Fix swallowed text between 2 mentions downstream

[akirk]

I've extracted some code to make it easier to see the fix:

const USER_ID_REGEX = /<@(\w+)\|?\w*?>/g;
let text = 'Hello <@U123> ! :wave: I\'m pinging <@U456> as he would be the best folk to answer your question :slightly_smiling_face:';

let match = null;
while ((match = USER_ID_REGEX.exec(text)) !== null) {
    // foreach userId, pull out the ID
    // (if this is an emote msg, the format is <@ID|nick>, but in normal msgs it's just <@ID>
    const id = match[1];
    let displayName = "";
    let userId = '';
    if ( id === 'U123') userId = '@randy:server';
    if ( id === 'U456') userId = '@akirk:server';

    const users = {};
    if ( id === 'U123') users.displayName = 'Randy';
    if ( id === 'U456') users.displayName = 'Alex Kirk';

    if (!userId) {
        log.warn("Mentioned user not in store. Looking up display name from slack.");
        // if the user is not in the store then we look up the displayname
        displayName = users.displayName;
        // If the user is not in the room, we can't pills them, we have to just plain text mention them.
        text = text.slice(0, match.index) + displayName + text.slice(match.index + match[0].length);
    } else {
        displayName = users.displayName || userId;
        text = text.slice(0, match.index) + `<https://matrix.to/#/${userId}|${displayName}>` + text.slice(match.index + match[0].length);
    }
}

// TODO: This is fixing plaintext mentions, but should be refactored.
// https://github.com/matrix-org/matrix-appservice-slack/issues/110
console.log( text.replace(/<https:\/\/matrix\.to\/#\/@.+:.+\|(.+)>/g, "$1") );
console.log( text.replace(/<https:\/\/matrix\.to\/#\/@[^|:]+(?::[^|]+\|)?([^>]+)>/g, "$1") );

outputs

Hello Alex Kirk as he would be the best folk to answer your question :slightly_smiling_face:
Hello Randy ! :wave: I'm pinging Alex Kirk as he would be the best folk to answer your question :slightly_smiling_face:

The first line is using the current regex which swallows text, the second one is the improved one.

[ashfame]

Thanks for fixing!