# Itinerary Reorder Refactor Design

**Date:** 2026-01-17
**Status:** Approved
**Scope:** Complete rewrite of TripDetailView itinerary with constrained drag-and-drop

## Overview

Refactor TripDetailView to support drag-and-drop reordering where:
- **Games** are fixed anchors (immovable, ordered by time)
- **Travel** is movable with hard constraints (must be after departure games, before arrival games)
- **Custom items** are freely movable anywhere

## Core Data Model

The itinerary is a flat list of items grouped by day headers. Each item has:

```swift
struct ItineraryItem: Identifiable, Codable {
    let id: UUID
    let tripId: UUID
    var day: Int                    // Which day (1, 2, 3...)
    var sortOrder: Double           // Position within the day (fractional)
    let kind: ItemKind              // game, travel, or custom
    var modifiedAt: Date
}

enum ItemKind: Codable {
    case game(gameId: String)                           // Fixed, ordered by game time
    case travel(fromCity: String, toCity: String)       // Constrained by games
    case custom(title: String, icon: String, time: Date?, location: CLLocationCoordinate2D?)
}
```

### Key Points

- Games and travel are stored as items (not derived) — full structure persisted
- Travel segments are system-generated when cities change, but stored with positions
- Custom items have optional time and location (location for map display only, no constraints)
- `sortOrder` uses fractional values for efficient insertion without reindexing

### Storage

- Items synced to CloudKit with debounced writes (1-2 seconds after last change)
- Local-first: changes persist locally immediately, sync retries silently on failure
- Clean break from existing `CustomItineraryItem` and `TravelDayOverride` records

## Constraint Logic

A separate `ItineraryConstraints` type handles all validation, making it testable in isolation.

### Game Constraints

- Games are **immovable** — fixed to their day, ordered by game time within the day
- Multiple games on same day sort by time (1pm above 7pm)
- Games act as **barriers** that travel cannot cross

### Travel Constraints

- Travel has a start city (departure) and end city (arrival)
- Must be **below** ALL games in the departure city (on any day)
- Must be **above** ALL games in the arrival city (on any day)
- Can be placed on any day within this valid window

**Example:**
- Day 1: Chicago game
- Day 2: Rest day
- Day 3: Detroit game

Chicago->Detroit travel is valid on:
- Day 1 (after the game)
- Day 2 (anywhere)
- Day 3 (before the game)

### Custom Item Constraints

- **No constraints** — can be placed on any day, in any position
- Location (if set) is for map display only, doesn't affect placement

### Constraint API

```swift
struct ItineraryConstraints {
    /// Returns all valid drop zones for an item being dragged
    func validDropZones(for item: ItineraryItem, in itinerary: [ItineraryItem]) -> [DropZone]

    /// Validates if a specific position is valid for an item
    func isValidPosition(item: ItineraryItem, day: Int, sortOrder: Double, in itinerary: [ItineraryItem]) -> Bool

    /// Returns the games that act as barriers for a travel item (for visual highlighting)
    func barrierGames(for travelItem: ItineraryItem, in itinerary: [ItineraryItem]) -> [ItineraryItem]
}
```

## Visual Design

### Layout Structure

- Full map header at top (current design, with save/heart button overlay)
- Flat list below — day headers are separators, not containers
- Day headers scroll with content (not sticky)

### Day Header

- Format: "Day 1 - Friday, January 17"
- Plus (+) button on the right to add custom items
- Empty state text when no items: "No items yet, tap + to add"
- Same styling for rest days (just no games)

### Game Rows (Prominent)

- Larger card style to show importance
- Sport badge, team matchup, stadium, time (current detailed design)
- **No drag handle** — absence signals they're immovable
- Ordered by game time within the day

### Travel Rows (Distinct)

- Gold/route-colored border and accent
- Shows "Chicago -> Detroit - 280 mi - 4h 30m"
- Drag handle on left (always visible)
- No EV charger info (removed for cleaner UI)

### Custom Item Rows (Minimal)

- Compact: icon + title only
- Time shown on right if set (e.g., "7:00 PM")
- Drag handle on left (always visible)

### Removed from Current Design

- Overview section (stats row, score card) — focus on itinerary
- EV charger expandable section in travel

## Drag & Drop Interaction

### Initiating Drag

- Drag handle (grip icon) on left side of travel and custom items
- Games have no handle — visually signals they're locked
- Standard iOS drag threshold (system default)

### During Drag

- Standard iOS drag appearance (system handles lift/shadow)
- **Invalid zones dim** — valid stays normal, invalid fades out
- **Barrier games highlight** (gold border) when dragging travel — shows which games create the constraint
- **Gap opens** between items at valid drop positions
- Auto-scroll when dragging near top/bottom edge
- Haptic feedback: on pickup, when hovering valid zone, and on drop

### Drop Behavior

- Drop to exact position between items (even across days)
- Dropping outside valid zones: item snaps back to original position
- After drop: smooth reflow animation as items settle

### Invalid Drop Prevention

- Travel dropped above a departure game -> prevented (no drop zone shown)
- Travel dropped below an arrival game -> prevented (no drop zone shown)
- Custom items have no restrictions — all zones valid

### Day-to-Day Movement

- Drag item to different day by scrolling (auto-scroll at edges)
- Drop at exact position within target day

## Persistence & Sync

### Storage Model

- Full itinerary structure stored (not derived)
- Each `ItineraryItem` is a CloudKit record linked to trip by `tripId`
- Clean break from old format — existing `CustomItineraryItem` and `TravelDayOverride` data not migrated

### Sync Behavior

- **Debounced writes**: Wait 1-2 seconds after last change, then sync
- **Local-first**: Changes persist locally immediately
- **Silent retry**: If sync fails, keep retrying in background
- **Last write wins**: No complex conflict resolution, most recent change overwrites

### Offline

- **Read-only offline**: Can view itinerary but editing requires connection
- Sync resumes automatically when back online

### Trip Changes (Game Added/Removed Externally)

- **Auto-update**: Detect changes to underlying trip, merge into stored itinerary
- New games inserted in time order on correct day
- Removed games simply disappear, other items stay in place
- If removing a game makes travel invalid (no games left in that city), auto-remove the travel segment

### Error Handling

- Corrupted data (e.g., invalid day reference): Show error, offer reset option

## Item Operations

### Adding Custom Items

- Tap (+) in day header -> opens AddItemSheet (current behavior)
- New item appears at end of day (user can drag to reorder)
- Sheet allows setting: title, icon/category, optional time, optional location

### Editing Custom Items

- Tap item -> opens edit sheet (current behavior)
- Can modify title, icon, time, location
- Delete button available in edit sheet

### Deleting Custom Items

- Multiple options: swipe to delete, long-press context menu, or delete button in edit sheet
- **Confirmation dialog** before delete: "Are you sure?"
- Games and travel cannot be deleted (system-managed)

### Reordering

- Drag handle to reorder within day or move to different day
- Single item drag only (no multi-select)
- No undo feature — moves are simple enough to redo manually

### Map Integration

- Route lines follow itinerary order (includes custom items with locations)
- Quick fade/flash animation when route updates after reorder
- Tap map marker -> list scrolls to that item
- Tapping list items does NOT affect map (list is for editing, map is overview)

## Implementation Approach

### Architecture

- `ItineraryConstraints` — separate testable type for all constraint logic
- `ItineraryItem` — unified model for games, travel, and custom items
- `ItineraryItemService` — handles persistence, sync, and CRUD operations
- View layer uses the constraint API to determine valid drop zones

### Implementation Order

1. Data model (`ItineraryItem`, `ItemKind`)
2. Constraint logic (`ItineraryConstraints` with unit tests)
3. Persistence layer (`ItineraryItemService` with CloudKit sync)
4. UI components (day header, item rows, drag handles)
5. Drag & drop integration with constraint validation
6. Map route updates

### Code Strategy

- Branch replacement — new code replaces old in a feature branch
- Clean break from existing `CustomItineraryItem`, `TravelDayOverride`, and related services
- Lazy rendering for performance (variable trip length, potentially hundreds of items)
- PDF export updated to respect user's itinerary order

### Testing

- Unit tests for `ItineraryConstraints` — all constraint rules
- Integration tests for drag/drop behavior
- Edge cases: multiple games same day, games in multiple cities same day, rest days

### Not in Scope

- Accessibility/VoiceOver reordering (touch first)
- Keyboard shortcuts
- Multi-select drag
- Undo feature

## Files to Create/Modify

### New Files

- `Core/Models/Domain/ItineraryItem.swift` — unified item model
- `Core/Models/Domain/ItineraryConstraints.swift` — constraint logic
- `Core/Services/ItineraryItemService.swift` — persistence and sync

### Modified Files

- `Features/Trip/Views/TripDetailView.swift` — complete rewrite of itinerary section
- `Features/Trip/Views/AddItemSheet.swift` — adapt to new model
- `Export/PDFGenerator.swift` — respect user's itinerary order

### Deleted Files

- `Core/Models/Domain/CustomItineraryItem.swift`
- `Core/Models/Domain/TravelDayOverride.swift`
- `Core/Services/CustomItemService.swift`
- `Core/Services/CustomItemSubscriptionService.swift`
- `Core/Services/TravelOverrideService.swift`
- `Features/Trip/Views/CustomItemRow.swift`

## Decision Log

| Question | Decision |
|----------|----------|
| Core model | List of days, each containing ordered items |
| Item order within day | User-controlled via drag |
| Item types | Games (fixed), Travel (constrained), Custom (free) |
| Travel constraints | After ALL departure games, before ALL arrival games |
| Custom item location | Optional, for map only, no placement constraints |
| Invalid drop handling | Don't show invalid drop zones (dim them) |
| Visual feedback for barriers | Highlight barrier games during travel drag |
| Persistence | Full structure stored, not derived |
| Sync strategy | Debounced (1-2s), local-first, silent retry |
| Conflict resolution | Last write wins |
| Offline | Read-only |
| Trip changes | Auto-merge, auto-remove invalid travel |
| Delete confirmation | Yes, dialog |
| Undo | No |
| Keyboard/accessibility | Not in scope (touch first) |
| Day header format | "Day 1 - Friday, January 17" |
| Add button location | In day header (+) |
| New item position | End of day |
| Game row style | Prominent card (current detailed design) |
| Travel row style | Distinct gold accent |
| Custom item row style | Minimal (icon + title + optional time) |
| EV charger info | Removed |
| Overview section | Removed (focus on itinerary) |
| Map at top | Yes, full map |
| Drag initiation | Drag handle (grip icon) |
| Haptic feedback | Yes (pickup, hover, drop) |
| Drop indicator | Gap opens between items |
| Scroll during drag | Auto-scroll at edges |
| Rest day styling | Same as game days |
| Empty day text | "No items yet, tap + to add" |
| PDF export | Respects user's itinerary order |
| Max trip length | Variable (optimize for long trips) |
| Max custom items | Unlimited (hundreds possible) |
