/**
 * @author Blake Embrey
 * Code from {@link https://github.com/blakeembrey/change-case}
 */

const SMALL_WORDS =
    /\b(?:an?d?|a[st]|because|but|by|en|for|i[fn]|neither|nor|o[fnr]|only|over|per|so|some|tha[tn]|the|to|up|upon|vs?\.?|versus|via|when|with|without|yet)\b/i;
const TOKENS = /[^\s:–—-]+|./g;
const WHITESPACE = /\s/;
const IS_MANUAL_CASE = /.(?=[A-Z]|\..)/;
const ALPHANUMERIC_PATTERN = /[A-Za-z0-9\u00C0-\u00FF]/;

/**
 * Title cases a string.
 * @param input The string to title-case.
 * @returns The title-cased string.
 */
export function titleCase(input: string) {
    let result = '';
    let m: RegExpExecArray | null;

    // tslint:disable-next-line
    while ((m = TOKENS.exec(input)) !== null) {
        const { 0: token, index } = m;

        if (
            // Ignore already capitalized words.
            !IS_MANUAL_CASE.test(token) &&
            // Ignore small words except at beginning or end.
            (!SMALL_WORDS.test(token) ||
                index === 0 ||
                index + token.length === input.length) &&
            // Ignore URLs.
            (input.charAt(index + token.length) !== ':' ||
                WHITESPACE.test(input.charAt(index + token.length + 1)))
        ) {
            // Find and uppercase first word character, skips over *modifiers*.
            result += token.replace(ALPHANUMERIC_PATTERN, (m) =>
                m.toUpperCase()
            );
            continue;
        }

        result += token;
    }

    return result;
}