# Phase 12: Shift & Cash Management - COMPLETE ✅

## Overview
Phase 12 implements a comprehensive shift and cash management system for cashiers. The system supports opening and closing shifts, tracking cash counts, calculating expected and actual closing cash, and automatically linking sales to shifts.

## Implementation Details

### 1. Shift Service
**File:** `server/modules/shifts/services/index.js`

Implemented the following functions:

#### openShift
Opens a new shift for a cashier:
- Validates user exists and user_id matches authenticated user
- Ensures user doesn't already have an open shift
- Creates Shift with status OPEN
- Creates opening cash count (CashCount with type OPENING)
- Returns created shift with associations

#### getCurrentShift
Retrieves the current open shift for a user:
- Finds shift with status OPEN for the user
- Calculates expected closing cash (opening cash + cash payments)
- Returns shift with expected closing cash

#### getShift
Retrieves a shift by ID with complete associations:
- Includes cashier (User)
- Includes cash counts (CashCounts)
- Includes sales (Sales)
- If shift is open, calculates and includes expected closing cash

#### listShifts
Lists shifts with optional filters and pagination:
- Supports filtering by user_id and status
- Paginated results with metadata
- Ordered by start time descending

#### closeShift
Closes a shift with closing cash count and discrepancy calculation:
- Validates shift exists and is open
- Validates user owns the shift
- Calculates expected closing cash (opening cash + cash payments)
- Calculates cash discrepancy (actual - expected)
- Updates shift:
  - Sets status to CLOSED
  - Sets expected_closing_cash
  - Sets actual_closing_cash
  - Sets cash_discrepancy
  - Sets ended_at timestamp
- Creates closing cash count (CashCount with type CLOSING)
- All operations in a transaction
- Returns closed shift with all data

#### calculateExpectedClosingCash
Calculates expected closing cash for a shift:
- Gets opening cash from shift
- Finds all CASH payments with status COMPLETED for sales in the shift
- Sums payment amounts
- Returns opening cash + total cash received

### 2. Cash Count Service

#### createCashCount
Creates a mid-shift cash count:
- Validates shift exists and is open
- Validates user owns the shift
- Creates CashCount with type MID_SHIFT
- Returns created cash count with associations

#### getCashCount
Retrieves a cash count by ID with associations

#### listCashCounts
Lists cash counts with optional filters and pagination:
- Supports filtering by shift_id and count_type
- Paginated results
- Ordered by count time descending

### 3. Sales Integration
**File:** `server/modules/sales/services/index.js`

Updated `createSale` to integrate with shifts:
- Accepts optional `shift_id` in sale data
- If `shift_id` not provided:
  - Automatically finds user's current open shift
  - Links sale to open shift if found
  - For POS sales: Requires an open shift (throws error if none found)
  - For INVOICE sales: Allows sales without shift (backward compatibility)
- If `shift_id` provided:
  - Validates shift exists and is open
  - Validates shift belongs to the user
- Links sale to shift via `shift_id` field
- All sales in a shift are automatically tracked

### 4. Controllers
**File:** `server/modules/shifts/controllers/index.js`

Implemented controllers for:
- openShift: Opens a new shift
- getCurrentShift: Gets current open shift
- getShift: Gets shift by ID
- listShifts: Lists shifts with filters
- closeShift: Closes a shift
- createCashCount: Creates mid-shift cash count
- getCashCount: Gets cash count by ID
- listCashCounts: Lists cash counts with filters

All controllers:
- Use asyncHandler for error handling
- Extract data from request (body, params, query)
- Call appropriate service functions
- Return standardized responses
- Log operations

### 5. Validations
**File:** `server/modules/shifts/validations/index.js`

Implemented comprehensive validation rules for:
- openShift: user_id (required), opening_cash (optional, non-negative), notes (optional)
- getCurrentShift: No validation (uses authenticated user)
- getShift: shift ID (required, positive integer)
- listShifts: Optional filters (user_id, status, page, limit)
- closeShift: shift ID (required), actual_closing_cash (required, non-negative), notes (optional)
- createCashCount: shift ID (required), amount (required, non-negative), notes (optional)
- getCashCount: cash count ID (required, positive integer)
- listCashCounts: Optional filters (shift_id, count_type, page, limit)

### 6. Routes
**File:** `server/modules/shifts/routes/index.js`

Implemented RESTful routes:
- `POST /api/shifts` - Open shift (cashier, manager, system_admin)
- `GET /api/shifts/current` - Get current open shift (authenticated)
- `GET /api/shifts` - List shifts (authenticated)
- `GET /api/shifts/:id` - Get shift by ID (authenticated)
- `POST /api/shifts/:id/close` - Close shift (cashier, manager, system_admin)
- `POST /api/shifts/:shiftId/cash-counts` - Create cash count (cashier, manager, system_admin)
- `GET /api/shifts/cash-counts` - List cash counts (authenticated)
- `GET /api/shifts/cash-counts/:id` - Get cash count by ID (authenticated)

All routes:
- Use authentication middleware
- Use role-based access control where appropriate
- Include request validation
- Have Swagger documentation

### 7. Routes Integration
**File:** `server/routes/index.js`

Added shift routes to main routes file:
- `router.use('/shifts', shiftRoutes)`

## Key Features

### 1. Automatic Shift Linking
- Sales automatically linked to user's current open shift
- No need to manually specify shift_id for POS sales
- Shift requirement enforced for POS sales (must have open shift)

### 2. Cash Discrepancy Calculation
- Calculates expected closing cash from opening cash + cash payments
- Calculates discrepancy as actual - expected
- Positive discrepancy = overage, negative = shortage
- Recorded in shift and closing cash count notes

### 3. Cash Count Tracking
- Opening cash count created when shift opens
- Closing cash count created when shift closes
- Mid-shift cash counts can be created anytime during open shift
- All counts linked to shift and timestamped

### 4. Expected Closing Cash Calculation
- Based on opening cash amount
- Plus all cash payments (CASH provider, COMPLETED status) for sales in the shift
- Calculated dynamically when viewing shift details
- Used for discrepancy calculation when closing

### 5. Transaction Safety
- Shift opening/closing operations are transactional
- All cash counts created atomically with shift operations
- Ensures data consistency

### 6. User Ownership Validation
- Cashiers can only open/close their own shifts
- Cashiers can only create cash counts for their own shifts
- Prevents unauthorized shift operations

## API Endpoints Summary

### Shift Endpoints
- `POST /api/shifts` - Open shift
- `GET /api/shifts/current` - Get current open shift
- `GET /api/shifts` - List shifts
- `GET /api/shifts/:id` - Get shift by ID
- `POST /api/shifts/:id/close` - Close shift

### Cash Count Endpoints
- `POST /api/shifts/:shiftId/cash-counts` - Create cash count
- `GET /api/shifts/cash-counts` - List cash counts
- `GET /api/shifts/cash-counts/:id` - Get cash count by ID

## Testing Checklist

- [x] Open shift for cashier
- [x] Verify cannot open second shift if one is open
- [x] Get current open shift
- [x] Calculate expected closing cash correctly
- [x] Create mid-shift cash count
- [x] Create sale (automatically linked to open shift)
- [x] Close shift with actual closing cash
- [x] Calculate cash discrepancy correctly
- [x] Verify closing cash count created
- [x] Verify sales require open shift for POS
- [x] Verify INVOICE sales can be created without shift (backward compatibility)
- [x] List shifts with filters
- [x] List cash counts with filters
- [x] Verify transaction rollback on error

## Dependencies

- Phase 1: Users (User model)
- Phase 4: Sales (Sale model - shift_id field already exists)
- Phase 5: Payments (Payment model for cash payment tracking)

## Notes

1. **Shift Requirement**: POS sales require an open shift, INVOICE sales don't (backward compatibility)
2. **Automatic Linking**: Sales automatically linked to current open shift if shift_id not provided
3. **Cash Tracking**: Only tracks CASH payments (not bank/mobile money) for expected closing cash
4. **Discrepancy**: Positive = overage, negative = shortage
5. **User Ownership**: Cashiers can only manage their own shifts
6. **Transaction Safety**: All shift operations are transactional

## Next Steps

Phase 12 is complete. The shift and cash management system is fully functional and integrated with sales. All endpoints are operational and ready for use.

