import {check} from '@augment-vir/assert';
import {join} from 'node:path';
import {type PackageJson} from 'type-fest';
import {readJsonFile} from '../fs/json.js';

/**
 * Read the `package.json` file contained within the given directory.
 *
 * @category Node : Npm
 * @category Package : @augment-vir/node
 * @throws `TypeError` if the given directory has no `package.json` or the `package.json` is
 *   invalid.
 * @package [`@augment-vir/node`](https://www.npmjs.com/package/@augment-vir/node)
 */
export async function readPackageJson(dirPath: string): Promise<PackageJson> {
    const packageJsonPath = join(dirPath, 'package.json');
    const packageJson = (await readJsonFile(packageJsonPath)) as PackageJson | undefined;

    if (!packageJson) {
        throw new TypeError(`package.json file does not exist in '${dirPath}'`);
    }

    if (!check.isObject(packageJson)) {
        throw new TypeError(`Parsing package.json file did not return an object in '${dirPath}'`);
    }

    return packageJson;
}