From 8b0927c63191cede7a90459cdb0aa89c5f0e57e6 Mon Sep 17 00:00:00 2001
From: Hamish Peebles <hamishpeebles@gmail.com>
Date: Wed, 24 Jul 2024 11:03:58 +0100
Subject: [PATCH] This is better

---
 .../user_index/impl/src/model/user.rs         |  4 ++++
 .../user_index/impl/src/model/user_map.rs     | 22 +++++++++++--------
 backend/libraries/utils/src/time.rs           | 14 ++++++++++++
 3 files changed, 31 insertions(+), 9 deletions(-)

diff --git a/backend/canisters/user_index/impl/src/model/user.rs b/backend/canisters/user_index/impl/src/model/user.rs
index 2cdef62a98..5534e10538 100644
--- a/backend/canisters/user_index/impl/src/model/user.rs
+++ b/backend/canisters/user_index/impl/src/model/user.rs
@@ -64,6 +64,8 @@ pub struct User {
     pub chit_updated: TimestampMillis,
     #[serde(rename = "lc", default)]
     pub latest_chit_event: TimestampMillis,
+    #[serde(rename = "lcp", default)]
+    pub latest_chit_event_previous_month: TimestampMillis,
     #[serde(rename = "uh", default, skip_serializing_if = "Option::is_none")]
     pub unique_person_proof: Option<UniquePersonProof>,
 }
@@ -125,6 +127,7 @@ impl User {
             streak: 0,
             streak_ends: 0,
             latest_chit_event: 0,
+            latest_chit_event_previous_month: 0,
             unique_person_proof: None,
         }
     }
@@ -246,6 +249,7 @@ impl Default for User {
             streak_ends: 0,
             chit_updated: 0,
             latest_chit_event: 0,
+            latest_chit_event_previous_month: 0,
             unique_person_proof: None,
         }
     }
diff --git a/backend/canisters/user_index/impl/src/model/user_map.rs b/backend/canisters/user_index/impl/src/model/user_map.rs
index 18d43cf38f..9d240039d4 100644
--- a/backend/canisters/user_index/impl/src/model/user_map.rs
+++ b/backend/canisters/user_index/impl/src/model/user_map.rs
@@ -210,19 +210,23 @@ impl UserMap {
         };
 
         let chit_event_month = MonthKey::from_timestamp(chit_event_timestamp);
-        let now_month = MonthKey::from_timestamp(now);
 
-        if chit_event_month == now_month && chit_event_timestamp <= user.latest_chit_event {
-            return false;
+        if chit_event_timestamp >= user.latest_chit_event {
+            user.latest_chit_event = chit_event_timestamp;
+            user.chit_balance = chit_balance;
+            user.streak = streak;
+            user.streak_ends = streak_ends;
+            user.chit_updated = now;
+        } else {
+            let previous_month = MonthKey::from_timestamp(now).previous();
+            if chit_event_month == previous_month && chit_event_timestamp >= user.latest_chit_event_previous_month {
+                user.latest_chit_event_previous_month = chit_event_timestamp;
+            } else {
+                return false;
+            }
         }
 
         user.chit_per_month.insert(chit_event_month, chit_balance);
-        user.latest_chit_event = chit_event_timestamp;
-        user.chit_balance = chit_balance;
-        user.streak = streak;
-        user.streak_ends = streak_ends;
-        user.chit_updated = now;
-
         true
     }
 
diff --git a/backend/libraries/utils/src/time.rs b/backend/libraries/utils/src/time.rs
index 443f181509..38e31dbaba 100644
--- a/backend/libraries/utils/src/time.rs
+++ b/backend/libraries/utils/src/time.rs
@@ -78,6 +78,20 @@ impl MonthKey {
         }
     }
 
+    pub fn previous(self) -> MonthKey {
+        if self.month == 1 {
+            MonthKey {
+                year: self.year.saturating_sub(1),
+                month: 12,
+            }
+        } else {
+            MonthKey {
+                year: self.year,
+                month: self.month.saturating_sub(1),
+            }
+        }
+    }
+
     pub fn timestamp_range(&self) -> Range<TimestampMillis> {
         let start = self.start_timestamp();
         let end = self.next().start_timestamp();