# Implementation Plan: Duration-Based Rental Filtering Based on Skipass Selection

## Overview
Implement cross-field dependency where rentals are only visible/selectable when a skipass is selected, and filter rentals to match the selected skipass's date range (dateFrom/dateTo).

## Analysis
Based on code review:
- Both rentals and skipasses have `dateFrom` and `dateTo` properties for duration
- Current system already filters services by travel date range using `getAdditionalServicesBySubTypes($token, true, true)`
- Need to implement skipass-to-rental date matching logic
- Field state conditions system is already in place for hiding/showing fields
- Need to create a custom field options provider for duration-filtered rentals

## Implementation Steps

### 1. Create SkiPassSelectionCondition
**File**: `src/Form/Service/Condition/SkiPassSelectionCondition.php`
- Similar to `RentalSelectionCondition` but checks for skipass selection
- Evaluates both form data and participant DTO for skipass
- Returns true if participant has selected a skipass

### 2. Update Field State Provider
**File**: `src/Form/Service/CreateFieldStateProvider.php`
- Add rentals field hidden condition based on skipass selection
- Similar to how rental insurance is hidden unless rentals are selected:
```php
$skiPassCondition = new SkiPassSelectionCondition();
$this->fieldStateConditions['rentals'] = [
    'hidden' => CompositeCondition::not($skiPassCondition),
];
```

### 3. Create Duration-Based Rental Filtering
**File**: `src/Form/Service/ParticipantFieldOptionsProvider.php`
- Modify existing rentals field provider to filter by selected skipass duration
- Extract selected skipass from participant data
- Filter available rentals to only those with matching dateFrom/dateTo ranges
- Use exact date matching: `rental.dateFrom == skipass.dateFrom && rental.dateTo == skipass.dateTo`

### 4. Update RentalsFieldHandler Dependencies
**File**: `src/Form/Service/ParticipantRentalsFieldHandler.php`
- Add `skiPass` to dependencies array: `['dateOfBirth', 'skiPass']`  
- Add DTO cleanup: clear rentals when no skipass is selected
- Filter rentals by skipass duration in `processField()` method

### 5. Update Field Handler Dependencies
**File**: `src/Form/Service/ParticipantRentalInsuranceFieldHandler.php`
- Update dependencies to include skipass: `['dateOfBirth', 'rentals', 'skiPass']`
- Modify visibility logic: rental insurance only shown when both skipass AND rentals selected

## Key Technical Details

### Duration Matching Logic
Rentals will be filtered to match skipass duration exactly:
```php
private function filterRentalsBySkiPassDuration(array $rentals, ?Service $selectedSkiPass): array
{
    if (null === $selectedSkiPass || null === $selectedSkiPass->dateFrom || null === $selectedSkiPass->dateTo) {
        return []; // No skipass or invalid dates = no rentals
    }
    
    return array_filter($rentals, function(Service $rental) use ($selectedSkiPass) {
        return $rental->dateFrom?->format('Y-m-d') === $selectedSkiPass->dateFrom?->format('Y-m-d') 
            && $rental->dateTo?->format('Y-m-d') === $selectedSkiPass->dateTo?->format('Y-m-d');
    });
}
```

### Field Visibility Chain
1. SkiPass: Always visible (after dateOfBirth)
2. Rentals: Only visible when skipass selected, filtered by skipass duration
3. Rental Insurance: Only visible when rentals selected (existing logic)
4. Body Dimensions: Only visible when rentals selected (existing logic)

### HTMX Integration
- Existing HTMX system will handle dynamic updates when skipass selection changes
- Field state conditions will automatically trigger rental field visibility
- Rental options will be re-rendered with duration-filtered choices

## Dependencies
- No new dependencies required
- Leverages existing field state condition system
- Uses existing Service model date properties
- Maintains backward compatibility with existing workflows

## Progress Tracking

### Status: Implementation Complete ✅
- [x] System architecture analysis
- [x] Existing code review
- [x] Implementation strategy defined
- [x] Technical approach documented

### Implementation Phase: COMPLETED ✅
- [x] Step 1: Create SkiPassSelectionCondition
- [x] Step 2: Update Field State Provider
- [x] Step 3: Create Duration-Based Rental Filtering
- [x] Step 4: Update RentalsFieldHandler Dependencies
- [x] Step 5: Update Field Handler Dependencies
- [x] Testing: Verify cross-field dependencies work correctly
- [x] Testing: Verify HTMX updates work properly
- [x] Documentation: Update CLAUDE.md with new feature details

## Notes
- Implementation follows existing architectural patterns
- Maintains consistency with current field state condition system
- Preserves backward compatibility
- Leverages existing HTMX infrastructure for dynamic updates