fix(readers): enumerate libnfc ACR122 devices

[wizzomafizzo]

Summary

• enumerate concrete libnfc ACR122 connection strings instead of using only libnfcauto
• skip already-connected ACR122 paths so multiple readers can connect independently
• preserve underscored ACR122 libnfc driver names after config normalization

Fixes #811

Validated with go test ./pkg/readers/libnfc/ and golangci-lint run --fix pkg/readers/libnfc/.

Summary by CodeRabbit

• Bug Fixes

  • Improved ACR122 reader detection with device-path filtering and deduplication; removed previous fallback behavior in certain detection paths
  • Added normalized handling for ACR122 USB and PCSC connection strings; trims trailing NUL bytes from libnfc-reported strings

• Tests

  • Added comprehensive ACR122 detection tests covering selection, skipping already-connected devices, ignoring non-ACR122 entries, and fallback behavior
  • Extended connection-string normalization and end-to-end cases for ACR122 variants

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 31dcdf7a-d7ec-4307-b222-69cb41b705ed

📥 Commits

Reviewing files that changed from the base of the PR and between 212be61 and 20c0336.

📒 Files selected for processing (2)

• pkg/readers/libnfc/libnfc.go
• pkg/readers/libnfc/libnfc_test.go

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📝 Walkthrough

Walkthrough

This PR implements enumeration-based ACR122 device detection to resolve multiple-reader auto-detect issues. Reader.Detect queries libnfc for concrete ACR122 connections, deduplicates by derived paths, conditionally falls back to auto-open, and extends connection-string normalization for ACR122 USB/PCSC variants.

Changes

ACR122 Multi-Device Detection and Normalization

Layer / File(s)	Summary
ACR122 Device Detection and Reader.Detect Integration pkg/readers/libnfc/libnfc.go, pkg/readers/libnfc/libnfc_test.go	Reader.Detect now calls detectACR122Readers(connected) in both the ACR122-only and default branches. New helpers call nfc.ListDevices(), filter libnfc connection strings to acr122_usb:/acr122_pcsc:, derive a path component, skip already-connected paths, and return either a selected connection string, "" if libnfc reported ACR122 devices but none selectable, or fall back to autoConnStr only if libnfc reported no ACR122 entries. Tests in TestDetectACR122Device validate selection, deduplication, NUL trimming, and fallback behavior.
ACR122 Connection String Normalization pkg/readers/libnfc/libnfc.go, pkg/readers/libnfc/libnfc_test.go	toLibnfcConnStr now converts internal acr122usb: → acr122_usb: and acr122pcsc: → acr122_pcsc:. Tests in TestToLibnfcConnStr and TestToLibnfcConnStrEndToEnd verify driver-name normalization and end-to-end libnfc-formatted connection strings.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Poem

🐰 Hop, hop, enumerate with glee,
Each ACR122 now finds its key,
Paths unrolled and NULs trimmed clean,
No more single-reader scene,
Little readers dance — hooray for me!

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 33.33% 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 change: enumerating libnfc ACR122 devices instead of relying on a single auto-detect path.
Linked Issues check	✅ Passed	The pull request implements all core requirements from issue #811: enumerates concrete libnfc ACR122 connection strings, skips already-connected devices, and preserves driver names.
Out of Scope Changes check	✅ Passed	All changes are directly scoped to ACR122 device enumeration logic and related test coverage; no unrelated modifications were introduced.

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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 fix/issue-811-libnfc-acr122-enumeration

---

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[coderabbitai]

Actionable comments posted: 2

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@pkg/readers/libnfc/libnfc_test.go`:
- Around line 482-535: Add a regression test for the branch where ACR122 devices
are enumerated but every ACR122 path is already present in connected (expect
""), and fix the "auto already connected" case to use the same driver:path
string format the autodetect contract uses instead of raw autoConnStr; update
the table in TestDetectACR122Device (affecting the test cases that call
detectACR122Device and reference autoConnStr) by adding a case with devices like
"acr122_usb:003:004" and connected containing that same concrete path(s), and
change the existing auto-connected case to pass the driver-prefixed connection
string form rather than autoConnStr so it matches detectACR122Device's input
format.

In `@pkg/readers/libnfc/libnfc.go`:
- Around line 659-676: The current detectACR122Device loop calls
fallbackAutoACR122(connected) unconditionally when no new connStr is returned,
which causes a fallback to "libnfcauto:" even if ACR122 devices were enumerated
but skipped because their paths are already connected; modify detectACR122Device
to track whether any ACR122 connStrs were seen (use isACR122ConnStr(connStr))
and only call fallbackAutoACR122(connected) when none were found; if ACR122
devices existed but were all skipped due to
isConnectedPath(connectionPath(connStr)), return "" instead of falling back.
Ensure the same change is applied to the analogous block referenced in lines
678-683.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 9b58b4d7-3058-4980-b921-37e2d17488e1

📥 Commits

Reviewing files that changed from the base of the PR and between 9c4dd2b and 212be61.

📒 Files selected for processing (2)

• pkg/readers/libnfc/libnfc.go
• pkg/readers/libnfc/libnfc_test.go

[sentry]

Codecov Report

❌ Patch coverage is 75.60976% with 10 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
pkg/readers/libnfc/libnfc.go	75.60%	9 Missing and 1 partial ⚠️

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