Refactor axial pathfinding for efficiency and simplicity

[candour]

This change refactors the pathfinding utility to be more efficient and simpler. It optimizes the A* algorithm implementation for a hexagonal grid using axial coordinates, significantly reducing memory allocations and improving algorithmic performance by avoiding costly queue removals. A new unit test suite verifies the functionality against various scenarios.

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PR created automatically by Jules for task 7602219207758408355 started by @candour

Summary by CodeRabbit

• Refactor

  • Improved pathfinding implementation for better performance and maintainability.

• Tests

  • Added comprehensive test coverage for pathfinding functionality, including path validation, blocked positions, and edge cases.

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ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

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Run ID: 4d800640-59b1-40f1-b128-509f4a24c650

📥 Commits

Reviewing files that changed from the base of the PR and between 6c50a6b and 0a4261e.

📒 Files selected for processing (2)

• app/src/main/java/com/messark/hawker/utils/Pathfinding.kt
• app/src/test/java/com/messark/hawker/PathfindingTest.kt

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📝 Walkthrough

Walkthrough

The A* pathfinding algorithm was rewritten from a Node-based approach to a PriorityQueue-backed implementation using gScores, parents maps, and closedSet for neighbor discovery via NEIGHBOR_OFFSETS. Comprehensive unit tests validate the new behavior across path discovery, blocked positions, and edge cases.

Changes

A* Pathfinding Refactor & Tests

Layer / File(s)	Summary
Data Structure & Constants app/src/main/java/com/messark/hawker/utils/Pathfinding.kt	Introduces static NEIGHBOR_OFFSETS array for axial-grid neighbor generation and adds ScoredCoordinate class for priority-queue ordering.
Core Algorithm app/src/main/java/com/messark/hawker/utils/Pathfinding.kt	findPath method reimplemented using A* with gScores map, parents map, closedSet, and PriorityQueue<ScoredCoordinate> replacing prior Node-based control flow.
Path Reconstruction app/src/main/java/com/messark/hawker/utils/Pathfinding.kt	Adds reconstructPath(end, parents) helper to rebuild paths via parent-chain traversal; removes prior getNeighbors, node-level reconstructPath, and Node class.
Test Coverage app/src/test/java/com/messark/hawker/PathfindingTest.kt	Four JUnit tests verify straight-line paths, blocked-position handling, reachability when destination is blocked, and start-equals-end cases.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~30 minutes

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 12.50% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately summarizes the main changes: refactoring the pathfinding algorithm for improved efficiency and simplicity, which aligns with the A* optimization, removal of Node class, and use of static neighbor offsets described in the PR objectives.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch refactor-pathfinding-efficiency-7602219207758408355

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