open List
open Printf
open Common

let (lines_starts : (string, int list) Hashtbl.t) = Hashtbl.create 4
let current_file_lines_starts = ref []
let current_file_current_line = ref 0
let current_file = ref ""

let start_a_new_file file = 
  if !current_file <> "" then Hashtbl.add lines_starts !current_file !current_file_lines_starts ;
  current_file := file ;
  current_file_lines_starts := [0]

let get_lines_starts_for_file file =
  if file = !current_file then !current_file_lines_starts else Hashtbl.find lines_starts file

let raw_pos2raw_line file a =
  let starts = map_index (fun a b -> a,b) (rev (get_lines_starts_for_file file)) in
  let ((offset, line), _) = find (fun (_,(e,_)) -> e > a) (combine starts (tl starts @ [999999999, 999999999])) in
  line, offset

let pos2line (file, a, b) = 
  let line, offset = raw_pos2raw_line file a in
  file, line, a - offset + 1, b - offset + 1

let pos2s (file, a, b) = sprintf "(%s, %d, %d)" file a b

let pos2sfull pos = 
  try
    let (file, line, n1,n2) = pos2line pos in
    sprintf "File \"%s\", line %d, character %d-%d\n" file (line + 1) n1 n2
  with Not_found -> failwith ("bad position " ^ pos2s pos)

let is_on_same_line file (a,b) =
  let line_a, _ = raw_pos2raw_line file a in
  let line_b, _ = raw_pos2raw_line file b in
  line_a = line_b

let is_on_same_line_current (a,b) = is_on_same_line !current_file (a,b)
let pos2sfull_current a b = pos2sfull (!current_file, a, b)