/**
 * @module categorize
 * @description Returns a mapping of platforms to the information about the files involved in the PR contained in each platform
 * @param {Map} fileOwners mapping of platform name to a list of files involved in the change located in that platform
 * @param {[FileMetadata]} fileMetadatas - gitStream's list of metadata about file changes in the PR including path

/**
 * @module nullToEmpty
 * @description Returns the specified value if non-null, otherwise an empty array.
 * @param {Object} input - The object to investigate
 * @returns Object - The specified value if non-null, otherwise an empty array
 * @example {{ readField('jvm', 'files') | nullToEmpty }}
 */
function nullToEmpty(input) {
    let output;
    if (input) {
        output = input;
    } else {
        output = [];
    }

const jvm = ["big-guy", "ghale", "jvandort", "octylFractal", "tresat"];

/**
 * @module isEnabledUser
 * @description Returns true if the username that is passed to this function is a member of the Gradle BT Team who has opted into gitStream automations.
 * @param {string} Input - The GitHub username to check.
 * @returns {boolean} Returns true if the user is specified in any of the lists of Gradle BT team members above, otherwise false.

 * </ul>
 *
 * @param {string} automationName - The automation name (*.cm file name containing the automation) to check.
 * @param {Map} pr - The gitStream PR instance to check (includes metadata related to the pull request).
 * @returns {boolean} Returns true if the outlined conditions are met, otherwise false.
 * @example {{ 'platform_labels' | isEnabledAutomation(pr) }}
 */

/**
 * @module computeStatistics
 * @description Summarizes the changes to files in the PR by platform.
 *
 * @param {Map} groupedFiles - map of platforms for containing info about the changes to files in that platform, from call to categorize
 * @param {[FileMetadata]} fileMetadatas - gitStream's list of metadata about file changes in the PR including path
 * @returns {[Object]} Returns list of computed summary statistic objects for each platform in the input groupedFiles

/**
 * @module readField
 * @description Returns one field for a particular named object in a list of objects.
 * @param {[Object]} objects - The objects to search
 * @param {String} objectName - The name of the particular object to find
 * @param {String} fieldName - The name of the field for the group to return
 * @returns String - The specified value
 * @example {{ files | byPlatform | categorize(branch.diff.files_metadata) | readField('jvm', 'name') }}
 */

// Sanitize the range of a regular expression
// The cases are complicated, see test cases for details
const sanitizeRange = range => range.replace(
    REGEX_REGEXP_RANGE,
    (match, from, to) => from.charCodeAt(0) <= to.charCodeAt(0)
        ? match
        // Invalid range (out of order) which is ok for gitignore rules but
        //   fatal for JavaScript regular expression, so eliminate it.
        : EMPTY
)

 * @param {Object} pr - the gitStream's pr context variable
 * @param {string} token - access token with repo:read scope, used to read the CODEOWNERS file
 * @param {string} pathToCodeOwners - path from repo root to CODEOWNERS file
 * @returns {Map} - Map from owner name to list of files they own
 * @example {{ files | byCodeowner(pr, env.CODEOWNERS_TOKEN, '.github/CODEOWNERS') }}
 **/

/**
 * @module byPlatform
 * @description Groups the PR's files by platform based on the file's path.
 * @param {string[]} files - the gitStream's files context variable
 * @returns {Map} - Map from platform to list of files in this PR in it
 * @example {{ owners | byPlatform }}
 */
function byPlatform(files) {
    const result = new Map();
    files.forEach(file => {
        const platform = getPlatform(file);
        if (!result.has(platform)) {