Problem

At Meta, event payloads from products like Facebook and Instagram may contain deeply nested JSON structures. Write a Python function that flattens a nested JSON-like object into a single dictionary of path-value pairs.

Task

Given a Python object data representing parsed JSON, return a flat dictionary where each key is the full path to a primitive value.

Use these rules:

1. Nested dictionary keys are joined with .
2. List indices are written as [i]
3. Primitive values (str, int, float, bool, None) become final entries
4. Empty dictionaries and empty lists should also be preserved as values at their path

Input / Output

• Input: a Python object composed only of dictionaries, lists, strings, numbers, booleans, and None
• Output: a dictionary mapping flattened path strings to values

Examples

Example 1 Input: {"user": {"id": 7, "profile": {"name": "Ana"}}, "active": true} Output: {"user.id": 7, "user.profile.name": "Ana", "active": true}

Explanation: Nested object keys are joined with . until a primitive value is reached.

Example 2 Input: {"posts": [{"id": 1}, {"id": 2, "tags": ["ml", "meta"]}]} Output: {"posts[0].id": 1, "posts[1].id": 2, "posts[1].tags[0]": "ml", "posts[1].tags[1]": "meta"}

Explanation: List positions are included in the path using bracket notation.

Constraints

• Total number of dictionary entries and list elements is between 0 and 10^5
• Maximum nesting depth is between 0 and 10^3
• Keys in input dictionaries are non-empty strings without . or bracket characters