import { LoadedConfigSelectors } from "@smithy/node-config-provider";
import { CONFIG_PREFIX_SEPARATOR } from "@smithy/shared-ini-file-loader";

const ENV_ENDPOINT_URL = "AWS_ENDPOINT_URL";
const CONFIG_ENDPOINT_URL = "endpoint_url";

export const getEndpointUrlConfig = (serviceId: string): LoadedConfigSelectors<string | undefined> => ({
  environmentVariableSelector: (env) => {
    // The value provided by a service-specific environment variable.
    const serviceSuffixParts = serviceId.split(" ").map((w) => w.toUpperCase());
    const serviceEndpointUrl = env[[ENV_ENDPOINT_URL, ...serviceSuffixParts].join("_")];
    if (serviceEndpointUrl) return serviceEndpointUrl;

    // The value provided by the global endpoint environment variable.
    const endpointUrl = env[ENV_ENDPOINT_URL];
    if (endpointUrl) return endpointUrl;

    return undefined;
  },

  configFileSelector: (profile, config) => {
    // The value provided by a service-specific parameter from a services definition section
    if (config && profile.services) {
      const servicesSection = config[["services", profile.services].join(CONFIG_PREFIX_SEPARATOR)];
      if (servicesSection) {
        const servicePrefixParts = serviceId.split(" ").map((w) => w.toLowerCase());
        const endpointUrl =
          servicesSection[[servicePrefixParts.join("_"), CONFIG_ENDPOINT_URL].join(CONFIG_PREFIX_SEPARATOR)];
        if (endpointUrl) return endpointUrl;
      }
    }

    // The value provided by the global parameter from a profile in the shared configuration file.
    const endpointUrl = profile[CONFIG_ENDPOINT_URL];
    if (endpointUrl) return endpointUrl;

    return undefined;
  },

  default: undefined,
});