This PR breaks the cyclic dependency between `Inventory` and its holder, which unblocks a lot of new developments.
### Related issues & PRs
- Fixes#5033
- Removes a blocker for #6147 (which in turn means that async tasks will eventually be able to work with tiles)
- Removes a blocker for #2684
## Changes
### API changes
- `Player->getCurrentWindow()` now returns `?InventoryWindow` instead of `?Inventory`
- `Player->setCurrentWindow()` now accepts `?InventoryWindow` instead of `?Inventory`
- `InventoryWindow` introduced, which is created for each player viewing the inventory, provides decorative information like holder info for `InventoryTransactionEvent`, and is destroyed when the window is closed, eliminating cyclic references
- Added:
- `player\InventoryWindow`
- `player\PlayerInventoryWindow` - wraps all permanent inventories of Player with type info for transactions
- `inventory\Hotbar` - replaces all hotbar usages in `PlayerInventory`
- `Human->getHotbar()`
- `Human->getMainHandItem()`, `Human->setMainHandItem()`, `Human->getOffHandItem()`, `Human->setOffHandItem()`
- `block\utils\AnimatedContainerLike` & `block\utils\AnimatedContainerLikeTrait` (for chests, shulkerboxes, etc)
- `block\utils\Container` & `block\utils\ContainerTrait` for blocks containing items (chests, etc)
- `block\utils\MenuAccessor` implemented by all blocks that can open inventory menus
- `block\utils\MenuAccessorTrait` used by blocks with menus but without inventories (anvils, crafting tables etc)
- Removed:
- `inventory\DelegateInventory` (only used for ender chests)
- `inventory\PlayerInventory`,
- `inventory\PlayerOffHandInventory`,
- `inventory\PlayerCraftingInventory`,
- `inventory\PlayerCursorInventory` - these have all been internally replaced by `SimpleInventory` & they will appear as `PlayerInventoryWindow` in transactions (check `getType()` against the `PlayerInventoryWindow::TYPE_*` constants to identify them)
- `block\inventory\AnimatedBlockInventoryTrait`, (blocks now handle this logic directly using `AnimatedContainer` and `AnimatedContainerTrait`)
- `block\inventory\BlockInventoryTrait`,
- `block\inventory\BlockInventory`
- Most `BlockInventory` classes have been transitioned to `InventoryWindow` wrappers
- Tiles now all use `SimpleInventory` internally (no cyclic references) except for `Chest` (which uses `CombinedInventory`, without holder info)
- `InventoryOpenEvent` and `InventoryCloseEvent` now provide `InventoryWindow` instead of `Inventory` (to provide type information)
- `InventoryTransaction` and `SlotChangeAction` now provide `InventoryWindow` instead of `Inventory`
- Renamed `TransactionBuilderInventory` to `SlotChangeActionBuilder`
- `TransactionBuilderInventory->getBuilder()` now accepts `InventoryWindow` instead of `Inventory`
- `DoubleChestInventory` superseded by `CombinedInventory` - this new class allows combining any number of inventories behind a single object; mainly used for double chests but plugins could use it to do lots of fun things
### Impacts to plugins
Plugins can now do the following:
```php
$block = $world->getBlockAt($x, $y, $z);
if($block instanceof MenuAccessor){
$block->openToUnchecked($player);
}
```
As compared to the old way:
```php
$tile = $world->getTileAt($x, $y, $z);
if($tile instanceof Container){
$player->setCurrentWindow($tile->getInventory());
}
```
#### Advantages
- No tile access needed
- Works for menu blocks without inventories as well as container blocks
- Less code
### Behavioural changes
Inventories no longer keep permanent cyclic references to their holders.
## Backwards compatibility
This makes significant BC breaks. However, all changes are able to be adapted to and the same amount of information is present on all APIs and events.
## Follow-up
- Implement #6147
- Support inventory inheritance when copying blocks from one position to another
