Task Management System with Smart Scheduling
A CLI task manager that intelligently organizes and prioritizes your tasks.
What it does:

Add/complete tasks with priorities and due dates
Smart task scheduling based on priority and deadlines
Group tasks by project categories
Track time estimates vs actual completion
Generate daily task recommendations

Key Features:

Interactive CLI with multiple command modes
Smart priority calculation algorithm
Task dependency system (some tasks block others)
Statistics and productivity insights
Persistent storage (simple text format, not CSV/JSON)

Project Structure:
task_manager/
├── src/
│   ├── main.rs           # CLI interface & command parsing
│   ├── task.rs           # Task struct and related types
│   ├── scheduler.rs      # Smart scheduling algorithms
│   ├── storage.rs        # File persistence (simple format)
│   ├── statistics.rs     # Analytics and insights
│   └── commands.rs       # Command handling and validation
Enhanced Concepts You'll Use:

Advanced Enums: Task status, priority levels, command types with data
Pattern Matching: Complex command parsing
Iterator Chains: Advanced filtering, sorting, grouping operations
Generic Collections: Different task containers and sorting strategies
Trait Objects: Different scheduling algorithms, pluggable filters
Lifetime Management: References between tasks and projects
Error Handling: Command validation, file operations, date parsing
Memory Management: Efficient task storage and retrieval
Advanced Modules: Clear separation with inter-module communication

Sample Complexity Features:

Smart Scheduling: Algorithm that considers deadlines, dependencies, and user productivity patterns
Query Language: Simple syntax like priority:high status:pending project:work
Task Dependencies: Some tasks can't start until others finish
Time Tracking: Compare estimated vs actual completion times
Productivity Insights: Show patterns in task completion

Implementation Timeline (8-10 hours):

Core Types & CLI (2h): Task struct, enums, basic command parsing
Storage System (2h): Custom text format, error handling
Task Operations (2h): CRUD operations, validation
Smart Scheduling (2h): Priority algorithms, dependency resolution
Statistics & Polish (1.5h): Analytics, improved UI

Core Usage Examples
Basic Operations:
bash# Add tasks
> add "Fix login bug" --priority high --estimate 2h --depends-on "None"
Task #1 created

> remove "Fix-login-bug" 
Task #1 removed

> add "Fix-login-bug" --priority high --estimate 2h --depends-on "None"
    0     1               2        3         4    5    6          7
Task #1 created

> add "Write-tests" --priority medium --estimate 2h --depends-on "Fix-login-bug"
Task #2 created (blocked by #1)

# View and update
> list
#1 [HIGH] Fix login bug (2h) - PENDING
#2 [MED]  Write tests (1h) - BLOCKED BY "Fix login bug"

> complete 1 --time 6h
Task #1 completed! Task #2 is now unblocked.
took 4 hours longer then expected

Smart Scheduling wiht 2 algs simple and advanced:
bash# Get today's recommended tasks
> schedule --time 3h --simple
Recommended for today:
1. [HIGH] Fix login bug (2h) PENDING
2. [MED]  Write tests (1h) BLOCKED BY #1
3. [LOW]  Update docs (1h) PENDING

Simple Stats:
bash> stats
today: 8 completed, 3 pending
Time accuracy: 90%

Skipping days:
next-day
today is day N. {day-count}