# SourceScribe Core - Diagram Generation

## File Purpose and Overview

The `diagram.py` file in the `sourcescribe/engine` directory of the SourceScribe Core project is responsible for generating Mermaid.js diagrams from code structure information. It provides a `DiagramGenerator` class that can generate various types of diagrams, including:

- Architecture diagrams
- Class diagrams
- Process flow diagrams
- Sequence diagrams
- Entity-relationship diagrams

These diagrams are useful for visualizing and documenting the structure and behavior of software systems.

## Main Components

The main components in this file are:

1. `DiagramNode` class
   - Represents a node in a diagram, with properties for `id`, `label`, and `type`.

2. `DiagramEdge` class
   - Represents an edge in a diagram, with properties for `source`, `target`, and an optional `label`.

3. `DiagramGenerator` class
   - The main class responsible for generating the different types of diagrams.

## Key Functionality

The `DiagramGenerator` class provides the following methods for generating diagrams:

1. `generate_architecture_diagram(modules, title)`:
   - Generates an architecture diagram based on a list of module information.
   - The diagram shows the modules as nodes and their dependencies as edges.

2. `generate_class_diagram(classes, title)`:
   - Generates a class diagram based on a list of class information.
   - The diagram shows the classes, their attributes, methods, and relationships (inheritance and associations).

3. `generate_flow_diagram(steps, title)`:
   - Generates a process flow diagram based on a list of process steps.
   - The diagram shows the steps as nodes and the flow of the process.

4. `generate_sequence_diagram(interactions, title)`:
   - Generates a sequence diagram based on a list of interactions between components.
   - The diagram shows the sequence of messages exchanged between the components.

5. `generate_entity_relationship_diagram(entities, relationships, title)`:
   - Generates an entity-relationship diagram based on a list of entities and their relationships.
   - The diagram shows the entities, their attributes, and the relationships between them.

## Dependencies and Imports

The `diagram.py` file imports the following modules and types:

- `typing`: For type annotations, including `List`, `Dict`, `Any`, and `Optional`.
- `dataclasses`: For creating data classes (`DiagramNode` and `DiagramEdge`).

## Usage Examples

Here's an example of how to use the `DiagramGenerator` class to generate a class diagram:

```python
from sourcescribe.engine.diagram import DiagramGenerator

classes = [
    {
        'name': 'Person',
        'attributes': ['name: str', 'age: int'],
        'methods': ['get_name()', 'get_age()'],
        'parent': 'LivingThing',
        'associations': ['Address']
    },
    {
        'name': 'Address',
        'attributes': ['street: str', 'city: str', 'state: str', 'zip: str']
    },
    {
        'name': 'LivingThing',
        'attributes': ['is_alive: bool']
    }
]

diagram_generator = DiagramGenerator()
class_diagram = diagram_generator.generate_class_diagram(classes, title='My Class Diagram')
print(class_diagram)
```

This will output the Mermaid.js code for the class diagram, which can then be rendered in a Mermaid.js-compatible environment.

## Important Implementation Details

1. The `DiagramNode` and `DiagramEdge` classes are used to represent the basic building blocks of the diagrams.
2. The `DiagramGenerator` class uses Mermaid.js syntax to generate the diagram code. Each diagram type has its own specific syntax requirements.
3. The diagram generation methods take in lists of dictionaries, where each dictionary represents the information for a node, edge, or other diagram element.
4. The methods return the generated Mermaid.js code as a string, which can be embedded in a larger document or rendered directly.
5. The code includes error handling and default values to ensure the diagrams are generated even when the input data is incomplete or missing.