I have a flat JSON data structure that I need to convert into a nested dictionary structure. For example:

Input:

{
    'name': 'John',
    'address.city': 'New York',
    'address.zip': '10001',
    'contacts[0].type': 'email',
    'contacts[0].value': '[email protected]',
    'contacts[1].type': 'phone',
    'contacts[1].value': '123-456-7890',
    'contacts[2].type': 'car'
    'contacts[2].value': 'harley-davidson',
}

Expected Output:

{
    "name": "John",
    "address": {
        "city": "New York",
        "zip": "10001"
    },
    "contacts": [
        {
            "type": "email",
            "value": "[email protected]"
        },
        {
            "type": "phone",
            "value": "123-456-7890"
        }
        {
            "type": "car",
            "value": "harley-davidson"
        }
    ]
}

I need a general solution that can handle nested structures of arbitrary depth. Please help me write a Python function to achieve this functionality.