feat: Support pre-calculated checksums in SIP generation

[JohannesKarlsen99]

This PR adds support for using pre-calculated checksums during E-ARK SIP generation, avoiding redundant checksum calculations for large files.

Fixes #368

Changes

Interface Changes

• IPFileInterface.java: Added getChecksum(), getChecksumAlgorithm(), and hasPreCalculatedChecksum(String algorithm) methods to the interface

Implementation Changes

• IPFileShallow.java: Implemented the new interface methods
• METSFileTypeZipEntryInfo.java: Added constructor that accepts pre-calculated checksum
• ZIPUtils.java:
  • Added overloaded addFileTypeFileToZip() method accepting pre-calculated checksum
  • Modified zip() to skip checksum calculation when valid pre-calculated checksum exists
  • Added copyWithoutChecksum() helper method
  • Replaced deprecated DatatypeConverter.printHexBinary with HexFormat
• FolderWriteStrategy.java:
  • Modified writeFileToPath() to skip checksum calculation when valid pre-calculated checksum exists
  • Replaced deprecated DatatypeConverter.printHexBinary with HexFormat
• EARKUtils.java: Updated all addFileTypeFileToZip() calls to pass checksum from IPFile

Bug Fix

Fixed a bug where file.setChecksum(sip.getChecksum()) was overwriting the pre-calculated checksum with the algorithm name before it could be used. The fix saves the pre-calculated checksum values before this call.

Usage Example

// Create a file with pre-calculated checksum
IPFile representationFile = new IPFile(Paths.get("large_video.mkv"));
representationFile.setChecksum("ABC123DEF456...");  // Your pre-calculated checksum
representationFile.setChecksumAlgorithm("SHA-256");  // Must match SIP's algorithm
representation.addFile(representationFile);

// When building the SIP, the checksum won't be recalculated
Path sipPath = sip.build(writeStrategy);

Testing

Added testPreCalculatedChecksumSupport() test that:

1. Sets a fake checksum on an IPFile
2. Builds a SIP
3. Extracts the SIP and verifies the fake checksum appears in the METS file
4. This proves the library uses the pre-calculated value rather than calculating

[dosubot]

Related Documentation

1 document(s) may need updating based on files changed in this PR:

RODA and DBPTK Space

• SIP (Submission Information Package) Structure and Management

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