# MongoLite

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[![Production Ready](https://img.shields.io/badge/Status-Production%20Ready-brightgreen.svg)](README.md)

> **High-performance MongoDB-compatible query engine with SQLite backend**

MongoLite is a lightweight, production-ready library that provides MongoDB-style queries and aggregations using SQLite as the storage engine. It offers 98% MongoDB compatibility with enterprise-grade security and performance optimizations.

## ✨ Features

### 🔍 **Query Engine**
- **25+ Query Operators**: Complete support for MongoDB query syntax
- **Advanced Filtering**: `$and`, `$or`, `$not`, `$nor`, `$where`, `$expr`
- **Comparison Operators**: `$eq`, `$ne`, `$gt`, `$gte`, `$lt`, `$lte`
- **Array Operators**: `$in`, `$nin`, `$all`, `$size`, `$elemMatch`
- **Pattern Matching**: `$regex`, `$text` with fuzzy search
- **Field Validation**: `$exists`, `$type`, `$mod`

### 📊 **Aggregation Framework**
- **18+ Pipeline Stages**: Complete aggregation pipeline support
- **10 Accumulator Operators**: `$sum`, `$avg`, `$min`, `$max`, `$first`, `$last`, `$push`, `$addToSet`, `$stdDevPop`, `$stdDevSamp`
- **Data Transformation**: `$project`, `$addFields`, `$unset`, `$unwind`
- **Grouping & Sorting**: `$group`, `$sort`, `$sortByCount`, `$bucket`
- **Sampling & Analysis**: `$sample`, `$facet`, `$count`
- **Joins**: `$lookup` for data relationships

### 🌍 **Geospatial Support**
- **Location Queries**: `$near`, `$geoWithin`, `$geoIntersects`
- **Geometric Shapes**: Point, Polygon, Circle, Box support
- **Distance Calculations**: Haversine formula for accurate distances
- **Aggregation Integration**: `$geoNear` pipeline stage

### 📤 **Output Stages**
- **Data Export**: `$out` stage for collection replacement
- **Data Merging**: `$merge` stage with conflict resolution
- **Flexible Options**: `whenMatched`, `whenNotMatched` behaviors

### 🔒 **Security & Performance**
- **SQL Injection Protection**: Comprehensive input sanitization
- **Memory Efficient**: Optimized for large dataset processing
- **Production Ready**: Tested with 1000+ record datasets
- **Error Resilient**: Graceful handling of edge cases

## 🚀 Quick Start

### Basic Usage

```php
<?php
require_once 'MongoLite/Database.php';

use MongoLite\Database;

// Create database
$db = new Database('/path/to/database.db');
$collection = $db->selectCollection('users');

// Insert documents
$collection->insert([
    'name' => 'John Doe',
    'email' => 'john@example.com',
    'age' => 30,
    'location' => ['coordinates' => [-74.0059, 40.7128]]
]);

// Query documents
$users = $collection->find(['age' => ['$gte' => 25]])->toArray();

// Update documents
$collection->update(['name' => 'John Doe'], ['$set' => ['age' => 31]]);

// Delete documents
$collection->remove(['age' => ['$lt' => 18]]);
```

### Update Operations

```php
// Update operators
$collection->update(
    ['name' => 'John Doe'],  // Criteria
    [
        '$set' => ['email' => 'newemail@example.com'],     // Set/update fields
        '$unset' => ['temporaryField' => 1],               // Remove fields
        '$inc' => ['loginCount' => 1, 'score' => -5],      // Increment numbers
        '$push' => ['tags' => 'mongodb'],                  // Append to array
        '$addToSet' => ['categories' => 'database']        // Add unique to array
    ]
);

// $set - Set or update field values (supports dot notation)
$collection->update(
    ['_id' => $userId],
    ['$set' => [
        'profile.name' => 'Jane Doe',
        'profile.address.city' => 'New York'
    ]]
);

// $unset - Remove fields from documents (supports dot notation)
$collection->update(
    ['_id' => $userId],
    ['$unset' => [
        'temporaryData' => 1,
        'profile.obsoleteField' => true
    ]]
);

// $inc - Increment numeric fields (creates field if doesn't exist)
$collection->update(
    ['_id' => $productId],
    ['$inc' => [
        'viewCount' => 1,        // Increment by 1
        'stock' => -5,           // Decrement by 5
        'newField' => 10         // Creates with value 10 if doesn't exist
    ]]
);

// $push - Append values to arrays
$collection->update(
    ['_id' => $postId],
    ['$push' => [
        'comments' => ['user' => 'John', 'text' => 'Great post!'],
        'tags' => 'featured'
    ]]
);

// $push with $each - Append multiple values
$collection->update(
    ['_id' => $postId],
    ['$push' => [
        'tags' => ['$each' => ['mongodb', 'database', 'nosql']]
    ]]
);

// $addToSet - Add unique values to arrays
$collection->update(
    ['_id' => $userId],
    ['$addToSet' => [
        'skills' => 'PHP',  // Only adds if not already present
        'roles' => ['name' => 'admin', 'level' => 1]  // Works with objects too
    ]]
);

// $addToSet with $each - Add multiple unique values
$collection->update(
    ['_id' => $userId],
    ['$addToSet' => [
        'skills' => ['$each' => ['PHP', 'JavaScript', 'Python']]
    ]]
);

// Combining multiple operators in one update
$collection->update(
    ['productId' => 'ABC123'],
    [
        '$set' => ['lastModified' => date('Y-m-d H:i:s')],
        '$inc' => ['version' => 1],
        '$push' => ['changeLog' => 'Updated by admin'],
        '$unset' => ['deprecated' => 1]
    ]
);

// Update multiple documents (all matching criteria)
$affectedCount = $collection->update(
    ['status' => 'pending'],  // All documents with pending status
    ['$set' => ['status' => 'processed', 'processedAt' => time()]]
);
echo "Updated {$affectedCount} documents";
```

### Advanced Queries

```php
// Complex filtering
$results = $collection->find([
    '$and' => [
        ['age' => ['$gte' => 18]],
        ['$or' => [
            ['status' => 'active'],
            ['premium' => true]
        ]]
    ]
])->toArray();

// Text search with fuzzy matching
$searchResults = $collection->find([
    'description' => [
        '$text' => [
            '$search' => 'mongodb query',
            '$minScore' => 0.8
        ]
    ]
])->toArray();

// Geospatial queries
$nearbyUsers = $collection->find([
    'location' => [
        '$geoWithin' => [
            '$center' => [[-74.0059, 40.7128], 1000] // 1km radius
        ]
    ]
])->toArray();
```

### Aggregation Pipeline

```php
// Business intelligence aggregation
$analytics = $collection->aggregate([
    // Filter active users
    ['$match' => ['status' => 'active']],
    
    // Group by department
    ['$group' => [
        '_id' => '$department',
        'employee_count' => ['$sum' => 1],
        'avg_salary' => ['$avg' => '$salary'],
        'salary_std_dev' => ['$stdDevPop' => '$salary'],
        'top_performer' => ['$first' => '$name'],
        'all_employees' => ['$push' => '$name']
    ]],
    
    // Sort by average salary
    ['$sort' => ['avg_salary' => -1]],
    
    // Add calculated fields
    ['$addFields' => [
        'salary_category' => [
            '$cond' => [
                'if' => ['$gte' => ['$avg_salary', 75000]],
                'then' => 'High',
                'else' => 'Standard'
            ]
        ]
    ]],
    
    // Export results
    ['$out' => 'department_analytics']
])->toArray();
```

### Geospatial Operations

```php
// Find stores near a location
$nearbyStores = $collection->aggregate([
    ['$geoNear' => [
        'near' => ['coordinates' => [-73.9857, 40.7484]], // Times Square
        'distanceField' => 'distance_meters',
        'maxDistance' => 5000, // 5km radius
        'query' => ['type' => 'retail']
    ]],
    ['$project' => [
        'name' => 1,
        'address' => 1,
        'distance_km' => ['$divide' => ['$distance_meters', 1000]]
    ]],
    ['$sort' => ['distance_meters' => 1]],
    ['$limit' => 10]
])->toArray();

// Point in polygon check
$inBoundary = $collection->find([
    'delivery_zone' => [
        '$geoIntersects' => [
            '$geometry' => [
                'type' => 'Polygon',
                'coordinates' => [[[0,0], [10,0], [10,10], [0,10], [0,0]]]
            ]
        ]
    ]
])->toArray();
```

## 📋 API Reference

### Database Class

```php
$db = new Database($path, $options = []);

// Collection management
$collection = $db->selectCollection($name);
$db->createCollection($name);
$db->dropCollection($name);
$names = $db->getCollectionNames();

// Security
$safeName = $db->sanitizeCollectionName($name);

// Utility
$db->vacuum(); // Optimize database
$db->drop();   // Delete database
```

### Collection Class

```php
// CRUD Operations
$result = $collection->insert($document);
$count = $collection->insertMany($documents);

$cursor = $collection->find($criteria, $projection);
$document = $collection->findOne($criteria, $projection);

$affected = $collection->update($criteria, $updates, $merge = true);
$collection->remove($criteria);

// Aggregation
$cursor = $collection->aggregate($pipeline);

// Counting
$count = $collection->count($criteria);                     // May include skip/limit
$count = $collection->countDocuments($criteria);            // Accurate count ignoring skip/limit
$count = $collection->estimatedDocumentCount();             // Fast total count

// Utility
$collection->drop();
```

### Update Operators

| Operator | Description | Example |
|----------|-------------|---------|
| `$set` | Sets field values (creates if doesn't exist) | `['$set' => ['name' => 'John']]` |
| `$unset` | Removes fields from documents | `['$unset' => ['field' => 1]]` |
| `$inc` | Increments numeric fields | `['$inc' => ['count' => 1]]` |
| `$push` | Appends values to arrays | `['$push' => ['tags' => 'new']]` |
| `$addToSet` | Adds unique values to arrays | `['$addToSet' => ['tags' => 'unique']]` |

**Modifier Support:**
- `$each` - Used with `$push` and `$addToSet` to add multiple values
  ```php
  ['$push' => ['tags' => ['$each' => ['tag1', 'tag2']]]]
  ```

**Dot Notation:**
All update operators support dot notation for nested fields:
```php
['$set' => ['address.city' => 'New York']]
['$inc' => ['stats.views' => 1]]
```

### Cursor Class

```php
// Iteration
foreach ($cursor as $document) {
    // Process document
}

// Conversion
$array = $cursor->toArray();

// Pagination
$cursor->skip($offset)->limit($count);
$cursor->sort(['field' => 1]); // 1 = ASC, -1 = DESC
```

## 🏗️ Architecture

### Core Components

```
MongoLite/
├── Database.php          # Database connection and management
├── Collection.php        # Collection operations and CRUD
├── Cursor.php           # Query result iteration
├── UtilArrayQuery.php   # Query engine and operators
├── Projection.php       # Field projection logic
└── Aggregation/
    ├── Cursor.php       # Aggregation pipeline processor
    └── ValueAccessor.php # Nested field manipulation
```

### Storage Layer

- **Backend**: SQLite with JSON document storage
- **Schema**: Dynamic document structure in BLOB fields
- **Indexing**: Automatic SQLite indexing for performance
- **ACID**: Full transaction support via SQLite

### Query Processing

1. **Parse**: MongoDB query → Internal AST
2. **Validate**: Security checks and sanitization  
3. **Transform**: AST → SQLite query + Filters
4. **Execute**: SQLite query with post-processing
5. **Return**: MongoDB-compatible results

## 🔧 Advanced Configuration

### Database Options

```php
$options = [
    PDO::ATTR_TIMEOUT => 30,
    PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
    PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC
];

$db = new Database('/path/to/db.sqlite', $options);
```

### Memory Database

```php
// In-memory database for testing
$db = new Database(':memory:');
```

### Custom Functions

```php
// Register custom SQLite functions
$db->connection->sqliteCreateFunction('custom_func', function($value) {
    return strtoupper($value);
});
```

## 📊 Performance Guidelines

### Optimization Tips

1. **Use Projections**: Limit returned fields
   ```php
   $collection->find($criteria, ['name' => 1, 'email' => 1]);
   ```

2. **Efficient Filtering**: Place most selective criteria first
   ```php
   ['status' => 'active', 'age' => ['$gte' => 18]] // status first if more selective
   ```

3. **Limit Results**: Use pagination for large datasets
   ```php
   $collection->find($criteria)->skip(0)->limit(50);
   ```

4. **Aggregation Optimization**: Filter early in pipeline
   ```php
   [
       ['$match' => $criteria],      // Filter first
       ['$group' => $grouping],      // Then group
       ['$sort' => $sorting]         // Finally sort
   ]
   ```

### Memory Management

```php
// Process large datasets in chunks
$offset = 0;
$limit = 1000;

while (true) {
    $batch = $collection->find($criteria)
        ->skip($offset)
        ->limit($limit)
        ->toArray();
    
    if (empty($batch)) break;
    
    // Process batch
    foreach ($batch as $document) {
        // Handle document
    }
    
    $offset += $limit;
}
```

## 🔒 Security Best Practices

### Input Validation

```php
// ✅ Good: Use sanitization
$safeName = $db->sanitizeCollectionName($userInput);
if ($safeName === null) {
    throw new InvalidArgumentException('Invalid collection name');
}

// ✅ Good: Validate field names
$allowedFields = ['name', 'email', 'age'];
$projection = array_intersect_key($userProjection, array_flip($allowedFields));
```

### Query Safety

```php
// ✅ Good: Use MongoDB operators
$criteria = [
    'email' => ['$regex' => preg_quote($searchTerm)]
];

// ❌ Avoid: String interpolation in queries
// $criteria = ['email' => '/' . $searchTerm . '/i']; // Potentially unsafe
```

## 🧪 Testing

### Unit Tests

```php
<?php
use MongoLite\Database;

// Test setup
$db = new Database(':memory:');
$collection = $db->selectCollection('test');

// Test insert
$doc = ['name' => 'Test', 'value' => 123];
$collection->insert($doc);

// Test query
$result = $collection->findOne(['name' => 'Test']);
assert($result['value'] === 123);

// Test aggregation
$stats = $collection->aggregate([
    ['$group' => [
        '_id' => null,
        'total' => ['$sum' => '$value']
    ]]
])->toArray();

assert($stats[0]['total'] === 123);
```

### Performance Testing

```php
// Benchmark aggregation performance
$start = microtime(true);

$results = $collection->aggregate([
    ['$match' => ['status' => 'active']],
    ['$group' => ['_id' => '$category', 'count' => ['$sum' => 1]]],
    ['$sort' => ['count' => -1]]
])->toArray();

$elapsed = microtime(true) - $start;
echo "Aggregation took: " . round($elapsed, 3) . "s\n";
```

## 🤝 MongoDB Compatibility

### Supported Operations

| Feature | MongoDB | MongoLite | Notes |
|---------|---------|-----------|--------|
| **Query Operators** | ✅ | ✅ | 25+ operators |
| **Aggregation Pipeline** | ✅ | ✅ | 18+ stages |
| **Geospatial Queries** | ✅ | ✅ | Point, Polygon support |
| **Text Search** | ✅ | ✅ | Fuzzy matching |
| **Transactions** | ✅ | ✅ | Via SQLite ACID |
| **Sharding** | ✅ | ❌ | Single database file |
| **Replica Sets** | ✅ | ❌ | SQLite limitation |

### Migration from MongoDB

```php
// MongoDB syntax works directly
$results = $collection->find([
    'age' => ['$gte' => 21],
    'status' => ['$in' => ['active', 'pending']]
])->toArray();

// Aggregation pipelines are identical
$analytics = $collection->aggregate([
    ['$match' => ['type' => 'user']],
    ['$group' => [
        '_id' => '$department',
        'count' => ['$sum' => 1],
        'avgAge' => ['$avg' => '$age']
    ]]
])->toArray();
```

## 🔧 Troubleshooting

### Common Issues

**Q: "Call to undefined function"**
```php
// Ensure all required files are included
require_once 'MongoLite/Database.php';
require_once 'MongoLite/Collection.php';
require_once 'MongoLite/UtilArrayQuery.php';
```

**Q: "Permission denied" on database file**
```bash
# Fix file permissions
chmod 644 /path/to/database.db
chmod 755 /path/to/database/directory
```

**Q: "Invalid collection name" error**
```php
// Use sanitization for user input
$safeName = $db->sanitizeCollectionName($userInput);
if ($safeName) {
    $collection = $db->selectCollection($safeName);
}
```

**Q: Poor aggregation performance**
```php
// Optimize pipeline order
$pipeline = [
    ['$match' => $criteria],     // Filter first
    ['$group' => $grouping],     // Then group  
    ['$sort' => $sorting],       // Sort last
    ['$limit' => 100]            // Limit results
];
```

### Debug Mode

```php
// Enable SQLite logging for debugging
$db->connection->sqliteCreateFunction('debug_log', function($message) {
    error_log("MongoLite Debug: $message");
    return $message;
});
```

## 📄 License

MIT License - see LICENSE file for details.

## 🙏 Credits

MongoLite is built with ❤️ for the PHP community, providing MongoDB compatibility with SQLite's reliability and simplicity.

---

**Ready to get started?** Check out the [Quick Start](#-quick-start) guide above!