CopyCat

Copies the contents from a source location to a destination location while handling various edge cases efficiently. Directory Copy Utility

Requirements and Edge Cases:

1. Objective Develop a C# utility to copy directory contents from a source location to a destination location while handling various edge cases efficiently.

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2. Features & Functional Requirements • Copy all files and subdirectories from source to destination. • Provide user-configurable options for overwrite behavior, symbolic links, logging, and concurrency. • Ensure robust error handling and efficient performance for large directories.

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3. Edge Cases & Considerations A. Functional Edge Cases
4. Source Directory Issues • Source directory does not exist → Throw an error or return failure? • Source is empty → Create an empty destination or skip? • Source is a file instead of a directory → Copy it or reject the request?
5. Destination Directory Issues • Destination does not exist → Automatically create it or require confirmation? • Destination is not empty: o Merge with existing files? o Overwrite existing files? o Rename duplicate files (file_copy.txt, file (1).txt)? o Skip existing files?
6. File Handling • File name conflicts: o Overwrite? o Skip? o Rename automatically? • Hidden/System Files → Should they be copied? • Symbolic Links: o Copy as links? o Resolve to actual files? • Special files (executables, DLLs, locked files, etc.) • Preserve timestamps, attributes, and permissions?
7. Subdirectory Handling • Handle deeply nested structures → Should we enforce a max depth? • Detect cyclic symbolic links to prevent infinite loops.

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B. Performance Edge Cases

1. Large Directory Handling • Process files sequentially or in parallel? • Limit max concurrent operations?
2. File Size Considerations • Handle large files efficiently → Use FileStream instead of File.Copy(). • Ensure no memory overflows.
3. Handling Network & External Drives • Support UNC paths (\server\share\folder).
4. Logging & Progress Updates • Provide real-time progress updates. • Track and log skipped/failed files.

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C. Failure & Error Handling

1. File in Use / Locked File • Retry? Skip? Log error?
2. Partial Copy & Rollback Strategy • Delete partially copied files on failure? • Allow partial copies to remain?
3. Disk Space Constraints • Check available space before copying.
4. Interruption Handling • Resume safely if the process is interrupted.

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4. Configurable Options (User Decisions Needed) • Overwrite behavior: Merge / Overwrite / Skip / Rename • Symbolic links: Copy as is / Resolve to actual file • Hidden files: Include / Exclude • Logging: Enable / Disable / Log level (Verbose, Errors only, etc.) • Parallel processing: Enable / Disable / Max concurrency • Error handling: Fail fast / Continue and log errors

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5. Implementation Considerations • Concurrency Strategy: Use Parallel.ForEach() for multi-threading. • Error Handling: Fail fast or log and continue based on user choice. • Logging: Use Serilog or Console.WriteLine(). • File Handling: Use FileStream for better performance on large files.

Build and run cmd: CopyCat.exe --source "C:\Source" --destination "D:\Backup" --overwrite true --log verbose --parallel true