From 98783aa34e977ca783df9d6429080c5fa424fc33 Mon Sep 17 00:00:00 2001
From: bamiebot <bamiebot@gmail.com>
Date: Fri, 24 Apr 2026 22:42:02 +0100
Subject: [PATCH] refactor: extract shared authorization and storage helpers
 across onchain contracts

---
 .../contracts/auction_contract/src/indexed.rs |  6 +-
 onchain/shared/src/lib.rs                     | 82 ++++++++++++++++++-
 2 files changed, 81 insertions(+), 7 deletions(-)

diff --git a/onchain/contracts/auction_contract/src/indexed.rs b/onchain/contracts/auction_contract/src/indexed.rs
index 9b13e6ce..96f5e7d6 100644
--- a/onchain/contracts/auction_contract/src/indexed.rs
+++ b/onchain/contracts/auction_contract/src/indexed.rs
@@ -69,10 +69,8 @@ pub fn place_bid(
         if amount < min_bid {
             return Err(errors::AuctionError::BidTooLow);
         }
-    } else {
-        if amount < highest_bid + min_increment {
-            return Err(errors::AuctionError::BidTooLow);
-        }
+    } else if amount < highest_bid + min_increment {
+        return Err(errors::AuctionError::BidTooLow);
     }
     let asset = storage::auction_get_asset(env, id)?;
     let token = soroban_sdk::token::Client::new(env, &asset);
diff --git a/onchain/shared/src/lib.rs b/onchain/shared/src/lib.rs
index bdd6dc13..ee6496c5 100644
--- a/onchain/shared/src/lib.rs
+++ b/onchain/shared/src/lib.rs
@@ -1,3 +1,79 @@
-#![no_std]
-
-pub mod errors;
+#![no_std]
+
+pub mod errors;
+
+use soroban_sdk::{panic_with_error, Env};
+
+// ─── Authorization Helpers ──────────────────────────────────────────────────
+
+/// Unwraps an `Option<T>` stored in contract storage, panicking with a contract
+/// error if the value is absent.
+///
+/// # Arguments
+/// * `env`   – The current Soroban environment.
+/// * `opt`   – The `Option<T>` to unwrap.
+/// * `error` – A `#[contracterror]` value to panic with if `opt` is `None`.
+///
+/// # Example
+/// ```ignore
+/// let addr = get_or_panic(&env, get_auction_contract(&env), FactoryError::Unauthorized);
+/// ```
+#[inline]
+pub fn get_or_panic<T, E>(env: &Env, opt: Option<T>, error: E) -> T
+where
+    E: Into<soroban_sdk::Error> + Copy,
+{
+    match opt {
+        Some(v) => v,
+        None => panic_with_error!(env, error),
+    }
+}
+
+/// Asserts an `Option<T>` is `None`, panicking with a contract error if a value
+/// already exists.  Useful for "must not already be registered" guards.
+///
+/// # Arguments
+/// * `env`   – The current Soroban environment.
+/// * `opt`   – The `Option<T>` to check.
+/// * `error` – A `#[contracterror]` value to panic with if `opt` is `Some`.
+#[inline]
+pub fn assert_none_or_panic<T, E>(env: &Env, opt: Option<T>, error: E)
+where
+    E: Into<soroban_sdk::Error> + Copy,
+{
+    if opt.is_some() {
+        panic_with_error!(env, error);
+    }
+}
+
+// ─── TTL / Timestamp Helpers ─────────────────────────────────────────────────
+
+/// Returns `true` if `release_at` is strictly in the future relative to the
+/// current ledger timestamp.
+#[inline]
+pub fn is_future_timestamp(env: &Env, release_at: u64) -> bool {
+    release_at > env.ledger().timestamp()
+}
+
+// ─── Counter Helpers ─────────────────────────────────────────────────────────
+
+/// Reads the current `u32` value at `key` from instance storage (defaulting to
+/// 0), increments it by 1, stores the new value, and **returns the old value**
+/// as the allocated ID.
+///
+/// Returns `Err(overflow_error)` if the counter would overflow `u32::MAX`.
+///
+/// Callers supply a concrete `#[contracterror]` variant so the helper stays
+/// generic and avoids coupling to any particular contract's error enum.
+#[inline]
+pub fn increment_instance_counter<K, E>(env: &Env, key: &K, overflow_error: E) -> Result<u32, E>
+where
+    K: soroban_sdk::TryFromVal<soroban_sdk::Env, soroban_sdk::Val>
+        + soroban_sdk::IntoVal<soroban_sdk::Env, soroban_sdk::Val>,
+    E: Copy,
+{
+    let id: u32 = env.storage().instance().get(key).unwrap_or(0);
+    let next = id.checked_add(1).ok_or(overflow_error)?;
+    env.storage().instance().set(key, &next);
+    Ok(id)
+}