# Requirements Document

## Introduction

This specification defines tag-based filtering functionality for Reverse Diagrams, enabling users to create focused architecture diagrams by filtering AWS resources based on their tags. This feature addresses the need to generate diagrams for specific environments, applications, or organizational units without the noise of unrelated resources.

## Glossary

- **Tag_Filter**: A key-value pair or key-only filter used to match AWS resource tags
- **Resource_Filter**: A filtering mechanism that includes or excludes AWS resources based on tag criteria
- **Diagram_Scope**: The subset of AWS resources included in a generated diagram after applying filters
- **Tag_Strategy**: The approach used for filtering (include-only, exclude, or mixed filtering)
- **Plugin_Filter**: A filter applied at the plugin level to control which resources are collected and processed
- **Account_Filter**: A filter that applies tag-based filtering across all AWS services within an account
- **Service_Filter**: A filter that applies tag-based filtering to specific AWS services (e.g., EC2 only)

## Requirements

### Requirement 1: Basic Tag Filtering

**User Story:** As a DevOps engineer, I want to filter AWS resources by tags, so that I can create diagrams showing only resources relevant to specific environments or applications.

#### Acceptance Criteria

1. WHEN a user specifies tag filters via CLI, THE System SHALL collect only resources matching those tag criteria
2. WHEN a user provides key-value tag filters (e.g., Environment=Production), THE System SHALL match resources with exact key-value pairs
3. WHEN a user provides key-only tag filters (e.g., Environment), THE System SHALL match resources that have the specified tag key regardless of value
4. WHEN no resources match the specified tag filters, THE System SHALL generate an empty diagram with appropriate messaging
5. WHEN tag filters are applied, THE System SHALL preserve all relationships between filtered resources

### Requirement 2: Multiple Tag Filter Support

**User Story:** As a cloud architect, I want to apply multiple tag filters simultaneously, so that I can create highly specific diagrams for complex filtering scenarios.

#### Acceptance Criteria

1. WHEN a user specifies multiple tag filters, THE System SHALL support both AND and OR logical operations
2. WHEN using AND logic (default), THE System SHALL include only resources matching ALL specified tag filters
3. WHEN using OR logic, THE System SHALL include resources matching ANY of the specified tag filters
4. WHEN combining include and exclude filters, THE System SHALL first apply include filters then remove resources matching exclude filters
5. WHEN tag filter logic is specified, THE System SHALL validate the logical operators and provide clear error messages for invalid combinations

### Requirement 3: Service-Specific Tag Filtering

**User Story:** As a system administrator, I want to apply tag filters to specific AWS services, so that I can create focused diagrams for particular service types while including all resources from other services.

#### Acceptance Criteria

1. WHEN a user specifies service-specific tag filters, THE System SHALL apply filters only to the specified AWS services
2. WHEN using the EC2 plugin with tag filters, THE System SHALL filter EC2 instances, VPCs, subnets, and security groups based on their respective tags
3. WHEN using service-specific filters, THE System SHALL include all resources from non-filtered services in the diagram
4. WHEN service-specific filters are combined with global filters, THE System SHALL apply both filter sets appropriately
5. WHEN a service doesn't support tags, THE System SHALL ignore tag filters for that service and include all resources

### Requirement 4: Account-Wide Tag Filtering

**User Story:** As an enterprise architect, I want to apply tag filters across all AWS services in an account, so that I can create comprehensive diagrams filtered by organizational or project criteria.

#### Acceptance Criteria

1. WHEN a user specifies account-wide tag filters, THE System SHALL apply the same filter criteria to all supported AWS services
2. WHEN using Organizations plugin with tag filters, THE System SHALL filter accounts based on account-level tags
3. WHEN using Identity Center plugin with tag filters, THE System SHALL filter permission sets and assignments based on their tags where applicable
4. WHEN account-wide filters are applied, THE System SHALL maintain service relationships even when some services have no matching resources
5. WHEN combining account-wide and service-specific filters, THE System SHALL apply the most restrictive filter for each service

### Requirement 5: CLI Tag Filter Interface

**User Story:** As a user, I want intuitive CLI options for specifying tag filters, so that I can easily create filtered diagrams without complex syntax.

#### Acceptance Criteria

1. WHEN a user wants to specify tag filters, THE System SHALL provide clear CLI options for tag filtering
2. WHEN using key-value filters, THE System SHALL accept format like `--tag Environment=Production`
3. WHEN using key-only filters, THE System SHALL accept format like `--tag-key Environment`
4. WHEN specifying multiple filters, THE System SHALL allow multiple `--tag` and `--tag-key` options
5. WHEN specifying logical operations, THE System SHALL provide `--tag-logic` option with values `AND` or `OR`
6. WHEN specifying exclude filters, THE System SHALL provide `--exclude-tag` and `--exclude-tag-key` options
7. WHEN using service-specific filters, THE System SHALL provide `--service-tag` option with service name and tag criteria

### Requirement 6: Tag Filter Validation and Error Handling

**User Story:** As a user, I want clear feedback when my tag filters are invalid or produce no results, so that I can correct my filtering criteria.

#### Acceptance Criteria

1. WHEN tag filter syntax is invalid, THE System SHALL provide clear error messages with examples of correct syntax
2. WHEN tag filters produce no matching resources, THE System SHALL display a warning message listing the applied filters
3. WHEN tag filters are applied but some services don't support tags, THE System SHALL log informational messages about which services were not filtered
4. WHEN conflicting filter options are specified, THE System SHALL validate the combination and provide guidance on resolution
5. WHEN tag filters result in broken relationships, THE System SHALL warn about orphaned resources in the diagram

### Requirement 7: Tag Filter Performance and Optimization

**User Story:** As a user working with large AWS environments, I want tag filtering to be performant, so that I can generate filtered diagrams efficiently even with thousands of resources.

#### Acceptance Criteria

1. WHEN tag filters are specified, THE System SHALL apply filters during data collection to minimize API calls
2. WHEN using pagination with tag filters, THE System SHALL leverage AWS API filtering capabilities where available
3. WHEN tag filters are applied, THE System SHALL cache tag information to avoid redundant API calls
4. WHEN processing large resource sets, THE System SHALL provide progress indicators for tag filtering operations
5. WHEN tag filtering is complete, THE System SHALL report the number of resources filtered and included

### Requirement 8: Tag Filter Configuration and Presets

**User Story:** As a team lead, I want to save and reuse common tag filter configurations, so that my team can consistently generate diagrams with standardized filtering criteria.

#### Acceptance Criteria

1. WHEN a user wants to save tag filter configurations, THE System SHALL provide options to save filter presets
2. WHEN using saved presets, THE System SHALL allow loading predefined tag filter combinations by name
3. WHEN managing presets, THE System SHALL provide options to list, create, update, and delete saved configurations
4. WHEN presets are used, THE System SHALL allow overriding specific filters while maintaining the preset base
5. WHEN sharing presets, THE System SHALL store configurations in a format that can be version controlled and shared across teams

### Requirement 9: Tag Filter Documentation and Examples

**User Story:** As a new user, I want comprehensive documentation and examples for tag filtering, so that I can quickly learn how to create filtered diagrams for my use cases.

#### Acceptance Criteria

1. WHEN a user requests help for tag filtering, THE System SHALL provide comprehensive CLI help with examples
2. WHEN documentation is accessed, THE System SHALL include common use case examples for different filtering scenarios
3. WHEN examples are provided, THE System SHALL cover single service filtering, multi-service filtering, and account-wide filtering
4. WHEN advanced features are documented, THE System SHALL explain logical operators, exclude filters, and preset management
5. WHEN troubleshooting information is needed, THE System SHALL provide guidance for common filtering issues and solutions

### Requirement 10: Integration with Existing Plugin Architecture

**User Story:** As a developer, I want tag filtering to integrate seamlessly with the existing plugin architecture, so that all current and future plugins can benefit from filtering capabilities.

#### Acceptance Criteria

1. WHEN plugins collect data, THE System SHALL provide a standardized interface for applying tag filters
2. WHEN new plugins are developed, THE System SHALL allow plugins to declare their tag filtering capabilities
3. WHEN tag filters are applied, THE System SHALL ensure consistent behavior across all plugins
4. WHEN plugins don't support tag filtering, THE System SHALL gracefully handle the limitation and inform users
5. WHEN plugin-specific tag filtering is needed, THE System SHALL provide extension points for custom filtering logic