import { remove, at } from 'lodash';
import { ItemSelector } from './interfaces';
import Operation from './Operation';

export default class OperationManager {
  operationByItemSelector: {
    [entityType: string]: {
      [id: string]: Operation // index of operations
    }
  }
  initialOperationItemSelector: ItemSelector
  allOperations: Array<ItemSelector>
  operationsNotResolved: Array<ItemSelector> // operations require resolving handlers
  operationsRequireRead: Array<ItemSelector>

  constructor(initialOperation: Operation) {
    this.operationByItemSelector = {};
    this.allOperations = [];
    this.operationsNotResolved = [];
    this.operationsRequireRead = [];
    this.initialOperationItemSelector = initialOperation.itemSelector;
    this.addOperation(initialOperation);
  }

  addOperation(newOperation: Operation) {
    const { itemSelector } = newOperation;
    const { entityType, id } = itemSelector;

    // check if already exists in operationsByItemSelector
    const prevOperation = this.getOperation(newOperation.itemSelector);

    if (prevOperation) {
      prevOperation.modify(newOperation.partialAfter);
    } else {
      newOperation.connectToOperationManager(
        // on resolved
        (operation) => {
          remove(
            this.operationsNotResolved,
            itemSelector =>
              (itemSelector.entityType === operation.itemSelector.entityType) &&
              (itemSelector.id === operation.itemSelector.id)
          );
        },
        // on setBefore (on read beforeItem)
        (operation) => {
          remove(
            this.operationsRequireRead,
            itemSelector =>
              (itemSelector.entityType === operation.itemSelector.entityType) &&
              (itemSelector.id === operation.itemSelector.id)
          );
        }
      );
      if (!this.operationByItemSelector[entityType]) this.operationByItemSelector[entityType] = {};
      this.operationByItemSelector[entityType][id] = newOperation;
      this.allOperations.push(itemSelector);
      this.operationsNotResolved.push(itemSelector);
      if (newOperation.requireRead) {
        this.operationsRequireRead.push(itemSelector);
      }
    }
  }

  getOperation(itemSelector: ItemSelector): Operation {
    const { entityType, id } = itemSelector;
    const opMap = this.operationByItemSelector;
    return opMap && opMap[entityType] && opMap[entityType][id];
  }

  getInitialOperation(): Operation {
    return this.getOperation(this.initialOperationItemSelector);
  }

  getOperationsRequireRead(): Array<Operation> {
    return this.operationsRequireRead.map(itemSelector => this.getOperation(itemSelector));
  }

  getOperationsNotResolved(): Array<Operation> {
    return this.operationsNotResolved.map(itemSelector => this.getOperation(itemSelector));
  }

  getAllOperations(): Array<Operation> {
    return this.allOperations.map(itemSelector => this.getOperation(itemSelector));
  }
}