Implement support for different users sending queries to the system. All users share a common filesystem in the cloud storage, but each user is assigned an individual storage capacity limit.

• add_user(self, user_id: str, capacity: int) -> bool
  Should add a new user to the system, with capacity as their storage limit in bytes. The total size of all files owned by user_id cannot exceed capacity. The operation fails if a user with user_id already exists. Returns True if a user with user_id is successfully created, or False otherwise.
• add_file_by(self, user_id: str, name: str, size: int) -> int | None
  Should behave in the same way as the add_file from Level 1, but the added file should be owned by the user with user_id. A new file cannot be added to the storage if doing so will exceed the user's capacity limit. Returns the remaining storage capacity for user_id if the file is successfully added or None otherwise. Note:
  • All queries calling the add_file operation implemented during Level 1 are run by the user with user_id = "admin", who has unlimited storage capacity.
  • Assume that the copy_file operation preserves the ownership of the original file.
• update_capacity(self, user_id: str, capacity: int) -> int | None
  Should change the maximum storage capacity for the user with user_id. If the total size of all user's files exceeds the new capacity, the largest files (sorted lexicographically in case of a tie) should be removed from the storage until the total size of all remaining files will no longer exceed the new capacity. Returns the number of removed files, or None if a user with user_id does not exist.

Examples

The example below shows how these operations should work:

Queries

1. add_user("user1", 125)
   • Returns True; creates user "user1".
2. add_user("user1", 100)
   • Returns False; "user1" already exists.
3. add_user("user2", 100)
   • Returns True; creates user "user2".
4. add_file_by("user2", "/file.med", 40)
   • Returns 75.
5. add_file_by("user1", "/dir/file.big", 50)
   • Returns 45.
6. add_file_by("user1", "/file.med", 30)
   • Returns None; file named "/file.med" already exists.
7. copy_file("/file.med", "/dir/another/file.med")
   • Returns True; copying preserves ownership.
8. copy_file("/dir/admin/file.med", "/dir/another/another/file.med")
   • Returns False; "user1" does not exist.
9. add_file_by("user1", "/dir/file.small", 10)
   • Returns 5.
10. add_file_by("user1", "/my_folder/file.huge", 100)
    • Returns None; "user1" does not have enough capacity.
11. add_file_by("user3", "/my_folder/file.huge", 100)
    • Returns None; "user3" doesn't exist.
12. update_capacity("user1", 300)
    • Returns 0; all files owned by "user1" fit into the new capacity.
13. update_capacity("user2", 50)
    • Returns 2; the files "/dir/file.big" and "/file.small" should be deleted to fit into the new capacity.
14. update_capacity("user2", 1000)
    • Returns None; "user2" does not exist.

Level 4

Implement support for file compression.

• compress_file(self, user_id: str, name: str) -> int | None
  Should compress the file name if it belongs to user_id. The compressed file should be replaced with a new file named <name>.COMPRESSED. The size of the newly created file should be equal to half of the original file. The size of all files is guaranteed to be even, so there should be no fractional calculations. It is also guaranteed that name for this operation never points to a compressed file (i.e., it never ends with .COMPRESSED). Compressed files should be owned by user_id—the owner of the original file. Returns the remaining storage capacity for user_id if the file was compressed successfully or None otherwise. Note:
  • Because file names can only contain lowercase letters, compressed files cannot be added via add_file.
  • It is guaranteed that all copy_file operations will preserve the suffix .COMPRESSED.
• decompress_file(self, user_id: str, name: str) -> int | None
  Should revert the compression of the file name if it belongs to user_id. It is guaranteed that name for this operation always ends with .COMPRESSED. If decompression results in the user_id exceeding their storage capacity limit or a decompressed version of the file with the given name already exists, the operation fails. Returns the remaining capacity of user_id if the file was decompressed successfully or None otherwise.

Examples

The example below shows how these operations should work:

Queries

1. add_user("user1", 1000)
   • Returns True.
2. add_user("user2", 5000)
   • Returns True.
3. add_file_by("user1", "/dir/file.mp4", 500)
   • Returns 500.
4. compress_file("user2", "/dir/file.mp4")
   • Returns None; user2 does not own the file.
5. compress_file("user1", "/dir/file.mp4")
   • Returns 750; the file is compressed to 250 bytes.
6. compress_file("user1", "/folder/non_existing_file")
   • Returns None; the file does not exist.
7. compress_file("user1", "/dir/file.mp4")
   • Returns None; the file is already compressed.
8. get_file_size("/dir/file.mp4.COMPRESSED")
   • Returns 250.
9. get_file_size("/dir/file.mp4")
   • Returns None; the file no longer exists.
10. copy_file("/dir/file.mp4.COMPRESSED", "/file.mp4.COMPRESSED")
    • Returns True.
11. add_file_by("user1", "/dir/file.mp4", 500)
    • Returns 0.
12. decompress_file("user1", "/dir/file.mp4.COMPRESSED")
    • Returns None; not enough capacity for decompression.
13. update_capacity("user1", 2000)
    • Returns 0.
14. decompress_file("user1", "/dir/file.mp4.COMPRESSED")
    • Returns 750.
15. decompress_file("user2", "/dir/file.mp4.COMPRESSED")
    • Returns None; user2 does not own the file.
16. decompress_file("user1", "/dir/file.mp4.COMPRESSED")
    • Returns None; the file is already decompressed.

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