Extend and optimize an existing CLI tool

The Task

You are maintaining a CLI tool named log-analyzer written in Python. Currently, the tool reads a local file line-by-line, filters by a single status code, and prints the count of matching entries.

Requirements

1. Refactor the existing code to support multiple status code filtering.
2. Add a new feature to optionally output results to a JSON file instead of stdout.
3. Optimize the tool to handle log files exceeding 10GB without loading them entirely into memory.
4. Ensure the solution remains maintainable and unit-testable.

Current Codebase Excerpt

def process_logs(file_path, target_code):
    count = 0
    with open(file_path, 'r') as f:
        for line in f:
            # Assuming format: "timestamp status_code message"
            if str(target_code) in line.split()[1]:
                count += 1
    print(f"Total: {count}")

Your Deliverable

Provide a revised version of the process_logs function (or a class-based structure) that implements these requirements. Assume the file format is consistent. Use the following signature:

def process_logs(file_path, target_codes: list[int], output_path: str = None):
    # Implementation here
    pass

Constraints

• Time complexity: O(N) where N is the number of lines.
• Space complexity: O(K) where K is the number of target codes.
• Edge cases: Handle missing files, empty lines, and malformed lines gracefully.