From 81903dddc9d159e21f87c138576c336059d90d8f Mon Sep 17 00:00:00 2001
From: achingbrain <alex@achingbrain.net>
Date: Tue, 9 Apr 2024 18:59:36 +0100
Subject: [PATCH] fix: identity blockstore should wrap child

---
 packages/blockstore-core/src/identity.ts      | 58 +++++++++++++++----
 .../blockstore-core/test/identity.spec.ts     | 15 +++++
 2 files changed, 62 insertions(+), 11 deletions(-)

diff --git a/packages/blockstore-core/src/identity.ts b/packages/blockstore-core/src/identity.ts
index 059902df..da4e8776 100644
--- a/packages/blockstore-core/src/identity.ts
+++ b/packages/blockstore-core/src/identity.ts
@@ -1,15 +1,31 @@
 import { BaseBlockstore } from './base.js'
-import * as Errors from './errors.js'
-import type { Pair } from 'interface-blockstore'
-import type { Await, AwaitIterable } from 'interface-store'
+import { Errors } from './index.js'
+import type { Blockstore, Pair } from 'interface-blockstore'
+import type { AbortOptions, Await, AwaitIterable } from 'interface-store'
 import type { CID } from 'multiformats/cid'
 
 // https://github.com/multiformats/multicodec/blob/d06fc6194710e8909bac64273c43f16b56ca4c34/table.csv#L2
 const IDENTITY_CODEC = 0x00
 
 export class IdentityBlockstore extends BaseBlockstore {
-  put (key: CID): CID {
-    return key
+  private readonly child?: Blockstore
+
+  constructor (child?: Blockstore) {
+    super()
+
+    this.child = child
+  }
+
+  put (key: CID, block: Uint8Array): Await<CID> {
+    if (key.code === IDENTITY_CODEC) {
+      return key
+    }
+
+    if (this.child == null) {
+      return key
+    }
+
+    return this.child.put(key, block)
   }
 
   get (key: CID): Await<Uint8Array> {
@@ -17,18 +33,38 @@ export class IdentityBlockstore extends BaseBlockstore {
       return key.multihash.digest
     }
 
-    throw Errors.notFoundError()
-  }
+    if (this.child == null) {
+      throw Errors.notFoundError()
+    }
 
-  has (key: CID): boolean {
-    return key.code === IDENTITY_CODEC
+    return this.child.get(key)
   }
 
-  delete (): void {
+  has (key: CID): Await<boolean> {
+    if (key.code === IDENTITY_CODEC) {
+      return true
+    }
 
+    if (this.child == null) {
+      return false
+    }
+
+    return this.child.has(key)
   }
 
-  * getAll (): AwaitIterable<Pair> {
+  delete (key: CID): Await<void> {
+    if (key.code === IDENTITY_CODEC) {
+      return
+    }
+
+    if (this.child != null) {
+      return this.child.delete(key)
+    }
+  }
 
+  * getAll (options?: AbortOptions): AwaitIterable<Pair> {
+    if (this.child != null) {
+      yield * this.child.getAll(options)
+    }
   }
 }
diff --git a/packages/blockstore-core/test/identity.spec.ts b/packages/blockstore-core/test/identity.spec.ts
index e0bfcdfc..2913dd99 100644
--- a/packages/blockstore-core/test/identity.spec.ts
+++ b/packages/blockstore-core/test/identity.spec.ts
@@ -7,13 +7,16 @@ import * as raw from 'multiformats/codecs/raw'
 import { identity } from 'multiformats/hashes/identity'
 import { sha256 } from 'multiformats/hashes/sha2'
 import { IdentityBlockstore } from '../src/identity.js'
+import { MemoryBlockstore } from '../src/memory.js'
 import type { Blockstore } from 'interface-blockstore'
 
 describe('identity', () => {
   let blockstore: Blockstore
+  let child: Blockstore
 
   beforeEach(() => {
     blockstore = new IdentityBlockstore()
+    child = new MemoryBlockstore()
   })
 
   it('has an identity CID', () => {
@@ -25,6 +28,18 @@ describe('identity', () => {
     expect(blockstore.get(cid)).to.equalBytes(block)
   })
 
+  it('retrieves CIDs from child', async () => {
+    const block = Uint8Array.from([0, 1, 2, 3, 4])
+    const multihash = await sha256.digest(block)
+    const cid = CID.createV1(raw.code, multihash)
+
+    await child.put(cid, block)
+
+    blockstore = new IdentityBlockstore(child)
+    expect(blockstore.has(cid)).to.be.true()
+    expect(blockstore.get(cid)).to.equalBytes(block)
+  })
+
   it('does not have a non-identity CID', async () => {
     const block = Uint8Array.from([0, 1, 2, 3, 4])
     const multihash = await sha256.digest(block)