Merge pull request #573 from yusufsharon/fix/414-timezone-achievement-date-tracking

fix: use UTC day boundaries for achievement date tracking (#414)

Author: LaGodxy

contracts/analytics/src/lib.rs

@@ -375,6 +375,10 @@ impl Analytics {
         require_initialized(&env)?;
         session.student.require_auth();
 
+        // Issue #414: validate that start_time is a plausible UTC epoch second so
+        // that achievement earned_date and streak calculations are timezone-safe.
+        validate_utc_timestamp(session.start_time).map_err(|_| AnalyticsError::InvalidTimestamp)?;
+
         if AnalyticsStorage::has_session(&env, &session.session_id) {
             return Err(AnalyticsError::SessionAlreadyExists);
         }

contracts/analytics/src/reports.rs

@@ -7,6 +7,7 @@ use crate::{
         LearningSession, OptionalSessionType, ProgressReport, ReportPeriod,
     },
 };
+use shared::timestamp_utils::{utc_day_start, SECS_PER_DAY};
 use soroban_sdk::{Address, Env, Symbol, Vec};
 
 /// Report generation and time-based analytics
@@ -69,7 +70,7 @@ impl ReportGenerator {
         }
 
         // Calculate average daily time
-        let report_days = ((end_date - start_date) / 86400) + 1; // +1 to include both start and end days
+        let report_days = ((end_date - start_date) / SECS_PER_DAY) + 1; // +1 to include both start and end days
         let average_daily_time = total_time.checked_div(report_days).unwrap_or(0);
 
         // Calculate consistency score
@@ -124,8 +125,8 @@ impl ReportGenerator {
         course_id: &Symbol,
         date: u64,
     ) -> Result<AggregatedMetrics, AnalyticsError> {
-        let day_start = (date / 86400) * 86400; // Start of day
-        let day_end = day_start + 86400; // End of day
+        let day_start = utc_day_start(date);
+        let day_end = day_start + SECS_PER_DAY;
 
         let students = AnalyticsStorage::get_course_students(env, course_id);
         let mut active_students = 0u32;
@@ -345,13 +346,13 @@ impl ReportGenerator {
             return 0;
         }
 
-        let total_days = ((end_date - start_date) / 86400) + 1;
+        let total_days = ((end_date - start_date) / SECS_PER_DAY) + 1;
         let mut active_days: Vec<u64> = Vec::new(env);
 
-        // Count unique active days
+        // Count unique active UTC days
         for i in 0..sessions.len() {
             let session = sessions.get(i).unwrap();
-            let day = session.start_time / 86400;
+            let day = session.start_time / SECS_PER_DAY;
 
             let mut day_exists = false;
             for j in 0..active_days.len() {

contracts/gamification/src/achievements.rs

@@ -8,6 +8,7 @@ use crate::types::{
     ActivityType, AdaptiveDifficulty, ChallengeDifficulty, GamificationKey, GamificationProfile,
     UserAchievement,
 };
+use shared::timestamp_utils::utc_day_index;
 
 /// First 25 IDs are reserved for milestone achievements seeded at init.
 const MILESTONE_RESERVE: u64 = 25;
@@ -615,22 +616,24 @@ impl AchievementManager {
         now: u64,
         config: &crate::types::GamificationConfig,
     ) -> u32 {
-        let one_day = 86_400u64;
-        let two_days = one_day * 2;
-
         if profile.current_streak == 0 {
             // Very first activity ever recorded for this user
             profile.current_streak = 1;
             profile.max_streak = 1;
             return 0;
         }
 
-        let elapsed = now.saturating_sub(profile.last_activity);
-
-        if elapsed < one_day {
-            // Same day — streak already counted, no change, no bonus
-        } else if elapsed <= two_days {
-            // Consecutive day — extend streak
+        // Compare UTC day indices so that a user active at 23:00 UTC and again
+        // at 01:00 UTC the next day (elapsed = 7 200 s < 86 400 s) is correctly
+        // treated as a new day rather than the same day.
+        let last_day = utc_day_index(profile.last_activity);
+        let now_day = utc_day_index(now);
+        let day_diff = now_day.saturating_sub(last_day);
+
+        if day_diff == 0 {
+            // Same UTC day — streak already counted, no change, no bonus
+        } else if day_diff == 1 {
+            // Consecutive UTC day — extend streak
             profile.current_streak += 1;
             if profile.current_streak > profile.max_streak {
                 profile.max_streak = profile.current_streak;
@@ -648,7 +651,7 @@ impl AchievementManager {
                 );
             }
         } else {
-            // Streak broken
+            // Streak broken (gap of 2+ UTC days)
             profile.current_streak = 1;
         }
 

contracts/gamification/src/social.rs

@@ -4,6 +4,7 @@ use crate::errors::Error;
 use crate::events::GamificationEvents;
 use crate::storage::GamificationStorage;
 use crate::types::{GamificationKey, PeerEndorsement, PeerRecognition, RecognitionType};
+use shared::timestamp_utils::utc_day_index;
 use shared::validation::{CoreValidator, ValidationConfig};
 
 pub struct SocialManager;
@@ -32,9 +33,9 @@ impl SocialManager {
 
         let config = GamificationStorage::get_config(env);
 
-        // Rate-limit: max N endorsements given per day (day = 86400s bucket)
+        // Rate-limit: max N endorsements given per UTC day
         let now = env.ledger().timestamp();
-        let day_bucket = now / 86_400;
+        let day_bucket = utc_day_index(now);
         let rate_key = GamificationKey::EndorserDailyCount(endorser.clone(), day_bucket);
         let given_today: u32 = env.storage().persistent().get(&rate_key).unwrap_or(0u32);
         if given_today >= config.max_endorsements_per_day {