API Design
=========

This document outlines the API design principles and specifications for the AI-Writer platform.

API Design Principles
-------------------

The AI-Writer API follows these core design principles:

1. **RESTful Architecture**
   
   * Resource-oriented design
   * Standard HTTP methods (GET, POST, PUT, DELETE)
   * Consistent URL structure
   * Stateless interactions

2. **Consistent Response Format**
   
   * JSON as the primary data format
   * Standard error response structure
   * Pagination for list endpoints
   * Hypermedia links where appropriate

3. **Versioning**
   
   * API versioning in URL path (e.g., `/api/v1/`)
   * Backward compatibility within major versions
   * Deprecation notices before removing features

4. **Security**
   
   * Authentication via API keys or OAuth 2.0
   * Rate limiting to prevent abuse
   * Input validation to prevent injection attacks
   * HTTPS for all communications

5. **Documentation**
   
   * OpenAPI/Swagger specification
   * Interactive documentation
   * Code examples for common operations
   * Changelog for API updates

API Endpoints
-----------

Content Management
~~~~~~~~~~~~~~~~

.. code-block:: text

   # Create content
   POST /api/v1/content
   
   # Get content by ID
   GET /api/v1/content/{content_id}
   
   # Update content
   PUT /api/v1/content/{content_id}
   
   # Delete content
   DELETE /api/v1/content/{content_id}
   
   # List content with filtering
   GET /api/v1/content?type={type}&limit={limit}&offset={offset}
   
   # Get content versions
   GET /api/v1/content/{content_id}/versions
   
   # Revert to specific version
   POST /api/v1/content/{content_id}/revert/{version_id}

AI Generation
~~~~~~~~~~~

.. code-block:: text

   # Generate content from keywords
   POST /api/v1/generate/content
   
   # Generate blog post
   POST /api/v1/generate/blog
   
   # Generate social media post
   POST /api/v1/generate/social
   
   # Generate email
   POST /api/v1/generate/email
   
   # Generate outline
   POST /api/v1/generate/outline
   
   # Generate image for content
   POST /api/v1/generate/image

Web Research
~~~~~~~~~~

.. code-block:: text

   # Perform web research
   POST /api/v1/research
   
   # Get research results
   GET /api/v1/research/{research_id}
   
   # Search previous research
   GET /api/v1/research/search?query={query}

SEO Tools
~~~~~~~~

.. code-block:: text

   # Analyze content for SEO
   POST /api/v1/seo/analyze
   
   # Generate meta description
   POST /api/v1/seo/meta-description
   
   # Generate SEO-friendly title
   POST /api/v1/seo/title
   
   # Generate structured data
   POST /api/v1/seo/structured-data
   
   # Generate alt text for images
   POST /api/v1/seo/alt-text

User Management
~~~~~~~~~~~~~

.. code-block:: text

   # Create user
   POST /api/v1/users
   
   # Get user profile
   GET /api/v1/users/{user_id}
   
   # Update user profile
   PUT /api/v1/users/{user_id}
   
   # Delete user
   DELETE /api/v1/users/{user_id}
   
   # Get user settings
   GET /api/v1/users/{user_id}/settings
   
   # Update user settings
   PUT /api/v1/users/{user_id}/settings

API Key Management
~~~~~~~~~~~~~~~

.. code-block:: text

   # Create API key
   POST /api/v1/api-keys
   
   # List API keys
   GET /api/v1/api-keys
   
   # Revoke API key
   DELETE /api/v1/api-keys/{key_id}

Analytics
~~~~~~~~

.. code-block:: text

   # Get content analytics
   GET /api/v1/analytics/content/{content_id}
   
   # Get user analytics
   GET /api/v1/analytics/user/{user_id}
   
   # Get system analytics
   GET /api/v1/analytics/system

Request and Response Examples
---------------------------

Create Content
~~~~~~~~~~~~

Request:

.. code-block:: json

   POST /api/v1/content
   Content-Type: application/json
   Authorization: Bearer {api_key}
   
   {
     "title": "How to Improve SEO with AI",
     "content_type": "blog",
     "content": "# How to Improve SEO with AI\n\nIn this article, we'll explore...",
     "metadata": {
       "keywords": ["SEO", "AI", "content marketing"],
       "category": "digital marketing",
       "language": "en"
     }
   }

Response:

.. code-block:: json

   HTTP/1.1 201 Created
   Content-Type: application/json
   
   {
     "id": "c123e4567-e89b-12d3-a456-426614174000",
     "title": "How to Improve SEO with AI",
     "content_type": "blog",
     "content": "# How to Improve SEO with AI\n\nIn this article, we'll explore...",
     "metadata": {
       "keywords": ["SEO", "AI", "content marketing"],
       "category": "digital marketing",
       "language": "en"
     },
     "created_at": "2023-01-01T12:00:00Z",
     "updated_at": "2023-01-01T12:00:00Z",
     "user_id": "u123e4567-e89b-12d3-a456-426614174000",
     "links": {
       "self": "/api/v1/content/c123e4567-e89b-12d3-a456-426614174000",
       "versions": "/api/v1/content/c123e4567-e89b-12d3-a456-426614174000/versions",
       "analytics": "/api/v1/analytics/content/c123e4567-e89b-12d3-a456-426614174000"
     }
   }

Generate Blog Post
~~~~~~~~~~~~~~~

Request:

.. code-block:: json

   POST /api/v1/generate/blog
   Content-Type: application/json
   Authorization: Bearer {api_key}
   
   {
     "keywords": ["artificial intelligence", "content creation"],
     "title": "The Future of Content Creation with AI",
     "tone": "informative",
     "length": "medium",
     "include_research": true,
     "target_audience": "marketers"
   }

Response:

.. code-block:: json

   HTTP/1.1 200 OK
   Content-Type: application/json
   
   {
     "id": "g123e4567-e89b-12d3-a456-426614174000",
     "title": "The Future of Content Creation with AI",
     "content": "# The Future of Content Creation with AI\n\nArtificial intelligence is revolutionizing...",
     "metadata": {
       "keywords": ["artificial intelligence", "content creation"],
       "tone": "informative",
       "length": "medium",
       "word_count": 1250,
       "research_sources": [
         {
           "title": "AI in Content Marketing Report 2023",
           "url": "https://example.com/report",
           "accessed_at": "2023-01-01T10:30:00Z"
         }
       ]
     },
     "created_at": "2023-01-01T12:05:00Z",
     "links": {
       "save": "/api/v1/content",
       "regenerate": "/api/v1/generate/blog",
       "edit": "/api/v1/generate/edit"
     }
   }

Error Response
~~~~~~~~~~~~

.. code-block:: json

   HTTP/1.1 400 Bad Request
   Content-Type: application/json
   
   {
     "error": {
       "code": "invalid_request",
       "message": "The request was invalid",
       "details": [
         {
           "field": "keywords",
           "issue": "required",
           "description": "The keywords field is required"
         }
       ]
     },
     "request_id": "req_123456",
     "documentation_url": "https://docs.alwrity.com/api/errors#invalid_request"
   }

API Authentication
----------------

The AI-Writer API supports the following authentication methods:

1. **API Key Authentication**
   
   * Include the API key in the Authorization header:
     `Authorization: Bearer {api_key}`
   * API keys can be generated and managed through the API or web interface
   * Different permission levels can be assigned to API keys

2. **OAuth 2.0 (for multi-user deployments)**
   
   * Standard OAuth 2.0 flow with authorization code
   * Supports scopes for fine-grained permissions
   * Refresh token rotation for enhanced security

Rate Limiting
-----------

To ensure fair usage and system stability, the API implements rate limiting:

* Rate limits are based on the user's plan
* Limits are applied per API key
* Rate limit information is included in response headers:
  * `X-RateLimit-Limit`: Total requests allowed in the current period
  * `X-RateLimit-Remaining`: Requests remaining in the current period
  * `X-RateLimit-Reset`: Time when the rate limit resets (Unix timestamp)

When a rate limit is exceeded, the API returns a 429 Too Many Requests response.

Pagination
---------

List endpoints support pagination with the following parameters:

* `limit`: Number of items per page (default: 20, max: 100)
* `offset`: Number of items to skip (for offset-based pagination)
* `cursor`: Cursor for the next page (for cursor-based pagination)

Response includes pagination metadata:

.. code-block:: json

   {
     "data": [...],
     "pagination": {
       "total": 45,
       "limit": 20,
       "offset": 0,
       "next_cursor": "cursor_for_next_page",
       "has_more": true
     }
   }

Filtering and Sorting
-------------------

List endpoints support filtering and sorting:

* Filtering: `?field=value&another_field=another_value`
* Range filtering: `?created_at_gte=2023-01-01&created_at_lte=2023-01-31`
* Sorting: `?sort=field` (ascending) or `?sort=-field` (descending)
* Multiple sort fields: `?sort=-created_at,title`

Versioning Strategy
-----------------

The API uses a versioning strategy to ensure backward compatibility:

1. **Major Versions**
   
   * Included in the URL path: `/api/v1/`, `/api/v2/`, etc.
   * Major versions may introduce breaking changes
   * Previous major versions are supported for at least 12 months after a new version is released

2. **Minor Updates**
   
   * Backward-compatible changes within a major version
   * New endpoints or parameters may be added
   * Existing functionality remains unchanged

3. **Deprecation Process**
   
   * Features to be removed are marked as deprecated
   * Deprecation notices are included in response headers
   * Deprecated features are supported for at least 6 months before removal

API Changelog
-----------

The API changelog is maintained to track changes:

* **v1.0.0 (2023-01-01)**
  
  * Initial release with core content management features
  * Basic AI generation capabilities
  * User management and authentication

* **v1.1.0 (2023-03-15)**
  
  * Added SEO analysis endpoints
  * Enhanced content generation with research integration
  * Improved error handling and validation

* **v1.2.0 (2023-06-30)**
  
  * Added analytics endpoints
  * Introduced cursor-based pagination
  * Added support for content versioning

Future API Roadmap
----------------

Planned API enhancements:

1. **Content Collaboration**
   
   * Endpoints for collaborative editing
   * Comment and feedback functionality
   * Role-based access control

2. **Advanced Analytics**
   
   * Predictive performance metrics
   * Competitive analysis
   * Content optimization recommendations

3. **Workflow Automation**
   
   * Scheduled content generation
   * Approval workflows
   * Integration with publishing platforms

4. **Multi-modal Content**
   
   * Enhanced image generation
   * Audio content generation
   * Video script generation