File Integrity Checker

You are required to develop a tool that verifies the integrity of log files to detect tampering. This tool can be used to enhance security measures by using techniques such as file integrity monitoring and hashing to ensure that no unauthorized changes have been made to the log files.

1. Accept a directory or a single log file as input.
2. Utilize a cryptographic hashing algorithm, such as SHA-256, to compute hashes for each log file provided.
3. On first use, store the computed hashes in a secure location.
4. For subsequent uses, compare the newly computed hashes against the previously stored ones.
5. Clearly report any discrepancies found as a result of the hash comparison, indicating possible file tampering.
6. Allow for manual re-initialization of log file integrity.