Design File Management System

Instructions

Design an in-memory file management system, built up over three levels:

1. Create & read — create files and retrieve them by ID.
2. Update — modify a file's name and content.
3. Delete — remove files; IDs are never reused.

Each file has a name, text content, and metadata timestamps for when it was created and last modified. Like most real filesystems, names must be unique and are compared case-insensitively ("Report.txt" and "report.txt" conflict).

Interfaces

class FileManager:
    def create_file(self, name: str, content: str, timestamp: int) -> str: ...
    def get_file(self, file_id: str) -> str: ...
    def update_file(self, file_id: str, name: str, content: str, timestamp: int) -> bool: ...
    def delete_file(self, file_id: str) -> bool: ...

Level 1: Create & Read

Implement create_file and get_file.

• create_file(name, content, timestamp) stores a new file and returns its assigned ID. IDs are formatted "file1", "file2", … and assigned sequentially starting from 1. The file's creation and modification times are both set to timestamp. If the name conflicts (case-insensitive) with an existing file, nothing is stored and "" is returned.
• get_file(file_id) returns the file as a pipe-delimited string, "<file_id>|<name>|<content>|<created_at>|<modified_at>", or "" if the ID does not exist.

fm.create_file("report.txt", "Q1 numbers", 100)   # "file1"
fm.create_file("notes.md", "draft", 105)          # "file2"
fm.create_file("REPORT.TXT", "other", 110)        # ""  — name conflict (case-insensitive)

fm.get_file("file1")   # "file1|report.txt|Q1 numbers|100|100"
fm.get_file("file9")   # ""

Function signature:

class FileManager:
    def __init__(self):
        pass

    def create_file(self, name: str, content: str, timestamp: int) -> str:
        pass

    def get_file(self, file_id: str) -> str:
        pass

Level 2: Update

Add update_file(file_id, name, content, timestamp), which replaces the file's name and content, sets its modification time to timestamp (creation time is unchanged), and returns True. It returns False if:

• file_id does not exist, or
• name conflicts (case-insensitive) with a different stored file.

Renaming a file to its own name — even with different casing — is allowed.

fm.create_file("report.txt", "v1", 100)                  # "file1"
fm.create_file("notes.md", "draft", 105)                 # "file2"

fm.update_file("file1", "Report.txt", "v2", 120)         # True — own name, new casing
fm.get_file("file1")                                     # "file1|Report.txt|v2|100|120"

fm.update_file("file2", "REPORT.TXT", "x", 125)          # False — conflicts with file1
fm.update_file("file9", "misc.txt", "x", 130)            # False — no such ID

Function signature:

class FileManager:
    def __init__(self):
        pass

    def create_file(self, name: str, content: str, timestamp: int) -> str:
        pass

    def get_file(self, file_id: str) -> str:
        pass

    def update_file(self, file_id: str, name: str, content: str, timestamp: int) -> bool:
        pass

Level 3: Delete

Add delete_file(file_id), which removes the file and returns True, or returns False if the ID does not exist. After deletion the name becomes available again, but the ID counter never goes back — deleted IDs are never reused.

fm.create_file("report.txt", "v1", 100)   # "file1"
fm.delete_file("file1")                   # True
fm.delete_file("file1")                   # False — already gone

fm.create_file("report.txt", "v2", 140)   # "file2" — name free again, ID not reused
fm.get_file("file1")                      # ""

Function signature:

class FileManager:
    def __init__(self):
        pass

    def create_file(self, name: str, content: str, timestamp: int) -> str:
        pass

    def get_file(self, file_id: str) -> str:
        pass

    def update_file(self, file_id: str, name: str, content: str, timestamp: int) -> bool:
        pass

    def delete_file(self, file_id: str) -> bool:
        pass