Rename hexagon_centers to h3_hex_ids and update related logic

app/models/stat.rb

@@ -57,9 +57,9 @@ class Stat < ApplicationRecord
   end
 
   def hexagons_available?
-    hexagon_centers.present? &&
-      hexagon_centers.is_a?(Array) &&
-      hexagon_centers.any?
+    h3_hex_ids.present? &&
+      h3_hex_ids.is_a?(Hash) &&
+      h3_hex_ids.any?
   end
 
   def generate_new_sharing_uuid!

app/services/maps/hexagon_center_manager.rb

@@ -9,7 +9,6 @@ module Maps
 
     def call
       return build_response_from_centers if pre_calculated_centers_available?
-      return handle_legacy_area_too_large if legacy_area_too_large?
 
       nil # No pre-calculated data available
     end
@@ -19,78 +18,59 @@ module Maps
     attr_reader :stat, :user
 
     def pre_calculated_centers_available?
-      return false if stat&.hexagon_centers.blank?
+      return false if stat&.h3_hex_ids.blank?
 
-      # Handle legacy hash format
-      if stat.hexagon_centers.is_a?(Hash)
-        !stat.hexagon_centers['area_too_large']
-      else
-        # Handle array format (actual hexagon centers)
-        stat.hexagon_centers.is_a?(Array) && stat.hexagon_centers.any?
-      end
-    end
-
-    def legacy_area_too_large?
-      stat&.hexagon_centers.is_a?(Hash) && stat.hexagon_centers['area_too_large']
+      stat.h3_hex_ids.is_a?(Hash) && stat.h3_hex_ids.any?
     end
 
     def build_response_from_centers
-      centers = stat.hexagon_centers
-      Rails.logger.debug "Using pre-calculated hexagon centers: #{centers.size} centers"
+      hex_ids = stat.h3_hex_ids
+      Rails.logger.debug "Using pre-calculated H3 hex IDs: #{hex_ids.size} hexagons"
 
-      result = build_hexagons_from_centers(centers)
+      result = build_hexagons_from_h3_ids(hex_ids)
       { success: true, data: result, pre_calculated: true }
     end
 
-    def handle_legacy_area_too_large
-      Rails.logger.info "Recalculating previously skipped large area hexagons for stat #{stat.id}"
-
-      new_centers = recalculate_hexagon_centers
-      return nil unless new_centers.is_a?(Array)
-
-      update_stat_with_new_centers(new_centers)
-    end
-
-    def recalculate_hexagon_centers
+    def recalculate_h3_hex_ids
       service = Stats::CalculateMonth.new(user.id, stat.year, stat.month)
-      service.send(:calculate_hexagon_centers)
+      service.send(:calculate_h3_hex_ids)
     end
 
-    def update_stat_with_new_centers(new_centers)
-      stat.update(hexagon_centers: new_centers)
-      result = build_hexagons_from_centers(new_centers)
-      Rails.logger.debug "Successfully recalculated hexagon centers: #{new_centers.size} centers"
+    def update_stat_with_new_hex_ids(new_hex_ids)
+      stat.update(h3_hex_ids: new_hex_ids)
+      result = build_hexagons_from_h3_ids(new_hex_ids)
+      Rails.logger.debug "Successfully recalculated H3 hex IDs: #{new_hex_ids.size} hexagons"
       { success: true, data: result, pre_calculated: true }
     end
 
-    def build_hexagons_from_centers(centers)
-      # Convert stored centers back to hexagon polygons
-      hexagon_features = centers.map.with_index { |center, index| build_hexagon_feature(center, index) }
+    def build_hexagons_from_h3_ids(hex_ids)
+      # Convert stored H3 IDs back to hexagon polygons
+      hexagon_features = hex_ids.map.with_index do |(h3_index, data), index|
+        build_hexagon_feature_from_h3(h3_index, data, index)
+      end
 
       build_feature_collection(hexagon_features)
     end
 
-    def build_hexagon_feature(center, index)
-      lng, lat, earliest, latest = center
+    def build_hexagon_feature_from_h3(h3_index, data, index)
+      count, earliest, latest = data
 
       {
         'type' => 'Feature',
         'id' => index + 1,
-        'geometry' => generate_hexagon_geometry(lng, lat),
-        'properties' => build_hexagon_properties(index, earliest, latest)
+        'geometry' => generate_hexagon_geometry_from_h3(h3_index),
+        'properties' => build_hexagon_properties(index, count, earliest, latest)
       }
     end
 
-    def generate_hexagon_geometry(lng, lat)
-      Maps::HexagonPolygonGenerator.new(
-        center_lng: lng,
-        center_lat: lat
-      ).call
+    def generate_hexagon_geometry_from_h3(h3_index)
+      Maps::HexagonPolygonGenerator.new(h3_index: h3_index).call
     end
 
-    def build_hexagon_properties(index, earliest, latest)
+    def build_hexagon_properties(index, count, earliest, latest)
       {
         'hex_id' => index + 1,
+        'point_count' => count,
         'earliest_point' => earliest ? Time.zone.at(earliest).iso8601 : nil,
         'latest_point' => latest ? Time.zone.at(latest).iso8601 : nil
       }

app/services/maps/hexagon_polygon_generator.rb

@@ -2,10 +2,11 @@
 
 module Maps
   class HexagonPolygonGenerator
-    def initialize(center_lng:, center_lat:, h3_resolution: 5)
+    def initialize(center_lng: nil, center_lat: nil, h3_resolution: 5, h3_index: nil)
       @center_lng = center_lng
       @center_lat = center_lat
       @h3_resolution = h3_resolution
+      @h3_index = h3_index
     end
 
     def call
@@ -14,7 +15,7 @@ module Maps
 
     private
 
-    attr_reader :center_lng, :center_lat, :h3_resolution
+    attr_reader :center_lng, :center_lat, :h3_resolution, :h3_index
 
     def generate_h3_hexagon_polygon
       # Convert coordinates to H3 format [lat, lng]

app/services/stats/calculate_month.rb

@@ -86,7 +86,7 @@ class Stats::CalculateMonth
         daily_distance: distance_by_day,
         distance: distance(distance_by_day),
         toponyms: toponyms,
-        hexagon_centers: calculate_hexagon_centers
+        h3_hex_ids: calculate_h3_hex_ids
       )
       stat.save
     end
@@ -132,22 +132,28 @@ class Stats::CalculateMonth
     Stat.where(year:, month:, user:).destroy_all
   end
 
-  def calculate_hexagon_centers
-    return nil if points.empty?
+  def calculate_h3_hex_ids
+    return {} if points.empty?
 
     begin
       result = calculate_h3_hexagon_centers
 
       if result.empty?
-        Rails.logger.info "No H3 hexagon centers calculated for user #{user.id}, #{year}-#{month} (no data)"
-        return nil
+        Rails.logger.info "No H3 hex IDs calculated for user #{user.id}, #{year}-#{month} (no data)"
+        return {}
       end
 
-      Rails.logger.info "Pre-calculated #{result.size} H3 hexagon centers for user #{user.id}, #{year}-#{month}"
-      result
+      # Convert array format to hash format: { h3_index => [count, earliest, latest] }
+      hex_hash = result.each_with_object({}) do |hex_data, hash|
+        h3_index, count, earliest, latest = hex_data
+        hash[h3_index] = [count, earliest, latest]
+      end
+
+      Rails.logger.info "Pre-calculated #{hex_hash.size} H3 hex IDs for user #{user.id}, #{year}-#{month}"
+      hex_hash
     rescue PostGISError => e
-      Rails.logger.warn "H3 hexagon centers calculation failed for user #{user.id}, #{year}-#{month}: #{e.message}"
-      nil
+      Rails.logger.warn "H3 hex IDs calculation failed for user #{user.id}, #{year}-#{month}: #{e.message}"
+      {}
     end
   end
 

db/migrate/20250913194134_add_hexagon_data_to_stats.rb

@@ -1,7 +0,0 @@
-# frozen_string_literal: true
-
-class AddHexagonDataToStats < ActiveRecord::Migration[8.0]
-  def change
-    add_column :stats, :hexagon_data, :jsonb
-  end
-end

db/migrate/20250914094851_add_hexagon_centers_to_stats.rb

@@ -1,5 +0,0 @@
-class AddHexagonCentersToStats < ActiveRecord::Migration[8.0]
-  def change
-    add_column :stats, :hexagon_centers, :jsonb
-  end
-end

db/migrate/20250914095157_add_index_to_hexagon_centers.rb

@@ -1,7 +0,0 @@
-class AddIndexToHexagonCenters < ActiveRecord::Migration[8.0]
-  disable_ddl_transaction!
-
-  def change
-    add_index :stats, :hexagon_centers, using: :gin, where: "hexagon_centers IS NOT NULL", algorithm: :concurrently
-  end
-end

db/migrate/20250918215512_add_h3_hex_ids_to_stats.rb

@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+class AddH3HexIdsToStats < ActiveRecord::Migration[8.0]
+  def change
+    add_column :stats, :h3_hex_ids, :jsonb, default: {}
+    add_index :stats, :h3_hex_ids, using: :gin, where: "(h3_hex_ids IS NOT NULL AND h3_hex_ids != '{}'::jsonb)"
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[8.0].define(version: 2025_09_14_095157) do
+ActiveRecord::Schema[8.0].define(version: 2025_09_10_224714) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "pg_catalog.plpgsql"
   enable_extension "postgis"
@@ -222,10 +222,7 @@ ActiveRecord::Schema[8.0].define(version: 2025_09_14_095157) do
     t.jsonb "daily_distance", default: {}
     t.jsonb "sharing_settings", default: {}
     t.uuid "sharing_uuid"
-    t.jsonb "hexagon_data"
-    t.jsonb "hexagon_centers"
     t.index ["distance"], name: "index_stats_on_distance"
-    t.index ["hexagon_centers"], name: "index_stats_on_hexagon_centers", where: "(hexagon_centers IS NOT NULL)", using: :gin
     t.index ["month"], name: "index_stats_on_month"
     t.index ["sharing_uuid"], name: "index_stats_on_sharing_uuid", unique: true
     t.index ["user_id"], name: "index_stats_on_user_id"

docs/SHAREABLE_STATS_FEATURE.md

@@ -0,0 +1,487 @@
+# Shareable Stats Feature Documentation
+
+## Overview
+
+The Shareable Stats feature allows Dawarich users to publicly share their monthly location statistics without requiring authentication. This system provides a secure, time-limited way to share location insights while maintaining user privacy through configurable expiration settings and unguessable UUID-based access.
+
+## Key Features
+
+- **Time-based expiration**: Share links can expire after 1 hour, 12 hours, 24 hours, or be permanent
+- **UUID-based security**: Each shared stat has a unique, unguessable UUID for secure access
+- **Public API access**: Hexagon map data can be accessed via API without authentication when sharing is enabled
+- **H3 Hexagon visualization**: Enhanced geographic data visualization using Uber's H3 hexagonal hierarchical spatial index
+- **Automatic expiration**: Expired shares are automatically inaccessible
+- **Privacy controls**: Users can enable/disable sharing and regenerate sharing URLs at any time
+
+## Database Schema
+
+### Stats Table Extensions
+
+The sharing functionality extends the `stats` table with the following columns:
+
+```sql
+-- Public sharing configuration
+sharing_settings JSONB DEFAULT {}
+sharing_uuid UUID
+
+-- Pre-calculated H3 hexagon data for performance
+h3_hex_ids JSONB DEFAULT {}
+
+-- Indexes for performance
+INDEX ON h3_hex_ids USING GIN WHERE (h3_hex_ids IS NOT NULL AND h3_hex_ids != '{}'::jsonb)
+```
+
+### Sharing Settings Structure
+
+```json
+{
+  "enabled": true,
+  "expiration": "24h",  // "1h", "12h", "24h", or "permanent"
+  "expires_at": "2024-01-15T12:00:00Z"
+}
+```
+
+### H3 Hex IDs Data Format
+
+The `h3_hex_ids` column stores pre-calculated H3 hexagon data as a hash:
+
+```json
+{
+  "8a1fb46622dffff": [15, 1640995200, 1640998800],
+  "8a1fb46622e7fff": [8, 1640996400, 1640999200],
+  // ... more H3 index entries
+  // Format: { "h3_index_string": [point_count, earliest_timestamp, latest_timestamp] }
+}
+```
+
+## Architecture Components
+
+### Models
+
+#### Stat Model (`app/models/stat.rb`)
+
+**Key Methods:**
+- `sharing_enabled?`: Checks if sharing is enabled
+- `sharing_expired?`: Validates expiration status
+- `public_accessible?`: Combined check for sharing availability
+- `hexagons_available?`: Verifies pre-calculated H3 hex data exists
+- `enable_sharing!(expiration:)`: Enables sharing with expiration
+- `disable_sharing!`: Disables sharing
+- `generate_new_sharing_uuid!`: Regenerates sharing UUID
+- `calculate_data_bounds`: Calculates geographic bounds for the month
+
+### Controllers
+
+#### Shared::StatsController (`app/controllers/shared/stats_controller.rb`)
+
+Handles public sharing functionality:
+
+**Routes:**
+- `GET /shared/stats/:uuid` - Public view of shared stats
+- `PATCH /stats/:year/:month/sharing` - Sharing management (authenticated)
+
+**Key Methods:**
+- `show`: Renders public stats view without authentication
+- `update`: Manages sharing settings (enable/disable, expiration)
+
+#### Api::V1::Maps::HexagonsController (`app/controllers/api/v1/maps/hexagons_controller.rb`)
+
+Provides hexagon data for both authenticated and public access:
+
+**Features:**
+- Skip authentication for public sharing requests (`uuid` parameter)
+- Context resolution for public vs. authenticated access
+- Error handling for missing or expired shares
+
+```ruby
+# Public access via UUID
+GET /api/v1/maps/hexagons?uuid=SHARING_UUID
+
+# Authenticated access
+GET /api/v1/maps/hexagons?start_date=2024-01-01&end_date=2024-01-31
+```
+
+### Services
+
+#### Maps::HexagonRequestHandler (`app/services/maps/hexagon_request_handler.rb`)
+
+Central service for processing hexagon requests:
+
+**Workflow:**
+1. Attempts to find matching stat for the request
+2. Delegates to `HexagonCenterManager` for pre-calculated data
+3. Returns empty feature collection if no data available
+
+#### Maps::HexagonCenterManager (`app/services/maps/hexagon_center_manager.rb`)
+
+Manages pre-calculated H3 hexagon data:
+
+**Responsibilities:**
+- Retrieves pre-calculated H3 hex IDs from database
+- Converts stored H3 indexes to GeoJSON polygons
+- Builds hexagon features with point counts and timestamps
+- Handles efficient polygon generation from H3 indexes
+
+**Data Flow:**
+1. Check if pre-calculated H3 hex IDs are available
+2. Convert H3 indexes to hexagon polygons using `HexagonPolygonGenerator`
+3. Build GeoJSON FeatureCollection with metadata and point counts
+
+#### Stats::CalculateMonth (`app/services/stats/calculate_month.rb`)
+
+Responsible for calculating and storing hexagon data during stats processing:
+
+**H3 Configuration:**
+- `DEFAULT_H3_RESOLUTION = 8`: Small hexagons for good detail
+- `MAX_HEXAGONS = 10_000`: Maximum to prevent memory issues
+
+**Key Methods:**
+- `calculate_h3_hex_ids`: Main method for H3 calculation and storage
+- `calculate_h3_hexagon_centers`: Internal H3 calculation logic
+- `calculate_h3_indexes`: Groups points into H3 hexagons
+- `fetch_user_points_for_period`: Retrieves points for date range
+
+**Algorithm:**
+1. Fetch user points for the specified month
+2. Convert each point to H3 index at specified resolution
+3. Aggregate points per hexagon with count and timestamp bounds
+4. Apply resolution reduction if hexagon count exceeds maximum
+5. Store as hash of { h3_index_string => [count, earliest, latest] }
+
+#### Maps::HexagonPolygonGenerator (`app/services/maps/hexagon_polygon_generator.rb`)
+
+Converts H3 indexes back to polygon geometry:
+
+**Features:**
+- Uses H3 library for accurate hexagon boundaries
+- Converts coordinates to GeoJSON Polygon format
+- Supports both center-based and H3-index-based generation
+- Direct H3 index to polygon conversion for efficiency
+
+**Usage Modes:**
+- **Center-based**: `new(center_lng: lng, center_lat: lat)`
+
+## H3 Hexagon System
+
+### What is H3?
+
+H3 is Uber's Hexagonal Hierarchical Spatial Index that provides:
+- **Uniform coverage**: Earth divided into hexagonal cells
+- **Hierarchical resolution**: 16 levels from global to local
+- **Efficient indexing**: Fast spatial queries and aggregations
+- **Consistent shape**: Hexagons have uniform neighbors
+
+### Resolution Levels
+
+Dawarich uses H3 resolution 8 by default:
+- **Resolution 8**: ~737m average hexagon edge length
+- **Fallback mechanism**: Reduces resolution if too many hexagons
+- **Maximum limit**: 10,000 hexagons to prevent memory issues
+
+### Performance Benefits
+
+1. **Pre-calculation**: H3 hexagons calculated once during stats processing
+2. **Efficient storage**: Hash-based storage with H3 index as key
+3. **Fast retrieval**: Database lookup instead of real-time calculation
+4. **Reduced bandwidth**: Compact JSON hash format for API responses
+5. **Direct polygon generation**: H3 index directly converts to polygon boundaries
+
+## Workflow
+
+### 1. Stats Calculation Process
+
+```mermaid
+graph TD
+    A[User Data Import] --> B[Stats::CalculateMonth Service]
+    B --> C[Calculate H3 Hexagon Centers]
+    C --> D[Store in hexagon_centers Column]
+    D --> E[Stats Available for Sharing]
+```
+
+**Detailed Steps:**
+1. User imports location data (GPX, JSON, etc.)
+2. Background job triggers `Stats::CalculateMonth`
+3. Service calculates monthly statistics including H3 hex IDs
+4. H3 indexes are calculated for all points in the month
+5. Results stored in `stats.h3_hex_ids` as JSON hash
+
+### 2. Sharing Activation
+
+```mermaid
+graph TD
+    A[User Visits Stats Page] --> B[Enable Sharing Toggle]
+    B --> C[Select Expiration Duration]
+    C --> D[PATCH /stats/:year/:month/sharing]
+    D --> E[Generate/Update sharing_uuid]
+    E --> F[Set sharing_settings]
+    F --> G[Return Public URL]
+```
+
+**Sharing Settings:**
+- **Expiration options**: 1h, 12h, 24h, permanent
+- **UUID generation**: Secure random UUID for each stat
+- **Expiration timestamp**: Calculated and stored in sharing_settings
+
+### 3. Public Access Flow
+
+```mermaid
+graph TD
+    A[Public User Visits Shared URL] --> B[Validate UUID & Expiration]
+    B --> C{Valid & Not Expired?}
+    C -->|Yes| D[Load Public Stats View]
+    C -->|No| E[Redirect with Error]
+    D --> F[Render Map with Hexagons]
+    F --> G[Load Hexagon Data via API]
+    G --> H[Display Interactive Map]
+```
+
+**Security Checks:**
+1. Verify sharing UUID exists in database
+2. Check `sharing_settings.enabled = true`
+3. Validate expiration timestamp if not permanent
+4. Return 404 if any check fails
+
+### 4. Hexagon Data Retrieval
+
+```mermaid
+graph TD
+    A[Map Requests Hexagon Data] --> B[GET /api/v1/maps/hexagons?uuid=UUID]
+    B --> C[HexagonsController]
+    C --> D[Skip Authentication for UUID Request]
+    D --> E[HexagonRequestHandler]
+    E --> F[Find Stat by UUID]
+    F --> G[HexagonCenterManager]
+    G --> H[Load Pre-calculated Centers]
+    H --> I[Convert to GeoJSON Polygons]
+    I --> J[Return FeatureCollection]
+```
+
+**Data Transformation:**
+1. Retrieve stored H3 hex IDs hash from database
+2. Convert each H3 index to hexagon boundary coordinates
+3. Build GeoJSON Feature with properties (point count, timestamps)
+4. Return complete FeatureCollection for map rendering
+
+## API Endpoints
+
+### Public Sharing
+
+#### View Shared Stats
+```http
+GET /shared/stats/:uuid
+```
+- **Authentication**: None required
+- **Response**: HTML page with public stats view
+- **Error Handling**: Redirects to root with alert if invalid/expired
+
+#### Get Hexagon Data
+```http
+GET /api/v1/maps/hexagons?uuid=:uuid
+```
+- **Authentication**: None required for UUID access
+- **Response**: GeoJSON FeatureCollection
+- **Features**: Each feature represents one hexagon with point count and timestamps
+
+### Authenticated Management
+
+#### Toggle Sharing
+```http
+PATCH /stats/:year/:month/sharing
+```
+**Parameters:**
+- `enabled`: "1" to enable, "0" to disable
+- `expiration`: "1h", "12h", "24h", or "permanent" (when enabling)
+
+**Response:**
+```json
+{
+  "success": true,
+  "sharing_url": "https://domain.com/shared/stats/uuid",
+  "message": "Sharing enabled successfully"
+}
+```
+
+## Security Features
+
+### UUID-based Access
+- **Unguessable URLs**: Uses secure random UUIDs
+- **No enumeration**: Can't guess valid sharing links
+- **Automatic generation**: New UUID created for each sharing activation
+
+### Time-based Expiration
+- **Configurable duration**: Multiple expiration options
+- **Automatic enforcement**: Expired shares become inaccessible
+- **Precise timestamping**: ISO8601 format with timezone awareness
+
+### Limited Data Exposure
+- **No user identification**: Public view doesn't expose user details
+- **Aggregated data only**: Only statistical summaries are shared
+- **No raw location points**: Individual coordinates not exposed
+
+### Privacy Controls
+- **User control**: Users can enable/disable sharing at any time
+- **UUID regeneration**: Can generate new sharing URL to invalidate old ones
+- **Granular permissions**: Per-month sharing control
+
+## Frontend Integration
+
+### Public View Template (`app/views/stats/public_month.html.erb`)
+
+**Features:**
+- **Responsive design**: Mobile-friendly layout with Tailwind CSS
+- **Monthly statistics**: Distance, active days, countries visited
+- **Interactive hexagon map**: Leaflet.js with H3 hexagon overlay
+- **Activity charts**: Daily distance visualization
+- **Location summary**: Countries and cities visited
+
+**Map Integration:**
+```erb
+<div id="public-monthly-stats-map"
+     data-controller="public-stat-map"
+     data-public-stat-map-uuid-value="<%= @stat.sharing_uuid %>"
+     data-public-stat-map-hexagons-available-value="<%= @hexagons_available.to_s %>">
+</div>
+```
+
+### JavaScript Controller
+
+**Stimulus Controller**: `public-stat-map`
+- **Leaflet initialization**: Sets up interactive map
+- **Hexagon layer**: Loads and renders hexagon data from API
+- **User interaction**: Click handlers, zoom controls
+- **Loading states**: Shows loading spinner during data fetch
+
+## Performance Considerations
+
+### Pre-calculation Strategy
+- **Background processing**: Hexagons calculated during stats job
+- **Storage efficiency**: H3 indexes are compact
+- **Query optimization**: GIN index on hexagon_centers column
+- **Caching**: Pre-calculated data serves multiple requests
+
+### Memory Management
+- **Hexagon limits**: Maximum 10,000 hexagons per month
+- **Resolution fallback**: Automatically reduces detail for large areas
+- **Lazy loading**: Only calculate when stats are processed
+- **Efficient formats**: JSON storage optimized for size
+
+### Database Optimization
+```sql
+-- Optimized queries
+SELECT h3_hex_ids FROM stats
+WHERE sharing_uuid = ? AND sharing_settings->>'enabled' = 'true';
+
+-- Index for performance
+CREATE INDEX index_stats_on_h3_hex_ids
+ON stats USING gin (h3_hex_ids)
+WHERE (h3_hex_ids IS NOT NULL AND h3_hex_ids != '{}'::jsonb);
+```
+
+## Error Handling
+
+### Validation Errors
+- **Missing UUID**: 404 response with user-friendly message
+- **Expired sharing**: Redirect with appropriate alert
+- **Invalid parameters**: Bad request with error details
+
+### Service Errors
+- **H3 calculation failures**: Graceful degradation, logs warning
+- **Database errors**: Transaction rollback, user notification
+- **Memory issues**: Resolution reduction, retry mechanism
+
+### Frontend Resilience
+- **Loading states**: User feedback during data fetching
+- **Fallback content**: Display stats even if hexagons fail
+- **Error messages**: Clear communication of issues
+
+## Configuration
+
+### Environment Variables
+```bash
+# H3 hexagon settings (optional, defaults shown)
+H3_DEFAULT_RESOLUTION=8
+H3_MAX_HEXAGONS=10000
+
+# Feature flags
+ENABLE_PUBLIC_SHARING=true
+```
+
+### Runtime Configuration
+- **Resolution adaptation**: Automatic based on data size
+- **Expiration options**: Configurable in sharing settings
+- **Security headers**: CORS configuration for API access
+
+## Monitoring and Analytics
+
+### Logging
+- **Share creation**: Log when sharing is enabled
+- **Public access**: Log UUID-based requests (without exposing UUID)
+- **Performance metrics**: H3 calculation timing
+- **Error tracking**: Failed calculations and API errors
+
+### Metrics
+- **Sharing adoption**: How many users enable sharing
+- **Expiration preferences**: Popular expiration durations
+- **Performance**: Hexagon calculation and rendering times
+- **Error rates**: Failed sharing requests
+
+## Troubleshooting
+
+### Common Issues
+
+#### No Hexagons Displayed
+1. Check if `hexagons_available?` returns true
+2. Verify `h3_hex_ids` column has data
+3. Confirm H3 library is properly installed
+4. Check API endpoint returns valid GeoJSON
+
+#### Sharing Link Not Working
+1. Verify UUID exists in database
+2. Check sharing_settings.enabled = true
+3. Validate expiration timestamp
+4. Confirm public routes are properly configured
+
+#### Performance Issues
+1. Monitor hexagon count (should be < 10,000)
+2. Check if resolution is too high for large areas
+3. Verify database indexes are present
+4. Consider increasing H3_MAX_HEXAGONS if needed
+
+### Debug Commands
+
+```bash
+# Check sharing status for a stat
+rails runner "
+stat = Stat.find_by(sharing_uuid: 'UUID_HERE')
+puts stat.public_accessible?
+puts stat.hexagons_available?
+"
+
+# Verify H3 hex data format
+rails runner "
+stat = Stat.first
+puts stat.h3_hex_ids.class
+puts stat.h3_hex_ids.first
+"
+```
+
+## Future Enhancements
+
+### Planned Features
+- **Social sharing**: Integration with social media platforms
+- **Embedding**: Iframe widgets for external sites
+- **Analytics**: View count and engagement metrics
+- **Custom styling**: User-configurable map themes
+
+### Technical Improvements
+- **CDN integration**: Faster global access to shared stats
+- **Compression**: Further optimize H3 hex data storage
+- **Real-time updates**: Live sharing for ongoing activities
+- **API versioning**: Stable API contracts for external integration
+- **H3 resolution optimization**: Dynamic resolution based on geographic area
+
+## Conclusion
+
+The Shareable Stats feature provides a robust, secure, and performant way for Dawarich users to share their location insights. The H3 hexagon system offers excellent visualization while maintaining privacy through aggregated data. The UUID-based security model ensures that only intended recipients can access shared statistics, while the configurable expiration system gives users complete control over data visibility.
+
+The architecture is designed for scalability and performance, with pre-calculated data reducing server load and providing fast response times for public viewers. The comprehensive error handling and monitoring ensure reliable operation in production environments.