feat: Add swipe/scroll search engine switching

[prem-k-r]

📌 Description

Added the ability to change search engines by swiping (touch) or scrolling (mouse wheel) on the dropdown icon when search engines are hidden, with smooth vertical carousel animations.

✅ Checklist

• I have read and followed the Contributing Guidelines.
• My code follows the project's coding style and conventions.
• I have tested my changes thoroughly to ensure expected behavior.
• I have verified compatibility across Chrome and Firefox (additional browsers if applicable).
• I have attached relevant visual evidence (screenshots/videos) if applicable.
• I have updated the CHANGELOG.md under the appropriate categories with all my changes in this PR.

Feature Overview

Adds touch-swipe and mouse-wheel gestures on the search dropdown button to switch search engines when the dropdown is hidden, using a smooth vertical carousel animation and persisting the selected engine.

Technical Implementation

JavaScript (scripts/search.js)

• New state, helpers and wiring:
  • State vars: engineSwipeStartY, engineSwipeEndY, isEngineSwiping, isEngineSwitching, engineSwitchTimeout, currentSearchEngineIndex.
  • Element ref: dropdownBtn ('.dropdown-btn').
  • Helpers added: getAllEngines(), getCurrentSearchEngineIndex().
• switchEngine(direction):
  • Computes next/previous engine (no-op if <2 engines).
  • Applies 'engine-switching' class to #searchbar and sets data-switch-direction ('next'|'prev') to drive CSS animation.
  • Performs radio swap and dropdown resort roughly 180ms into the animation, persists selection to localStorage (selectedSearchEngine- and activeSearchMode), and refreshes engine hints via toggleSearchEngines(newCategory).
  • Removes animation class at ~400ms and enforces a ~400ms cooldown to throttle rapid repeats.
• Input handlers:
  • Touch: touchstart/touchmove/touchend on .dropdown-btn to detect vertical swipes and call switchEngine('next'|'prev').
  • Wheel: wheel handler on .dropdown-btn to call switchEngine based on deltaY.
  • Handlers early-return when the dropdown is visible or when the shortcut that shows engines is active.
• Implementation note: the swipe/scroll control block is duplicated in scripts/search.js (two identical blocks). Consolidation recommended to avoid duplicate handlers.

CSS (style.css)

• Adds vertical carousel animations:
  • Keyframes slideUpFade and slideDownFade.
  • Styles for .searchbar.engine-switching[data-switch-direction="next"|"prev"] targeting .dropdown-btn > * to animate vertical slide + fade.
  • Minor transition wrapper adjustments for .dropdown-btn > *.
• Selector change: .authorName → .authorWrapper in quotes/author display rules (verify this is intentional).

Manifests & Changelog

• manifest(firefox).json and manifest.json: version bumped 3.3.5 → 3.3.6.
• CHANGELOG.md: Unreleased entry added noting support for touch-swipe and mouse-wheel gestures on the search engine icon.

Behavior & Edge Cases

• No action if fewer than two engines, if dropdown is open, or if the shortcut that shows engines is enabled.
• Engine swap occurs mid-animation (~180ms) with animation completing ≈400ms.
• 400ms cooldown prevents rapid repeated switches.
• Verified on Chrome and Firefox; visual evidence attached where applicable.

Files & Size Impact

• scripts/search.js: ~+122/-2 (new swipe/scroll logic; duplicate block present).
• style.css: ~+65/-10 (animation + selector rename).
• CHANGELOG.md: +4/-0.
• manifest files: +1/-1 each (version bumps).

Testing & Checklist

• Author reports testing on Chrome and Firefox; contributing guidelines and code style followed.
• CHANGELOG.md updated in this PR.

Notes for Reviewers

• Remove the duplicated swipe/scroll block in scripts/search.js to ensure handlers are attached once.
• Verify throttling/cooldown logic prevents overlapping switches.
• Confirm the .authorName → .authorWrapper selector change is intentional and does not hide unintended elements.

[itz-rj-here]

I will check tomorrow morning 🫡

[coderabbitai]

Actionable comments posted: 2

🤖 Fix all issues with AI agents

In `@scripts/search.js`:
- Around line 414-420: Rename the function getcurrentSearchEngineIndex to
getCurrentSearchEngineIndex to match camelCase; inside it, call getAllEngines()
as before but guard against
document.querySelector('input[name="search-engine"]:checked') returning null by
checking selectedOption and returning -1 (or another sentinel) when it's null,
and only access selectedOption.value when non-null; update any call sites that
referenced getcurrentSearchEngineIndex to the new getCurrentSearchEngineIndex
name.
- Around line 479-485: The touchstart handler on dropdownBtn currently calls
e.preventDefault(), which suppresses the synthesized click and prevents tapping
from opening the dropdown when hideSearchWith.checked is true; update the touch
handling in the touchstart listener (for dropdownBtn) to NOT call
e.preventDefault() unconditionally — instead record engineSwipeStartY in the
touchstart handler only, and move any call to preventDefault() to touchmove or
touchend after detecting a swipe beyond your threshold (or remove it entirely)
so taps still fire their click; adjust the listener options if you no longer
need passive: false.

🧹 Nitpick comments (1)

scripts/search.js (1)

400-406: currentSearchEngineIndex doesn't need to be module-scoped.

currentSearchEngineIndex is assigned on line 429 via getcurrentSearchEngineIndex() and only used within switchEngine. It can be a local let inside switchEngine instead, eliminating unnecessary shared mutable state.

[itz-rj-here]

Working fine in both browsers with no issues