open Unix
open Scanf

(* Chargeable interface *)
module type Chargeable = sig
  val calculateFare : unit -> float
  val calculateFire : unit -> float
end

(* Vehicle abstract class *)
module type Vehicle = sig
  val getLicensePlate : unit -> string
  val setLicensePlate : string -> unit
  val getBaseTime : unit -> int
  val setBaseTime : int -> unit
  val getTotalParkingTime : unit -> int
  val setTotalParkingTime : int -> unit
  val toString : unit -> string
end

module Vehicle : Vehicle = struct
  let licensePlate = ref ""
  let baseTime = ref 0
  let totalParkingTime = ref 0

  let getLicensePlate () = !licensePlate
  let setLicensePlate lp = licensePlate := lp

  let getBaseTime () = !baseTime
  let setBaseTime bt = baseTime := bt

  let getTotalParkingTime () = !totalParkingTime
  let setTotalParkingTime tpt = totalParkingTime := tpt

  let toString () = ""
end

(* Car class *)
module Car : Vehicle = struct
  include Vehicle

  let calculateFare () = 500.0

  let calculateFire () =
    if getTotalParkingTime () <= getBaseTime () then
      0.0
    else
      calculateFare () *. 0.3

  let toString () =
    "Car [License Plate=" ^ getLicensePlate () ^ ", Base Time=" ^ string_of_int (getBaseTime ()) ^
    ", Total Parking Time=" ^ string_of_int (getTotalParkingTime ()) ^ ", Fare Fee=" ^
    string_of_float (calculateFare ()) ^ ", Fire Fee=" ^ string_of_float (calculateFire ()) ^ "]"
end

(* Motorbike class *)
module Motorbike : Vehicle = struct
  include Vehicle

  let calculateFare () = 300.0

  let calculateFire () =
    if getTotalParkingTime () <= getBaseTime () then
      0.0
    else
      calculateFare () *. 0.2

  let toString () =
    "Motorbike [License Plate=" ^ getLicensePlate () ^ ", Base Time=" ^ string_of_int (getBaseTime ()) ^
    ", Total Parking Time=" ^ string_of_int (getTotalParkingTime ()) ^ ", Fare Fee=" ^
    string_of_float (calculateFare ()) ^ ", Fire Fee=" ^ string_of_float (calculateFire ()) ^ "]"
end

(* Wheelchair class *)
module Wheelchair : Vehicle = struct
  include Vehicle

  let calculateFare () = 200.0

  let calculateFire () =
    if getTotalParkingTime () <= getBaseTime () then
      0.0
    else
      calculateFare () *. 0.2

  let toString () =
    "Wheelchair [License Plate=" ^ getLicensePlate () ^ ", Base Time=" ^ string_of_int (getBaseTime ()) ^
    ", Total Parking Time=" ^ string_of_int (getTotalParkingTime ()) ^ ", Fare Fee=" ^
    string_of_float (calculateFare ()) ^ ", Fire Fee=" ^ string_of_float (calculateFire ()) ^ "]"
end

(* Ticket class *)
module Ticket = struct
  let id = ref 0L
  let startTime = ref (Unix.time ())
  let endTime = ref (Unix.time ())
  let vehicle = ref (Obj.magic ())

  let setId i = id := i
  let setStartTime st = startTime := st
  let setVehicle v = vehicle := v

  let addVehicle licensePlate =
    try
      id := Int64.of_float (Unix.time ());
      let rec loop () =
        print_string "What kind of vehicle: {0-Car, 1-Motobike, 2-Wheelchair, -1-Exit}? ";
        let kind = read_int () in
        if kind < -1 || kind > 2 then begin
          print_string "Invalid vehicle!\n";
          loop ()
        end else begin
          match kind with
          | 0 -> vehicle := Car
          | 1 -> vehicle := Motorbike
          | 2 -> vehicle := Wheelchair
          | _ -> ()
        end
      in
      loop ();
      let rec parseDate () =
        print_string "Input start time (format yyyy-MM-dd hh:mm): ";
        let input = read_line () in
        try
          startTime := Unix.(
            let tm = strptime input "%Y-%m-%d %H:%M" in
            mktime tm
          );
        with _ ->
          print_string "Invalid start time!\n";
          parseDate ()
      in
      true
    with _ ->
      print_string "An error occurs!\n";
      false

  let removeVehicle () =
    try
      let rec parseDate () =
        print_string "Input end time (format yyyy-MM-dd hh:mm): ";
        let input = read_line () in
        try
          endTime := Unix.(
            let tm = strptime input "%Y-%m-%d %H:%M" in
            mktime tm
          );
          if !endTime < !startTime then begin
            print_string "End time must be after start time!\n";
            parseDate ()
          end else
            true
        with _ ->
          print_string "Invalid end time!\n";
          parseDate ()
      in
      true
    with _ ->
      print_string "An error occurs!\n";
      false

  let getVehicle () = !vehicle

  let toString () =
    if !endTime = !startTime then begin
      let now = Unix.time () in
      let diff = now -. !startTime in
      let minutes = int_of_float (diff /. 60.0) in
      Vehicle.setTotalParkingTime minutes
    end;
    "Ticket [ID=" ^ Int64.to_string !id ^ ", Start Time=" ^ string_of_float !startTime ^
    ", End Time=" ^ string_of_float !endTime ^ ", Vehicle=" ^ Vehicle.toString () ^
    ", Total Fee=" ^ string_of_float (Vehicle.calculateFare () +. Vehicle.calculateFire ()) ^ "]"

  let getId () = !id
  let getStartTime () = !startTime
  let getEndTime () = !endTime
end

(* TicketIterator class *)
module TicketIterator : sig
  val hasNext : unit -> bool
  val next : unit -> Ticket.t
end = struct
  let currentIndex = ref 0
  let tickets = ref []

  let hasNext () =
    while !currentIndex < List.length !tickets do
      if List.nth !tickets !currentIndex <> Obj.magic () then
        true
      else
        currentIndex := !currentIndex + 1
    done;
    false

  let next () =
    if not (hasNext ()) then
      raise Not_found
    else
      let ticket = List.nth !tickets !currentIndex in
      currentIndex := !currentIndex + 1;
      ticket
end

(* TicketComparatorByTypeVehicle class *)
module TicketComparatorByTypeVehicle : sig
  val compare : Ticket.t -> Ticket.t -> int
end = struct
  let compare t1 t2 =
    compare (Obj.magic (Ticket.getVehicle t1)) (Obj.magic (Ticket.getVehicle t2))
end

(* TicketComparatorByParkingTime class *)
module TicketComparatorByParkingTime : sig
  val compare : Ticket.t -> Ticket.t -> int
end = struct
  let compare t1 t2 =
    compare (Ticket.getStartTime t1) (Ticket.getStartTime t2)
end

(* ParkingManagementOcaml class *)
module ParkingManagementOcaml = struct
  let tickets = ref []
  let fileName = "data.csv"

  let menu () =
    print_string "-------------------MENU-------------------\n";
    print_string "1. Vehicle in/out\n";
    print_string "2. Print all parking vehicle\n";
    print_string "3. Sort tickets by type vehicle\n";
    print_string "4. Sort tickets by parking time\n";
    print_string "5. Find a vehicle\n";
    print_string "6. Save data to file " ^ fileName ^ "\n";
    print_string "7. Read data from file " ^ fileName ^ "\n";
    print_string "0. Exit!\n";
    print_string "Please choose an option: ";
    let rec loop () =
      try
        let option = read_int () in
        if option >= 0 && option <= 7 then
          option
        else
          loop ()
      with _ ->
        print_string "Invalid option!\n";
        print_string "Please choose an option: ";
        loop ()
    in
    loop ()

  let checkExists licensePlate =
    let rec loop index = function
      | [] -> -1
      | ticket :: tickets ->
        if Ticket.getVehicle ticket = licensePlate then
          index
        else
          loop (index + 1) tickets
    in
    loop 0 !tickets
  
  let parkVehicle () =
    try
      print_string "Please enter the license plate: ";
      let licensePlate = read_line () in
      let index = checkExists licensePlate in
        if index = -1 then
          begin
            print_string "Adding new ticket....\n";
            let ticket = Ticket.(setId (Int64.of_float (Unix.time ())));
            if addVehicle licensePlate then
              begin
                tickets := ticket :: !tickets;
                print_string "Parking vehicle successfully....\n"
              end
            else
              print_string "Fail to add new ticket! Try again!\n"
          end
        else 
          begin
            print_string "Removing existing ticket....\n";
            let ticket = List.nth !tickets index in
            tickets := List.filter (fun t -> t <> ticket) !tickets;
            if Ticket.removeVehicle ticket then
              begin
                let diff = Ticket.getEndTime ticket -. Ticket.getStartTime ticket in
                let minutes = int_of_float (diff /. 60.0) in
                Vehicle.setTotalParkingTime minutes;
                print_string "Payment ticket information....\n";
                print_string (Ticket.toString ticket ^ "\n")
              end
            else
              begin
                print_string "Fail to remove existing ticket! Try again!\n";
                tickets := ticket :: !tickets
              end
          end
    with _ ->
      print_string "An error occurs!\n"      

  let printListTicket () =
    print_string "-------------------LIST TICKET-------------------\n";
    let rec loop = function
      | [] -> ()
      | ticket :: tickets ->
        print_string (Ticket.toString ticket ^ "\n");
        loop tickets
    in
    loop !tickets

  let sortTicketByType () =
    print_string "Sorting tickets by type increasement.....\n";
    tickets := List.sort TicketComparatorByTypeVehicle.compare !tickets;
    print_string "List tickets after sorting....\n";
    printListTicket ()

  let sortTicketByParkingTime () =
    print_string "Sorting tickets by parking time increasement.....\n";
    tickets := List.sort TicketComparatorByParkingTime.compare !tickets;
    print_string "List tickets after sorting....\n";
    printListTicket ()

  let searchTicket () =
    print_string "Searching a ticket by license plate.....\n";
    print_string "Enter license plate to search: ";
    let licensePlate = read_line () in
    let index = checkExists licensePlate in
    if index = -1 then
      print_string ("Oooops! We can not find the ticket with license plate " ^ licensePlate ^ "\n")
    else begin
      print_string "The ticket is: \n";
      print_string (Ticket.toString (List.nth !tickets index) ^ "\n")
    end

  let writeCSV () =
    let fileWriter = open_out fileName in
    let rec loop = function
      | [] -> ()
      | ticket :: tickets ->
        output_string fileWriter (Int64.to_string (Ticket.getId ticket) ^ ",");
        output_string fileWriter (string_of_float (Ticket.getStartTime ticket) ^ ",");
        output_string fileWriter (string_of_int (if Ticket.getVehicle ticket = Car then 0 else if Ticket.getVehicle ticket = Motorbike then 1 else 2) ^ ",");
        output_string fileWriter (Vehicle.getLicensePlate () ^ ",");
        output_string fileWriter (string_of_int (Vehicle.getBaseTime ()) ^ "\n");
        loop tickets
    in
    output_string fileWriter "id,startTime,type,licensePlate,baseTime\n";
    loop !tickets;
    close_out fileWriter;
    print_string "Write data to CSV file successfully!\n"

  let readCSV () =
    tickets := [];
    let fileReader = open_in fileName in
    let rec loop () =
      try
        let line = input_line fileReader in
        let fields = String.split_on_char ',' line in
        let ticket = Ticket.(setId (Int64.of_string (List.nth fields 0));
          setStartTime (float_of_string (List.nth fields 1));
          let vehicle = match int_of_string (List.nth fields 2) with
            | 0 -> Car
            | 1 -> Motorbike
            | _ -> Wheelchair
          in
          setVehicle vehicle);
        tickets := ticket :: !tickets;
        loop ()
      with _ -> ()
    in
    loop ();
    close_in fileReader;
    print_string "Read data from CSV file successfully!\n"

  let run () =
    let functions = [
      (fun () -> parkVehicle ());
      (fun () -> printListTicket ());
      (fun () -> sortTicketByType ());
      (fun () -> sortTicketByParkingTime ());
      (fun () -> searchTicket ());
      (fun () -> writeCSV ());
      (fun () -> readCSV ());
    ] in
    let rec loop () =
      let option = menu () in
      if option = 0 then
        print_string "Good bye!\n"
      else
        let runFunction = List.nth functions (option - 1) in
        runFunction ();
        print_string "------------------------------------------\n";
        loop ()
    in
    loop ()

  let main () =
    run ()
end

let () = ParkingManagementOcaml.main ()

Line 126, characters 12-15:
Syntax error