feat: implement minimum donation amount enforcement

campaign/src/lib.rs

@@ -3,8 +3,8 @@
 pub mod storage;
 pub mod types;
 
-use soroban_sdk::{contract, contractimpl, Env, Vec};
-use types::{CampaignData, CampaignStatus, Error, MilestoneData, MilestoneStatus, StellarAsset, CampaignEvent};
+use soroban_sdk::{contract, contractimpl, Address, Env, Vec};
+use types::{CampaignData, CampaignStatus, Error, MilestoneData, MilestoneStatus, StellarAsset, CampaignEvent, AssetInfo};
 use storage::{get_campaign, set_campaign, set_milestone};
 
 pub const VERSION: u32 = 1;
@@ -39,6 +39,7 @@ impl CampaignContract {
         end_time: u64,
         accepted_assets: Vec<StellarAsset>,
         milestones: Vec<MilestoneData>,
+        min_donation_amount: i128,
     ) -> Result<(), Error> {
         // Authorization check: creator must authorize this call
         creator.require_auth();
@@ -85,6 +86,7 @@ impl CampaignContract {
             status: CampaignStatus::Active,
             accepted_assets: accepted_assets.clone(),
             milestone_count,
+            min_donation_amount,
         };
 
         set_campaign(&env, &campaign);
@@ -107,6 +109,27 @@ impl CampaignContract {
         Ok(())
     }
 
+    /// Issue #192 – Donate to the campaign, enforcing the minimum donation amount.
+    ///
+    /// Panics with `Error::DonationTooSmall` if `amount < min_donation_amount` (when min > 0).
+    /// Set `min_donation_amount` to 0 during `initialize` to disable enforcement.
+    pub fn donate(env: Env, donor: Address, amount: i128, _asset: AssetInfo) {
+        donor.require_auth();
+
+        let mut campaign: CampaignData = get_campaign(&env)
+            .unwrap_or_else(|| panic_with_error(&env, Error::AlreadyInitialized));
+
+        // Issue #192 – enforce minimum donation amount
+        if campaign.min_donation_amount > 0 && amount < campaign.min_donation_amount {
+            panic_with_error(&env, Error::DonationTooSmall);
+        }
+
+        campaign.raised_amount += amount;
+        set_campaign(&env, &campaign);
+
+        env.events().publish(("campaign", "donation_received"), (donor, amount));
+    }
+
     pub fn hello(env: Env) -> soroban_sdk::Symbol {
         soroban_sdk::Symbol::new(&env, "campaign")
     }
@@ -173,6 +196,7 @@ fn panic_with_error(env: &Env, error: Error) -> ! {
         Error::CampaignNotActive => "CampaignNotActive",
         Error::CampaignEnded => "CampaignEnded",
         Error::GoalNotReached => "GoalNotReached",
+        Error::DonationTooSmall => "DonationTooSmall",
     };
     env.panic_with_error(soroban_sdk::Symbol::new(env, error_name))
 }

campaign/src/types.rs

@@ -23,6 +23,8 @@ pub enum Error {
     CampaignNotActive,        // campaign must be Active to accept donations
     CampaignEnded,            // campaign end_time has passed
     GoalNotReached,           // cannot transition to GoalReached before reaching goal
+    /// Issue #192 – donation amount is below the campaign minimum
+    DonationTooSmall,
 }
 
 // ── Supporting enums ─────────────────────────────────────────────────────────
@@ -123,6 +125,8 @@ pub struct CampaignData {
     pub status: CampaignStatus,
     pub accepted_assets: Vec<StellarAsset>,
     pub milestone_count: u32,
+    /// Issue #192 – minimum donation amount; set to 0 to disable enforcement
+    pub min_donation_amount: i128,
 }
 
 // ── Issue #168 – MilestoneData struct ────────────────────────────────────────