Creating funnel documentation that never needs manual updates using AST

A Funnel structure, where numerous branches occur depending on conditions (such as a seller onboarding process), has the problem of quickly becoming Outdated when documentation is written manually, since code changes are not immediately reflected.

To solve this, instead of runtime analysis that records paths by executing the code, a Static Analysis approach was introduced, which parses the code into a tree structure for analysis. By using AST (Abstract Syntax Tree) to extract navigation information within the code, synchronization between documentation and code is automated.

The implementation process is as follows:

• FileScanner: Uses glob patterns to scan page files within a Next.js project.
• Data Structure: Designs a NavigationEdge structure that includes origin, destination, navigation method (push/replace), branch conditions, query parameters, and more.
• NavigationExtractor: Parses the AST using the ts-morph library to find call patterns like router.push(), and extracts conditional statements (such as if statements) by tracing parent nodes.

Through this process, it's possible to build 'never-outdated' funnel documentation where code changes are immediately reflected in the documentation.