(** Longitude module *)

type t = float

let normalize_180 f =
  let x = mod_float (f +. 180.0) 360.0 in
  if x < 0.0 then x +. 360.0 -. 180.0
  else x -. 180.0

let normalize_360 f =
  let x = mod_float f 360.0 in
  if x < 0.0 then x +. 360.0 else x

let create f = normalize_180 f

let unsafe_create f = f

let of_dms ~degree ~minute ~second =
  let sign = if degree < 0 || minute < 0 || second < 0.0 then -1.0 else 1.0 in
  let d = abs degree in
  let m = abs minute in
  let s = abs_float second in
  let decimal = float_of_int d +. (float_of_int m /. 60.0) +. (s /. 3600.0) in
  create (sign *. decimal)

let to_float t = t

let to_range_180 t = normalize_180 t
let to_range_360 t = normalize_360 t

let degree t = int_of_float t

let decimal_minute t =
  let d = abs_float t in
  (d -. floor d) *. 60.0

let minute t = int_of_float (decimal_minute t)

let second t =
  let dm = decimal_minute t in
  (dm -. floor dm) *. 60.0

let hemisphere t = if t < 0.0 then `W else `E

let add t delta = create (t +. delta)
let sub t delta = create (t -. delta)
let neg t = create (-.t)
let abs t = abs_float t

let equal a b =
  (* Longitudes wrap around, so normalize before comparing *)
  normalize_180 a = normalize_180 b

let compare a b = Float.compare (normalize_180 a) (normalize_180 b)
let ( = ) = equal
let ( < ) a b = compare a b < 0
let ( > ) a b = compare a b > 0
let ( <= ) a b = compare a b <= 0
let ( >= ) a b = compare a b >= 0

let to_string t = Printf.sprintf "%.6f" t

let format ?(precision = 6) t =
  Printf.sprintf "%.*f" precision t

let to_dms_string t =
  let h = match hemisphere t with `E -> "E" | `W -> "W" in
  let d = abs_float (float_of_int (degree t)) |> int_of_float in
  let m = minute (abs_float t) in
  let s = second (abs_float t) in
  Printf.sprintf "%03d°%02d'%05.2f\"%s" d m s h