# Location Service Refactoring Plan

## 🎯 Objectives

1. **Centralize location logic** - Single source of truth for all location operations
2. **Eliminate duplication** - Remove scattered location code across modules
3. **Maintain privacy** - Only track agent location during active journey (already implemented)
4. **Zero breaking changes** - Work with existing DB schema, no new fields
5. **Enhance maintainability** - Clean architecture, reusable components

---

## 📊 Current State Analysis

### Existing Location Data (Already in DB)

| Entity | Location Fields | Usage |
|--------|----------------|-------|
| **customers** | `primary_latitude`, `primary_longitude`, `primary_maps_link` | Customer home address |
| **sales_orders** | `installation_latitude`, `installation_longitude`, `installation_maps_link` | Service installation location |
| **subscriptions** | `service_latitude`, `service_longitude`, `service_maps_link` | Active service location |
| **tasks** | `task_latitude`, `task_longitude`, `task_maps_link` | Infrastructure work location |
| **project_regions** | `latitude`, `longitude`, `maps_link` | Regional hub location |
| **users** | `current_latitude`, `current_longitude`, `current_maps_link` | Agent current position |
| **ticket_assignments** | `journey_start_lat/lng`, `arrival_lat/lng`, `journey_location_history` | Journey tracking |

### Existing Location Logic (Scattered)

| Location | Code | Issue |
|----------|------|-------|
| **Distance calculation** | `TicketAssignment.journey_distance_km` (Haversine) | Hardcoded in model, not reusable |
| **Region assignment** | `SalesOrderService.auto_assign_region()` (Euclidean distance) | Inaccurate distance formula |
| **Journey tracking** | `TicketAssignment.add_location_breadcrumb()` | Works fine, keep as-is |
| **Location updates** | `TicketAssignmentService.update_location()` | Works fine, keep as-is |

---

## 🏗️ Refactoring Architecture

```
┌─────────────────────────────────────────────────────────────┐
│                   CENTRALIZED LOCATION LAYER                 │
├─────────────────────────────────────────────────────────────┤
│                                                              │
│  ┌──────────────────────┐    ┌──────────────────────┐      │
│  │   Geo Utilities      │    │  Location Schemas    │      │
│  │  (Pure Functions)    │    │  (Response Models)   │      │
│  │                      │    │                      │      │
│  │ - haversine()        │    │ - Coordinates        │      │
│  │ - is_within_radius() │    │ - EntityLocation     │      │
│  │ - extract_coords()   │    │ - MapPoint           │      │
│  │ - validate_coords()  │    │ - JourneyDetails     │      │
│  └──────────────────────┘    └──────────────────────┘      │
│                                                              │
│  ┌──────────────────────────────────────────────┐          │
│  │         LocationService (Read-Only)          │          │
│  │                                              │          │
│  │ - get_entity_location(entity_type, id)      │          │
│  │ - get_entities_map_view(project_id, types)  │          │
│  │ - calculate_distance(point1, point2)        │          │
│  │ - find_nearest_entity(point, entities)      │          │
│  │ - get_region_locations(project_id)          │          │
│  └──────────────────────────────────────────────┘          │
│                                                              │
│  ┌──────────────────────────────────────────────┐          │
│  │      JourneyService (Analytics Only)         │          │
│  │                                              │          │
│  │ - get_journey_details(assignment_id)        │          │
│  │ - calculate_journey_stats(user_id, dates)   │          │
│  │ - get_journey_breadcrumbs(assignment_id)    │          │
│  │ - validate_journey_route(assignment_id)     │          │
│  └──────────────────────────────────────────────┘          │
│                                                              │
└─────────────────────────────────────────────────────────────┘
                            ▲
                            │ Uses (Read from existing fields)
                            │
┌─────────────────────────────────────────────────────────────┐
│                     EXISTING DB MODELS                       │
│  (No changes - just read existing location fields)          │
├─────────────────────────────────────────────────────────────┤
│  Customer, SalesOrder, Subscription, Task, ProjectRegion,   │
│  User, TicketAssignment (journey_location_history JSONB)    │
└─────────────────────────────────────────────────────────────┘
```

---

## 📝 Implementation Steps

### **Phase 1: Core Utilities (No Dependencies)**

#### Step 1.1: Create `src/app/utils/geo.py`

**Purpose**: Pure utility functions for geographic calculations

```python
"""
Geographic Utilities

Pure functions for location calculations. No database dependencies.
Uses Haversine formula for accurate Earth-surface distances.
"""

from typing import Optional, Tuple
import math
import re


def haversine_distance(lat1: float, lon1: float, lat2: float, lon2: float) -> float:
    """
    Calculate distance between two GPS points using Haversine formula.
    
    Args:
        lat1, lon1: First point coordinates
        lat2, lon2: Second point coordinates
        
    Returns:
        Distance in kilometers (accurate for Earth's curvature)
        
    Example:
        >>> haversine_distance(-1.2921, 36.8219, -1.2965, 36.7809)
        4.23  # km
    """
    # Implementation...


def is_within_radius(
    center_lat: float, 
    center_lon: float, 
    point_lat: float, 
    point_lon: float, 
    radius_km: float
) -> bool:
    """
    Check if point is within radius of center.
    
    Example:
        >>> is_within_radius(-1.2921, 36.8219, -1.2925, 36.8225, 1.0)
        True  # Point is within 1km
    """
    # Implementation...


def extract_coordinates_from_maps_link(maps_link: str) -> Optional[Tuple[float, float]]:
    """
    Extract latitude and longitude from Google Maps share link.
    
    Supports formats:
    - https://maps.google.com/?q=-1.2921,36.8219
    - https://www.google.com/maps/place/@-1.2921,36.8219,15z
    - https://goo.gl/maps/... (shortened URLs not supported)
    
    Returns:
        Tuple of (latitude, longitude) or None if not found
    """
    # Implementation...


def validate_coordinates(lat: float, lon: float) -> bool:
    """
    Validate latitude and longitude ranges.
    
    Returns:
        True if coordinates are valid (-90 <= lat <= 90, -180 <= lon <= 180)
    """
    # Implementation...
```

**Migration**: Remove `TicketAssignment.journey_distance_km` Haversine code → Use `geo.haversine_distance()`

---

### **Phase 2: Unified Schemas**

#### Step 2.1: Create `src/app/schemas/map.py`

**Purpose**: Consistent response models for location data

```python
"""
Location & Map Schemas

Unified response models for location data across all entities.
"""

from pydantic import BaseModel, Field
from typing import Optional, Literal, List, Dict, Any
from datetime import datetime
from uuid import UUID
from decimal import Decimal


class Coordinates(BaseModel):
    """GPS coordinates"""
    latitude: float = Field(..., ge=-90, le=90)
    longitude: float = Field(..., ge=-180, le=180)
    accuracy: Optional[float] = Field(None, description="Accuracy in meters")


class EntityLocation(BaseModel):
    """Generic location wrapper for any entity"""
    entity_id: UUID
    entity_type: Literal[
        "customer", "sales_order", "subscription", 
        "ticket", "task", "region", "agent"
    ]
    name: str
    coordinates: Coordinates
    
    # Entity-specific metadata
    status: Optional[str] = None
    icon: Optional[str] = None  # For map markers
    color: Optional[str] = None  # For map markers
    additional_info: Dict[str, Any] = {}


class MapPoint(BaseModel):
    """Simplified point for map visualization"""
    id: UUID
    type: str
    name: str
    lat: float
    lng: float
    status: Optional[str] = None


class JourneyBreadcrumb(BaseModel):
    """Single GPS point in journey trail"""
    lat: float
    lng: float
    timestamp: datetime
    accuracy: Optional[float] = None
    speed: Optional[float] = None
    battery: Optional[int] = None
    network: Optional[str] = None


class JourneyDetails(BaseModel):
    """Complete journey information"""
    assignment_id: UUID
    ticket_id: UUID
    agent_id: UUID
    agent_name: str
    
    # Timeline
    journey_started_at: datetime
    arrived_at: Optional[datetime]
    journey_duration_minutes: Optional[int]
    
    # Locations
    start_location: Coordinates
    end_location: Optional[Coordinates]
    customer_location: Optional[Coordinates]
    
    # Route
    breadcrumbs: List[JourneyBreadcrumb]
    total_distance_km: Optional[float]
    average_speed_kmh: Optional[float]
    
    # Status
    journey_status: Literal["in_progress", "arrived", "completed"]


class MapEntitiesResponse(BaseModel):
    """Aggregated map data for frontend"""
    project_id: UUID
    customers: List[MapPoint] = []
    sales_orders: List[MapPoint] = []
    subscriptions: List[MapPoint] = []
    tickets: List[MapPoint] = []
    tasks: List[MapPoint] = []
    regions: List[MapPoint] = []
    # No agents - privacy (only during journey via journey_location_history)
```

---

### **Phase 3: LocationService (Read-Only)**

#### Step 3.1: Create `src/app/services/location_service.py`

**Purpose**: Centralized location data aggregation (reads existing fields)

```python
"""
Location Service

Centralized service for location operations.
READ-ONLY: Queries existing location fields, no writes.
"""

from typing import List, Optional, Dict, Any, Tuple
from uuid import UUID
from sqlalchemy.orm import Session
from sqlalchemy import and_, or_

from app.models import (
    Customer, SalesOrder, Subscription, Ticket, Task, 
    ProjectRegion, User, TicketAssignment
)
from app.schemas.map import (
    EntityLocation, Coordinates, MapPoint, MapEntitiesResponse
)
from app.utils.geo import haversine_distance, is_within_radius


class LocationService:
    """Centralized location operations service"""
    
    def __init__(self, db: Session):
        self.db = db
    
    # ============================================
    # Entity Location Extraction
    # ============================================
    
    def get_customer_locations(
        self, 
        project_id: UUID, 
        region_id: Optional[UUID] = None
    ) -> List[MapPoint]:
        """Get all customer locations for a project"""
        query = self.db.query(Customer).join(
            SalesOrder, Customer.id == SalesOrder.customer_id
        ).filter(
            SalesOrder.project_id == project_id,
            Customer.primary_latitude.isnot(None),
            Customer.primary_longitude.isnot(None)
        )
        
        if region_id:
            query = query.filter(Customer.project_region_id == region_id)
        
        customers = query.all()
        
        return [
            MapPoint(
                id=c.id,
                type="customer",
                name=c.customer_name,
                lat=float(c.primary_latitude),
                lng=float(c.primary_longitude),
                status=None
            )
            for c in customers
        ]
    
    def get_sales_order_locations(
        self, 
        project_id: UUID,
        status: Optional[str] = None
    ) -> List[MapPoint]:
        """Get installation locations from sales orders"""
        # Implementation...
    
    def get_ticket_locations(
        self,
        project_id: UUID,
        status: Optional[str] = None
    ) -> List[MapPoint]:
        """Get ticket work locations"""
        # Tickets inherit location from source (sales_order/subscription/task)
        # Implementation...
    
    def get_region_locations(self, project_id: UUID) -> List[MapPoint]:
        """Get regional hub locations"""
        regions = self.db.query(ProjectRegion).filter(
            ProjectRegion.project_id == project_id,
            ProjectRegion.latitude.isnot(None),
            ProjectRegion.longitude.isnot(None),
            ProjectRegion.is_active == True
        ).all()
        
        return [
            MapPoint(
                id=r.id,
                type="region",
                name=r.region_name,
                lat=float(r.latitude),
                lng=float(r.longitude),
                status="active" if r.is_active else "inactive"
            )
            for r in regions
        ]
    
    def get_entities_map_view(
        self,
        project_id: UUID,
        entity_types: List[str]
    ) -> MapEntitiesResponse:
        """
        Aggregate all entity locations for map visualization.
        
        Args:
            project_id: Project UUID
            entity_types: List of entity types to include
                         ['customers', 'sales_orders', 'tickets', 'regions']
        
        Returns:
            Aggregated map data
        """
        response = MapEntitiesResponse(project_id=project_id)
        
        if "customers" in entity_types:
            response.customers = self.get_customer_locations(project_id)
        
        if "sales_orders" in entity_types:
            response.sales_orders = self.get_sales_order_locations(project_id)
        
        if "tickets" in entity_types:
            response.tickets = self.get_ticket_locations(project_id)
        
        if "regions" in entity_types:
            response.regions = self.get_region_locations(project_id)
        
        # NO agents - privacy (only during active journey)
        
        return response
    
    # ============================================
    # Distance Calculations
    # ============================================
    
    def calculate_distance_km(
        self, 
        point1: Coordinates, 
        point2: Coordinates
    ) -> float:
        """Calculate distance between two points (delegates to geo utils)"""
        return haversine_distance(
            point1.latitude, point1.longitude,
            point2.latitude, point2.longitude
        )
    
    def find_nearest_region(
        self,
        project_id: UUID,
        lat: float,
        lon: float
    ) -> Optional[Tuple[UUID, float]]:
        """
        Find nearest regional hub to given coordinates.
        
        Returns:
            Tuple of (region_id, distance_km) or None
        """
        regions = self.db.query(ProjectRegion).filter(
            ProjectRegion.project_id == project_id,
            ProjectRegion.latitude.isnot(None),
            ProjectRegion.longitude.isnot(None),
            ProjectRegion.is_active == True
        ).all()
        
        if not regions:
            return None
        
        nearest = None
        min_distance = float('inf')
        
        for region in regions:
            distance = haversine_distance(
                lat, lon,
                float(region.latitude), float(region.longitude)
            )
            
            if distance < min_distance:
                min_distance = distance
                nearest = region
        
        return (nearest.id, min_distance) if nearest else None
```

**Migration**: Update `SalesOrderService.auto_assign_region()` to use `LocationService.find_nearest_region()`

---

### **Phase 4: JourneyService (Analytics)**

#### Step 4.1: Create `src/app/services/journey_service.py`

**Purpose**: Journey analytics (reads `journey_location_history` JSONB)

```python
"""
Journey Service

Analytics for agent journey tracking.
READ-ONLY: Analyzes existing journey_location_history data.
"""

from typing import List, Optional
from uuid import UUID
from datetime import datetime, timedelta
from sqlalchemy.orm import Session

from app.models import TicketAssignment, User, Ticket
from app.schemas.map import JourneyDetails, JourneyBreadcrumb, Coordinates
from app.utils.geo import haversine_distance


class JourneyService:
    """Journey analytics service"""
    
    def __init__(self, db: Session):
        self.db = db
    
    def get_journey_details(self, assignment_id: UUID) -> Optional[JourneyDetails]:
        """
        Get complete journey details with breadcrumb trail.
        
        Reads from existing ticket_assignments fields:
        - journey_started_at, arrived_at
        - journey_start_latitude/longitude
        - arrival_latitude/longitude
        - journey_location_history (JSONB)
        """
        assignment = self.db.query(TicketAssignment).filter(
            TicketAssignment.id == assignment_id
        ).first()
        
        if not assignment or not assignment.journey_started_at:
            return None
        
        # Parse breadcrumbs from JSONB
        breadcrumbs = [
            JourneyBreadcrumb(**bc)
            for bc in (assignment.journey_location_history or [])
        ]
        
        # Calculate journey stats
        duration_minutes = None
        if assignment.arrived_at:
            duration_minutes = int(
                (assignment.arrived_at - assignment.journey_started_at).total_seconds() / 60
            )
        
        # Calculate total distance from breadcrumbs
        total_distance = self._calculate_breadcrumb_distance(breadcrumbs)
        
        # Calculate average speed
        avg_speed = None
        if duration_minutes and duration_minutes > 0 and total_distance:
            avg_speed = (total_distance / duration_minutes) * 60  # km/h
        
        # Determine journey status
        status = "in_progress"
        if assignment.arrived_at:
            status = "arrived"
        if assignment.ended_at:
            status = "completed"
        
        return JourneyDetails(
            assignment_id=assignment.id,
            ticket_id=assignment.ticket_id,
            agent_id=assignment.user_id,
            agent_name=assignment.user.full_name if assignment.user else "Unknown",
            journey_started_at=assignment.journey_started_at,
            arrived_at=assignment.arrived_at,
            journey_duration_minutes=duration_minutes,
            start_location=Coordinates(
                latitude=float(assignment.journey_start_latitude),
                longitude=float(assignment.journey_start_longitude)
            ) if assignment.journey_start_latitude else None,
            end_location=Coordinates(
                latitude=float(assignment.arrival_latitude),
                longitude=float(assignment.arrival_longitude)
            ) if assignment.arrival_latitude else None,
            customer_location=self._get_customer_location(assignment.ticket),
            breadcrumbs=breadcrumbs,
            total_distance_km=total_distance,
            average_speed_kmh=avg_speed,
            journey_status=status
        )
    
    def _calculate_breadcrumb_distance(
        self, 
        breadcrumbs: List[JourneyBreadcrumb]
    ) -> Optional[float]:
        """Calculate total distance from breadcrumb trail"""
        if len(breadcrumbs) < 2:
            return None
        
        total = 0.0
        for i in range(len(breadcrumbs) - 1):
            bc1, bc2 = breadcrumbs[i], breadcrumbs[i + 1]
            total += haversine_distance(bc1.lat, bc1.lng, bc2.lat, bc2.lng)
        
        return round(total, 2)
    
    def validate_journey_route(self, assignment_id: UUID) -> Dict[str, Any]:
        """
        Validate journey for fraud detection.
        
        Checks:
        - No teleportation (impossible speed between points)
        - Route makes sense (not zigzagging)
        - Distance matches expected (not too short/long)
        
        Returns:
            Validation report with warnings
        """
        # Implementation...
    
    def get_agent_journey_history(
        self,
        user_id: UUID,
        start_date: datetime,
        end_date: datetime
    ) -> List[JourneyDetails]:
        """Get all journeys for agent in date range"""
        # Implementation...
```

---

### **Phase 5: Map API Endpoints**

#### Step 5.1: Create `src/app/api/v1/map.py`

```python
"""
Map API Endpoints

Endpoints for map visualization and journey tracking.
"""

from fastapi import APIRouter, Depends, Query, HTTPException, status
from sqlalchemy.orm import Session
from typing import List, Optional
from uuid import UUID

from app.core.deps import get_db, get_current_user
from app.models import User
from app.services.location_service import LocationService
from app.services.journey_service import JourneyService
from app.schemas.map import (
    MapEntitiesResponse, MapPoint, JourneyDetails
)

router = APIRouter()


@router.get("/entities", response_model=MapEntitiesResponse)
def get_map_entities(
    project_id: UUID,
    entity_types: List[str] = Query(
        default=["customers", "sales_orders", "tickets", "regions"],
        description="Entity types to include in map"
    ),
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user)
):
    """
    Get aggregated entity locations for map visualization.
    
    **Authorization:** Project team members only
    
    **Entity Types:**
    - customers: Customer home addresses
    - sales_orders: Installation locations
    - subscriptions: Active service locations
    - tickets: Ticket work locations
    - tasks: Infrastructure task locations
    - regions: Regional hub locations
    
    **Privacy:** Agent locations NOT included (only during active journey)
    """
    service = LocationService(db)
    return service.get_entities_map_view(project_id, entity_types)


@router.get("/regions/{project_id}", response_model=List[MapPoint])
def get_regional_hubs(
    project_id: UUID,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user)
):
    """
    Get regional hub locations for project.
    
    **Use Case:** Show regional hubs on map for inventory distribution
    """
    service = LocationService(db)
    return service.get_region_locations(project_id)


@router.get("/journeys/{assignment_id}", response_model=JourneyDetails)
def get_journey_details(
    assignment_id: UUID,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user)
):
    """
    Get journey details with breadcrumb trail for playback.
    
    **Authorization:** 
    - Agent: Own journeys only
    - Manager/Admin: All journeys
    
    **Use Cases:**
    - Route playback on map
    - Journey audit/review
    - Travel reimbursement validation
    - Performance analysis
    
    **Privacy:** Only journeys during active work (journey_started_at → arrived_at)
    """
    service = JourneyService(db)
    journey = service.get_journey_details(assignment_id)
    
    if not journey:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="Journey not found"
        )
    
    # Authorization check
    if current_user.role == "field_agent" and journey.agent_id != current_user.id:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Can only view own journeys"
        )
    
    return journey
```

**Register in router.py:**
```python
from app.api.v1 import map

api_router.include_router(map.router, prefix="/map", tags=["Map & Location"])
```

---

## 🔄 Refactoring Steps (No Breaking Changes)

### **Step 1: Replace distance calculations**

**Before (Scattered):**
```python
# In TicketAssignment model
@property
def journey_distance_km(self) -> Optional[float]:
    # Haversine implementation hardcoded here...
```

```python
# In SalesOrderService
distance = (
    (region.latitude - installation_latitude) ** 2 +
    (region.longitude - installation_longitude) ** 2
) ** 0.5  # WRONG: Euclidean distance
```

**After (Centralized):**
```python
# In TicketAssignment model
from app.utils.geo import haversine_distance

@property
def journey_distance_km(self) -> Optional[float]:
    if len(self.journey_location_history) < 2:
        return None
    
    total = 0.0
    for i in range(len(self.journey_location_history) - 1):
        p1 = self.journey_location_history[i]
        p2 = self.journey_location_history[i + 1]
        total += haversine_distance(p1["lat"], p1["lng"], p2["lat"], p2["lng"])
    
    return round(total, 2)
```

```python
# In SalesOrderService
from app.services.location_service import LocationService

service = LocationService(db)
result = service.find_nearest_region(project_id, installation_latitude, installation_longitude)
if result:
    region_id, distance = result
    # Use region_id
```

---

### **Step 2: Update existing services**

**Files to update:**
1. `src/app/services/sales_order_service.py` - Use LocationService for region assignment
2. `src/app/models/ticket_assignment.py` - Use geo.haversine_distance()

**Testing checklist:**
- [ ] Region auto-assignment still works (same results)
- [ ] Journey distance calculation matches old values
- [ ] No new DB queries (performance unchanged)

---

## ✅ Privacy & Data Integrity

### **Agent Privacy (Already Implemented)**

✅ **What we track:**
- Journey start location (when agent clicks "Start Journey")
- Breadcrumb trail (every 1-5 min during journey)
- Arrival location (when agent clicks "Arrived")

✅ **What we DON'T track:**
- Agent location when not on active journey
- Agent location outside work hours
- Agent location before/after shift

✅ **Database support:**
- `journey_location_history` JSONB field already exists
- Journey tracking already implemented in `TicketAssignmentService`
- No changes needed to existing privacy model

---

## 🧪 Testing Strategy

### **Unit Tests**

```python
# tests/unit/test_geo_utils.py
def test_haversine_distance():
    # Nairobi coordinates
    dist = haversine_distance(-1.2921, 36.8219, -1.2965, 36.7809)
    assert 4.0 <= dist <= 4.5  # ~4.23 km

def test_extract_coords_from_maps_link():
    link = "https://maps.google.com/?q=-1.2921,36.8219"
    lat, lon = extract_coordinates_from_maps_link(link)
    assert lat == -1.2921
    assert lon == 36.8219
```

### **Integration Tests**

```python
# tests/integration/test_location_service.py
def test_get_entities_map_view(db, project):
    service = LocationService(db)
    result = service.get_entities_map_view(
        project.id, 
        ["customers", "regions"]
    )
    
    assert result.project_id == project.id
    assert len(result.customers) > 0
    assert len(result.regions) > 0

def test_find_nearest_region(db, project, regions):
    service = LocationService(db)
    region_id, distance = service.find_nearest_region(
        project.id, -1.2921, 36.8219
    )
    
    assert region_id in [r.id for r in regions]
    assert distance >= 0
```

---

## 📋 Implementation Checklist

- [ ] **Phase 1: Core Utilities**
  - [ ] Create `src/app/utils/geo.py`
  - [ ] Write unit tests for geo functions
  - [ ] Test Haversine accuracy against known distances

- [ ] **Phase 2: Schemas**
  - [ ] Create `src/app/schemas/map.py`
  - [ ] Test schema validation

- [ ] **Phase 3: LocationService**
  - [ ] Create `src/app/services/location_service.py`
  - [ ] Implement entity location extraction
  - [ ] Implement distance calculations
  - [ ] Write integration tests

- [ ] **Phase 4: JourneyService**
  - [ ] Create `src/app/services/journey_service.py`
  - [ ] Implement journey details extraction
  - [ ] Implement journey validation
  - [ ] Test with existing journey data

- [ ] **Phase 5: Map API**
  - [ ] Create `src/app/api/v1/map.py`
  - [ ] Implement GET /entities endpoint
  - [ ] Implement GET /regions endpoint
  - [ ] Implement GET /journeys endpoint
  - [ ] Register router in `router.py`

- [ ] **Phase 6: Refactor Existing Code**
  - [ ] Update `TicketAssignment.journey_distance_km`
  - [ ] Update `SalesOrderService.auto_assign_region()`
  - [ ] Remove duplicated distance logic
  - [ ] Run full test suite

- [ ] **Phase 7: Integration Testing**
  - [ ] Test map endpoints with real data
  - [ ] Verify journey playback works
  - [ ] Confirm region assignment unchanged
  - [ ] Test distance calculations match old results
  - [ ] Performance testing (no new queries)

---

## 🎯 Success Criteria

1. ✅ **Zero DB changes** - Work with existing schema
2. ✅ **Zero breaking changes** - All existing features work
3. ✅ **Centralized logic** - No duplicated distance calculations
4. ✅ **Privacy maintained** - Only track journey during active work
5. ✅ **Same performance** - No additional DB queries
6. ✅ **Clean architecture** - Clear separation of concerns
7. ✅ **Testable** - Unit tests for utilities, integration tests for services

---

## 📚 Benefits After Refactor

| Before | After |
|--------|-------|
| Distance logic in 3 places | Distance logic in 1 place (`geo.py`) |
| Euclidean distance (wrong) | Haversine distance (correct) |
| No map visualization API | Unified map endpoints |
| Journey data hard to query | JourneyService for analytics |
| Location code scattered | LocationService as single source |
| No journey validation | Fraud detection capabilities |

---

## 🚀 Next Steps After This Refactor

1. **Frontend map component** - Use new `/map/entities` endpoint
2. **Journey playback UI** - Visualize routes on map
3. **Distance-based features** - "Find nearest agent" functionality
4. **Route optimization** - Multi-stop route planning (future)
5. **Geofencing** - Alert when agent enters/exits area (future)

---

## 📝 Notes

- **No new database migrations** - Uses existing location fields
- **Backward compatible** - Old code continues to work during migration
- **Privacy first** - Agent location only during active journey
- **Read-only services** - LocationService and JourneyService don't write to DB
- **Pure utilities** - `geo.py` has zero dependencies (easy to test)