From ec35e5f14cb25193d5c49a41d4b016691c15c6a2 Mon Sep 17 00:00:00 2001
From: Matt Hill <MattDHill@users.noreply.github.com>
Date: Wed, 29 Jun 2022 17:43:12 -0600
Subject: [PATCH] refactor apply operation to account for arrays (#38)

* refactor apply operation to account for arrays

* fix buig
---
 client/lib/json-patch-lib.ts | 38 +++++++++++++++++++++++++++++-------
 1 file changed, 31 insertions(+), 7 deletions(-)

diff --git a/client/lib/json-patch-lib.ts b/client/lib/json-patch-lib.ts
index 8f2ab0e..aa251d9 100644
--- a/client/lib/json-patch-lib.ts
+++ b/client/lib/json-patch-lib.ts
@@ -39,7 +39,7 @@ export function applyOperation<T> (
   const add = { op: PatchOp.ADD, path, value: current} as const
   const replace = { op: PatchOp.REPLACE, path, value: current } as const
 
-  doc.data = recursiveApply(doc.data, jsonPathToKeyArray(path), value)
+  doc.data = recursiveApply(doc.data, jsonPathToKeyArray(path), op, value)
 
   switch (op) {
     case PatchOp.REMOVE:
@@ -54,14 +54,22 @@ export function applyOperation<T> (
   }
 }
 
-function recursiveApply<T extends Record<string, T>> (data: T, path: readonly string[], value?: any): T {
+function recursiveApply<T extends Record<string, any> | any[]> (data: T, path: readonly string[], op: PatchOp, value?: any): T {
   if (!path.length) return value
-
-  if (!isObject(data)) {
-    throw Error('Patch cannot be applied. Path contains non object')
+  
+  // object
+  if (isObject(data)) {
+    return recursiveApplyObject(data, path, op, value)
+  // array
+  } else if (Array.isArray(data)) {
+    return recursiveApplyArray(data, path, op, value)
+  } else {
+    throw 'unreachable'
   }
+}
 
-  const updated = recursiveApply(data[path[0]], path.slice(1), value)
+function recursiveApplyObject<T extends Record<string, any>> (data: T, path: readonly string[], op: PatchOp, value?: any): T {
+  const updated = recursiveApply(data[path[0]], path.slice(1), op, value)
   const result = {
     ...data,
     [path[0]]: updated,
@@ -74,8 +82,24 @@ function recursiveApply<T extends Record<string, T>> (data: T, path: readonly st
   return result
 }
 
+function recursiveApplyArray<T extends any[]> (data: T, path: readonly string[], op: PatchOp, value?: any): T {
+  const index = parseInt(path[0])
+
+  const updated = recursiveApply(data[index], path.slice(1), op, value)
+  const result = [...data] as T
+  if (op === PatchOp.ADD) {
+    result.splice(index, 0, updated)
+  } else if (op === PatchOp.REPLACE) {
+    result.splice(index, 1, updated)
+  } else {
+    result.splice(index, 1)
+  }
+
+  return result
+}
+
 function isObject (val: any): val is Record<string, unknown> {
-  return typeof val === 'object' && val !== null
+  return typeof val === 'object' && val !== null && !Array.isArray(val)
 }
 
 function jsonPathToKeyArray (path: string): string[] {