Working Hours Register

Build a four-level Working Hours Register that records employee entry and exit, ranks employees by accumulated work time, activates pending promotions on a later entry, calculates pay using historical compensation, and applies double-pay grant periods. Requirements Complete four progressively unlocked levels within 90 minutes. Level 1 — employee and attendance basics: Add an employee. Record entry and exit badge events. Query an employee's total worked time. Level 2 — ranking: Return the top n employees ordered by worked time. Level 3 — promotions and salary: Schedule a promotion with a new position and compensation without immediately changing the current role. Keep the promotion pending until the employee next badges into the office, then activate it. Calculate salary across historical compensation periods; each completed work session is priced using the compensation active for that session. Level 4 — grant periods: Register periods during which qualifying work is paid at double rate. Apply the multiplier only when an entire work session falls within a grant period. Query the total amount of double-pay compensation issued. Notes Promotion scheduling and activation are separate state transitions; the next entry event is the activation boundary. Historical payroll cannot be reconstructed from only the employee's current compensation. Preserve the compensation associated with each session. Grant-period eligibility uses full containment of a session, not partial overlap. Later levels depend on the correctness of the earlier attendance and session model. Preparation Build the attendance state machine first and test duplicate entry, exit without entry, and total-time aggregation across multiple sessions. Add a pending-promotion transition and verify that compensation changes only on the next entry. Drill salary aggregation over sessions with different compensation values, then add full-containment checks for double-pay intervals. Practice extending the same data model level by level without rewriting earlier methods.