make revert button do thing

src/lib/RevertButton.svelte

@@ -0,0 +1,10 @@
+<script lang="ts">
+	export let id: string
+
+	async function revert() {
+		// post request to /api/revert/<id>.json
+		await fetch(`/api/revert/${id}.json`, { method: 'POST' })
+	}
+</script>
+
+<button on:click={revert} class="revert-button">Revert</button>

src/lib/database/history.ts

@@ -95,7 +95,7 @@ export async function fetchEntryHistoryItemsAfter(item: HistoryItem): Promise<Hi
 /**
  * Get the history item that was made right before this one, so we can calculate the diff
  */
-export async function getEntryHistoryItemBefore(item: HistoryItem): Promise<HistoryItem | null> {
+export async function fetchEntryHistoryItemBefore(item: HistoryItem): Promise<HistoryItem | null> {
 	const collection = await getCollection()
 
 	const result = await collection
@@ -107,3 +107,15 @@ export async function getEntryHistoryItemBefore(item: HistoryItem): Promise<Hist
 	if (result.length === 0) return null
 	return replaceUuidWithId(result[0])
 }
+
+/**
+ * Get the history item that was made right before this one, so we can calculate the diff
+ */
+export async function fetchEntryHistoryItem(id: string): Promise<HistoryItem | null> {
+	const collection = await getCollection()
+
+	const result = await collection.findOne(replaceIdWithUuid({ id }))
+
+	if (result === null) return null
+	return replaceUuidWithId(result)
+}

src/lib/revert.ts

@@ -2,7 +2,7 @@ import type { Entry } from './database/entries'
 import {
 	fetchEntryHistory,
 	fetchEntryHistoryItemsAfter,
-	getEntryHistoryItemBefore,
+	fetchEntryHistoryItemBefore,
 	HistoryItem,
 } from './database/history'
 import * as diff from 'fast-myers-diff'
@@ -13,9 +13,9 @@ import { createUuid } from './database'
  *
  * This code is very bad and buggy
  */
-async function getRevertResult(historyItem: HistoryItem) {
+export async function getRevertResult(historyItem: HistoryItem) {
 	const historyItemsAfter = await fetchEntryHistoryItemsAfter(historyItem)
-	const historyItemBefore = await getEntryHistoryItemBefore(historyItem)
+	const historyItemBefore = await fetchEntryHistoryItemBefore(historyItem)
 
 	if (historyItemBefore === null) {
 		// this was the initial edit, so we can't revert it
@@ -24,15 +24,13 @@ async function getRevertResult(historyItem: HistoryItem) {
 
 	// the difference between this edit and the previous one
 	let patch = Array.from(diff.calcPatch(historyItem.content, historyItemBefore.content))
-	console.log('patch', patch)
+	console.log('initial patch', patch)
 
 	// we update the initial patch based on all the edits that occured after this one
 	let tempBefore = historyItem
 	for (const historyItemAfter of historyItemsAfter) {
 		const diffAfter = Array.from(diff.diff(tempBefore.content, historyItemAfter.content))
-		console.log('tempDiff', diffAfter)
 		for (const [removeStart, removeEnd, insertStart, insertEnd] of diffAfter) {
-			const initialPatch = JSON.parse(JSON.stringify(patch))
 			patch = patch.map(([patchRemoveStart, patchRemoveEnd, insertSlice]) => {
 				// if the patch is removing something, subtract from the patchRemoveStart and patchRemoveEnd
 				if (removeStart !== removeEnd) {
@@ -57,12 +55,12 @@ async function getRevertResult(historyItem: HistoryItem) {
 
 				return [patchRemoveStart, patchRemoveEnd, insertSlice]
 			})
-			console.log(initialPatch, patch)
 		}
-		console.log(diffAfter)
 		tempBefore = historyItem
 	}
 
+	console.log('patch', patch)
+
 	// apply the patch to the current version
 	const newContent = Array.from(
 		diff.applyPatch(
@@ -73,24 +71,5 @@ async function getRevertResult(historyItem: HistoryItem) {
 		.flat()
 		.join('')
 
-	console.log(
-		'new',
-		Array.from(
-			diff.calcPatch(
-				historyItemsAfter[0] ? historyItemsAfter[0].content : historyItem.content,
-				newContent
-			)
-		)
-	)
-
 	return newContent
 }
-
-;(async () => {
-	console.log('...')
-	const history = await fetchEntryHistory(createUuid('a8942d398dd845b28822b2c19ae443e2'), 20, 0)
-	console.log('.....', history.items.length)
-	const newContent = await getRevertResult(history.items[1])
-
-	console.log(newContent)
-})()

src/routes/api/revert/[id].json.ts

@@ -0,0 +1,42 @@
+import type { RequestHandler } from '@sveltejs/kit'
+import type { JSONString } from '@sveltejs/kit/types/helper'
+import { fetchEntryHistoryItem } from '../../../lib/database/history'
+import { getRevertResult } from '../../../lib/revert'
+
+export interface APIHistoryItem {
+	id: string
+	entryId: string
+	userId: string
+	title: string
+	content: string
+	timestamp: Date
+}
+
+export interface APIHistoryResponse {
+	count: number
+	items: APIHistoryItem[]
+}
+
+// revert an entry history item
+export const post: RequestHandler = async req => {
+	const historyItemId = req.params.id
+
+	const historyItem = await fetchEntryHistoryItem(historyItemId)
+
+	if (historyItem === null)
+		return {
+			status: 404,
+			body: {
+				error: 'Not found',
+			},
+		}
+
+	const newContent = await getRevertResult(historyItem)
+
+	console.log(newContent)
+	return {
+		body: {
+			content: newContent,
+		} as unknown as JSONString,
+	}
+}

src/routes/history/[id].svelte

@@ -29,6 +29,7 @@
 	import User from '../../lib/User.svelte'
 	import { format as formatTimeAgo } from 'timeago.js'
 	import { browser } from '$app/env'
+	import RevertButton from '../../lib/RevertButton.svelte'
 
 	export let entry: Entry
 	export let historyItems: APIHistoryItem[]
@@ -74,7 +75,7 @@
 	{#if i > 0}
 		<div class="history-item">
 			<User id={historyItem.userId} /> - {formatTimeAgo(historyItem.timestamp)}
-			<button class="revert-button">Revert</button>
+			<RevertButton id={historyItems[i - 1].id} />
 
 			<div class="history-diff">
 				<Diff