type fahrplan = (int*(int*int) list) list
type wochentag = fahrplan
type samstag = fahrplan
type haltestelle = wochentag * samstag

val dudw_str :haltestelle =
  ([(7,[(05,124),(10,112),(11,101),(20,124),(22,150),(35,124),(40,112),(41,101),(42,150),(43,124),(50,124)]),
  (8,[(05,124),(08,112),(10,112),(11,101),(20,124),(35,124),(38,112),(40,112),(41,101),(50,124)]),
  (9,[(10,112),(11,101),(20,124),(36,150),(38,112),(40,112),(41,101),(42,112),(50,124)]),
  (10,[(10,112),(11,101),(20,124),(40,112),(41,101),(50,124),(52,150)]),
  (11,[(10,112),(11,101),(20,124),(40,112),(41,101),(50,124)]),
  (12,[(10,112),(11,101),(20,124),(40,112),(41,101),(50,124),(52,150)]),
  (13,[(10,112),(11,101),(20,124),(40,112),(41,101),(42,150),(50,124)]),
  (14,[(10,112),(11,101),(20,124),(40,112),(41,101),(50,124)]),
  (15,[(05,124),(10,112),(11,101),(20,124),(35,124),(40,112),(41,101),(50,124),(52,150)]),
  (16,[(05,124),(10,112),(11,101),(20,124),(35,124),(37,150),(40,112),(41,101),(50,124)]),
  (17,[(05,124),(10,112),(11,101),(20,124),(35,124),(40,112),(41,101),(50,124)]),
  (18,[(05,124),(11,101),(20,124),(41,101),(50,124),(52,150)]),
  (19,[(11,101),(20,124),(41,101),(50,124)]),
  (20,[(11,101),(22,150)]),
  (21,[(02,101)])],
  [(7,[(02,101),(41,101)]),(8,[(11,101),(41,101)]),(9,[(11,101),(41,101)]),(10,[(11,101),(41,101)]),
  (11,[(11,101),(41,101)]),(12,[(11,101),(41,101),(57,150)]),(13,[(11,101),(41,101)]),
  (14,[(11,101),(17,150),(41,101)]),(15,[(11,101),(41,101)]),(16,[(11,101),(17,150),(41,101)]),
  (17,[(11,101),(41,101)]),(18,[(11,101),(52,101)]),(19,[(52,101)]),(20,[]),(21,[(02,101)])])

val r_w_str :haltestelle =
  ([(7,[(18,109),(27,102),(41,102),(48,109),(50,111),(57,102)]),
  (8,[(05,111),(14,109),(20,111),(27,102),(35,111),(48,109),(50,111),(57,102)]),
  (9,[(05,111),(18,109),(27,102),(35,111),(48,109),(57,102)]),
  (10,[(05,111),(18,109),(27,102),(35,111),(48,109),(57,102)]),
  (11,[(05,111),(18,109),(27,102),(35,111),(48,109),(57,102)]),
  (12,[(05,111),(18,109),(27,102),(35,111),(48,109),(57,102)]),
  (13,[(05,111),(18,109),(27,102),(35,111),(48,109),(57,102)]),
  (14,[(05,111),(18,109),(27,102),(35,111),(48,109),(57,102)]),
  (15,[(05,111),(18,109),(27,102),(35,111),(48,109),(57,102)]),
  (16,[(05,111),(18,109),(27,102),(35,111),(48,109),(57,102)]),
  (17,[(05,111),(18,109),(27,102),(35,111),(48,109),(57,102)]),
  (18,[(05,111),(18,109),(27,102),(35,111),(48,109),(57,102)]),
  (19,[(27,102),(57,102)]),(20,[(27,102)]),(21,[(31,102)])],
  [(7,[(31,102),(57,102)]),(8,[(27,102),(57,102)]),(9,[(27,102),(57,102)]),
  (10,[(27,102),(57,102)]),(11,[(27,102),(57,102)]),(12,[(27,102),(57,102)]),
  (13,[(27,102),(57,102)]),(14,[(27,102),(57,102)]),(15,[(27,102),(57,102)]),
  (16,[(27,102),(57,102)]),(17,[(27,102),(57,102)]),(18,[(27,102)]),
  (19,[(27,102)]),(20,[(27,102)]),(21,[(31,102)])])

fun bus() =

let

exception BadTime
datatype weekday = Sun | Mon | Tue | Wed | Thu | Fri | Sat

fun getDate() = Date.fromTimeLocal(Time.now())
fun getTime(d) =
      if Date.minute(d)+5<60 then (Date.hour(d),Date.minute(d)+5)
      else (Date.hour(d)+1,(Date.minute(d)+5) mod 10)
fun getDay(d) = Date.weekDay(d)
fun findHour(stunde,nil) = raise BadTime
    | findHour(stunde,(p::pr):fahrplan) = if stunde = #1p then #2p else findHour(stunde,pr)
fun findBus(minute,nil) = NONE
    | findBus(minute,(b::br) :(int*int) list) = if  #1b < minute then findBus(minute,br) else SOME(b)



val datum = getDate()
 val tag = getDay(datum)
 val (stunde,minute) = getTime(datum)

 val bus_dudw_str =
      if tag = Sun then (NONE,0)
      else if tag = Sat then (if findBus(minute, findHour(stunde,#2dudw_str)) = NONE then
                             (findBus(0, findHour(stunde+1,#2dudw_str)),stunde+1)
                             else (findBus(minute, findHour(stunde,#2dudw_str)),stunde)) handle BadTime => (NONE,0)
                 else (if findBus(minute, findHour(stunde,#1dudw_str)) = NONE then
                             (findBus(0, findHour(stunde+1,#1dudw_str)),stunde+1)
                             else (findBus(minute, findHour(stunde,#1dudw_str)),stunde)) handle BadTime => (NONE,0)

 val bus_r_w_str =
        if tag = Sun then (NONE,0)
        else if tag = Sat then (if findBus(minute, findHour(stunde,#2r_w_str)) = NONE then
                             (findBus(0, findHour(stunde+1,#2r_w_str)),stunde+1)
                             else (findBus(minute, findHour(stunde,#2r_w_str)),stunde)) handle BadTime => (NONE,0)
                else (if findBus(minute, findHour(stunde,#1r_w_str)) = NONE then
                             (findBus(0, findHour(stunde+1,#1r_w_str)),stunde+1)
                             else (findBus(minute, findHour(stunde,#1r_w_str)),stunde)) handle BadTime => (NONE,0)


fun printBus((NONE,_),(NONE,_)) = print("Was willst du denn jetzt an der Uni??? \n")
    | printBus((SOME(bus_dud :int*int),a),(NONE,_)) = print("Der naechste Bus: Linie "^Int.toString(#2bus_dud)^" um "^Int.toString(a)^":"^Int.toString(#1bus_dud)^" ab Haltestelle Dudweiler Strasse \n")

    | printBus((NONE,_),(SOME(bus_r_w :int*int),b)) = print("Der naechste Bus: Linie "^Int.toString(#2bus_r_w)^" um "^Int.toString(b)^":"^Int.toString(#1bus_r_w)^" ab Haltestelle Richard-Wagner-Strasse \n")

    | printBus((SOME(bus_dud :int*int),a),(SOME(bus_r_w :int*int),b)) =
  if a = b then
      if #1bus_dud < #1bus_r_w then
        print("Der naechste Bus: Linie "^Int.toString(#2bus_dud)^" um "^Int.toString(a)^":"^Int.toString(#1bus_dud)^" ab Haltestelle Dudweiler Strasse \n")
      else print("Der naechste Bus: Linie "^Int.toString(#2bus_r_w)^" um "^Int.toString(b)^":"^Int.toString(#1bus_r_w)^" ab Haltestelle Richard-Wagner-Strasse \n")

  else if a < b then print("Der naechste Bus: Linie "^Int.toString(#2bus_dud)^" um "^Int.toString(a)^":"^Int.toString(#1bus_dud)^" ab Haltestelle Dudweiler Strasse \n")

  else print("Der naechste Bus: Linie "^Int.toString(#2bus_r_w)^" um "^Int.toString(b)^":"^Int.toString(#1bus_r_w)^" ab Haltestelle Richard-Wagner-Strasse \n")

in printBus(bus_dudw_str,bus_r_w_str)
end