feat(cntr): implement dispute window checker and cancellation policy enforcer

contracts/cntr/src/cancellation_policy.rs

@@ -0,0 +1,92 @@
+#[derive(Debug, PartialEq, Clone)]
+pub enum CancellationPolicy {
+    Flexible,
+    Moderate,
+    Strict,
+}
+
+/// Computes the refund amount in stroops based on the cancellation policy.
+///
+/// - Flexible:  always 100% refund.
+/// - Moderate:  100% if >= 48h before start, 50% if 24–47h, 0% if < 24h.
+/// - Strict:    100% if >= 96h before start, 0% otherwise.
+pub fn apply_policy(
+    policy: CancellationPolicy,
+    hours_before_start: u64,
+    amount_stroops: i128,
+) -> i128 {
+    match policy {
+        CancellationPolicy::Flexible => amount_stroops,
+        CancellationPolicy::Moderate => {
+            if hours_before_start >= 48 {
+                amount_stroops
+            } else if hours_before_start >= 24 {
+                amount_stroops / 2
+            } else {
+                0
+            }
+        }
+        CancellationPolicy::Strict => {
+            if hours_before_start >= 96 {
+                amount_stroops
+            } else {
+                0
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const AMOUNT: i128 = 1_000_000;
+
+    // Flexible
+    #[test]
+    fn flexible_always_full_refund() {
+        assert_eq!(apply_policy(CancellationPolicy::Flexible, 0, AMOUNT), AMOUNT);
+    }
+
+    #[test]
+    fn flexible_full_refund_at_48h() {
+        assert_eq!(apply_policy(CancellationPolicy::Flexible, 48, AMOUNT), AMOUNT);
+    }
+
+    #[test]
+    fn flexible_full_refund_at_100h() {
+        assert_eq!(apply_policy(CancellationPolicy::Flexible, 100, AMOUNT), AMOUNT);
+    }
+
+    // Moderate
+    #[test]
+    fn moderate_full_refund_at_48h_or_more() {
+        assert_eq!(apply_policy(CancellationPolicy::Moderate, 48, AMOUNT), AMOUNT);
+    }
+
+    #[test]
+    fn moderate_half_refund_between_24_and_47h() {
+        assert_eq!(apply_policy(CancellationPolicy::Moderate, 24, AMOUNT), AMOUNT / 2);
+    }
+
+    #[test]
+    fn moderate_no_refund_under_24h() {
+        assert_eq!(apply_policy(CancellationPolicy::Moderate, 10, AMOUNT), 0);
+    }
+
+    // Strict
+    #[test]
+    fn strict_full_refund_at_96h_or_more() {
+        assert_eq!(apply_policy(CancellationPolicy::Strict, 96, AMOUNT), AMOUNT);
+    }
+
+    #[test]
+    fn strict_no_refund_at_95h() {
+        assert_eq!(apply_policy(CancellationPolicy::Strict, 95, AMOUNT), 0);
+    }
+
+    #[test]
+    fn strict_no_refund_under_24h() {
+        assert_eq!(apply_policy(CancellationPolicy::Strict, 0, AMOUNT), 0);
+    }
+}

contracts/cntr/src/dispute_window.rs

@@ -0,0 +1,49 @@
+/// Default dispute window: 48 hours in seconds.
+pub const DEFAULT_DISPUTE_WINDOW_SECONDS: u64 = 172_800;
+
+/// Returns `true` if `current_timestamp` is within the dispute window after checkout.
+pub fn is_within_dispute_window(
+    checkout_timestamp: u64,
+    current_timestamp: u64,
+    window_seconds: u64,
+) -> bool {
+    current_timestamp < checkout_timestamp.saturating_add(window_seconds)
+}
+
+/// Returns the timestamp at which the dispute window expires.
+pub fn dispute_window_expires_at(checkout_timestamp: u64, window_seconds: u64) -> u64 {
+    checkout_timestamp.saturating_add(window_seconds)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const CHECKOUT: u64 = 1_000_000;
+    const WINDOW: u64 = DEFAULT_DISPUTE_WINDOW_SECONDS;
+
+    #[test]
+    fn inside_window() {
+        assert!(is_within_dispute_window(CHECKOUT, CHECKOUT + 1000, WINDOW));
+    }
+
+    #[test]
+    fn outside_window() {
+        assert!(!is_within_dispute_window(CHECKOUT, CHECKOUT + WINDOW + 1, WINDOW));
+    }
+
+    #[test]
+    fn exactly_at_boundary_is_outside() {
+        assert!(!is_within_dispute_window(CHECKOUT, CHECKOUT + WINDOW, WINDOW));
+    }
+
+    #[test]
+    fn at_checkout_moment() {
+        assert!(is_within_dispute_window(CHECKOUT, CHECKOUT, WINDOW));
+    }
+
+    #[test]
+    fn expires_at_returns_correct_timestamp() {
+        assert_eq!(dispute_window_expires_at(CHECKOUT, WINDOW), CHECKOUT + WINDOW);
+    }
+}

contracts/cntr/src/lib.rs

@@ -10,7 +10,6 @@ pub mod credit_topup;
 pub mod token_validator;
 pub mod grace_period;
 pub mod payment_validator;
-pub mod credit_topup;
 pub mod multi_booking;
-pub mod payment_validator;
-pub mod role_checker;
+pub mod dispute_window;
+pub mod cancellation_policy;