Specification

This document describes abstractly the behavior and structure of the Duplicate File Finder tool.

Command line interface

The implementation must provide a command line interface with the following features.

Zero subcommands
A variadic argument for paths to search
A variadic option --exclude for path patterns to exclude
A boolean flag --fail-on-duplicate to exit with a non-zero exit code if duplicates are found
An enum option --compare-method to specify the method of comparing files
- The enum must have the following variants:
  - size
  - partial-hash
  - hash
- The default value must be hash
An enum option --output-format to specify the format of the output
- The enum must have the following variants:
  - json
  - list
- The default value must be json

An example of an invocation command is given below.

executable path1 path2 --exclude pattern1 --exclude pattern2 --fail-on-duplicate --compare-method partial-hash --output-format list

The implementation must implement the following functions.

A function to recursively find all files in a directory, excluding those matching an exclude pattern
- Which accepts the following parameters:
  - A collection of directory paths to search
  - A collection of path patterns to exclude
- And returns the following values:
  - A collection of file paths or implementation-specific objects which represent files
A function to calculate an MD5 hash of a file
- Which accepts the following parameters:
  - A file path or implementation-specific object representing a file
  - An enum member representing the type of hash to calculate, must be either partial or full
- And returns the following values:
  - An MD5 hash of the file or an implementation-specific object which represents a file and contains the hash
A function that serves as an entrypoint to invoke the CLI
- Which accepts the parameters necessary to implement the CLI
- Returns no values
- And performs the actions described in Behavior

Upon invocation, the implementation must perform the following actions.

Search for files in the specified paths, excluding those matching the exclude patterns
Filter the files by comparing them and ignoring unique files
- The comparison methods performed must be all methods up to and including the specified method, in the order of size, partial hash, and full hash
Output the results in the specified format to stdout as a mapping of hashes to collections of file paths

The implementation may output additional information to stderr, including but not limited to the following.