wikimedia/mediawiki-core

/*!
 * Finnish (Suomi) language functions
 * @author Santhosh Thottingal
 */

mw.language.convertGrammar = function ( word, form ) {
    let grammarForms, aou, origWord;

    grammarForms = mw.language.getData( 'fi', 'grammarForms' );
    if ( grammarForms && grammarForms[ form ] ) {
        return grammarForms[ form ][ word ];
    }

    // vowel harmony flag
    aou = /[aou][^äöy]*$/i.test( word );
    origWord = word;
    if ( /wiki$/i.test( word ) ) {
        aou = false;
    }
    // append i after final consonant
    if ( /[bcdfghjklmnpqrstvwxz]$/i.test( word ) ) {
        word += 'i';
    }

    switch ( form ) {
        case 'genitive':
            word += 'n';
            break;
        case 'elative':
            word += ( aou ? 'sta' : 'stä' );
            break;
        case 'partitive':
            word += ( aou ? 'a' : 'ä' );
            break;
        case 'illative':
            // Double the last letter and add 'n'
            word += word.slice( -1 ) + 'n';
            break;
        case 'inessive':
            word += ( aou ? 'ssa' : 'ssä' );
            break;
        default:
            word = origWord;
            break;
    }
    return word;
};