From 0d166644c3c9b0e461a432cafb341f00c709efae Mon Sep 17 00:00:00 2001
From: Andre Staltz <andre@staltz.com>
Date: Sat, 15 Apr 2023 16:38:06 +0300
Subject: [PATCH] erase() API

---
 lib/feed-v1/index.js |  9 +++++
 lib/plugin.js        |  8 ++++
 test/erase.test.js   | 96 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 113 insertions(+)
 create mode 100644 test/erase.test.js

diff --git a/lib/feed-v1/index.js b/lib/feed-v1/index.js
index d694381..02ddf80 100644
--- a/lib/feed-v1/index.js
+++ b/lib/feed-v1/index.js
@@ -185,6 +185,14 @@ function createRoot(keys, type) {
   return msg
 }
 
+/**
+ * @param {Msg} msg
+ * @returns {Msg}
+ */
+function erase(msg) {
+  return {...msg, content: null}
+}
+
 /**
  * @param {Buffer} plaintextBuf
  * @param {Msg} msg
@@ -203,6 +211,7 @@ module.exports = {
   // isMsg,
   create,
   createRoot,
+  erase,
   stripAuthor,
   toPlaintextBuffer,
   fromPlaintextBuffer,
diff --git a/lib/plugin.js b/lib/plugin.js
index 126fdbb..d72fe14 100644
--- a/lib/plugin.js
+++ b/lib/plugin.js
@@ -280,6 +280,13 @@ exports.init = function initDB(peer, config) {
     })
   }
 
+  function erase(msgId, cb) {
+    const rec = getRecord(msgId)
+    recs[rec.misc.seq].msg = FeedV1.erase(rec.msg)
+    // FIXME: persist this change to disk!! Not supported by AAOL yet
+    cb()
+  }
+
   function* msgs() {
     for (let i = 0; i < recs.length; i++) {
       const rec = recs[i]
@@ -304,6 +311,7 @@ exports.init = function initDB(peer, config) {
     getRecord,
     get,
     del,
+    erase,
     onRecordAdded,
     msgs,
     records,
diff --git a/test/erase.test.js b/test/erase.test.js
new file mode 100644
index 0000000..40545aa
--- /dev/null
+++ b/test/erase.test.js
@@ -0,0 +1,96 @@
+const test = require('tape')
+const path = require('path')
+const os = require('os')
+const rimraf = require('rimraf')
+const SecretStack = require('secret-stack')
+const AAOL = require('async-append-only-log')
+const push = require('push-stream')
+const caps = require('ssb-caps')
+const p = require('util').promisify
+const { generateKeypair } = require('./util')
+
+const DIR = path.join(os.tmpdir(), 'ppppp-db-erase')
+rimraf.sync(DIR)
+
+test('erase', async (t) => {
+  const keys = generateKeypair('alice')
+  const peer = SecretStack({ appKey: caps.shs })
+    .use(require('../'))
+    .call(null, { keys, path: DIR })
+
+  await peer.db.loaded()
+
+  const rootHash = 'PpkBfa8C4sB8wHrqiNmHqe'
+  const msgHashes = []
+  for (let i = 0; i < 5; i++) {
+    const rec = await p(peer.db.create)({
+      type: 'post',
+      content: { text: 'm' + i },
+    })
+    msgHashes.push(rec.hash)
+  }
+
+  const before = []
+  for (const msg of peer.db.msgs()) {
+    if (msg.content) before.push(msg.content.text)
+  }
+
+  t.deepEqual(before, ['m0', 'm1', 'm2', 'm3', 'm4'], '5 msgs before the erase')
+
+  await p(peer.db.erase)(msgHashes[2])
+
+  const after = []
+  for (const msg of peer.db.msgs()) {
+    if (msg.content) after.push(msg.content.text)
+  }
+
+  t.deepEqual(after, ['m0', 'm1', 'm3', 'm4'], '4 msgs after the erase')
+
+  const after2 = []
+  for (const msg of peer.db.msgs()) {
+    if (msg.metadata.tangles[rootHash]) {
+      after2.push(msg.metadata.tangles[rootHash].depth)
+    }
+  }
+
+  t.deepEqual(after2, [1, 2, 3, 4, 5], '5 metadata exists after the erase')
+
+  await p(peer.close)(true)
+
+  // FIXME:
+  // const log = AAOL(path.join(DIR, 'db.bin'), {
+  //   cacheSize: 1,
+  //   blockSize: 64 * 1024,
+  //   codec: {
+  //     encode(msg) {
+  //       return Buffer.from(JSON.stringify(msg), 'utf8')
+  //     },
+  //     decode(buf) {
+  //       return JSON.parse(buf.toString('utf8'))
+  //     },
+  //   },
+  // })
+
+  // const persistedMsgs = await new Promise((resolve, reject) => {
+  //   let persistedMsgs = []
+  //   log.stream({ offsets: true, values: true, sizes: true }).pipe(
+  //     push.drain(
+  //       function drainEach({ offset, value, size }) {
+  //         if (value) {
+  //           persistedMsgs.push(value.msg)
+  //         }
+  //       },
+  //       function drainEnd(err) {
+  //         if (err) return reject(err)
+  //         resolve(persistedMsgs)
+  //       }
+  //     )
+  //   )
+  // })
+
+  // t.deepEqual(
+  //   persistedMsgs.filter((msg) => msg.content).map((msg) => msg.content.text),
+  //   ['m0', 'm1', 'm3', 'm4'],
+  //   'msgs in disk after the delete'
+  // )
+})