feat: refactor VerifyLeafHashes to compute root separately and then verify it

[gupadhyaya]

Fixes #290

Summary by CodeRabbit

• New Features
  • Enhanced data integrity verification with a refined cryptographic proof process and improved error handling.
• Refactor
  • Streamlined the underlying verification flow to simplify the validation logic and bolster system reliability.
  • Isolated root computation logic into a dedicated method for improved modularity.

[coderabbitai]

Walkthrough

The pull request introduces a new method, ComputeRoot, within the Proof struct to encapsulate the logic for computing the Merkle tree root from given leaf hashes and proof nodes. The inline root computation previously in VerifyLeafHashes is removed and replaced with a call to ComputeRoot, which now handles recursive traversal and error handling. This refactor modularizes the code and aligns with the objective of exposing the root computation separately.

Changes

File(s)	Change Summary
proof.go	Added a public method ComputeRoot(nth *NmtHasher, leafHashes [][]byte) ([]byte, error) for computing the Merkle tree root using recursive traversal; updated VerifyLeafHashes to call ComputeRoot, removing the previous inline root calculation logic.

Sequence Diagram(s)

Loading

sequenceDiagram
    participant C as Client
    participant V as VerifyLeafHashes
    participant CR as ComputeRoot
    participant R as RecursiveHelper
    C->>V: Call VerifyLeafHashes(proof, data, root)
    V->>CR: ComputeRoot(nth, leafHashes)
    CR->>R: Recursively compute root hash
    R-->>CR: Return computed hash or error
    CR-->>V: Return computed hash/error
    V->>C: Return verification result

Assessment against linked issues

Objective (Issue #)	Addressed	Explanation
Expose root computation as a separate function (#290)	✅

Poem

I'm a bunny in the code garden, hopping with delight,
New ComputeRoot shines like a carrot in the light,
Old tangled logic is now trimmed and neat,
With recursive hops, the tree's roots meet,
Celebrate the modular magic—hop, skip, and byte! 🐰💻

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📥 Commits

Reviewing files that changed from the base of the PR and between 5c74103 and a5dee5b.

📒 Files selected for processing (1)

• proof.go (2 hunks)

🔇 Additional comments (2)

proof.go (2)

251-325: Well-implemented modular approach to root computation

The new ComputeRoot method is a good example of code modularization. It extracts the root computation logic from VerifyLeafHashes into a separate method, making the code more maintainable and potentially reusable by other parts of the codebase.

The implementation features:

• Thorough documentation explaining the purpose, parameters, and return values
• Comprehensive error handling with detailed error messages
• A clean recursive approach for traversing the Merkle tree structure
• Proper handling of edge cases (e.g., non-existent subtrees)

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415-418: Good refactoring of root verification logic

The replacement of the inline root computation logic with a call to the new ComputeRoot method simplifies the VerifyLeafHashes function and makes the code more maintainable. The error handling is properly preserved.

✨ Finishing Touches

• 📝 Generate Docstrings

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