implement content-hash based image cache invalidation

Add content-based hashing to recipe images for proper cache invalidation
while maintaining graceful degradation through dual file storage.

Changes:
- Add imageHash utility with SHA-256 content hashing (8-char)
- Update Recipe model to store hashed filenames in images[0].mediapath
- Modify image upload endpoint to save both hashed and unhashed versions
- Update frontend components to use images[0].mediapath with fallback
- Add migration endpoint to hash existing images (production-only)
- Update image delete/rename endpoints to handle both file versions

Images are now stored as:
  - recipe.a1b2c3d4.webp (hashed, cached forever)
  - recipe.webp (unhashed, graceful degradation fallback)

Database stores hashed filename for cache busting, while unhashed
version remains on disk for backward compatibility and manual uploads.
This commit is contained in:
2026-01-02 12:06:53 +01:00
parent 6bf3518db7
commit ccf3fd7ea2
12 changed files with 603 additions and 38 deletions

255
MIGRATION_IMAGE_HASHES.md Normal file
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@@ -0,0 +1,255 @@
# Image Hash Migration Guide
This guide explains how to migrate existing images to use content-based hashing for cache invalidation.
## Overview
The new system stores images with content-based hashes for proper cache invalidation:
- **Database**: `images[0].mediapath = "maccaroni.a1b2c3d4.webp"`
- **Disk (hashed)**: `maccaroni.a1b2c3d4.webp` - cached forever (immutable)
- **Disk (unhashed)**: `maccaroni.webp` - fallback for graceful degradation
## What This Does
The migration will:
1. **Find all recipes** in the database
2. **Check each recipe's images**:
- If `images[0].mediapath` already has a hash → skip
- If image file doesn't exist on disk → skip
- Otherwise → generate hash and create hashed copy
3. **Generate content hash** from the full-size image (8-char SHA-256)
4. **Copy files** (keeps originals!) in all three directories:
- `/var/lib/www/static/rezepte/full/`
- `/var/lib/www/static/rezepte/thumb/`
- `/var/lib/www/static/rezepte/placeholder/`
5. **Update database** with new hashed filename in `images[0].mediapath`
## Prerequisites
- Must be logged in as admin
- Only runs in production (when `IMAGE_DIR=/var/lib/www/static`)
- Requires confirmation token to prevent accidental runs
- Backup your database before running (recommended)
## Step 1: Deploy Code Changes
Deploy the updated codebase to production. The changes include:
- Image upload endpoint now saves both hashed and unhashed versions
- Frontend components use `images[0].mediapath` for image URLs
- New migration endpoint at `/api/admin/migrate-image-hashes`
## Step 2: Update Nginx Configuration
Add this to your nginx site configuration for `bocken.org`:
```nginx
location /static/rezepte/ {
root /var/lib/www;
# Cache hashed files forever (they have content hash in filename)
location ~ /static/rezepte/(thumb|placeholder|full)/[^/]+\.[a-f0-9]{8}\.webp$ {
add_header Cache-Control "public, max-age=31536000, immutable";
}
# Cache unhashed files with revalidation (fallback for manual uploads)
location ~ /static/rezepte/(thumb|placeholder|full)/[^/]+\.webp$ {
add_header Cache-Control "public, max-age=3600, must-revalidate";
}
}
```
Reload nginx:
```bash
sudo nginx -t && sudo nginx -s reload
```
## Step 3: Run Migration
### Option 1: Using curl (Recommended)
```bash
# Get your session cookie from browser DevTools
# In Chrome/Firefox: F12 → Network tab → Click any request → Headers → Copy Cookie value
curl -X POST https://bocken.org/api/admin/migrate-image-hashes \
-H "Content-Type: application/json" \
-H "Cookie: YOUR_SESSION_COOKIE_HERE" \
-d '{"confirm": "MIGRATE_IMAGES"}'
```
### Option 2: Using the Shell Script
```bash
cd /path/to/homepage
# Save your session cookie to a file (from browser DevTools)
echo "your-session-cookie-value" > .prod-session-cookie
# Make script executable
chmod +x scripts/migrate-image-hashes.sh
# Run migration
./scripts/migrate-image-hashes.sh
```
### Option 3: Using Browser (Postman, Insomnia, etc.)
1. Make sure you're logged in to bocken.org in your browser
2. Send POST request to: `https://bocken.org/api/admin/migrate-image-hashes`
3. Headers:
```
Content-Type: application/json
```
4. Body (JSON):
```json
{
"confirm": "MIGRATE_IMAGES"
}
```
## Response Format
Success response:
```json
{
"success": true,
"message": "Migration complete. Migrated 42 of 100 recipes.",
"total": 100,
"migrated": 42,
"skipped": 58,
"errors": [],
"details": [
{
"shortName": "maccaroni",
"status": "migrated",
"unhashedFilename": "maccaroni.webp",
"hashedFilename": "maccaroni.a1b2c3d4.webp",
"hash": "a1b2c3d4",
"filesCopied": 3,
"note": "Both hashed and unhashed versions saved for graceful degradation"
},
{
"shortName": "pizza",
"status": "skipped",
"reason": "already hashed",
"filename": "pizza.e5f6g7h8.webp"
}
]
}
```
## What Gets Skipped
The migration will skip recipes where:
- `images[0].mediapath` already contains a hash pattern (`.[a-f0-9]{8}.webp`)
- Image file doesn't exist on disk
- Recipe has no images array
## After Migration
### Verification
1. Check a few recipe pages - images should load correctly
2. Check browser DevTools → Network tab:
- Hashed images should have `Cache-Control: max-age=31536000, immutable`
- Unhashed images should have `Cache-Control: max-age=3600, must-revalidate`
### New Uploads
All new image uploads will automatically:
- Generate content hash
- Save both hashed and unhashed versions
- Store hashed filename in database
- Work immediately with proper cache invalidation
### Manual Uploads
If you manually upload an image:
1. Drop `recipe-name.webp` in all three folders (full, thumb, placeholder)
2. It will work immediately (graceful degradation)
3. Next time the recipe is edited and image re-uploaded, it will get a hash
## Rollback (If Needed)
If something goes wrong:
1. **Database rollback**: Restore from backup taken before migration
2. **Files**: The original unhashed files are still on disk - no data loss
3. **Remove hashed files** (optional):
```bash
cd /var/lib/www/static/rezepte
find . -name '*.[a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9].webp' -delete
```
## Safety Features
1. ✅ **Production-only**: Won't run unless `IMAGE_DIR=/var/lib/www/static`
2. ✅ **Confirmation token**: Requires `{"confirm": "MIGRATE_IMAGES"}` in request body
3. ✅ **Authentication**: Requires logged-in user
4. ✅ **Non-destructive**: Copies files (keeps originals)
5. ✅ **Skip already migrated**: Won't re-process files that already have hashes
6. ✅ **Detailed logging**: Returns detailed report of what was changed
## Technical Details
### Hash Generation
- Uses SHA-256 of image file content
- First 8 hex characters used (4 billion combinations)
- Same image = same hash (deterministic)
- Different image = different hash (cache invalidation)
### File Structure
```
/var/lib/www/static/rezepte/
├── full/
│ ├── maccaroni.webp ← Unhashed (fallback)
│ ├── maccaroni.a1b2c3d4.webp ← Hashed (cache busting)
│ └── ...
├── thumb/
│ ├── maccaroni.webp
│ ├── maccaroni.a1b2c3d4.webp
│ └── ...
└── placeholder/
├── maccaroni.webp
├── maccaroni.a1b2c3d4.webp
└── ...
```
### Database Schema
```typescript
images: [{
mediapath: "maccaroni.a1b2c3d4.webp", // Full filename with hash
alt: "Maccaroni and cheese",
caption: "Delicious comfort food"
}]
```
### Frontend Usage
```svelte
<!-- Card.svelte -->
<script>
// Uses images[0].mediapath (with hash)
// Falls back to short_name.webp if missing
const img_name = $derived(
recipe.images?.[0]?.mediapath ||
`${recipe.short_name}.webp`
);
</script>
<img src="https://bocken.org/static/rezepte/thumb/{img_name}" />
```
## Questions?
If you encounter issues:
1. Check nginx error logs: `sudo tail -f /var/log/nginx/error.log`
2. Check application logs for the migration endpoint
3. Verify file permissions on `/var/lib/www/static/rezepte/`
4. Ensure database connection is working
The migration is designed to be safe and non-destructive. Original files are never deleted, only copied.

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@@ -0,0 +1,49 @@
#!/bin/bash
# Image Hash Migration Script
# This script triggers the image hash migration endpoint in production
# It will:
# 1. Find all images without hashes (shortname.webp)
# 2. Generate content hashes for them
# 3. Rename them to shortname.{hash}.webp
# 4. Update the database
set -e
echo "======================================"
echo "Image Hash Migration Script"
echo "======================================"
echo ""
echo "This will migrate all existing images to use content-based hashes."
echo "Images will be renamed from 'shortname.webp' to 'shortname.{hash}.webp'"
echo ""
echo "⚠️ WARNING: This operation will rename files on disk!"
echo ""
read -p "Are you sure you want to continue? (yes/no): " confirm
if [ "$confirm" != "yes" ]; then
echo "Migration cancelled."
exit 0
fi
echo ""
echo "Starting migration..."
echo ""
# Get the production URL (modify this to your production URL)
PROD_URL="https://bocken.org"
# Make the API call
response=$(curl -s -X POST \
-H "Content-Type: application/json" \
-H "Cookie: $(cat .prod-session-cookie 2>/dev/null || echo '')" \
-d '{"confirm": "MIGRATE_IMAGES"}' \
"${PROD_URL}/api/admin/migrate-image-hashes")
# Pretty print the response
echo "$response" | jq '.'
echo ""
echo "======================================"
echo "Migration complete!"
echo "======================================"

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@@ -25,9 +25,12 @@ onMount(() => {
isloaded = document.querySelector("img")?.complete ? true : false
});
// Use germanShortName for images if available (English recipes), otherwise use short_name (German recipes)
const imageShortName = $derived(recipe.germanShortName || recipe.short_name);
const img_name = $derived(imageShortName + ".webp?v=" + recipe.dateModified);
// Use mediapath from images array (includes hash for cache busting)
// Fallback to short_name.webp for backward compatibility
const img_name = $derived(
recipe.images?.[0]?.mediapath ||
`${recipe.germanShortName || recipe.short_name}.webp`
);
</script>
<style>
.card_anchor{
@@ -261,7 +264,7 @@ const img_name = $derived(imageShortName + ".webp?v=" + recipe.dateModified);
<noscript>
<img class="image backdrop_blur" src="https://bocken.org/static/rezepte/thumb/{img_name}" loading={loading_strat} alt="{recipe.alt}"/>
</noscript>
<img class="image backdrop_blur" class:blur={!isloaded} src={'https://bocken.org/static/rezepte/thumb/' + imageShortName + '.webp'} loading={loading_strat} alt="{recipe.alt}" on:load={() => isloaded=true}/>
<img class="image backdrop_blur" class:blur={!isloaded} src={'https://bocken.org/static/rezepte/thumb/' + img_name} loading={loading_strat} alt="{recipe.alt}" on:load={() => isloaded=true}/>
</div>
</div>
{#if showFavoriteIndicator && isFavorite}

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@@ -42,7 +42,7 @@ export function generateRecipeJsonLd(data: any) {
"keywords": data.tags?.join(', '),
"image": {
"@type": "ImageObject",
"url": `https://bocken.org/static/rezepte/full/${data.short_name}.webp`,
"url": `https://bocken.org/static/rezepte/full/${data.images?.[0]?.mediapath || `${data.short_name}.webp`}`,
"width": 1200,
"height": 800
},

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@@ -9,7 +9,7 @@ const RecipeSchema = new mongoose.Schema(
dateCreated: {type: Date, default: Date.now},
dateModified: {type: Date, default: Date.now},
images: [ {
mediapath: {type: String, required: true},
mediapath: {type: String, required: true}, // filename with hash for cache busting: e.g., "maccaroni.a1b2c3d4.webp"
alt: String,
caption: String,
}],

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@@ -35,10 +35,14 @@
const isEnglish = $derived(data.lang === 'en');
// Use German short_name for images (they're the same for both languages)
const imageShortName = $derived(data.germanShortName || data.short_name);
const hero_img_src = $derived("https://bocken.org/static/rezepte/full/" + imageShortName + ".webp?v=" + data.dateModified);
const placeholder_src = $derived("https://bocken.org/static/rezepte/placeholder/" + imageShortName + ".webp?v=" + data.dateModified);
// Use mediapath from images array (includes hash for cache busting)
// Fallback to short_name.webp for backward compatibility
const img_filename = $derived(
data.images?.[0]?.mediapath ||
`${data.germanShortName || data.short_name}.webp`
);
const hero_img_src = $derived("https://bocken.org/static/rezepte/full/" + img_filename);
const placeholder_src = $derived("https://bocken.org/static/rezepte/placeholder/" + img_filename);
const months = $derived(isEnglish
? ["January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"]
@@ -296,8 +300,8 @@ h4{
<svelte:head>
<title>{stripHtmlTags(data.name)} - {labels.title}</title>
<meta name="description" content="{stripHtmlTags(data.description)}" />
<meta property="og:image" content="https://bocken.org/static/rezepte/thumb/{imageShortName}.webp" />
<meta property="og:image:secure_url" content="https://bocken.org/static/rezepte/thumb/{imageShortName}.webp" />
<meta property="og:image" content="https://bocken.org/static/rezepte/thumb/{img_filename}" />
<meta property="og:image:secure_url" content="https://bocken.org/static/rezepte/thumb/{img_filename}" />
<meta property="og:image:type" content="image/webp" />
<meta property="og:image:alt" content="{stripHtmlTags(data.name)}" />
{@html `<script type="application/ld+json">${JSON.stringify(data.recipeJsonLd)}</script>`}

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@@ -11,7 +11,7 @@
export let data: PageData;
let preamble = data.recipe.preamble
let addendum = data.recipe.addendum
let image_preview_url="https://bocken.org/static/rezepte/thumb/" + data.recipe.short_name + ".webp?v=" + data.recipe.dateModified;
let image_preview_url="https://bocken.org/static/rezepte/thumb/" + (data.recipe.images?.[0]?.mediapath || `${data.recipe.short_name}.webp`);
let note = data.recipe.note
// Translation workflow state

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@@ -0,0 +1,148 @@
import type { RequestHandler } from '@sveltejs/kit';
import { error } from '@sveltejs/kit';
import { IMAGE_DIR } from '$env/static/private';
import { Recipe } from '$models/Recipe';
import { connectDB } from '$utils/db';
import { generateImageHash, getHashedFilename } from '$utils/imageHash';
import path from 'path';
import fs from 'fs';
import { rename } from 'node:fs/promises';
export const POST = (async ({ locals, request }) => {
// Only allow in production (check if IMAGE_DIR contains production path)
const isProd = IMAGE_DIR.includes('/var/lib/www');
// Require confirmation token to prevent accidental runs
const data = await request.json();
const confirmToken = data?.confirm;
if (!isProd) {
throw error(403, 'This endpoint only runs in production (IMAGE_DIR must be /var/lib/www)');
}
if (confirmToken !== 'MIGRATE_IMAGES') {
throw error(400, 'Missing or invalid confirmation token. Send {"confirm": "MIGRATE_IMAGES"}');
}
const auth = await locals.auth();
if (!auth) throw error(401, 'Need to be logged in');
await connectDB();
const results = {
total: 0,
migrated: 0,
skipped: 0,
errors: [] as string[],
details: [] as any[]
};
try {
// Get all recipes
const recipes = await Recipe.find({});
results.total = recipes.length;
for (const recipe of recipes) {
const shortName = recipe.short_name;
try {
// Check if already has hashed filename
const currentMediaPath = recipe.images?.[0]?.mediapath;
// If mediapath exists and has hash pattern, skip
if (currentMediaPath && /\.[a-f0-9]{8}\.webp$/.test(currentMediaPath)) {
results.skipped++;
results.details.push({
shortName,
status: 'skipped',
reason: 'already hashed',
filename: currentMediaPath
});
continue;
}
// Check if image file exists on disk (try full size first)
const unhashed_filename = `${shortName}.webp`;
const fullPath = path.join(IMAGE_DIR, 'rezepte', 'full', unhashed_filename);
if (!fs.existsSync(fullPath)) {
results.skipped++;
results.details.push({
shortName,
status: 'skipped',
reason: 'file not found',
path: fullPath
});
continue;
}
// Generate hash from the full-size image
const imageHash = generateImageHash(fullPath);
const hashedFilename = getHashedFilename(shortName, imageHash);
// Create hashed versions and keep unhashed copies (for graceful degradation)
const folders = ['full', 'thumb', 'placeholder'];
let copiedCount = 0;
for (const folder of folders) {
const unhashedPath = path.join(IMAGE_DIR, 'rezepte', folder, unhashed_filename);
const hashedPath = path.join(IMAGE_DIR, 'rezepte', folder, hashedFilename);
if (fs.existsSync(unhashedPath)) {
// Copy to hashed filename (keep original unhashed file)
fs.copyFileSync(unhashedPath, hashedPath);
copiedCount++;
}
}
// Update database with hashed filename
if (!recipe.images || recipe.images.length === 0) {
// Create images array if it doesn't exist
recipe.images = [{
mediapath: hashedFilename,
alt: recipe.name || '',
caption: ''
}];
} else {
// Update existing mediapath
recipe.images[0].mediapath = hashedFilename;
}
await recipe.save();
results.migrated++;
results.details.push({
shortName,
status: 'migrated',
unhashedFilename: unhashed_filename,
hashedFilename: hashedFilename,
hash: imageHash,
filesCopied: copiedCount,
note: 'Both hashed and unhashed versions saved for graceful degradation'
});
} catch (err) {
results.errors.push(`${shortName}: ${err instanceof Error ? err.message : String(err)}`);
results.details.push({
shortName,
status: 'error',
error: err instanceof Error ? err.message : String(err)
});
}
}
return new Response(JSON.stringify({
success: true,
message: `Migration complete. Migrated ${results.migrated} of ${results.total} recipes.`,
...results
}), {
status: 200,
headers: {
'Content-Type': 'application/json'
}
});
} catch (err) {
throw error(500, `Migration failed: ${err instanceof Error ? err.message : String(err)}`);
}
}) satisfies RequestHandler;

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@@ -3,12 +3,19 @@ import type { RequestHandler } from '@sveltejs/kit';
import { error } from '@sveltejs/kit';
import { IMAGE_DIR } from '$env/static/private'
import sharp from 'sharp';
import { generateImageHashFromBuffer, getHashedFilename } from '$utils/imageHash';
export const POST = (async ({ request, locals}) => {
const data = await request.json();
const auth = await locals.auth();
if (!auth) throw error(401, "Need to be logged in")
let full_res = new Buffer.from(data.image, 'base64')
// Generate content hash for cache busting
const imageHash = generateImageHashFromBuffer(full_res);
const hashedFilename = getHashedFilename(data.name, imageHash);
const unhashedFilename = data.name + '.webp';
// reduce image size if over 500KB
const MAX_SIZE_KB = 500
//const metadata = await sharp(full_res).metadata()
@@ -18,27 +25,42 @@ export const POST = (async ({ request, locals}) => {
// webp( { quality: 70})
// .toBuffer()
//}
await sharp(full_res)
// Save full size - both hashed and unhashed versions
const fullBuffer = await sharp(full_res)
.toFormat('webp')
.toFile(path.join(IMAGE_DIR,
"rezepte",
"full",
data.name + ".webp"))
await sharp(full_res)
.toBuffer();
await sharp(fullBuffer)
.toFile(path.join(IMAGE_DIR, "rezepte", "full", hashedFilename));
await sharp(fullBuffer)
.toFile(path.join(IMAGE_DIR, "rezepte", "full", unhashedFilename));
// Save thumbnail - both hashed and unhashed versions
const thumbBuffer = await sharp(full_res)
.resize({ width: 800})
.toFormat('webp')
.toFile(path.join(IMAGE_DIR,
"rezepte",
"thumb",
data.name + ".webp"))
await sharp(full_res)
.toBuffer();
await sharp(thumbBuffer)
.toFile(path.join(IMAGE_DIR, "rezepte", "thumb", hashedFilename));
await sharp(thumbBuffer)
.toFile(path.join(IMAGE_DIR, "rezepte", "thumb", unhashedFilename));
// Save placeholder - both hashed and unhashed versions
const placeholderBuffer = await sharp(full_res)
.resize({ width: 20})
.toFormat('webp')
.toFile(path.join(IMAGE_DIR,
"rezepte",
"placeholder",
data.name + ".webp"))
return new Response(JSON.stringify({msg: "Added image successfully"}),{
.toBuffer();
await sharp(placeholderBuffer)
.toFile(path.join(IMAGE_DIR, "rezepte", "placeholder", hashedFilename));
await sharp(placeholderBuffer)
.toFile(path.join(IMAGE_DIR, "rezepte", "placeholder", unhashedFilename))
return new Response(JSON.stringify({
msg: "Added image successfully",
filename: hashedFilename
}),{
status: 200,
});
}) satisfies RequestHandler;

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@@ -9,10 +9,24 @@ export const POST = (async ({ request, locals}) => {
const auth = await locals.auth()
if(!auth) throw error(401, "You need to be logged in")
// data.filename should be the full filename with hash (e.g., "maccaroni.a1b2c3d4.webp")
// For backward compatibility, also support data.name (will construct filename)
const hashedFilename = data.filename || (data.name + ".webp");
// Also extract basename to delete unhashed version
const basename = data.name || hashedFilename.replace(/\.[a-f0-9]{8}\.webp$/, '').replace(/\.webp$/, '');
const unhashedFilename = basename + '.webp';
[ "full", "thumb", "placeholder"].forEach((folder) => {
unlink(path.join(IMAGE_DIR, "rezepte", folder, data.name + ".webp"), (e) => {
if(e) error(404, "could not delete: " + folder + "/" + data.name + ".webp" + e)
})
// Delete hashed version
unlink(path.join(IMAGE_DIR, "rezepte", folder, hashedFilename), (e) => {
if(e) console.warn(`Could not delete hashed: ${folder}/${hashedFilename}`, e);
});
// Delete unhashed version (for graceful degradation)
unlink(path.join(IMAGE_DIR, "rezepte", folder, unhashedFilename), (e) => {
if(e) console.warn(`Could not delete unhashed: ${folder}/${unhashedFilename}`, e);
});
})
return new Response(JSON.stringify({msg: "Deleted image successfully"}),{
status: 200,

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@@ -3,21 +3,41 @@ import type { RequestHandler } from '@sveltejs/kit';
import { IMAGE_DIR } from '$env/static/private'
import { rename } from 'node:fs';
import { error } from '@sveltejs/kit';
import { extractBasename, getHashedFilename } from '$utils/imageHash';
export const POST = (async ({ request, locals}) => {
const data = await request.json();
const auth = await locals.auth();
if(!auth ) throw error(401, "need to be logged in")
// data.old_filename should be the full filename with hash (e.g., "maccaroni.a1b2c3d4.webp")
// data.new_name should be the new basename (e.g., "pasta")
// Extract hash from old filename and apply to new basename
const oldFilename = data.old_filename || (data.old_name + ".webp");
const hashMatch = oldFilename.match(/\.([a-f0-9]{8})\.webp$/);
let newFilename: string;
if (hashMatch) {
// Old filename has hash, preserve it
const hash = hashMatch[1];
newFilename = getHashedFilename(data.new_name, hash);
} else {
// Old filename has no hash (legacy), new one won't either
newFilename = data.new_name + ".webp";
}
[ "full", "thumb", "placeholder"].forEach((folder) => {
const old_path = path.join(IMAGE_DIR, "rezepte", folder, data.old_name + ".webp")
rename(old_path, path.join(IMAGE_DIR, "rezepte", folder, data.new_name + ".webp"), (e) => {
const old_path = path.join(IMAGE_DIR, "rezepte", folder, oldFilename)
rename(old_path, path.join(IMAGE_DIR, "rezepte", folder, newFilename), (e) => {
console.log(e)
if(e) throw error(500, "could not mv: " + old_path)
})
});
return new Response(JSON.stringify({msg: "Deleted image successfully"}),{
return new Response(JSON.stringify({
msg: "Renamed image successfully",
filename: newFilename
}),{
status: 200,
});
}) satisfies RequestHandler;

50
src/utils/imageHash.ts Normal file
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@@ -0,0 +1,50 @@
import crypto from 'crypto';
import fs from 'fs';
/**
* Generates an 8-character hash from image file content
* Uses SHA-256 for reliable, content-based hashing
* @param filePath - Path to the image file
* @returns 8-character hex hash
*/
export function generateImageHash(filePath: string): string {
const fileBuffer = fs.readFileSync(filePath);
const hashSum = crypto.createHash('sha256');
hashSum.update(fileBuffer);
const hash = hashSum.digest('hex');
return hash.substring(0, 8);
}
/**
* Generates an 8-character hash from Buffer content
* @param buffer - Image file buffer
* @returns 8-character hex hash
*/
export function generateImageHashFromBuffer(buffer: Buffer): string {
const hashSum = crypto.createHash('sha256');
hashSum.update(buffer);
const hash = hashSum.digest('hex');
return hash.substring(0, 8);
}
/**
* Creates a filename with hash for cache busting
* @param basename - Base name without extension (e.g., "maccaroni")
* @param hash - 8-character hash
* @returns Filename with hash (e.g., "maccaroni.a1b2c3d4.webp")
*/
export function getHashedFilename(basename: string, hash: string): string {
return `${basename}.${hash}.webp`;
}
/**
* Extracts basename from a potentially hashed filename
* @param filename - Filename (e.g., "maccaroni.a1b2c3d4.webp" or "maccaroni.webp")
* @returns Basename without hash or extension (e.g., "maccaroni")
*/
export function extractBasename(filename: string): string {
// Remove .webp extension
const withoutExt = filename.replace(/\.webp$/, '');
// Remove hash if present (8 hex chars preceded by a dot)
return withoutExt.replace(/\.[a-f0-9]{8}$/, '');
}