feat: add memes exercise

bin.js

@@ -5,6 +5,7 @@ import * as SpaceOutProblem from './problems/1-space-out/index.js'
 import * as CatGifsProblem from './problems/2-cat-gifs/index.js'
 import * as DelegationProblem from './problems/3-delegation/index.js'
 import * as InfiniteCompressionProblem from './problems/4-infinite-compression/index.js'
+import * as MemesProblem from './problems/5-memes/index.js'
 // import * as PlaceholderProblem from './problems/placeholder/index.js'
 
 const shop = adventure({
@@ -18,7 +19,7 @@ shop.add('Lets space out', () => SpaceOutProblem)
 shop.add('Storing cat gifs for fun and gossip', () => CatGifsProblem)
 shop.add('Delegation, invocation and procrastination', () => DelegationProblem)
 shop.add('Infinite avatar compression!', () => InfiniteCompressionProblem)
-// shop.add('Memes for my eyes', () => PlaceholderProblem)
+shop.add('Memes for my eyes', () => MemesProblem)
 // shop.add('DUDE, WHERE\'S MY CAR?', () => PlaceholderProblem)
 // shop.add('CommP at the edge or die trying', () => PlaceholderProblem)
 // shop.add('Revocation station', () => PlaceholderProblem)

problems/5-memes/cat.txt

@@ -0,0 +1,7 @@
+    /\_____/\
+   /  o   o  \
+  ( ==  ^  == )
+   )         (
+  (           )
+ ( (  )   (  ) )
+(__(__)___(__)__)

problems/5-memes/index.js

@@ -0,0 +1,35 @@
+import fs from 'node:fs'
+import path from 'node:path'
+import { Buffer } from 'node:buffer'
+import { execaNode } from 'execa'
+import msee from 'msee'
+import * as Link from 'multiformats/link'
+
+const cat = Link.parse('bafkreicn5krrora5gx47hrbj6kbfwrrskh7iawngpdudmzqp72i6jaalyu')
+const catData = fs.readFileSync(new URL('./cat.txt', import.meta.url), 'utf8')
+
+export const problem = msee.parse(fs.readFileSync(new URL('./problem.md', import.meta.url), 'utf8'))
+
+export const solution = msee.parse(fs.readFileSync(new URL('./solution.md', import.meta.url), 'utf8'))
+
+/**
+ * @param {string[]} args
+ * @param {(success: boolean) => void} cb
+ */
+export const verify = (args, cb) => {
+  (async () => {
+    const filepath = path.resolve(args[0])
+    console.log(`Verifying ${filepath}...\n`)
+    const { stdout, all } = await execaNode(filepath, [], {
+      input: Buffer.from(cat.bytes),
+      all: true
+    })
+    console.log(all ?? '')
+
+    if (stdout !== catData) {
+      return cb(false)
+    }
+
+    cb(true)
+  })()
+}

problems/5-memes/problem.md

@@ -0,0 +1,22 @@
+# Memes for my eyes
+
+Any meme you upload is almost instantly available for retrieval. Other files also. Content is made available by root CID and by CAR shard CID. In this exercise you are going to fetch a text file from the public gateway by it's root CID and log it to the console.
+
+You can use the `w3s.link` gateway to retrieve the data but the magic of decentralized peer to peer networking means that you should be able to use any gateway.
+
+To retrieve data from a gateway you should format the request like:
+
+```
+https://w3s.link/ipfs/<CID>
+```
+
+The CID of the data to fetch will be provided to `process.stdin`.
+
+You should use the `multiformats` library to `decode` the CID from it's compact binary form and then format it as a string in the URL.
+
+Finally send a HTTP request to fetch the content and write the data directly to `process.stdout`.
+
+─────────────────────────────────────────────────────────────────────────────
+* To print these instructions again, run: `$ADVENTURE_NAME print`
+* To verify your program, run: `$ADVENTURE_NAME verify program.js`
+* For help run: `$ADVENTURE_NAME help`

problems/5-memes/solution.js

@@ -0,0 +1,6 @@
+import fs from 'node:fs'
+import { CID } from 'multiformats'
+
+const cid = CID.decode(fs.readFileSync(process.stdin.fd))
+const res = await fetch(`https://w3s.link/ipfs/${cid}`)
+process.stdout.write(await res.text())

problems/5-memes/solution.md

@@ -0,0 +1,14 @@
+Here's the official solution in case you want to compare notes:
+
+```js
+import fs from 'node:fs'
+import { CID } from 'multiformats'
+
+const cid = CID.decode(fs.readFileSync(process.stdin.fd))
+const res = await fetch(`https://w3s.link/ipfs/${cid}`)
+process.stdout.write(await res.text())
+```
+
+# YOU DID IT!
+
+Type `$ADVENTURE_NAME` to show the menu.