import { CredentialsProviderError } from "@smithy/property-provider";
import { getProfileName, loadSharedConfigFiles, SourceProfileInit } from "@smithy/shared-ini-file-loader";
import { ParsedIniData, Profile, Provider } from "@smithy/types";

export interface SharedConfigInit extends SourceProfileInit {
  /**
   * The preferred shared ini file to load the config. "config" option refers to
   * the shared config file(defaults to `~/.aws/config`). "credentials" option
   * refers to the shared credentials file(defaults to `~/.aws/credentials`)
   */
  preferredFile?: "config" | "credentials";
}

export type GetterFromConfig<T> = (profile: Profile, configFile?: ParsedIniData) => T | undefined;

/**
 * Get config value from the shared config files with inferred profile name.
 */
export const fromSharedConfigFiles = <T = string>(
  configSelector: GetterFromConfig<T>,
  { preferredFile = "config", ...init }: SharedConfigInit = {}
): Provider<T> => async () => {
  const profile = getProfileName(init);
  const { configFile, credentialsFile } = await loadSharedConfigFiles(init);

  const profileFromCredentials = credentialsFile[profile] || {};
  const profileFromConfig = configFile[profile] || {};
  const mergedProfile =
    preferredFile === "config"
      ? { ...profileFromCredentials, ...profileFromConfig }
      : { ...profileFromConfig, ...profileFromCredentials };

  try {
    const cfgFile = preferredFile === "config" ? configFile : credentialsFile;
    const configValue = configSelector(mergedProfile, cfgFile);
    if (configValue === undefined) {
      throw new Error();
    }
    return configValue;
  } catch (e) {
    throw new CredentialsProviderError(
      e.message || `Cannot load config for profile ${profile} in SDK configuration files with getter: ${configSelector}`
    );
  }
};