import { unionBy, remove, assign } from 'lodash';
import { HandlerSetter, DuplicateChildren } from 'interfaces';
import Operation from '../Operation';
import checkCondition from './checkCondition';

export default function getDuplicateChildrenHandlers(
  parentEntityType: string,
  propKey: string,
  propValue: DuplicateChildren
): {selfHandlerSetters: Array<HandlerSetter>, childHandlerSetters: Array<HandlerSetter>} {
  // ---------- selfHandler ----------
  const selfHandlerSetter: HandlerSetter = {
    handlerHolder: 'SELF',
    onAdd: [{
      updatingParentType: null,
      operationModifier: (parentOperation: Operation) => {
        parentOperation.modify({ [propKey]: [] });
      }
    }],
    onUpdate: [],
    onDelete: []
  };

  // ---------- childHandler ----------
  const { childEntityType, mapFunc, limit, conditions } = propValue;

  const updateChildrenOfParentOperations = (
    childOperation: Operation,
    beforeParentOperations: Array<Operation>,
    afterParentOperations: Array<Operation>
  ) => {
    const newChildPartialItem = mapFunc(childOperation.after);
    const newChildItemSelector = childOperation.itemSelector;

    const isBeforeChildOnCondition = checkCondition(childOperation.before, conditions);
    if (isBeforeChildOnCondition) {
      beforeParentOperations.forEach((parentOperation) => {
        parentOperation.delItemFromProp(propKey, newChildItemSelector);
      });
    }

    const isAfterChildOnCondition = checkCondition(childOperation.after, conditions);
    if (isAfterChildOnCondition) {
      afterParentOperations.forEach((parentOperation) => {
        parentOperation.setItemToProp(propKey, newChildPartialItem, newChildItemSelector, limit);
      });
    }
  };

  const childHandlerSetter: HandlerSetter = {
    handlerHolder: childEntityType,
    onAdd: [{
      updatingParentType: parentEntityType,
      operationModifier: (
        childOperation: Operation,
        beforeParentOperations: Array<Operation>,
        afterParentOperations: Array<Operation>
      ) => {
        updateChildrenOfParentOperations(childOperation, beforeParentOperations, afterParentOperations);
      }
    }],
    onUpdate: [{
      updatingParentType: parentEntityType,
      operationModifier: (
        childOperation: Operation,
        beforeParentOperations: Array<Operation>,
        afterParentOperations: Array<Operation>
      ) => {
        updateChildrenOfParentOperations(childOperation, beforeParentOperations, afterParentOperations);
      }
    }],
    onDelete: [{
      updatingParentType: parentEntityType,
      operationModifier: (
        childOperation: Operation,
        beforeParentOperations: Array<Operation>,
        afterParentOperations: Array<Operation>
      ) => {
        updateChildrenOfParentOperations(childOperation, beforeParentOperations, afterParentOperations);
      }
    }]
  };

  return { selfHandlerSetters: [selfHandlerSetter], childHandlerSetters: [childHandlerSetter] };
}