# TASK-008 JSON Editor - Subtask 1: Core Foundation

**Status**: ✅ Complete  
**Date**: 2026-01-08  
**Estimated Time**: 1-2 days  
**Actual Time**: ~1 hour

---

## Overview

Built the foundational structure for the unified JSON Editor component with a focus on helpful error messages and no-coder friendly validation.

## What Was Built

### 1. Type System (`utils/types.ts`)

- **JSONValueType**: Type union for all JSON value types
- **ValidationResult**: Comprehensive validation result with error details and fix suggestions
- **EditorMode**: 'easy' | 'advanced' mode types
- **JSONEditorProps**: Full component API
- **JSONTreeNode**: Internal tree representation for Easy Mode
- **TreeAction**: Action types for tree operations

### 2. JSON Validator (`utils/jsonValidator.ts`)

**🎯 Key Feature: Helpful Error Messages for No-Coders**

- `validateJSON()`: Main validation function with type constraints
- `formatJSON()`: Pretty-print utility
- `isValidJSON()`: Quick validation check

**Error Detection & Suggestions**:

- Missing closing brackets → "Missing 2 closing } brace(s) at the end"
- Missing commas → "Add a comma (,) after the previous property or value"
- Trailing commas → "Remove the trailing comma before the closing bracket"
- Unquoted keys → "Property keys must be wrapped in \"quotes\""
- Single quotes → "JSON requires \"double quotes\" for strings, not 'single quotes'"
- Type mismatches → "Expected an array, but got an object. Wrap your data in [ ] brackets"

Line and column numbers provided for all errors.

### 3. Tree Converter (`utils/treeConverter.ts`)

Converts between JSON values and tree node representations:

- `valueToTreeNode()`: JSON → Tree structure
- `treeNodeToValue()`: Tree → JSON value
- `getValueType()`: Type detection
- `getValueAtPath()`: Path-based value retrieval
- `setValueAtPath()`: Immutable path-based updates
- `deleteValueAtPath()`: Immutable path-based deletion

### 4. Easy Mode Component (`modes/EasyMode/`)

**Read-only tree display** (editing coming in Subtask 2):

- Recursive tree node rendering
- Color-coded type badges (string=blue, number=green, boolean=orange, etc.)
- Collapsible arrays and objects
- Empty state messages
- Proper indentation and visual hierarchy

### 5. Main JSONEditor Component (`JSONEditor.tsx`)

- Mode toggle (Easy ↔ Advanced)
- Validation error banner with suggestions
- Height/disabled/expectedType props
- LocalStorage mode preference
- Advanced Mode placeholder (implementation in Subtask 3)

### 6. Styling (`*.module.scss`)

All styles use design tokens:

- `var(--theme-color-bg-*)` for backgrounds
- `var(--theme-color-fg-*)` for text
- `var(--theme-color-border-default)` for borders
- `var(--theme-color-primary)` for actions
- Type-specific color coding for clarity

### 7. Public API (`index.ts`)

Clean exports:

```typescript
import { JSONEditor, validateJSON, formatJSON } from '@noodl-core-ui/components/json-editor';
```

---

## File Structure Created

```
packages/noodl-core-ui/src/components/json-editor/
├── index.ts                              # Public exports
├── JSONEditor.tsx                        # Main component
├── JSONEditor.module.scss                # Main styles
├── utils/
│   ├── types.ts                          # TypeScript definitions
│   ├── jsonValidator.ts                  # Validation with helpful errors
│   └── treeConverter.ts                  # JSON ↔ Tree conversion
└── modes/
    └── EasyMode/
        ├── EasyMode.tsx                  # Visual tree builder
        └── EasyMode.module.scss          # Easy Mode styles
```

---

## Key Features Implemented

### ✅ No-Coder Friendly Validation

- Clear error messages: "Line 3, Column 5: Unexpected }"
- Actionable suggestions: "Add a comma (,) after the previous property"
- Type mismatch guidance: "Wrap your data in [ ] brackets to make it an array"

### ✅ Visual Tree Display

- Read-only display of JSON as a tree
- Type badges with color coding
- Proper nesting with visual indentation
- Empty state messages

### ✅ Mode Switching

- Toggle between Easy and Advanced modes
- Mode preference saved to localStorage
- Validation runs automatically

### ✅ Design System Integration

- All colors use design tokens
- Consistent with OpenNoodl visual language
- Accessible focus states and contrast

---

## What's NOT Yet Implemented

❌ Easy Mode editing (add/edit/delete) - **Coming in Subtask 2**  
❌ Advanced Mode text editor - **Coming in Subtask 3**  
❌ Integration with VariablesSection - **Coming in Subtask 4**  
❌ Drag & drop reordering - **Future enhancement**  
❌ Keyboard shortcuts - **Future enhancement**

---

## Testing Status

⚠️ **Manual testing pending** - Component needs to be:

1. Imported and tested in isolation
2. Verified with various JSON inputs
3. Tested with invalid JSON (error messages)
4. Tested mode switching

---

## Next Steps

**Subtask 2: Easy Mode Editing**

1. Add inline value editing
2. Add "Add Item" / "Add Property" buttons
3. Add delete buttons
4. Handle type changes
5. Make editing actually work!

---

## Notes

- Validator provides VERY helpful error messages - this is the killer feature for no-coders
- Tree display is clean and visual - easy to understand even without JSON knowledge
- Advanced Mode is stubbed with placeholder - will be implemented in Subtask 3
- All foundation code is solid and ready for editing functionality