part of '../terminal.dart';

typedef Callback = Future<void> Function();

class Act {
  String label;
  Callback callback;

  // If true, then push this to the top of the menu.
  // Note that if multiple actions are isDefault, then they just get a section of their own
  bool isDefault;

  // If true, then left clicking can trigger this.
  // If false, then the user must _always_ right click.
  bool canBeDefaultedTo;

  // If true, then right clicking can open a menu where this is the only item.
  // (Ordinary command buttons will never be interesting.)
  // Note that if canBeDefaultedTo is false and yet this is the only item,
  //then isInteresting will be ignored.
  bool isInteresting;

  Act(
      {required this.label,
      required this.callback,
      this.isDefault = false,
      this.canBeDefaultedTo = true,
      this.isInteresting = true});
}

int _compareAct(Act a1, Act a2) {
  // compare on defaultness
  final dl1 = a1.isDefault ? 1 : 0;
  final dl2 = a2.isDefault ? 1 : 0;
  final compare0 = dl1.compareTo(dl2);
  if (compare0 != 0) {
    return -compare0; // higher defaulting levels go towards the top
  }

  // compare on label
  return a1.label.compareTo(a2.label);
}

Future<void> _waitMenu(Terminal t, bool modal) async {
  var oldState = t._state;
  t._state = _State.waitMenu;
  loop:
  await for (var inp in t.rawInput()) {
    switch (inp) {
      case Click(button: var btn, x: var x, y: var y):
        final i = t._fromXY(x, y);
        List<Act> acts = [];
        if (i != null) {
          final tile = t._tiles[i];
          acts = tile.actions;

          if (!modal && acts.isEmpty) {
            break loop;
          } // if not modal, then skip out on clicking an empty tile
        }

        var menu = _Menu(acts, x, y);

        switch (btn) {
          case Button.left:
            var act = menu.defaultAct;
            if (act != null) {
              await act.callback();
              break loop;
            }
          case Button.right:
            if (menu.canShow) {
              await _showMenu(t, menu);
              break loop;
            }
        }
        break;

      default:
    }
  }
  t._state = oldState;
}

Future<void> _showMenu(Terminal t, _Menu menu) async {
  // First of all, save the old state of the view
  var oldTiles = t._tiles;
  t._tiles = [for (Tile tile in oldTiles) tile.fadeDisable()];

  menu.draw();
  await _waitMenu(t, false);
  t._tiles = oldTiles;
}

class _Menu {
  List<Act> acts = [];
  Act? defaultAct;
  bool canShow = false;

  int displayX = 0;
  int displayY = 0;
  int displayWidth = 0;
  int displayHeight = 0;

  _Menu(List<Act> a, int mouseX, int mouseY) {
    // == compute act list ==
    acts.addAll(a);
    acts.sort(_compareAct);

    // == compute defaulting status ==
    var hasDefaulting = false;

    if (acts.isEmpty) {
      hasDefaulting = false;
      canShow = false;
    } else if (acts.length == 1) {
      hasDefaulting = acts[0].canBeDefaultedTo;
      if (acts[0].isInteresting || !hasDefaulting) {
        canShow = true;
      }
    } else {
      var def1 = acts[0].isDefault;
      hasDefaulting = acts[0].canBeDefaultedTo;
      canShow = true;
      for (var i = 1; hasDefaulting && i < acts.length; i++) {
        if (acts[i].isDefault == def1) {
          hasDefaulting = false;
        }
      }
    }

    if (hasDefaulting) {
      defaultAct = acts[0];
    }
    // == compute dimensions ==
    final (int h, int w) = (Font.normal.cellHeight, Font.normal.cellWidth);
    displayHeight = h * 2;
    for (var a in acts) {
      displayWidth = math.max(displayWidth, (a.label.length + 4) * w);
      displayHeight += h;
    }

    displayX = mouseX - w * 2;
    displayY = mouseY - h;
    // TODO: Do this with math
    while (displayX + displayWidth > Terminal.width) {
      displayX -= 1;
    }
    while (displayY + displayHeight > Terminal.height) {
      displayY -= 1;
    }
  }

  void draw() {
    final (int h, int w) = (Font.normal.cellHeight, Font.normal.cellWidth);
    for (var y = 0; y < displayHeight; y += h) {
      for (var x = 0; x < displayWidth; x += w) {
        at(displayX + x, displayY + y)
            .bg(Palette.defaultBg)
            .fg(Palette.defaultFg)
            .putc(0xb0);
      }
    }

    for (var i = 0; i < acts.length; i++) {
      at(displayX + w * 2, displayY + (i + 1) * h)
          .bg(Palette.defaultBg)
          .fg(Palette.defaultFg)
          .highlight()
          .act(Act(
              label: acts[i].label,
              callback: acts[i].callback,
              isInteresting: false))
          .puts(acts[i].label);
    }
  }
}