Refactoring: Improve Maintainability, Readability, and Structure without Changing Functionality

[ani28-bit]

Issues Addressed

This PR addresses several code quality problems identified during Phase 2, including:

• Repeated Logic and Duplicate Code
• Large Classes with excessive responsibilities
• Single Responsibility Principle (SRP) violations
• Magic Numbers
• Long Parameter Lists
• Hidden Fields
• Avoid Branching Statement as Last in Loop
• Inheritance-related unnecessary methods
• Inefficient String Concatenation in Loops
• Feature Envy
• Primitive Obsession

The affected components include:

• Parser
• Parser.Builder
• HtmlRenderer.Builder
• HtmlRenderer.RendererContext
• MarkdownRenderer.RendererContext
• HtmlBlockParser
• DocumentParser
• BlockQuoteParser
• BlockStartImpl
• CoreTextContentNodeRenderer
• Nodes
• HeadingIdAttributeProvider
• Scanner
• CoreHtmlNodeRenderer
• LinkReferenceDefinitionParser

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Why These Changes Improve the System

The refactoring improves the overall quality of the codebase by:

• Increasing readability and reducing code duplication.
• Improving maintainability by separating responsibilities into smaller methods.
• Enhancing extensibility and reducing coupling between components.
• Making domain concepts more explicit through better abstractions.
• Eliminating unnecessary complexity and improving cohesion.
• Making future modifications safer and easier.
• Reducing the risk of defects caused by duplicated or tightly coupled code.

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Summary of Refactoring Approach

ID	Refactoring Technique	Target
1	Extract Method	parse(), parseReader()
2	Extract Method	Parser.Builder
3	Extract Method	HtmlRenderer.Builder
4	Extract Method	HtmlRenderer.RendererContext
5	Extract Method	MarkdownRenderer.RendererContext
6	Extract Constant	HtmlBlockParser.java
7	Introduce Parameter Object	createDocumentParser()
8	Extract Method	BlockQuoteParser.java
9	Rename Parameter	BlockStartImpl.java
10	Loop Structure Improvement	DocumentParser.java
11	Extract Method	CoreTextContentNodeRenderer.java
12	Remove Method	Nodes.java
13	Efficient String Handling	HeadingIdAttributeProvider.java
14	Extract Method	Scanner.java
15	Extract Method	CoreHtmlNodeRenderer.visit(Link) and visit(Image)
16	Replace Primitive with Enum	LinkReferenceDefinitionParser.java

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Functionality Assurance

These changes are strictly refactoring improvements. No external behavior, APIs, or output formats were modified. The refactoring only reorganizes and simplifies the internal implementation while preserving existing functionality. Existing features and test behavior remain unchanged, ensuring backward compatibility and consistent system behavior.

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Overall, this Phase 3 refactoring focuses on improving code readability, maintainability, structure, and extensibility while preserving the original functionality of the system.