Mongoose plugin to add debug() timings to all pre/post middlewares

mongoose-middleware-debug-timings.js

const debug = require('debug');

function debugMiddlewareTimings(schema) {
  const vanityNames = {
    _pres: 'pre',
    _posts: 'post',
  };
  Object.keys(schema.s.hooks).forEach(hookType => {
    schema.s.hooks[hookType].forEach((value, key) => {
      value.forEach((hook, i) => {
        const { fn } = hook;
        const _old = fn;
        const name = fn.name || 'anonymous';
        const fnSource = _old.toString();

        // This is an internal mongoose middleware
        if (fnSource.match(/if \(mpath.has\(name, obj\)\)/)) {
          return;
        }
        if (fnSource === 'function() {}') return;

        const debugKey = `middleware:${vanityNames[hookType]}('${key}', ${name})`;

        let _new;
        switch (hook.fn.length) {
          case 0:
            _new = function debugOverride() {
              debug(debugKey);
              _old.call(this);
              debug(debugKey);
            };
            break;
          case 1:
            _new = function debugOverride(next) {
              debug(debugKey);
              _old.call(this, next);
              debug(debugKey);
            };
            break;
          case 2:
            _new = function debugOverride(doc, next) {
              debug(debugKey);
              _old.call(this, doc, next);
              debug(debugKey);
            };
            break;
          default:
            throw new Error('Unexpected fn.length in hook');
        }

        // eslint-disable-next-line no-param-reassign
        schema.s.hooks[hookType].get(key)[i].fn = _new;
      });
    });
  });
}