#!/usr/bin/env python3

import os
import sys
import json
import argparse


# Function to get hard links between source and target directories
def get_hard_links(source_dir, target_dir):
    # Dictionary to store hard links
    source_links = {}
    target_links = {}

    # Walk through the source directory to collect hard links
    for dirpath, _, filenames in os.walk(source_dir):
        for filename in filenames:
            filepath = os.path.join(dirpath, filename)
            try:
                inode = os.stat(filepath).st_ino
                if inode not in source_links:
                    source_links[inode] = []
                source_links[inode].append(filepath)
            except FileNotFoundError:
                continue

    # Walk through the target directory to collect hard links
    for dirpath, _, filenames in os.walk(target_dir):
        for filename in filenames:
            filepath = os.path.join(dirpath, filename)
            try:
                inode = os.stat(filepath).st_ino
                if inode not in target_links:
                    target_links[inode] = []
                target_links[inode].append(filepath)
            except FileNotFoundError:
                continue

    # Generate the list of tuples (relative_src, relative_dst)
    hard_links = []
    for inode, target_files in target_links.items():
        if inode in source_links:
            for target_file in target_files:
                relative_target = os.path.relpath(target_file, target_dir)
                for source_file in source_links[inode]:
                    relative_source = os.path.relpath(source_file, source_dir)
                    hard_links.append([relative_source, relative_target])

    return hard_links


def main():
    # Argument parser for CLI arguments
    parser = argparse.ArgumentParser(description="Collect hard links between source and target directories.")
    parser.add_argument('source_dir', help="Path to the source directory")
    parser.add_argument('target_dir', help="Path to the target directory")

    args = parser.parse_args()

    hard_links = get_hard_links(args.source_dir, args.target_dir)
    print(json.dumps(hard_links, indent=2))


if __name__ == "__main__":
    main()