@conveyal/commute/client/utils/reducers.js

Commute analysis

import update from 'react-addons-update'

import {addToEntityMap, addEntitiesToEntityMap, deleteFromEntityMap, deleteManyFromEntityMap} from './entities'

function addChildEntityToParent (parentMap, newEntity, parentIdField, childPluralName) {
  return update(parentMap, {
    [newEntity[parentIdField]]: {
      [childPluralName]: {
        $push: [newEntity._id]
      }
    }
  })
}

export function getGenericReducerInitialState () {
  return {
    _lastUpdate: now()
  }
}

/**
 * Make handlers for children creation and deletion events
 *
 * @param  {Object} cfg  An configuration object structured as follows:
 *   - childPluralName (String): Plural name of child (parent's child id array)
 *   - childSingularName (String): Singular name of child (for making reducer title)
 *   - parentIdField (String): Id field of parent in child entity
 * @return {Object}     Reducers
 */
export function makeChildrenHandlers (cfg) {
  const reducers = {}
  reducers[`add ${cfg.childSingularName}`] = function (state, action) {
    const newEntity = action.payload
    return updateTime(addChildEntityToParent(
      state,
      newEntity,
      cfg.parentIdField,
      cfg.childPluralName
    ))
  }

  reducers[`add many ${cfg.childPluralName}`] = function (state, action) {
    const newEntities = action.payload
    let updatedState = state
    newEntities.forEach(newEntity => {
      updatedState = addChildEntityToParent(
        updatedState,
        newEntity,
        cfg.parentIdField,
        cfg.childPluralName
      )
    })
    return updateTime(updatedState)
  }

  reducers[`delete ${cfg.childSingularName}`] = function (state, action) {
    const entity = action.payload
    const childIds = state[entity[cfg.parentIdField]][cfg.childPluralName]
    return updateTime(update(state, {
      [entity[cfg.parentIdField]]: {
        [cfg.childPluralName]: {
          $set: childIds.filter((id) => id !== entity._id)
        }
      }
    }))
  }

  return reducers
}

/**
 * Make generic reducers for an entity type
 *
 * @param  {Object} cfg  An object with name and handlers parameters structured as follows:
 *   - name: must have singular and plural keys with the corresponding strings
 *   - handlers: An array of strings of handlers.  Possible values: ['add', 'add many', 'delete', 'set', 'set many']
 * @return {Object}      The generated reducers
 */
export function makeGenericReducerHandlers (cfg) {
  const reducers = {
    'log out' (state, action) {
      return updateTime({})
    }
  }
  if (cfg.handlers.indexOf('add') !== -1) {
    reducers[`add ${cfg.name.singular}`] = function (state, action) {
      return updateTime(addToEntityMap(state, action.payload))
    }
  }

  if (cfg.handlers.indexOf('add many') !== -1) {
    reducers[`add many ${cfg.name.plural}`] = function (state, action) {
      return updateTime(addEntitiesToEntityMap(state, action.payload))
    }
  }

  if (cfg.handlers.indexOf('delete') !== -1) {
    reducers[`delete ${cfg.name.singular}`] = function (state, action) {
      return updateTime(deleteFromEntityMap(state, action.payload._id))
    }
  }

  if (cfg.handlers.indexOf('delete many') !== -1) {
    reducers[`delete many ${cfg.name.plural}`] = function (state, action) {
      return updateTime(deleteManyFromEntityMap(state, action.payload))
    }
  }

  if (cfg.handlers.indexOf('set') !== -1) {
    reducers[`set ${cfg.name.singular}`] = function (state, action) {
      return updateTime(addToEntityMap(state, action.payload))
    }
  }

  if (cfg.handlers.indexOf('set many') !== -1) {
    reducers[`set ${cfg.name.plural}`] = function (state, action) {
      return updateTime(addEntitiesToEntityMap(state, action.payload))
    }
  }

  return reducers
}

function now () {
  return (new Date()).getTime()
}

export function updateTime (state) {
  return update(state, {
    _lastUpdate: {
      $set: now()
    }
  })
}