errorScan and verifyKeys functions from valStringer

valueStringer.js

// scans a custom attachment object for errors
errorScan = (type, customAttachment) => {

    const expectedKeys = ['text', 'callback_id', 'actions'];
    const expectedSubKeys = type === 'menu' ? ['name', 'type', 'data_source'] : ['text', 'name', 'type'];

    const keysError = verifyKeys(customAttachment, expectedKeys, 'outer attachment properties');
    if(keysError){
        return keysError;
    }

    const actions = customAttachment.actions[0];
    const subKeysError = verifyKeys(actions, expectedSubKeys, 'actions array object');
    if(subKeysError){
        return subKeysError;
    }

    else {
        switch(type){
            case 'menu':
                switch(true) {
                    case actions.type !== 'select':
                        return `invalid custom attachment: action type must be "select" for interactive menus`;
                    case actions.data_source !== 'static':
                        return `invalid custom attachment: data_source must be "static" for interactive menus`;
                }
                break;
            case 'button':
                switch(true){
                    case actions.type !== 'button':
                        return `invalid custom attachment: action type must be "button" for interactive buttons`;
                }
                break;
        }
    }

    return false;
};


// verifies the keys of a custom attachment object
verifyKeys = (object, expectedKeys, location) => {
    let error;

    expectedKeys.forEach( e => {
        if(!object.hasOwnProperty(e)){
            error = `invalid custom attachment: missing the property "${e}" in the ${location}`;
        }
    });

    return error ? error : false;
};