From a939fb5cde76da185d75ddee2612e1979fdc05ba Mon Sep 17 00:00:00 2001
From: "Abdel @ StarkWare" <abdelhamid.bakhta@gmail.com>
Date: Mon, 23 Sep 2024 12:45:38 +0200
Subject: [PATCH] =?UTF-8?q?=E2=9C=A8=20mint=20pubkey=20in=20/info?=
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---
 lib/gakimint/core/mint.ex                     | 56 ++++++++++++++++---
 .../web/controllers/mint_controller.ex        |  7 ++-
 2 files changed, 52 insertions(+), 11 deletions(-)

diff --git a/lib/gakimint/core/mint.ex b/lib/gakimint/core/mint.ex
index 820f295..64a4158 100644
--- a/lib/gakimint/core/mint.ex
+++ b/lib/gakimint/core/mint.ex
@@ -4,12 +4,14 @@ defmodule Gakimint.Mint do
   """
 
   use GenServer
-  alias Gakimint.Repo
+  alias Gakimint.{Crypto, Repo}
   alias Gakimint.Schema.{Key, Keyset, MintConfiguration}
   import Ecto.Query
 
   @keyset_generation_seed_key "keyset_generation_seed"
   @keyset_generation_derivation_path "m/0'/0'/0'"
+  @mint_pubkey_key "mint_pubkey"
+  @mint_privkey_key "mint_privkey"
 
   def start_link(_) do
     GenServer.start_link(__MODULE__, %{}, name: __MODULE__)
@@ -17,14 +19,15 @@ defmodule Gakimint.Mint do
 
   @impl true
   def init(_) do
-    {:ok, %{keysets: []}, {:continue, :load_keysets}}
+    {:ok, %{keysets: [], mint_pubkey: nil}, {:continue, :load_keysets_and_mint_key}}
   end
 
   @impl true
-  def handle_continue(:load_keysets, state) do
+  def handle_continue(:load_keysets_and_mint_key, state) do
     seed = get_or_create_seed()
     keysets = load_or_create_keysets(seed)
-    {:noreply, %{state | keysets: keysets}}
+    {_, mint_pubkey} = get_or_create_mint_key(seed)
+    {:noreply, %{state | keysets: keysets, mint_pubkey: mint_pubkey}}
   end
 
   defp get_or_create_seed do
@@ -56,11 +59,51 @@ defmodule Gakimint.Mint do
     end
   end
 
+  defp get_or_create_mint_key(seed) do
+    case {Repo.get_by(MintConfiguration, key: @mint_pubkey_key),
+          Repo.get_by(MintConfiguration, key: @mint_privkey_key)} do
+      {nil, nil} ->
+        {privkey, pubkey} = derive_mint_key(seed)
+
+        %MintConfiguration{}
+        |> MintConfiguration.changeset(%{
+          key: @mint_pubkey_key,
+          value: Base.encode16(pubkey, case: :lower)
+        })
+        |> Repo.insert!()
+
+        %MintConfiguration{}
+        |> MintConfiguration.changeset(%{
+          key: @mint_privkey_key,
+          value: Base.encode16(privkey, case: :lower)
+        })
+        |> Repo.insert!()
+
+        {privkey, pubkey}
+
+      {pubkey_config, privkey_config} ->
+        pubkey = Base.decode16!(pubkey_config.value, case: :lower)
+        privkey = Base.decode16!(privkey_config.value, case: :lower)
+        {privkey, pubkey}
+    end
+  end
+
+  defp derive_mint_key(seed) do
+    private_key = :crypto.hash(:sha256, seed)
+    {private_key, public_key} = Crypto.generate_keypair(private_key)
+    {private_key, public_key}
+  end
+
   @impl true
   def handle_call(:get_keysets, _from, state) do
     {:reply, state.keysets, state}
   end
 
+  @impl true
+  def handle_call(:get_mint_pubkey, _from, state) do
+    {:reply, state.mint_pubkey, state}
+  end
+
   # Public API
 
   def get_keysets do
@@ -77,10 +120,7 @@ defmodule Gakimint.Mint do
   end
 
   def get_pubkey do
-    [keyset | _] = get_keysets()
-    keys = get_keys_for_keyset(keyset.id)
-    keys_map = Enum.into(keys, %{}, fn key -> {key.amount, key.public_key} end)
-    keys_map["1"]
+    GenServer.call(__MODULE__, :get_mint_pubkey)
   end
 
   def get_active_keysets do
diff --git a/lib/gakimint/web/controllers/mint_controller.ex b/lib/gakimint/web/controllers/mint_controller.ex
index dc06f64..202610b 100644
--- a/lib/gakimint/web/controllers/mint_controller.ex
+++ b/lib/gakimint/web/controllers/mint_controller.ex
@@ -1,11 +1,12 @@
 defmodule Gakimint.Web.MintController do
   use Gakimint.Web, :controller
+  alias Gakimint.Mint
   alias Gakimint.Web.{Keys, KeysetResponse}
 
   def info(conn, _params) do
     info = %{
       name: "Gakimint Cashu Mint",
-      pubkey: "",
+      pubkey: Base.encode16(Mint.get_pubkey(), case: :lower),
       version: "Gakimint/0.1.0",
       description: "An Elixir implementation of Cashu Mint",
       description_long: "A Cashu Mint implementation in Elixir.",
@@ -66,11 +67,11 @@ defmodule Gakimint.Web.MintController do
   end
 
   def keys(conn, _params) do
-    keysets = Gakimint.Mint.get_active_keysets()
+    keysets = Mint.get_active_keysets()
 
     keysets_responses =
       Enum.map(keysets, fn keyset ->
-        keys = Gakimint.Mint.get_keys_for_keyset(keyset.id)
+        keys = Mint.get_keys_for_keyset(keyset.id)
 
         keys_list =
           Enum.map(keys, fn key -> {key.amount, Base.encode16(key.public_key, case: :lower)} end)