const LINK_REMOVED = "[web link removed]";
const OBFUSCATING_SPACE = "[\\s\\u0000-\\u001f\\u007f\\u200b-\\u200d\\ufeff]*";
const SCHEME = `h${OBFUSCATING_SPACE}t${OBFUSCATING_SPACE}t${OBFUSCATING_SPACE}p(?:${OBFUSCATING_SPACE}s)?${OBFUSCATING_SPACE}:${OBFUSCATING_SPACE}\\/${OBFUSCATING_SPACE}\\/`;
const DOMAIN = "(?:[a-z0-9](?:[a-z0-9-]{0,61}[a-z0-9])?\\.)+[a-z]{2,63}";
const URL_TAIL = "[^\\s<>\\\"']*";

const explicitUrlPattern = () => new RegExp(`${SCHEME}${DOMAIN}${URL_TAIL}`, "gi");
const wwwUrlPattern = () => new RegExp(`\\bwww\\.${DOMAIN}${URL_TAIL}`, "gi");
const bareDomainWithPathPattern = () =>
    new RegExp(`(^|[^a-z0-9@._-])(${DOMAIN}\\/[^\\s<>\\\"']*)`, "gi");

const stripTrailingPunctuation = (value) => {
    let destination = value;
    let punctuation = "";

    while (/[.,!;:]$/.test(destination)) {
        punctuation = destination.slice(-1) + punctuation;
        destination = destination.slice(0, -1);
    }

    while (/[)\]}]$/.test(destination)) {
        punctuation = destination.slice(-1) + punctuation;
        destination = destination.slice(0, -1);
    }

    return { destination, punctuation };
};

const replaceUrlMatch = (value) => {
    const { destination, punctuation } = stripTrailingPunctuation(value);
    return destination ? LINK_REMOVED + punctuation : value;
};

const containsWebDestination = (value) => {
    explicitUrlPattern().lastIndex = 0;
    wwwUrlPattern().lastIndex = 0;
    bareDomainWithPathPattern().lastIndex = 0;

    return (
        explicitUrlPattern().test(value) ||
        wwwUrlPattern().test(value) ||
        bareDomainWithPathPattern().test(value)
    );
};

export default function removeContactUsEmailLinks(message) {
    if (typeof message !== "string") {
        return message;
    }

    let transformed = message;

    transformed = transformed.replace(
        /<a\b[^>]*>([\s\S]*?)<\/a\s*>/gi,
        (match, linkText) =>
            containsWebDestination(match)
                ? `${linkText}${linkText ? " " : ""}${LINK_REMOVED}`
                : match
    );

    transformed = transformed.replace(/<[^>]+>/gi, (tag) =>
        containsWebDestination(tag) ? LINK_REMOVED : tag
    );

    transformed = transformed.replace(
        /\[([^\]]*)\]\(([^)]*)\)/gi,
        (match, linkText, destination) =>
            containsWebDestination(destination)
                ? `${linkText}${linkText ? " " : ""}${LINK_REMOVED}`
                : match
    );

    transformed = transformed.replace(explicitUrlPattern(), replaceUrlMatch);
    transformed = transformed.replace(wwwUrlPattern(), replaceUrlMatch);
    transformed = transformed.replace(
        bareDomainWithPathPattern(),
        (match, prefix, destination) => prefix + replaceUrlMatch(destination)
    );

    return transformed;
}