From eee6f0f5e08732356d5c77784420211cc2bf3fe7 Mon Sep 17 00:00:00 2001
From: Steve Kellock <steve@kellock.ca>
Date: Sat, 20 Aug 2016 13:31:03 -0400
Subject: [PATCH] Adds subscription diffs. (#143)

---
 .../App/Commands/StateValuesChangeCommand.js  | 29 +++++++---
 .../reactotron-app/App/Lib/ShallowDiff.js     | 54 +++++++++++++++++++
 .../reactotron-app/App/Stores/SessionStore.js |  5 ++
 3 files changed, 82 insertions(+), 6 deletions(-)
 create mode 100644 packages/reactotron-app/App/Lib/ShallowDiff.js

diff --git a/packages/reactotron-app/App/Commands/StateValuesChangeCommand.js b/packages/reactotron-app/App/Commands/StateValuesChangeCommand.js
index 1dbc357c9..3c9dd9200 100644
--- a/packages/reactotron-app/App/Commands/StateValuesChangeCommand.js
+++ b/packages/reactotron-app/App/Commands/StateValuesChangeCommand.js
@@ -4,7 +4,8 @@ import ObjectTree from '../Shared/ObjectTree'
 import Colors from '../Theme/Colors'
 import isShallow from '../Lib/IsShallow'
 import makeTable from '../Shared/MakeTable'
-import { map, fromPairs } from 'ramda'
+import { keys, concat, join } from 'ramda'
+import { mapKeys, isNilOrEmpty } from 'ramdasauce'
 
 const COMMAND_TITLE = 'SUBSCRIPTIONS'
 
@@ -32,15 +33,31 @@ class StateValuesChangeCommand extends Component {
 
   render () {
     const { command } = this.props
-    const changes = map(change => ([change.path, change.value]), this.props.command.payload.changes)
-    const changeObject = fromPairs(changes)
-    const preview = null // `${changes.length} change${changes.length !== 1 && 's'}`
+    const { payload } = command
+    const phrase = []
+    let { changed, added, removed } = payload
+    const hasAdded = !isNilOrEmpty(added)
+    const hasRemoved = !isNilOrEmpty(removed)
+    const hasChanged = !isNilOrEmpty(changed)
+    if (hasChanged) {
+      phrase.push(`${keys(changed).length} changed`)
+    }
+    if (hasAdded) {
+      added = mapKeys(concat('+ '), added)
+      phrase.push(`${keys(added).length} added`)
+    }
+    if (hasRemoved) {
+      removed = mapKeys(concat('- '), removed)
+      phrase.push(`${keys(removed).length} removed`)
+    }
+    const preview = join(' ', phrase)
 
     return (
       <Command command={command} title={COMMAND_TITLE} preview={preview}>
         <div style={Styles.container}>
-          <div style={Styles.name}>{name}</div>
-          {this.renderContent(changeObject)}
+          {hasChanged && this.renderContent(changed)}
+          {hasAdded && this.renderContent(added)}
+          {hasRemoved && this.renderContent(removed)}
         </div>
       </Command>
     )
diff --git a/packages/reactotron-app/App/Lib/ShallowDiff.js b/packages/reactotron-app/App/Lib/ShallowDiff.js
new file mode 100644
index 000000000..0aa4dd953
--- /dev/null
+++ b/packages/reactotron-app/App/Lib/ShallowDiff.js
@@ -0,0 +1,54 @@
+// https://github.com/ramda/ramda/wiki/Cookbook#diffobjs---diffing-objects-similar-to-guavas-mapsdifference
+import {
+  curry, pipe, useWith, __, map,
+  toPairs, last, fromPairs,
+  groupBy, mergeWith, always, has, both,
+  objOf, merge, prop, apply, ifElse,
+  cond, values, equals, evolve
+} from 'ramda' // boom
+
+const groupObjBy = curry(
+  pipe(
+  // Call groupBy with the object as pairs, passing only the value to the key function
+    useWith(groupBy, [useWith(__, [last]), toPairs]),
+    map(fromPairs)
+  )
+)
+
+const LEFT_VALUE = 'leftValue'
+const RIGHT_VALUE = 'rightValue'
+const COMMON = 'common'
+const DIFFERENCE = 'difference'
+const ONLY_ON_LEFT = 'onlyOnLeft'
+const ONLY_ON_RIGHT = 'onlyOnRight'
+
+const diffObjs = pipe(
+  useWith(
+    mergeWith(merge),
+    [map(objOf(LEFT_VALUE)), map(objOf(RIGHT_VALUE))]
+  ),
+
+  groupObjBy(cond([
+    [
+      both(has(LEFT_VALUE), has(RIGHT_VALUE)),
+      pipe(
+        values,
+        ifElse(
+          apply(equals),
+          always(COMMON),
+          always(DIFFERENCE)
+        )
+      )
+    ],
+    [has(LEFT_VALUE), always(ONLY_ON_LEFT)],
+    [has(RIGHT_VALUE), always(ONLY_ON_RIGHT)]
+  ])),
+
+  evolve({
+    [COMMON]: map(prop(LEFT_VALUE)),
+    [ONLY_ON_LEFT]: map(prop(LEFT_VALUE)),
+    [ONLY_ON_RIGHT]: map(prop(RIGHT_VALUE))
+  })
+)
+
+export default diffObjs
diff --git a/packages/reactotron-app/App/Stores/SessionStore.js b/packages/reactotron-app/App/Stores/SessionStore.js
index ccb1fa7c9..054490cd0 100644
--- a/packages/reactotron-app/App/Stores/SessionStore.js
+++ b/packages/reactotron-app/App/Stores/SessionStore.js
@@ -3,6 +3,7 @@ import { createServer } from 'reactotron-core-server'
 import { computed, reaction } from 'mobx'
 import { last, isNil, reject, equals, reverse, pipe, propEq, map, fromPairs } from 'ramda'
 import { dotPath } from 'ramdasauce'
+import shallowDiff from '../Lib/ShallowDiff'
 
 const isSubscription = propEq('type', 'state.values.change')
 const isSubscriptionCommandWithEmptyChanges = command => isSubscription(command) && dotPath('payload.changes.length', command) === 0
@@ -21,6 +22,10 @@ class Session {
 
     // 🚨🚨🚨 side effect alert 🚨🚨🚨
     if (isNew) {
+      const diff = shallowDiff(this.subscriptions, newSubscriptions)
+      command.payload.changed = map(v => v.rightValue, diff.difference || [])
+      command.payload.added = diff.onlyOnRight || []
+      command.payload.removed = diff.onlyOnLeft || []
       this.subscriptions = newSubscriptions
     }
     // 🚨🚨🚨 side effect alert 🚨🚨🚨