let to_string c = String.make 1 c
let space = to_string ' '
let axis = "┬"
let axis_spc = "─"

type t  = { vals: int list; opts: Options.t }
let default = { vals = []; opts = Options.default }
let plot v c = { c with vals = v; }
let with_options v c = { v with opts = c; }
let pp channel {vals: int list; opts: Options.t } =
    let open Utils in
    let height = opts.height in
    let min_val = list_min vals in
    let max_val = list_max vals in
    let range = max_val - min_val in
    let scale v = ((v - min_val) * height) / range in
    let new_vals = List.map scale vals in
    let rec pad left right s =
        if left = 0
        then s :: repeat right space
        else space :: pad (left - 1) right s
    in
    let new_vals' = zip new_vals (List.tl new_vals) in
    let make_marker prefix left right s =
        prefix ::
        (if left = 0
        then s :: repeat right space
        else space :: pad (left - 1) right s)
    in
    let make_connector s e =
        match Stdlib.compare s e with
        | 0 -> make_marker axis_spc s (height - s) "-"
        | x ->
            let (ltr_chr, rtl_chr) =
                match x with
                | 1 -> ("└", "┐")
                | _ -> ("┘", "┌")
            in
            let (st, en) = Stdlib.((min s e, max s e)) in
            let l = en - st |> saturating_sub 1 in
            let (left, right) = (repeat st space, repeat (height - l - st) space) in
            List.flatten [[axis_spc]; left; [ltr_chr]; repeat l "│"; [rtl_chr]; right]
        in
    let m = Printf.sprintf opts.marker in
    let rec make_graph = function
        | [] -> []
        | (s, e) :: [] ->
                make_marker axis s (height - s) m
                :: make_connector s e
                :: make_marker axis e (height - e) m
                :: []
        | (s, e) :: tl ->
                make_marker axis s (height - s) m
                :: make_connector s e 
                :: make_graph tl
    in
    make_graph new_vals' 
        |> rot_left
        |> List.map (String.concat "")
        |> String.concat "\n"
        |> Printf.fprintf channel "%s"