lore/src/app/sortHooksByLoadOrder.js

Convention-driven framework for building React-Redux applications

import topsort from 'topsort';

/**
 * Convert the set of hooks in Object form to a format topsort can work with
 *
 * @param {Object} hooks Set of hooks to load
 * @returns {Array} Hooks converted to an array format recognizable by topsort
 */
function getDependencyGraph(hooks) {
  const dependencyGraph = [];

  Object.keys(hooks).forEach(function(hookName) {
    if (!hooks[hookName]) {
      return;
    }

    const dependencies = hooks[hookName].dependencies || [];

    if (dependencies.length === 0) {
      dependencyGraph.push([hookName]);
    }

    dependencies.forEach(function(dependency) {
      dependencyGraph.push([dependency, hookName]);
    });
  });

  return dependencyGraph;
}

/**
 * Examines all the  hooks and reorder them so they execute in the proper sequence (so that
 * hooks that depend on other hooks are only loaded after those hooks are).
 *
 * @param {Object} hooks Set of hooks to load
 * @returns {Array} List of hooks, sorted by execution order
 */
export default function sortHooksByLoadOrder(hooks, log) {
  const dependencyGraph = getDependencyGraph(hooks);
  // log.debug('hook dependency graph: ', dependencyGraph);

  const sortedDependencies = topsort(dependencyGraph);
  // log.debug('loading sorted hooks: ', sortedDependencies);

  return sortedDependencies.map(function(hookName) {
    const hook = hooks[hookName];
    if (!hook) {
      throw new Error(`Expected to find hook named '${hookName}' but none was included`);
    }
    return hook;
  });
}