Problem

Given a local file path file_path and an expected checksum string expected_checksum, write a function that verifies whether the file exists, is non-empty, and its SHA-256 checksum matches the expected value. Return True if the file passes all checks; otherwise return False.

Examples

Example 1:

Input: file_path = "report.bin", expected_checksum = "abc123..."
Output: True
Explanation: The file exists, has content, and its computed SHA-256 matches the expected checksum.

Example 2:

Input: file_path = "missing.bin", expected_checksum = "abc123..."
Output: False
Explanation: The file does not exist, so verification fails.

Constraints

• 1 <= len(file_path) <= 10^3
• len(expected_checksum) should be 64 hexadecimal characters for SHA-256
• The file size may be large, so the solution should avoid loading the entire file into memory
• Return False for missing files, empty files, unreadable files, or checksum mismatches