EntityAIWorkFarmer

private IAIState prepareForFarming()
{
    @Nullable final BuildingFarmer building = getOwnBuilding();
    if (building == null || building.getBuildingLevel() < 1)
    {
        return PREPARING;
    }

    if (!job.getTaskQueue().isEmpty())
    {
        return START_WORKING;
    }
    
    building.syncWithColony(world);
    if (building.getFarmerFields().size() < getOwnBuilding().getBuildingLevel() && !building.assignManually())
    {
        searchAndAddFields();
    }

    final int amountOfCompostInBuilding = InventoryUtils.getItemCountInProvider(getOwnBuilding(), this::isCompost);
    final int amountOfCompostInInv = InventoryUtils.getItemCountInItemHandler(worker.getInventoryCitizen(), this::isCompost);

    if (amountOfCompostInBuilding + amountOfCompostInInv <= 0)
    {
        if (!getOwnBuilding().hasWorkerOpenRequestsOfType(Objects.requireNonNull(worker.getCitizenData()), TypeToken.of(StackList.class)))
        {
            final List<ItemStack> compostAbleItems = new ArrayList<>();
            compostAbleItems.add(new ItemStack(ModItems.compost, 1));
            compostAbleItems.add(new ItemStack(Items.BONE_MEAL, 1));
            worker.getCitizenData().createRequestAsync(new StackList(compostAbleItems, FERTLIZER, STACKSIZE, 1));
        }
    }
    else if (amountOfCompostInInv <= 0 && amountOfCompostInBuilding > 0)
    {
        needsCurrently = new Tuple<>(this::isCompost, STACKSIZE);
        return GATHERING_REQUIRED_MATERIALS;
    }

    if (building.hasNoFields())
    {
        if (worker.getCitizenData() != null)
        {
            worker.getCitizenData().triggerInteraction(new StandardInteractionResponseHandler(new TranslationTextComponent(NO_FREE_FIELDS), ChatPriority.BLOCKING));
        }
        worker.getCitizenData().setIdleAtJob(true);
        return PREPARING;
    }
    worker.getCitizenData().setIdleAtJob(false);

    //If the farmer has no currentField and there is no field which needs work, check fields.
    if (building.getCurrentField() == null && building.getFieldToWorkOn(world) == null)
    {
        building.resetFields();
        return IDLE;
    }

    @Nullable final BlockPos currentField = building.getCurrentField();
    final TileEntity entity = world.getTileEntity(currentField);
    if (entity instanceof ScarecrowTileEntity && ((ScarecrowTileEntity) entity).needsWork())
    {
        if (((ScarecrowTileEntity) entity).getFieldStage() == ScarecrowFieldStage.PLANTED && checkIfShouldExecute((ScarecrowTileEntity) entity, this::shouldHarvest))
        {
            return FARMER_HARVEST;
        }
        else if (((ScarecrowTileEntity) entity).getFieldStage() == ScarecrowFieldStage.HOED)
        {
            return canGoPlanting((ScarecrowTileEntity) entity, building);
        }
        else if (((ScarecrowTileEntity) entity).getFieldStage() == ScarecrowFieldStage.EMPTY && checkIfShouldExecute((ScarecrowTileEntity) entity,
          pos -> this.shouldHoe(pos, (ScarecrowTileEntity) entity)))
        {
            return FARMER_HOE;
        }
        ((ScarecrowTileEntity) entity).nextState();
    }
    else
    {
        getOwnBuilding().setCurrentField(null);
    }
    return PREPARING;
}

private IAIState canGoPlanting(@NotNull final ScarecrowTileEntity currentField, @NotNull final BuildingFarmer buildingFarmer)
{
		//地块设置种什么了没?
    if (currentField.getSeed() == null)
    {
        worker.getCitizenData()
          .triggerInteraction(new PosBasedInteractionResponseHandler(new TranslationTextComponent(NO_SEED_SET, currentField.getPos()),
            ChatPriority.BLOCKING,
            new TranslationTextComponent(NO_SEED_SET),
            currentField.getPos()));
        buildingFarmer.setCurrentField(null);
        worker.getCitizenData().setIdleAtJob(true);
        return PREPARING;
    }
    worker.getCitizenData().setIdleAtJob(false);
		
    final ItemStack seeds = currentField.getSeed().copy();
		//查找并获得对应的种子
    final int slot = worker.getCitizenInventoryHandler().findFirstSlotInInventoryWith(seeds.getItem());
    //有种子,转为种地状态
		if (slot != -1)
    {
        return FARMER_PLANT;
    }

    if (walkToBuilding())
    {
        return PREPARING;
    }
		//请求一组种子
    seeds.setCount(seeds.getMaxStackSize());
    checkIfRequestForItemExistOrCreateAsynch(seeds);

    currentField.nextState();
    return PREPARING;
}

/**
 * This (re)initializes a field. Checks the block above to see if it is a plant, if so, breaks it. Then tills.
 *
 * @return the next state to go into.
 */
private IAIState workAtField()
{
    @Nullable final BuildingFarmer buildingFarmer = getOwnBuilding();

    if (buildingFarmer == null || checkForToolOrWeapon(ToolType.HOE) || buildingFarmer.getCurrentField() == null)
    {
        return PREPARING;
    }
    @Nullable final BlockPos field = buildingFarmer.getCurrentField();
    final TileEntity entity = world.getTileEntity(field);
    if (entity instanceof ScarecrowTileEntity)
    {
        final ScarecrowTileEntity scarecrow = (ScarecrowTileEntity) entity;
        if (workingOffset != null)
        {
            if (scarecrow.getOwnerId() != worker.getCitizenId())
            {
                buildingFarmer.freeField(buildingFarmer.getCurrentField());
                buildingFarmer.setCurrentField(null);
                return getState();
            }

            final BlockPos position = field.down().south(workingOffset.getZ()).east(workingOffset.getX());

            if (workingOffset.getX() <= scarecrow.getLengthPlusX()
                  && workingOffset.getZ() <= scarecrow.getWidthPlusZ()
                  && workingOffset.getX() >= -scarecrow.getLengthMinusX()
                  && workingOffset.getZ() >= -scarecrow.getWidthMinusZ())
            {
                // Still moving to the block
                if (walkToBlock(position.up()))
                {
                    return getState();
                }

                switch ((AIWorkerState) getState())
                {
                    case FARMER_HOE:
                        worker.getCitizenStatusHandler().setLatestStatus(new TranslationTextComponent("com.minecolonies.coremod.status.hoeing"));

                        if (!hoeIfAble(position, scarecrow))
                        {
                            return getState();
                        }
                        break;
                    case FARMER_PLANT:
                        worker.getCitizenStatusHandler().setLatestStatus(new TranslationTextComponent("com.minecolonies.coremod.status.planting"));
                        if (!tryToPlant(scarecrow, position))
                        {
                            return PREPARING;
                        }
                        break;
                    case FARMER_HARVEST:
                        worker.getCitizenStatusHandler().setLatestStatus(new TranslationTextComponent("com.minecolonies.coremod.status.harvesting"));
                        if (!harvestIfAble(position))
                        {
                            return getState();
                        }
                        break;
                    default:
                        return PREPARING;
                }
                prevPos = position;
            }
            setDelay(getLevelDelay());
        }

        if (!handleOffset(scarecrow))
        {
            shouldDumpInventory = true;
            scarecrow.nextState();
            prevPos = null;
            return IDLE;
        }
    }
    else
    {
        return IDLE;
    }
    return getState();
}