pricing4ts/src/server/configuration/PricingContext.ts

 Pricing4TS is a TypeScript-based toolkit designed to enhance the server-side functionality of a pricing-driven SaaS by enabling the seamless integration of pricing plans into the application logic. T

import { Feature, Pricing, UsageLimit } from '../../types';
import { PricingPlanEvaluationError } from '../exceptions/PricingPlanEvaluationError';
import { retrievePricingFromPath } from '../server';

export type Configuration = Record<
  'features' | 'usageLimits',
  Record<string, Feature | UsageLimit>
>;

/**
 * An abstract class from which to create a component that adapts the pricing
 * configuration to the application domain
 */
export abstract class PricingContext {
  /**
   * Returns path of the pricing configuration YAML file.
   * This file should be located in the resources folder, and the path should be
   * relative to it.
   *
   * @returns Configuration file path
   */
  abstract getConfigFilePath(): string;

  /**
   * Returns the secret used to encode the pricing JWT.
   *
   * @returns JWT secret string
   */
  abstract getJwtSecret(): string;

  /**
   * Returns the expiration time of the JWT in milliseconds
   *
   * @returns JWT expiration time in milliseconds
   */
  getJwtExpiration(): number {
    return 86400000;
  }

  /**
   * This method can be used to determine which users are affected
   * by the pricing, so a pricing-driven JWT will be only generated
   * for them.
   *
   * @returns A boolean indicating the condition to include or exclude the pricing evaluation context in the JWT.
   */
  userAffectedByPricing(): boolean {
    return true;
  }

  /**
   * This method should return the user context that will be used to evaluate the pricing plan.
   * It should consider which users have accessed the service and what
   * information is available.
   *
   * @returns Map with the user context
   */
  abstract getSubscriptionContext(): Record<string, boolean | string | number>;

  /**
   * This method should return the plan name of the current user.
   * With this information, the library will be able to build the Plan
   * object of the user from the configuration.
   *
   * @returns String with the current user's plan name
   */
  abstract getUserPlan(): string;

  /**
   * This method should return the add-ons that the user has
   * subscribed to. The add-ons are used to extend the features and usage limits
   * of the user's plan.
   *
   * @returns Array of strings with the add-ons names
   */
  abstract getUserAddOns(): string[];

  /**
   * This method returns the plan context of the current user, represented by a
   * *Record<string, boolean | string | number | PaymentType[]>*. It's used to evaluate the pricing plan.
   *
   * @return current user's plan context
   */
  getPlanContext(): Configuration {
    const userPlan = this.getPricing().plans![this.getUserPlan()];
    const pricingAddOns = this.getPricing().addOns ?? {};
    const pricingContextToReturn = {
      features: { ...userPlan.features },
      usageLimits: userPlan.usageLimits ? { ...userPlan.usageLimits } : {},
    };

    for (const addOn of Object.keys(pricingAddOns)) {
      if (this.getUserAddOns().includes(addOn)) {
        if (pricingAddOns[addOn].features) {
          for (const feature of Object.keys(pricingAddOns[addOn].features)) {
            pricingContextToReturn.features![feature].value =
              pricingAddOns[addOn].features![feature].value;
          }
        }

        if (pricingAddOns[addOn].usageLimits) {
          for (const usageLimit of Object.keys(pricingAddOns[addOn].usageLimits)) {
            pricingContextToReturn.usageLimits![usageLimit].value =
              pricingAddOns[addOn].usageLimits![usageLimit].value;
          }
        }

        if (pricingAddOns[addOn].usageLimitsExtensions) {
          for (const usageLimit of Object.keys(pricingAddOns[addOn].usageLimitsExtensions)) {
            if (pricingContextToReturn.usageLimits![usageLimit].value) {
              (pricingContextToReturn.usageLimits![usageLimit].value as number) += pricingAddOns[
                addOn
              ].usageLimitsExtensions![usageLimit].value as number;
            } else {
              pricingContextToReturn.usageLimits![usageLimit].value =
                pricingAddOns[addOn].usageLimitsExtensions![usageLimit].value;
            }
          }
        }
      }
    }

    return pricingContextToReturn;
  }

  /**
   * This method returns the PricingManager object that is being used to
   * evaluate the pricing plan.
   *
   * @returns PricingManager object
   */
  getPricing(): Pricing {
    try {
      return retrievePricingFromPath(this.getConfigFilePath());
    } catch (error) {
      throw new PricingPlanEvaluationError((error as Error).message);
    }
  }
}