From 39dd45b65d4b292372ee0441a9846c5f93d471ba Mon Sep 17 00:00:00 2001
From: Peter Stuifzand <peter@stuifzand.eu>
Date: Fri, 30 Oct 2020 23:43:00 +0100
Subject: [PATCH] Rotate items to moveBefore

---
 list-editor/index.js           |  4 ++++
 list-editor/spec/store.spec.js | 29 +++++++++++++++++++++++++++++
 list-editor/store.js           | 19 +++++++++++++------
 list-editor/util.js            | 20 ++++++++++++++++++++
 4 files changed, 66 insertions(+), 6 deletions(-)

diff --git a/list-editor/index.js b/list-editor/index.js
index 4b8b866..88cfcd1 100644
--- a/list-editor/index.js
+++ b/list-editor/index.js
@@ -280,12 +280,16 @@ function editor(root, inputData, options) {
         })
 
         drake.on('drop', function (el, target, source, sibling) {
+            stopEditing(root, store, currentEditor)
             let stopID = $(sibling).attr('data-id')
             if (startID === stopID) {
                 return
             }
 
             let id = store.moveBefore(startID, stopID)
+            if (id === startID) {
+                return
+            }
 
             let position = store.index(id);
             cursor.set(position)
diff --git a/list-editor/spec/store.spec.js b/list-editor/spec/store.spec.js
index 5d9509f..9b95aa1 100644
--- a/list-editor/spec/store.spec.js
+++ b/list-editor/spec/store.spec.js
@@ -160,4 +160,33 @@ describe("A store", function () {
             },
         ])
     })
+
+    describe("contains a moveBefore method 2", function () {
+        let store
+
+        beforeEach(function () {
+            store = createStore([
+                {text: "a", id: "_a", indented: 0},
+                {text: "b", id: "_b", indented: 0},
+                {text: "c", id: "_c", indented: 0},
+                {text: "d", id: "_d", indented: 0},
+            ])
+        })
+        it("moveBefore _d, _a", function () {
+            store.moveBefore("_d", "_a")
+            expect(store.debug().idList).toEqual(["_d", "_a", "_b", "_c"])
+        })
+        it("moveBefore _d, _b", function () {
+            store.moveBefore("_d", "_b")
+            expect(store.debug().idList).toEqual(["_a", "_d", "_b", "_c"])
+        })
+        it("moveBefore _a, _d", function() {
+            store.moveBefore("_a", "_d")
+            expect(store.debug().idList).toEqual(["_b", "_c", "_a", "_d"])
+        })
+        it("moveBefore _b, _d", function() {
+            store.moveBefore("_b", "_d")
+            expect(store.debug().idList).toEqual(["_a", "_c", "_b", "_d"])
+        })
+    })
 })
diff --git a/list-editor/store.js b/list-editor/store.js
index 1c1ecd2..532e085 100644
--- a/list-editor/store.js
+++ b/list-editor/store.js
@@ -1,4 +1,5 @@
 import _ from 'lodash';
+import rotate from './util'
 
 /**
  * NOTE: Store should contain all methods that work with items. At the moment
@@ -285,12 +286,18 @@ function Store(inputData) {
      * @returns {string}
      */
     function moveBefore(from, to) {
-        let fromIndex = _.findIndex(idList, (id) => id === from)
-        let item = values[from]
-        internalRemove(fromIndex, 1)
-        let result = insertBefore(to, item)
-        changed = true
-        return result
+        let fromIndex = index(from)
+        let toIndex = to ? index(to) : idList.length
+        let n = lastHigherIndented(fromIndex) - fromIndex
+        if (toIndex >= fromIndex && toIndex < fromIndex + n) return index(from)
+        if (fromIndex < toIndex) {
+            rotate(idList, fromIndex, toIndex, n)
+            changed = true
+        } else if (toIndex < fromIndex) {
+            rotate(idList, toIndex, fromIndex + n, fromIndex - toIndex)
+            changed = true
+        }
+        return index(from)
     }
 
     /**
diff --git a/list-editor/util.js b/list-editor/util.js
index e69de29..fecd9b5 100644
--- a/list-editor/util.js
+++ b/list-editor/util.js
@@ -0,0 +1,20 @@
+function reverse(a, from, to) {
+    --from;
+    while (++from < --to) {
+        var tmp = a[from];
+        a[from] = a[to];
+        a[to] = tmp;
+    }
+}
+
+function rotate(a, from, to, k) {
+    var n = to - from;
+    k = (k % n + n) % n;
+    if (k > 0) {
+        reverse(a, from, from + k);
+        reverse(a, from + k, to);
+        reverse(a, from, to);
+    }
+}
+
+export default rotate;