(**
 * Copyright (c) 2015, Fabien Freling
 * All rights reserved.
 *
 * This source code is licensed under the BSD 2-clause license found in the
 * LICENSE file at the top level directory of this source tree.
 *)

open Printf

let fps = 60
let cycles_per_frame = Cpu.frequence / fps

let rec run (cpu: Cpu.t) (mem: Memory.t) (screen: Screen.t) =
  let start = Unix.gettimeofday () in
  printf "start %f\n" start;

  let rec run_for cpu (mem: Memory.t) cycles_remaining =
    if cycles_remaining > 0 then begin
      printf "\n";
      let inst, cycles = Cpu.run cpu mem.map in
      printf "[Instruction] %s\n" inst;

      Cpu.handle_interrupts cpu mem.map;

      Memory.update_timers mem cycles;

      run_for cpu mem (cycles_remaining - cycles)
    end
  in
  run_for cpu mem cycles_per_frame;

  let stop = Unix.gettimeofday () in
  let delay = (1. -. (stop -. start)) /. (float_of_int fps) in
  printf "stop %f\n" stop;
  printf "delta %f\n" (stop -. start);
  printf "delay %f\n" delay;
  flush_all ();

  if delay > 0. then Thread.delay delay;
  run cpu mem screen

(** Power up sequence
    http://bgb.bircd.org/pandocs.htm#powerupsequence *)
let power_up cartridge =
  (* Nintendo logo scrolling *)
  if not (Cartridge.check_nintendo_logo cartridge)
  then print_endline "Invalid ROM."
  else
    print_endline "Valid ROM.";
    Cartridge.print_info cartridge;

    let cpu = Cpu.init_cpu in
    let mem = Memory.init cartridge in
    let screen = Screen.init in

    (*Graphics.open_graph "";
    Graphics.resize_window Screen.width Screen.height;
    *)
    run cpu mem screen


let () =
  if Array.length Sys.argv < 2 then begin
    prerr_endline "Please specify a ROM.";
    eprintf "Usage: %s path/to/rom\n" Sys.argv.(0);
    exit 1;
  end;

  let cartridge = Cartridge.read_cartridge Sys.argv.(1) in
  match cartridge with
  | None -> print_endline "Invalid ROM file."
  | Some c -> power_up c