From 2fdee4395056ba9629bfdd1984b6a40cc71c3e44 Mon Sep 17 00:00:00 2001
From: cha0s <git@cha0s.io>
Date: Wed, 20 Nov 2019 00:53:35 -0600
Subject: [PATCH] feat: hooks!

---
 packages/core/array.js         |  8 ++++
 packages/core/hook/entry.js    |  1 +
 packages/core/hook/loader.js   | 72 ++++++++++++++++++++++++++++++++++
 packages/core/hook/registry.js | 27 +++++++++++++
 packages/core/index.js         |  3 +-
 5 files changed, 110 insertions(+), 1 deletion(-)
 create mode 100644 packages/core/hook/entry.js
 create mode 100644 packages/core/hook/loader.js
 create mode 100644 packages/core/hook/registry.js

diff --git a/packages/core/array.js b/packages/core/array.js
index b567689..fcacdca 100644
--- a/packages/core/array.js
+++ b/packages/core/array.js
@@ -5,3 +5,11 @@ export function arrayUnique(array) {
 export function flatten(array) {
   return array.reduce((flattened, elm) => flattened.concat(elm), []);
 }
+
+export function fromObject(object) {
+  const array = [];
+  for (const key in object) {
+    array.push(object[key]);
+  }
+  return array;
+}
diff --git a/packages/core/hook/entry.js b/packages/core/hook/entry.js
new file mode 100644
index 0000000..22488e5
--- /dev/null
+++ b/packages/core/hook/entry.js
@@ -0,0 +1 @@
+// I don't know how to create assets out of thin air with webpack.
diff --git a/packages/core/hook/loader.js b/packages/core/hook/loader.js
new file mode 100644
index 0000000..739bcc7
--- /dev/null
+++ b/packages/core/hook/loader.js
@@ -0,0 +1,72 @@
+const glob = require('glob');
+const {getOptions} = require('loader-utils');
+const path = require('path');
+const validateOptions = require('schema-utils');
+const schema = {
+  type: 'object',
+  properties: {
+    paths: {
+      items: {
+        type: 'string',
+      },
+      type: 'array',
+    },
+  },
+  required: [
+    'paths',
+  ],
+};
+
+// Dynamically require all traits.
+module.exports = function(source) {
+  const options = getOptions(this);
+  // Validate schema.
+  validateOptions(schema, options, 'Avocado hooks');
+  // Extract options.
+  const {paths} = options;
+  // Search avocado.
+  const avocadoPath = path.normalize(
+    path.join(__dirname, '..', '..'),
+  );
+  paths.push(avocadoPath);
+  // Get source paths.
+  const sourcePaths = [];
+  paths.forEach((path) => {
+    const files = glob.sync(`${path}/**/hooks.js`, {
+      follow: true,
+    });
+    sourcePaths.push(...files);
+  });
+  // Build registers.
+  const registers = sourcePaths.map((sourcePath) => {
+    const relativePath = path.relative(__dirname, sourcePath);
+    const basename = path.basename(relativePath, '.js');
+    const parts = relativePath.split('/');
+    // Chop off basename.
+    parts.pop();
+    // Module or local?
+    let importDirectory;
+    if ('..' === parts[0]) {
+      const avocadoPathParts = ['@avocado', 'core', 'hook'].concat(parts);
+      importDirectory = path.normalize(avocadoPathParts.join('/'));
+    }
+    else if ('node_modules' === parts[0]) {
+      importDirectory = parts.slice(1).join('/');
+    }
+    else {
+      importDirectory = `./${parts.join('/')}`;
+    }
+    // Register hooks.
+    const importPath = `${importDirectory}/hooks`;
+    return [
+      `registerHooks('${importDirectory}', require('${importPath}'));`,
+    ].join('\n');
+  });
+  // Import trait registry first.
+  const output = [
+    `import {registerHooks} from '@avocado/core/hook/registry'`,
+    '',
+    ...registers
+  ].join('\n');
+  return output;
+}
diff --git a/packages/core/hook/registry.js b/packages/core/hook/registry.js
new file mode 100644
index 0000000..3fb6e09
--- /dev/null
+++ b/packages/core/hook/registry.js
@@ -0,0 +1,27 @@
+import {fromObject} from '../array';
+
+const impl = {};
+export function registerHooks(name, implementations) {
+  for (const hook in implementations) {
+    if (!impl[hook]) {
+      impl[hook] = {};
+    }
+    impl[hook][name] = implementations[hook];
+  }
+}
+
+export function invoke(hook, ...args) {
+  const hookImpl = impl[hook];
+  if (!hookImpl) {
+    return {};
+  }
+  const result = {};
+  for (const name in hookImpl) {
+    result[name] = hookImpl[name](...args);
+  }
+  return result;
+}
+
+export function invokeFlat(hook, ...args) {
+  return fromObject(invoke(hook, ...args));
+}
diff --git a/packages/core/index.js b/packages/core/index.js
index d454277..47ebf61 100644
--- a/packages/core/index.js
+++ b/packages/core/index.js
@@ -1,5 +1,6 @@
-export {arrayUnique, flatten} from './array';
+export {arrayUnique, flatten, fromObject as arrayFromObject} from './array';
 export {EventEmitterMixin as EventEmitter} from './event-emitter';
+export {invoke as invokeHook, invokeFlat as invokeHookFlat} from './hook/registry';
 export {merge} from './merge';
 export {
   mergeDiff,