import type { Context } from "./context.ts";

export type FeatureValue = boolean | string | number;
export type FeatureRule = FeatureValue | ((ctx: Context) => FeatureValue | Promise<FeatureValue>);

export interface FeatureFlags {
  get(name: string, ctx: Context): Promise<FeatureValue | undefined>;
  enabled(name: string, ctx: Context): Promise<boolean>;
}

export function defineFeatureFlags(rules: Record<string, FeatureRule>): FeatureFlags {
  return {
    async get(name, ctx) {
      const rule = rules[name];
      return typeof rule === "function" ? rule(ctx) : rule;
    },
    async enabled(name, ctx) {
      return (await this.get(name, ctx)) === true;
    },
  };
}