const capacitor = require('capacitor');

const server = capacitor(expressServer);

server.get('...').loadShedding({
  flowPosition: capacitor.FLOW_POSITION.START,
  endpointClass: capacitor.ENDPOINT_CLASS.BUSINESS_CRITICAL,
  directCost: capacitor.COST_CLASSES.LOW
});

const shedder = capacitor.build({
  limits: {
    cpu: {
      softLimit: 0.75,
      hardLimit: 0.8
      fn: capacitor.cost.cpu
    },
    eventLoop: {
      softLimit: 100,
      hardLimit: 150,
      fn: capacitor.cost.eventLoopLag
    }
  },

  opportunityCost: (reqData) => {
    // Example /test endpoint from LB
    if (reqData.endpointClass === capacitor.ENDPOINT_CLASS.INFRA_CRITICAL) {
      return capacitor.COST_CLASSES.EXTREMELY_HIGH;
    }

    if (reqData.payingTier === 'enterprice' && reqData.usageTier === 'production') {
      if (reqData.endpointClass === capacitor.ENDPOINT_CLASS.BUSINESS_CRITICAL) {
        return reqData.entityRPS < 100 ? capacitor.COST_CLASSES.HIGH : capacitor.COST_CLASSES.MEDIUM;
      }

      // If we have started an operation better to finish it than having the user
      // retry the whole flow adding more load to the system
      if (reqData.flowPosition === capacitor.FLOW_POSITION.INTERMEDIATE) {
        return capacitor.COST_CLASSES.MEDIUM;
      }

      return capacitor.COST_CLASSES.LOW;
    }

    return capacitor.COST_CLASSES.LOW;
  }

  directCost: (reqData) => {
    return reqData.requestDirectCost;
  },

  resolveEntity: (reqData) => {
    return reqData.tenant;
  },

  fairnessLimit: 0.10,

  requestClassifier: (directCost, oportunityCost) => {
    if (oportunityCost > directCost) {
      return capacitor.REQUEST_CLASSES.HIGH;
    }

    if (oportunityCost === directCost) {
      return capacitor.REQUEST_CLASSES.MEDIUM;
    }

    if (oportunityCost < directCost) {
      return capacitor.REQUEST_CLASSES.LOW;
    }
  }
});