// the error handling of this module was taken from `@github-docs/frontmatter`.

// but, it's no longer maintained (in fact, the repo is just gone).

// the code is still available on npm:

// https://www.npmjs.com/package/@github-docs/frontmatter

//

// also, for some reason, it doesn't expose the error location that

// it gets from `gray-matter`, but we could use it for nicer errors.

// using `@gr2m/gray-matter` instead of `gray-matter` because the original

// library hasn't been updated in years and this fork updates the `js-yaml`

// dependency, which is much smaller and more performant.

const grayMatter = require('@gr2m/gray-matter');

const yaml = require('js-yaml');

const DEFAULT_REASON = 'Invalid frontmatter entry';

/**

* @typedef {Object} FrontmatterParseResult

* @property {Record<string, unknown>} attributes

* @property {string} body

* @property {YAMLException | null} error

*/

/**

* Parse the frontmatter and body from the content of a Markdown/MDX string.

*

* @example

* ```js

* import { frontmatter } from './scripts/utils/frontmatter'

*

* const mdxString = `---

* key: value

* list:

* - item 1

* - item 2

* ---

* howdy pardner 🤠`;

*

* const { attributes, body, error } = frontmatter(mdxString)

* console.log(attributes)

* // {

* // key: 'value',

* // list: ['item 1', 'item 2']

* // }

*

* console.log(body)

* // 'howdy pardner 🤠'

*

* console.log(error)

* // null

* ```

*

* @param {string} mdString - Full content of the MD(X) file to parse.

* @return {FrontmatterParseResult} { attributes, body, error }

*/

const frontmatter = (mdString) => {

let result;

try {

const { content, data } = grayMatter(mdString);

result = {

attributes: data,

body: content,

error: null,

};

} catch (error) {

if (error.reason.startsWith('can not read a block mapping entry;')) {

error.reason = DEFAULT_REASON;

}

result = {

attributes: {},

body: null,

error,

};

}

return result;

};

const stringifyFrontmatter = (body, attributes, options) => {

try {

return grayMatter.stringify(body, attributes, options);

} catch (error) {

return error;

}

};

/**

* Parse the frontmatter and check for required freshnessValidatedDate field on most content doc pages.

* Valid options are `never` or `YYYY-MM-DD`

*

* @example

* ```yaml

* ---

* title: This is a doc page

* freshnessValidatedDate: 2021-03-15

* ---

* ```

*

*```js

* // error.message = undefined

* ```

*

* ```yaml

* ---

* title: This is a doc page with an invalid date

* freshnessValidatedDate: 21-03-15

* ---

* ```

*

*```js

* // error.message = freshnessValidatedDate is not a valid value. Must be date format YYYY-MM-DD or `never`

* ```

*

*

*

* @param {string} mdString - Full content of the MD(X) file to parse.

* @returns error | undefined

*/

const validateFreshnessDate = (mdString) => {

let error;

const { data } = grayMatter(mdString, {

engines: {

yaml: {

parse: (string) => yaml.safeLoad(string, { schema: yaml.JSON_SCHEMA }),

},

},

});

const isValidDate = (date) => {

const regex = /\d{4}\-(0[1-9]|1[012])\-(0[1-9]|[12][0-9]|3[01])/;

return regex.test(date);

};

// freshnessValidatedDate is a required field and must be a date or `never`

if (data.freshnessValidatedDate) {

const stringDate = data.freshnessValidatedDate.toString();

if (!isValidDate(stringDate) && !stringDate.includes('never')) {

error = new Error(

'freshnessValidatedDate is not a valid value. Must be date format YYYY-MM-DD or `never`'

);

}

} else {

error = new Error('freshnessValidatedDate field missing from frontmatter');

}

return error;

};

/**

* Parse the frontmatter and check for required releaseDate field on whats-new, security-bulletins, and release-notes.

* Valid format is `YYYY-MM-DD`

*

* @example

* ```yaml

* ---

* title: This is a security bulletin

* releaseDate: '2021-03-15'

* ---

* ```

*

*```js

* // error.message = undefined

* ```

*

* ```yaml

* ---

* title: This is a security bulletin with an invalid date

* releaseDate: 21-03-15

* ---

* ```

*

*```js

* // error.message = releaseDate is not a valid value. Must be date string formatted like 'YYYY-MM-DD' wrapped in single quotes

* ```

*

*

*

* @param {string} mdString - Full content of the MD(X) file to parse.

* @returns error | undefined

*/

const validateReleaseDate = (mdString) => {

let error;

const { data } = grayMatter(mdString, {

engines: {

yaml: {

parse: (string) => yaml.safeLoad(string, { schema: yaml.JSON_SCHEMA }),

},

},

});

const isValidDate = (date) => {

const regex = /\d{4}\-(0[1-9]|1[012])\-(0[1-9]|[12][0-9]|3[01])/;

return regex.test(date);

};

// releaseDate is a required field and must be a date wrapped in single quotes

if (data.releaseDate) {

if (!isValidDate(data.releaseDate)) {

error = new Error(

"releaseDate is not a valid value. Must be date string formatted like 'YYYY-MM-DD' wrapped in single quotes"

);

}

} else {

error = new Error('releaseDate field missing from frontmatter');

}

return error;

};

module.exports = {

frontmatter,

stringifyFrontmatter,

validateFreshnessDate,

validateReleaseDate,

};