Update README with comprehensive due date API documentation

Added detailed documentation for new due date functionality:
- Updated features list to include due date capabilities
- Added specialized due date endpoints documentation
- Documented query parameters for filtering and sorting
- Added usage examples for all due date operations
- Updated project structure to reflect current state
- Added timezone support documentation
- Included complex filtering examples

README.md

@@ -7,7 +7,12 @@ A simple todo application built with FastAPI and SQLite.
 - Create, read, update, and delete todos
 - Category management system for organizing todos
 - Priority levels for todos (low, medium, high)
-- Search and filtering by category, priority, and completion status
+- Due date functionality with timezone support
+- Comprehensive filtering by category, priority, completion status, due dates, and overdue status
+- Search functionality across title and description
+- Specialized endpoints for overdue, due soon, and due today todos
+- Sorting by due date or creation date
+- Subtask management with hierarchical organization
 - SQLite database with SQLAlchemy ORM
 - Database migrations with Alembic
 - FastAPI with automatic OpenAPI documentation
@@ -23,12 +28,22 @@ A simple todo application built with FastAPI and SQLite.
 - `GET /redoc` - Alternative API documentation
 
 ### Todos
-- `GET /api/v1/todos` - Get all todos (with filtering by category, priority, completion status, and search)
+- `GET /api/v1/todos` - Get all todos (with comprehensive filtering and sorting)
 - `POST /api/v1/todos` - Create a new todo
 - `GET /api/v1/todos/{todo_id}` - Get a specific todo
 - `PUT /api/v1/todos/{todo_id}` - Update a specific todo
 - `DELETE /api/v1/todos/{todo_id}` - Delete a specific todo
 
+### Due Date Endpoints
+- `GET /api/v1/todos/overdue` - Get all overdue todos
+- `GET /api/v1/todos/due-soon` - Get todos due within next N days (default 7)
+- `GET /api/v1/todos/due-today` - Get todos due today
+
+### Subtasks
+- `POST /api/v1/todos/{todo_id}/subtasks` - Create a subtask for a specific todo
+- `GET /api/v1/todos/{todo_id}/subtasks` - Get all subtasks for a specific todo
+- `PUT /api/v1/todos/subtasks/{subtask_id}/move` - Move a subtask to different parent or make it a main todo
+
 ### Categories
 - `GET /api/v1/categories` - Get all categories
 - `POST /api/v1/categories` - Create a new category
@@ -63,11 +78,13 @@ The API will be available at `http://localhost:8000`
 │   │   └── v1/
 │   │       ├── __init__.py
 │   │       ├── todos.py
-│   │       └── categories.py
+│   │       ├── categories.py
+│   │       └── projects.py
 │   ├── crud/
 │   │   ├── __init__.py
 │   │   ├── todo.py
-│   │   └── category.py
+│   │   ├── category.py
+│   │   └── project.py
 │   ├── db/
 │   │   ├── __init__.py
 │   │   ├── base.py
@@ -75,17 +92,27 @@ The API will be available at `http://localhost:8000`
 │   ├── models/
 │   │   ├── __init__.py
 │   │   ├── todo.py
-│   │   └── category.py
+│   │   ├── category.py
+│   │   ├── project.py
+│   │   └── tag.py
 │   ├── schemas/
 │   │   ├── __init__.py
 │   │   ├── todo.py
-│   │   └── category.py
+│   │   ├── category.py
+│   │   └── project.py
+│   ├── utils/
+│   │   ├── __init__.py
+│   │   └── date_utils.py
 │   └── __init__.py
 ├── alembic/
 │   ├── versions/
 │   │   ├── 001_initial_todo_table.py
 │   │   ├── 002_add_priority_field.py
-│   │   └── 003_add_categories.py
+│   │   ├── 003_add_categories.py
+│   │   ├── 004_add_projects.py
+│   │   ├── 005_add_tags.py
+│   │   ├── 006_add_subtasks.py
+│   │   └── 007_add_due_date.py
 │   ├── env.py
 │   └── script.py.mako
 ├── alembic.ini
@@ -117,6 +144,11 @@ Each todo has the following fields:
 #### Due Date Features
 - `is_overdue`: Computed property indicating if todo is past due date
 - `days_until_due`: Computed property showing days until due (negative if overdue)
+- `is_due_soon`: Computed property indicating if todo is due within next 7 days
+- `is_due_today`: Computed property indicating if todo is due today
+
+#### Timezone Support
+All due dates are stored with timezone information (UTC). The API accepts ISO 8601 formatted datetime strings and automatically handles timezone conversion.
 
 ### Category Model
 Each category has the following fields:
@@ -164,3 +196,42 @@ curl "http://localhost:8000/api/v1/todos?priority=high&completed=false"
 ```bash
 curl "http://localhost:8000/api/v1/todos?search=presentation"
 ```
+
+## Due Date Features
+
+### Query Parameters for /api/v1/todos
+- `overdue`: Filter overdue todos (`true`/`false`)
+- `due_soon`: Filter todos due within next 7 days (`true`/`false`)
+- `due_date_from`: Filter todos due after this date (ISO format)
+- `due_date_to`: Filter todos due before this date (ISO format)
+- `sort_by`: Sort by `due_date` or `created_at`
+
+### Get Overdue Todos
+```bash
+curl "http://localhost:8000/api/v1/todos/overdue"
+```
+
+### Get Todos Due Soon (next 7 days)
+```bash
+curl "http://localhost:8000/api/v1/todos/due-soon"
+```
+
+### Get Todos Due Today
+```bash
+curl "http://localhost:8000/api/v1/todos/due-today"
+```
+
+### Filter by Date Range
+```bash
+curl "http://localhost:8000/api/v1/todos?due_date_from=2024-01-01T00:00:00Z&due_date_to=2024-12-31T23:59:59Z"
+```
+
+### Sort by Due Date
+```bash
+curl "http://localhost:8000/api/v1/todos?sort_by=due_date"
+```
+
+### Complex Filtering Example
+```bash
+curl "http://localhost:8000/api/v1/todos?priority=high&overdue=true&sort_by=due_date&page=1&per_page=20"
+```