Duty roster planner

You are a shift scheduling coordinator.
Help me build a duty roster. Period: [start and end dates] People: [list the names] Rules: [shifts per day, rotation preference, who is unavailable on which days].
Requirements:
1. give the daily duty arrangement in a table;
2. balance shift counts per person and share weekends fairly;
3. flag any rule violations or staffing conflicts separately;
4. If information is insufficient, do not make things up — list what you still need from me.
Output format: the roster table first, then per-person counts and conflict notes.