Wire StatsPeriodFilterBar to BLoC and data refresh
epic-coordinator-statistics-dashboard-ui-task-012 — Connect the StatsPeriodFilterBar widget to the Coordinator Statistics BLoC so that period or activity-type filter changes dispatch a filter-changed event, trigger a new data fetch, and cause all chart and card widgets to re-render with updated data. Include debouncing on rapid filter changes. Ensure the PersonalStatsView also responds to period filter changes.
Acceptance Criteria
Technical Requirements
Execution Context
Tier 5 - 253 tasks
Can start after Tier 4 completes
Implementation Notes
Implement debouncing using a Timer stored in the BLoC's event handler (cancel and restart the timer on each filter event, emit state only when timer fires). Alternatively use RxDart's debounceTime operator on the event stream if RxDart is already a dependency. Keep filter state inside the BLoC state object (not in the widget) so the filter bar widget is purely reactive — it reads from BLoC state and emits events, with no local StatefulWidget state for filter values. Use BlocSelector to limit rebuilds: each widget section should only rebuild when its own data slice changes, not on every BLoC state update.
Pass the CoordinatorStatsFilter model to the Supabase repository as a typed parameter; the repository converts it to query parameters, keeping business logic out of the UI layer.
Testing Requirements
Write flutter_test widget tests and BLoC unit tests: (1) verify tapping a period chip dispatches the correct StatsFilterChangedEvent, (2) verify debounce — simulate 5 rapid taps within 200ms and confirm only one event is dispatched, (3) verify StatsPeriodFilterBar reflects the active filter from BLoC state (not local state), (4) use bloc_test's emitsInOrder to verify state sequence: loading → loaded with filtered data, (5) verify PersonalStatsView receives the same period filter, (6) verify empty state widget appears when BLoC emits empty data state. Integration test: verify end-to-end filter change triggers correct Supabase query parameters using a mock Supabase client.
PeerMentorStatsList must handle rosters of 40+ mentors efficiently. A naive ListView implementation that re-renders all rows on filter change may cause frame drops on mid-range devices, degrading the experience for coordinators managing large chapters.
Mitigation & Contingency
Mitigation: Use ListView.builder with const constructors for row widgets. Profile the list with Flutter DevTools on a release build against a 60-mentor dataset before submitting for review. Implement sort in the BLoC layer, not in the widget.
Contingency: If frame drops persist, introduce pagination (load 20 mentors, scroll to load more) and add a search filter to reduce visible row count in practice.
The ActivityTypeDonutChart must render org-configured activity type labels from the org-labels system. If the terminology provider is not available or returns stale labels, chart segments will display raw key strings instead of human-readable organisation-specific names, confusing coordinators.
Mitigation & Contingency
Mitigation: Always resolve labels through the OrganizationLabelsProvider before passing data to the donut chart widget. Implement a fallback that formats the raw key as a readable string (e.g., 'peer_support' → 'Peer Support') if the provider returns null.
Contingency: If the org-labels system is unavailable, display the formatted fallback label and log a warning. Do not block chart rendering on label resolution — render with fallbacks immediately.
fl_chart widgets do not natively expose semantic labels for individual bars and donut segments. Without explicit Semantics wrappers, VoiceOver and TalkBack users will receive no meaningful chart information, failing accessibility requirements critical for Blindeforbundet and NHF deployments.
Mitigation & Contingency
Mitigation: Wrap each fl_chart widget in a Semantics widget with a descriptive label summarising the chart data. Implement the data table fallback toggle from the start, not as an afterthought. Validate with VoiceOver on iOS and TalkBack on Android during development.
Contingency: If fl_chart's rendering pipeline prevents semantic overlay from working reliably, replace chart widgets with a custom Canvas-based implementation that has full semantic control, or use a different charting library with better accessibility support.
The period filter state must be preserved when navigating away from the dashboard (e.g., drilling into a mentor's detail screen and pressing back). If the BLoC is re-created on navigation, the filter resets to default, forcing coordinators to re-select their period every time they drill down, degrading operational workflow efficiency.
Mitigation & Contingency
Mitigation: Provide the StatsBloc at a route level above the dashboard screen using a BlocProvider scoped to the statistics navigation shell, not inside the screen widget itself. Verify persistence with a widget integration test that navigates away and back.
Contingency: If route-level scoping is not achievable within the current navigation architecture, persist the last-used filter to a local session store and restore it on screen re-entry.