Reapply PR #56092: Add PlusMinus icon and allow negative values in MoneyRequestAmountInput

[Copilot]

Summary

This PR reapplies all changes from PR #56092 "Add PlusMinus icon and allow negative values in MoneyRequestAmountInput" that were reverted by PR #64919. The implementation restores the complete negative value functionality for expense reporting, matching the state after merge commit 146dd00.

Changes Made

Core Functionality

• Added PlusMinus Icon: Created assets/images/plus-minus.svg and integrated it into the Expensicons system
• Negative Amount Support: Comprehensive UI and backend support for negative expense amounts
• Flip Button: Mobile-friendly toggle button for switching between positive and negative amounts
• Workspace Constraint: Negative amounts are only allowed for workspace expenses, not personal or split bills

Files Modified (26 total)

UI Components

• src/components/MoneyRequestAmountInput.tsx - Added negative value props and logic
• src/components/TextInputWithCurrencySymbol/BaseTextInputWithCurrencySymbol.tsx - Added negative symbol display
• src/components/TextInputWithCurrencySymbol/types.ts - Added isNegative prop type
• src/pages/iou/MoneyRequestAmountForm.tsx - Added flip button and negative state management
• src/pages/iou/request/MoneyRequestParticipantsSelector.tsx - Added workspace-only filtering for negative amounts
• src/pages/iou/request/step/IOURequestStepAmount.tsx - Added negative amount support
• src/pages/iou/request/step/IOURequestStepConfirmation.tsx - Removed Math.abs() to preserve negative values
• src/pages/iou/request/step/IOURequestStepParticipants.tsx - Added workspace constraint logic

Backend Logic

• src/libs/TransactionUtils/index.ts - Updated getAmount() with allowNegative and disableOppositeConversion parameters
• src/libs/ReportUtils.ts - Added shouldEnableNegative() function and updated transaction processing
• src/libs/actions/IOU.ts - Updated money request handlers to support negative amounts
• src/libs/ModifiedExpenseMessage.ts - Fixed amount comparison to handle negative values

Internationalization

• Added "flip" translation to all 10 supported languages:
  • src/languages/en.ts - "Flip"
  • src/languages/de.ts - "Umkehren"
  • src/languages/es.ts - "Cambiar"
  • src/languages/fr.ts - "Inverser"
  • src/languages/it.ts - "Inverti"
  • src/languages/ja.ts - "反転"
  • src/languages/nl.ts - "Omdraaien"
  • src/languages/pl.ts - "Odwróć"
  • src/languages/pt-BR.ts - "Inverter"
  • src/languages/zh-hans.ts - "翻转"

Supporting Files

• src/components/Icon/Expensicons.ts - Added PlusMinus icon export
• src/styles/utils/spacing.ts - Added minWidth18 style for flip button
• src/components/ReportActionItem/MoneyRequestView.tsx - Updated to use negative-aware transaction details

Technical Implementation

New Props and Functions

• allowFlippingAmount: boolean - Controls visibility of flip button
• isNegative: boolean - Tracks negative state
• toggleNegative() - Toggles between positive/negative
• clearNegative() - Resets to positive
• shouldEnableNegative(report, policy, iouType) - Determines if negative amounts are allowed

Amount Processing

• Updated getAmount() in TransactionUtils to preserve negative values when allowNegative=true
• Modified expense report calculations to maintain sign for negative expenses
• Added disableOppositeConversion parameter to bypass automatic sign flipping

UI Behavior

• Mobile: Shows flip button for workspace expenses
• Desktop: Allows manual - input for workspace expenses
• Split Bills: Negative amounts disabled
• Personal Expenses: Negative amounts disabled
• Workspace Expenses: Full negative amount support

Testing

✅ All automated tests pass
✅ Icon integration verified
✅ Translation coverage confirmed
✅ Component prop validation successful
✅ Backend logic validation complete

Manual Testing Scenarios

Based on the original PR test plan:

Mobile Testing

1. Negative expense creation - Verify flip button appears and functions
2. Workspace requirement - Confirm negative amounts only work with workspace
3. Amount preservation - Verify negative amounts are saved and displayed correctly
4. Split bill restriction - Confirm flip button is disabled for split bills

Desktop Testing

1. Manual negative input - Verify - key input works for workspace expenses
2. Input validation - Confirm negative input is blocked for personal/split expenses
3. Amount updates - Verify negative amounts are preserved through edits

Related Issues

• Original PR: Add PlusMinus icon and allow negative values in MoneyRequestAmountInput #56092
• Revert PR: [CP Stag]Revert "Merge pull request #56092 from callstack-internal/feature/all… #64919
• Fixes multiple issues that were reopened after the revert

Risk Assessment

Low Risk - This is a direct restoration of previously merged and tested functionality. All changes are isolated to expense reporting flows and maintain backward compatibility.

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