From 34bb591bfed318266ca1acee2aafa1dbaba1fb86 Mon Sep 17 00:00:00 2001
From: Derrick Hammer <derrick@derrickhammer.com>
Date: Wed, 24 Jan 2024 02:53:56 -0500
Subject: [PATCH] feat: implement PrepareProvideMessage

---
 interfaces/p2p.go |  1 +
 service/p2p.go    | 43 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+)

diff --git a/interfaces/p2p.go b/interfaces/p2p.go
index e389d09..9568e77 100644
--- a/interfaces/p2p.go
+++ b/interfaces/p2p.go
@@ -25,5 +25,6 @@ type P2PService interface {
 	DownVote(nodeId *encoding.NodeId) error
 	NodeId() *encoding.NodeId
 	SelfConnectionUris() []*url.URL
+	PrepareProvideMessage(hash *encoding.Multihash, location StorageLocation) []byte
 	Service
 }
diff --git a/service/p2p.go b/service/p2p.go
index 7bb5965..f0d47f2 100644
--- a/service/p2p.go
+++ b/service/p2p.go
@@ -1,6 +1,7 @@
 package service
 
 import (
+	ed25519p "crypto/ed25519"
 	"errors"
 	"fmt"
 	"git.lumeweb.com/LumeWeb/libs5-go/ed25519"
@@ -661,3 +662,45 @@ func (p *P2PImpl) vote(nodeId *encoding.NodeId, upvote bool) error {
 func (p *P2PImpl) NodeId() *encoding.NodeId {
 	return p.localNodeID
 }
+
+func (p *P2PImpl) PrepareProvideMessage(hash *encoding.Multihash, location interfaces.StorageLocation) []byte {
+	// Initialize the list with the record type.
+	list := []byte{byte(types.RecordTypeStorageLocation)}
+
+	// Append the full bytes of the hash.
+	list = append(list, hash.FullBytes()...)
+
+	// Append the location type.
+	list = append(list, byte(location.Type()))
+
+	// Append the expiry time of the location, encoded as 4 bytes.
+	list = append(list, utils.EncodeEndian(uint64(location.Expiry()), 4)...)
+
+	// Append the number of parts in the location.
+	list = append(list, byte(len(location.Parts())))
+
+	// Iterate over each part in the location.
+	for _, part := range location.Parts() {
+		// Convert part to bytes.
+		bytes := []byte(part)
+
+		// Encode the length of the part as 4 bytes and append.
+		list = append(list, utils.EncodeEndian(uint64(len(bytes)), 4)...)
+
+		// Append the actual part bytes.
+		list = append(list, bytes...)
+	}
+
+	// Append a null byte at the end of the list.
+	list = append(list, 0)
+
+	// Sign the list using the node's private key.
+	signature := ed25519p.Sign(p.nodeKeyPair.PublicKeyRaw(), list)
+
+	// Append the public key and signature to the list.
+	finalList := append(list, p.nodeKeyPair.PublicKey()...)
+	finalList = append(finalList, signature...)
+
+	// Return the final byte slice.
+	return finalList
+}