type RootOptions = {
  filename?: string;
  filenameRelative?: string;
  sourceRoot?: string;
};

type PluginOptions = {
  moduleId?: string;
  moduleIds?: boolean;
  getModuleId?: (moduleName: string) => string | null | undefined;
  moduleRoot?: string;
};

if (!process.env.BABEL_8_BREAKING) {
  const originalGetModuleName = getModuleName;

  // @ts-expect-error TS doesn't like reassigning a function.
  // eslint-disable-next-line no-func-assign
  getModuleName = function getModuleName(
    rootOpts: RootOptions & PluginOptions,
    pluginOpts: PluginOptions,
  ): string | null {
    return originalGetModuleName(rootOpts, {
      moduleId: pluginOpts.moduleId ?? rootOpts.moduleId,
      moduleIds: pluginOpts.moduleIds ?? rootOpts.moduleIds,
      getModuleId: pluginOpts.getModuleId ?? rootOpts.getModuleId,
      moduleRoot: pluginOpts.moduleRoot ?? rootOpts.moduleRoot,
    });
  };
}

export default function getModuleName(
  rootOpts: RootOptions,
  pluginOpts: PluginOptions,
): string | null {
  const {
    filename,
    filenameRelative = filename,
    sourceRoot = pluginOpts.moduleRoot,
  } = rootOpts;

  const {
    moduleId,
    moduleIds = !!moduleId,

    getModuleId,

    moduleRoot = sourceRoot,
  } = pluginOpts;

  if (!moduleIds) return null;

  // moduleId is n/a if a `getModuleId()` is provided
  if (moduleId != null && !getModuleId) {
    return moduleId;
  }

  let moduleName = moduleRoot != null ? moduleRoot + "/" : "";

  if (filenameRelative) {
    const sourceRootReplacer =
      sourceRoot != null ? new RegExp("^" + sourceRoot + "/?") : "";

    moduleName += filenameRelative
      // remove sourceRoot from filename
      .replace(sourceRootReplacer, "")
      // remove extension
      .replace(/\.(\w*?)$/, "");
  }

  // normalize path separators
  moduleName = moduleName.replace(/\\/g, "/");

  if (getModuleId) {
    // If return is falsy, assume they want us to use our generated default name
    return getModuleId(moduleName) || moduleName;
  } else {
    return moduleName;
  }
}