From 9d76b1249baf2c31c668a77fe9b3d3020a601087 Mon Sep 17 00:00:00 2001
From: Gregor <gregor@martynus.net>
Date: Mon, 15 Jan 2018 22:43:44 -0800
Subject: [PATCH] refactor: combine implementation of adding/removing hooks

---
 index.js             | 24 ++++++++----------------
 lib/add.js           | 13 +++++++++++++
 lib/after.js         | 14 --------------
 lib/before.js        | 14 --------------
 lib/error.js         | 14 --------------
 lib/register.js      |  7 +++++++
 lib/remove-after.js  | 15 ---------------
 lib/remove-before.js | 15 ---------------
 lib/remove-error.js  | 15 ---------------
 lib/remove.js        | 15 +++++++++++++++
 10 files changed, 43 insertions(+), 103 deletions(-)
 create mode 100644 lib/add.js
 delete mode 100644 lib/after.js
 delete mode 100644 lib/before.js
 delete mode 100644 lib/error.js
 delete mode 100644 lib/remove-after.js
 delete mode 100644 lib/remove-before.js
 delete mode 100644 lib/remove-error.js
 create mode 100644 lib/remove.js

diff --git a/index.js b/index.js
index 269bdbb..97bd874 100644
--- a/index.js
+++ b/index.js
@@ -1,12 +1,8 @@
 module.exports = Hook
 
 var register = require('./lib/register')
-var before = require('./lib/before')
-var error = require('./lib/error')
-var after = require('./lib/after')
-var removeBefore = require('./lib/remove-before')
-var removeError = require('./lib/remove-error')
-var removeAfter = require('./lib/remove-after')
+var addHook = require('./lib/add')
+var removeHook = require('./lib/remove')
 
 function Hook () {
   var state = {
@@ -14,17 +10,13 @@ function Hook () {
   }
 
   var hook = register.bind(null, state)
-  hook.api = {}
+  hook.remove = {}
+  hook.api = {remove: {}}
 
-  hook.api.before = hook.before = before.bind(null, state)
-  hook.api.error = hook.error = error.bind(null, state)
-  hook.api.after = hook.after = after.bind(null, state)
-
-  hook.api.remove = hook.remove = {
-    before: removeBefore.bind(null, state),
-    error: removeError.bind(null, state),
-    after: removeAfter.bind(null, state)
-  }
+  ;['before', 'error', 'after'].forEach(function (kind) {
+    hook[kind] = hook.api[kind] = addHook.bind(null, state, kind)
+    hook.remove[kind] = hook.api.remove[kind] = removeHook.bind(null, state, kind)
+  })
 
   return hook
 }
diff --git a/lib/add.js b/lib/add.js
new file mode 100644
index 0000000..001701e
--- /dev/null
+++ b/lib/add.js
@@ -0,0 +1,13 @@
+module.exports = addHook
+
+function addHook (state, kind, name, hook) {
+  if (!state.registry[name]) {
+    state.registry[name] = {
+      before: [],
+      error: [],
+      after: []
+    }
+  }
+
+  state.registry[name][kind][kind === 'before' ? 'unshift' : 'push'](hook)
+}
diff --git a/lib/after.js b/lib/after.js
deleted file mode 100644
index 46af160..0000000
--- a/lib/after.js
+++ /dev/null
@@ -1,14 +0,0 @@
-module.exports = afterHook
-
-function afterHook (state, name, afterHook) {
-  if (state.registry[name]) {
-    state.registry[name].after.push(afterHook)
-    return
-  }
-
-  state.registry[name] = {
-    before: [],
-    error: [],
-    after: [afterHook]
-  }
-}
diff --git a/lib/before.js b/lib/before.js
deleted file mode 100644
index 0dbbe19..0000000
--- a/lib/before.js
+++ /dev/null
@@ -1,14 +0,0 @@
-module.exports = beforeHook
-
-function beforeHook (state, name, beforeHook) {
-  if (state.registry[name]) {
-    state.registry[name].before.unshift(beforeHook)
-    return
-  }
-
-  state.registry[name] = {
-    before: [beforeHook],
-    error: [],
-    after: []
-  }
-}
diff --git a/lib/error.js b/lib/error.js
deleted file mode 100644
index 3edfa02..0000000
--- a/lib/error.js
+++ /dev/null
@@ -1,14 +0,0 @@
-module.exports = errorHook
-
-function errorHook (state, name, errorHook) {
-  if (state.registry[name]) {
-    state.registry[name].error.unshift(errorHook)
-    return
-  }
-
-  state.registry[name] = {
-    before: [],
-    error: [errorHook],
-    after: []
-  }
-}
diff --git a/lib/register.js b/lib/register.js
index dbb5316..c048591 100644
--- a/lib/register.js
+++ b/lib/register.js
@@ -21,6 +21,7 @@ function register (state, name, options, method) {
   }
 
   var hooks = state.registry[name]
+
   if (!hooks) {
     return invokeMethod(options, method)
   }
@@ -29,12 +30,17 @@ function register (state, name, options, method) {
   var errorHooks = hooks.error
   var afterHooks = hooks.after
 
+  // 1. run "before hooks" which may mutate options
   return Promise.all(beforeHooks.map(invokeBeforeHook.bind(null, options)))
 
+  // 2. Once all finish without error, call the method with the (mutated) options
   .then(function () {
     return method(options)
   })
 
+  // 3. If an error occurs in 1. or 2. run the "error hooks" which may mutate
+  //    the error object. If one of them does not return an error then set the
+  //    result to that. Otherwise throw (mutated) error.
   .catch(function (error) {
     return Promise.all(errorHooks.map(invokeErrorHook.bind(null, error, options)))
 
@@ -49,6 +55,7 @@ function register (state, name, options, method) {
     })
   })
 
+  // 4. Run the "after hooks". They may mutate the result
   .then(function (result) {
     return Promise.all(afterHooks.map(invokeAfterHook.bind(null, result, options)))
 
diff --git a/lib/remove-after.js b/lib/remove-after.js
deleted file mode 100644
index 1e442c7..0000000
--- a/lib/remove-after.js
+++ /dev/null
@@ -1,15 +0,0 @@
-module.exports = removeAfterHook
-
-function removeAfterHook (state, name, method) {
-  if (!state.registry[name]) {
-    return
-  }
-
-  var index = state.registry[name].after.indexOf(method)
-
-  if (index === -1) {
-    return
-  }
-
-  state.registry[name].after.splice(index, 1)
-}
diff --git a/lib/remove-before.js b/lib/remove-before.js
deleted file mode 100644
index c613e66..0000000
--- a/lib/remove-before.js
+++ /dev/null
@@ -1,15 +0,0 @@
-module.exports = removeBeforeHook
-
-function removeBeforeHook (state, name, method) {
-  if (!state.registry[name]) {
-    return
-  }
-
-  var index = state.registry[name].before.indexOf(method)
-
-  if (index === -1) {
-    return
-  }
-
-  state.registry[name].before.splice(index, 1)
-}
diff --git a/lib/remove-error.js b/lib/remove-error.js
deleted file mode 100644
index f06db20..0000000
--- a/lib/remove-error.js
+++ /dev/null
@@ -1,15 +0,0 @@
-module.exports = removeErrorHook
-
-function removeErrorHook (state, name, method) {
-  if (!state.registry[name]) {
-    return
-  }
-
-  var index = state.registry[name].error.indexOf(method)
-
-  if (index === -1) {
-    return
-  }
-
-  state.registry[name].error.splice(index, 1)
-}
diff --git a/lib/remove.js b/lib/remove.js
new file mode 100644
index 0000000..f548c42
--- /dev/null
+++ b/lib/remove.js
@@ -0,0 +1,15 @@
+module.exports = removeHook
+
+function removeHook (state, kind, name, method) {
+  if (!state.registry[name]) {
+    return
+  }
+
+  var index = state.registry[name][kind].indexOf(method)
+
+  if (index === -1) {
+    return
+  }
+
+  state.registry[name][kind].splice(index, 1)
+}