = function
    | Date -> DataType.Num.nan
    | Number -> DataType.Num.nan
    | Bool -> false
    | String -> UTF8.empty

  let compare_format: type a b. a dataFormat -> b dataFormat -> (a, b) equality =
    fun a b -> begin match a, b with
    | Date, Date -> Eq
    | String, String -> Eq
    | Number, Number -> Eq
    | Date, Number -> Eq
    | Number, Date -> Eq
    | Bool, Bool -> Eq
    | _, _ -> raise Errors.TypeError
    end

end

module Type = struct
  (* Required because Num.Big_int cannot be compared with Pervasives.(=) *)
  let (=) : type a b. a types -> b types -> bool = fun t1 t2 ->
    match t1, t2 with
    | Num (_, n1), Num (_, n2) -> DataType.Num.eq n1 n2
    | Bool b1, Bool b2 -> b1 = b2
    | Str s1, Str s2 -> s1 = s2
    | _, _ -> false

  (** Show a list of elements
   *)
  let rec show_list printer buffer = begin function
    | [] -> ()
    | hd::[] ->
        UTF8.Printf.bprintf buffer "%a"
        printer hd
    | hd::tl ->
        UTF8.Printf.bprintf buffer "%a, "
        printer hd;
        show_list printer buffer tl
  end

  and show: type a. UTF8.Buffer.buffer -> a types -> unit = fun buffer -> begin function
    | Str x     -> UTF8.Buffer.add_string buffer x
    | Bool b    -> UTF8.Printf.bprintf buffer "%B" b
    | Num (Number, n)     ->
      let n = DataType.Num.to_num n in
      if Num.is_integer_num n then
        UTF8.Buffer.add_string buffer @@ u(Num.string_of_num n)
      else
        let to_b = UTF8.Format.formatter_of_buffer buffer in
        ignore @@ UTF8.Format.fprintf to_b "%.2f" (Num.float_of_num n);
        Format.pp_print_flush to_b ()
    | Num (Date, n)    ->
        let y, m, d = Date.date_from_julian_day (DataType.Num.to_num n) in
        UTF8.Printf.bprintf buffer "%d/%d/%d" y m d
  end

  type t =
    | Value: 'a dataFormat * 'a -> t

  let get_content : type a. a types -> t = begin function
    | Num (format, data) -> Value (format, data)
    | Str s -> Value (String, s)
    | Bool b -> Value (Bool, b)
  end

end

module Refs = struct

  type 'a range =
    | Single of 'a
    | Array1 of 'a list
    | Array2 of 'a list list

  let collect = function
    | Cell x -> Single (Pervasives.fst x)
    | Range (fst, snd) ->
        let (x1, y1) = Pervasives.fst fst
        and (x2, y2) = Pervasives.fst snd in
        let min_x = min x1 x2
        and max_x = max x1 x2
        and min_y = min y1 y2
        and max_y = max y1 y2 in
        if (min_x = max_x) || (min_y = max_y) then (
          (* There is only a one dimension array *)
          let elms = ref [] in
          for x = min_x to max_x do
            for y = min_y to max_y do
              elms := (x, y)::!elms
            done
          done;
          Array1 (!elms)
        ) else (
          (* This a two-dimension array *)
          let elmx = ref [] in
          for x = min_x to max_x do
            let elmy = ref [] in
            for y = min_y to max_y do
              elmy := (x, y)::!elmy
            done;
            elmx := !elmy::!elmx
          done;
          Array2 (!elmx)
        )

  let map f = function
    | Single coord ->  Single (f coord)
    | Array1 values -> Array1 (List.map f values)
    | Array2 values -> Array2 (List.map (List.map f) values)

  let shift (vector_x, vector_y) ref =
    let _shift ((x, y), (fixed_x, fixed_y)) =
      let x' = if fixed_x then x else x + vector_x
      and y' = if fixed_y then y else y + vector_y in
        (x', y'), (fixed_x, fixed_y)
    in match ref with
    | Cell x -> Cell (_shift x)
    | Range (fst, snd) -> Range (_shift fst, _shift snd)

  let show buffer = begin function
    | Cell r      -> UTF8.Buffer.add_string buffer @@ Cell.to_string r
    | Range (f,t) ->
        Tools.Tuple2.printb ~first:"" ~last:"" ~sep:":" Cell.to_buffer Cell.to_buffer buffer (f,t)
  end

  type 'a content =
    | Value: 'a dataFormat * 'a -> 'a content
    | List: 'a dataFormat * 'a list -> 'a list content
    | Matrix: 'a dataFormat * 'a list list -> 'a list list content

  type refContent =
    | C: 'a content -> refContent [@@unboxed]

  type ('a, 'b) equality = Eq : ('a, 'a) equality

  (** Add one element in a typed list.

      The function will raise Error.TypeError if the elements does not match
      with the list type.
  *)
  let add_elem: type a b. a dataFormat * a list -> result option -> a dataFormat * a list =
  fun (format, elements) result ->
    begin match result with
    | None -> format, (DataFormat.default_value_for format)::elements
    | Some (Error x) -> raise x
    | Some (Result r) ->
      let Type.Value (format', element) = Type.get_content r in
      let Eq = DataFormat.compare_format format format' in
      let new_format = if (DataFormat.priority format) > (DataFormat.priority format') then
          format
        else
          format' in
      new_format, element::elements
    end

  let get_content = begin function
  | Single None -> raise Errors.TypeError
  | Single (Some (Error x)) -> raise x
  | Single (Some (Result r)) ->
    let Type.Value (format, c) = Type.get_content r in C (Value (format, c))
  | Array1 l ->
    (* Get the first element in the list in order to get the format *)
    let Type.Value (format, _) =
      begin match (Tools.List.find_map (fun x -> x) l) with
      | Error x -> raise x
      | Result r -> Type.get_content r
      end in
    (* Then build an unified list (if we can) *)
    let format, values =  List.fold_left add_elem (format, []) l in
    C (List(format, List.rev values))
  | Array2 l ->
    (* Get the first element in the list *)
    let Type.Value (format, _) =
      begin match (Tools.List.find_map2 (fun x -> x) l) with
      | Error x -> raise x
      | Result r -> Type.get_content r
      end in
    (* Then build an unified list *)
    let format, values =  List.fold_left (fun (format, result) elems ->
        let format, elems = List.fold_left add_elem (format, []) elems in
        (format, List.rev (elems::result))
      )(format, []) l in
    C (Matrix(format, List.rev values))
  end

end

module Result = struct
  let (=) t1 t2 =
    match t1, t2 with
    | Result v1, Result v2 -> Type.(=) v1 v2
    | _, _ -> t1 = t2

  let show = begin function
    | Error x ->
        (*
        let buffer = Buffer.create 16 in
        let b = Format.formatter_of_buffer buffer in
        Errors.printf b x;
        Format.pp_print_flush b ();
        u(Buffer.contents buffer)
        *)
        u"#Error"
    | Result v ->
          let buffer = UTF8.Buffer.create 16 in
          Type.show buffer v;
          UTF8.Buffer.contents buffer
  end

end

(** Represent an expression.
 *)
let rec show_expr buffer : expression -> unit = begin function
  | Value (Str x) ->
      (** Print the value with quotes *)
      UTF8.Printf.bprintf buffer "\"%s\"" (UTF8.to_utf8string x)
  | Value v -> Type.show buffer v
  | Ref r -> Refs.show buffer r
  | Call (ident, params) ->
    let utf8ident = UTF8.to_utf8string ident in
    begin match utf8ident with
    | "+" | "*" | "-" | "/" | "^" | "="
    | "<>" | "<=" | ">=" | "<" | ">" -> begin match params with
      | v1::[] ->
        UTF8.Printf.bprintf buffer "%s%a"
        utf8ident
        show_expr v1
      | v1::v2::[] ->
        UTF8.Printf.bprintf buffer "%a%s%a"
        show_expr v1
          utf8ident
        show_expr v2
      | _ ->
        UTF8.Buffer.add_string buffer ident;
        Tools.List.printb ~sep:(u";") show_expr buffer params
    end
    | _ ->
      UTF8.Buffer.add_string buffer ident;
      Tools.List.printb ~sep:(u";") show_expr buffer params
    end
  | Expression expr ->
      UTF8.Printf.bprintf buffer "(%a)" show_expr expr
end