lana.js

const Defaults = {
    clientId: 'merch-at-scale',
    delimiter: '¶',
    ignoredProperties: ['analytics', 'literals'],
    serializableTypes: ['Array', 'Object'],
    // Sample rate is set to 100 meaning each error will get logged in Splunk
    sampleRate: 30,
    tags: 'consumer=milo/commerce',
};

const seenPayloads = new Set();

const isError = (value) =>
    value instanceof Error ||
    // WCS error response
    // TODO: check if still actual
    typeof value.originatingRequest === 'string';

function serializeValue(value) {
    if (value == null) return undefined;
    const type = typeof value;
    if (type === 'function') {
        const { name } = value;
        return name ? `${type} ${name}` : type;
    }
    if (type === 'object') {  
        if (value instanceof Error) return value.message;
        if (typeof value.originatingRequest === 'string') {
          /* c8 ignore next 4 */
            const { message, originatingRequest, status } = value;
            return [message, status, originatingRequest]
                .filter((v) => v)
                .join(' ');
        }
        const name =
            value[Symbol.toStringTag] ??
            Object.getPrototypeOf(value).constructor.name;
        if (!Defaults.serializableTypes.includes(name)) return name;
    }
    return value;
}

function serializeParam(key, value) {
    if (Defaults.ignoredProperties.includes(key)) return undefined;
    return serializeValue(value);
}

/** @type {Commerce.Log.Appender} */
const lanaAppender = {
    append(entry) {
        const { delimiter, sampleRate, tags, clientId } = Defaults;
        const { message, params } = entry;
        const errors = [];
        let payload = message;
        const values = [];

        params.forEach((param) => {
            if (param != null) {
                (isError(param) ? errors : values).push(param);
            }
        });

        if (errors.length) {
            payload += ' ';
            payload += errors.map(serializeValue).join(' ');
        }

        // TODO: Lana backend extracts referer from the header sent,
        // sometimes it includes page path and query, sometimes - not
        const { pathname, search } = window.location;
        payload += `${delimiter}page=`;
        payload += pathname + search;

        if (values.length) {
            payload += `${delimiter}facts=`;
            payload += JSON.stringify(values, serializeParam);
        }

        if (!seenPayloads.has(payload)) {
            seenPayloads.add(payload);
            window.lana?.log(payload, { sampleRate, tags, clientId });
        }
    },
};

export { Defaults, lanaAppender };