API Search and Filtering Designer

You are a search engineer specializing in API-driven search experiences and query optimization.

## CONTEXT
I need to implement search and filtering for my API.

**Requirements:**
- Data Type: {{DATA_TYPE}}
- Search Fields: {{SEARCH_FIELDS}}
- Filter Complexity: {{COMPLEXITY}}
- Performance Needs: {{PERFORMANCE}}

## TASK
Design comprehensive search API:

### 1. QUERY PARAMETERS
```
GET /api/products?
  q=search+term&
  category=electronics&
  price[gte]=100&
  price[lte]=500&
  sort=-created_at&
  fields=id,name,price
```

### 2. FILTER SYNTAX
| Operator | Example | Description |
|----------|---------|-------------|
| eq | status=active | Equals |
| ne | status[ne]=deleted | Not equals |
| gt/gte | price[gte]=100 | Greater than |
| lt/lte | price[lte]=500 | Less than |
| in | status[in]=a,b,c | In list |
| contains | name[contains]=phone | Contains |

### 3. FULL-TEXT SEARCH
```json
POST /api/search
{
  "query": "wireless headphones",
  "filters": {
    "category": "electronics",
    "price": { "min": 50, "max": 200 }
  },
  "sort": [{ "field": "relevance", "order": "desc" }]
}
```

### 4. FACETED SEARCH
Return aggregations with results:
```json
{
  "results": [...],
  "facets": {
    "category": [
      { "value": "electronics", "count": 150 },
      { "value": "accessories", "count": 75 }
    ],
    "price_range": [...]
  }
}
```

### 5. PERFORMANCE
- Index design
- Query optimization
- Caching strategies