//: A debugging helper that lets you zoom in/out on a trace.

//: browse the trace we just created
:(before "End Primitive Recipe Declarations")
_BROWSE_TRACE,
:(before "End Primitive Recipe Numbers")
put(Recipe_ordinal, "$browse-trace", _BROWSE_TRACE);
:(before "End Primitive Recipe Checks")
case _BROWSE_TRACE: {
  break;
}
:(before "End Primitive Recipe Implementations")
case _BROWSE_TRACE: {
  start_trace_browser();
  break;
}

//: browse a trace loaded from a file
:(after "Commandline Parsing")
if (argc == 3 && is_equal(argv[1], "browse-trace")) {
  load_trace(argv[2]);
  start_trace_browser();
  return 0;
}

:(before "End Globals")
set<int> Visible;
int Top_of_screen = 0;
int Last_printed_row = 0;
map<int, int> Trace_index;  // screen row -> trace index

:(code)
void start_trace_browser() {
  if (!Trace_stream) return;
  cerr << "computing min depth to display\n";
  int min_depth = 9999;
  for (int i = 0; i < SIZE(Trace_stream->past_lines); ++i) {
    trace_line& curr_line = Trace_stream->past_lines.at(i);
    if (curr_line.depth < min_depth) min_depth = curr_line.depth;
  }
  cerr << "min depth is " << min_depth << '\n';
  cerr << "computing lines to display\n";
  for (int i = 0; i < SIZE(Trace_stream->past_lines); ++i) {
    if (Trace_stream->past_lines.at(i).depth == min_depth)
      Visible.insert(i);
  }
  tb_init();
  Display_row = Display_column = 0;
  tb_event event;
  Top_of_screen = 0;
  refresh_screen_rows();
  while (true) {
    render();
    do {
      tb_poll_event(&event);
    } while (event.type != TB_EVENT_KEY);
    int key = event.key ? event.key : event.ch;
    if (key == 'q' || key == 'Q') break;
    if (key == 'j' || key == TB_KEY_ARROW_DOWN) {
      // move cursor one line down
      if (Display_row < Last_printed_row) ++Display_row;
    }
    if (key == 'k' || key == TB_KEY_ARROW_UP) {
      // move cursor one line up
      if (Display_row > 0) --Display_row;
    }
    if (key == 'H') {
      // move cursor to top of screen
      Display_row = 0;
    }
    if (key == 'M') {
      // move cursor to center of screen
      Display_row = tb_height()/2;
    }
    if (key == 'L') {
      // move cursor to bottom of screen
      Display_row = tb_height()-1;
    }
    if (key == 'J' || key == TB_KEY_PGDN) {
      // page-down
      if (Trace_index.find(tb_height()-1) != Trace_index.end()) {
        Top_of_screen = get(Trace_index, tb_height()-1) + 1;
        refresh_screen_rows();
      }
    }
    if (key == 'K' || key == TB_KEY_PGUP) {
      // page-up is more convoluted
      for (int screen_row = tb_height(); screen_row > 0 && Top_of_screen > 0; --screen_row) {
        --Top_of_screen;
        if (Top_of_screen <= 0) break;
        while (Top_of_screen > 0 && !contains_key(Visible, Top_of_screen))