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         DATA STRUCTURES AND ALGORITHMS
         ASSIGNMENT 7: File System Simulator Using Trees
         State University of Zanzibar (SUZA)
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ANTI-PLAGIARISM NOTICE:
This assignment requires LIVE DEMONSTRATION (viva). You must:
1. Explain every function in your code
2. Modify your code on the spot when asked
3. Answer questions about your design choices
4. Submit a HANDWRITTEN design document
AI-generated or copied code will result in ZERO marks.

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PROJECT DESCRIPTION
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Build a simplified file system simulator using a tree data structure.
The file system should support directories (folders) and files,
organized in a hierarchical tree structure.

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REQUIREMENTS
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DATA STRUCTURES:
   struct FileNode {
       char name[50];
       int isDirectory;        // 1 for directory, 0 for file
       int size;               // file size in bytes (0 for directories)
       struct FileNode *child;  // first child (for directories)
       struct FileNode *sibling; // next sibling in same directory
       struct FileNode *parent;  // parent directory
   };

OPERATIONS TO IMPLEMENT:

1. mkdir <dirname>
   - Create a new directory inside the current directory
   - Print error if name already exists

2. touch <filename> <size>
   - Create a new file with given size inside current directory
   - Print error if name already exists

3. ls
   - List all files and directories in current directory
   - Display type (DIR/FILE), name, and size
   - Format:
     DIR   documents
     DIR   pictures
     FILE  readme.txt      1024
     FILE  notes.txt       512

4. cd <dirname>
   - Change to specified directory
   - Support "cd .." to go to parent
   - Print error if directory not found

5. pwd
   - Print current working directory path
   - Example: /home/student/documents

6. find <name>
   - Search for file/directory by name in entire tree
   - Print full path of all matches

7. rm <name>
   - Remove a file or empty directory from current directory
   - If directory is not empty, ask for confirmation
   - Recursively delete contents if confirmed

8. tree
   - Display entire file system as a visual tree:
     /
     |-- documents/
     |   |-- report.txt (2048)
     |   |-- notes.txt (512)
     |-- pictures/
     |   |-- photo1.jpg (4096)
     |-- readme.txt (1024)

9. size <dirname>
   - Calculate total size of all files in a directory (recursively)

10. save <filename>
    - Save entire file system structure to a text file
    - Format: PATH TYPE SIZE (one entry per line)

11. load <filename>
    - Load file system from saved file
    - Reconstruct the tree

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MENU INTERFACE
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The program should have a command-line style interface:

   File System Simulator
   Type 'help' for available commands

   /> mkdir home
   Directory 'home' created.
   /> cd home
   /home> mkdir documents
   /home> touch readme.txt 1024
   /home> ls
   DIR   documents
   FILE  readme.txt      1024
   /home> pwd
   /home
   /home> tree
   ...
   /home> quit

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TEST SCENARIOS
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Build this structure and verify all operations:
   /
   |-- home/
   |   |-- student/
   |   |   |-- assignment.c (2048)
   |   |   |-- notes.txt (512)
   |   |-- shared/
   |       |-- data.csv (4096)
   |-- tmp/
   |   |-- temp.txt (100)

Test: pwd from student -> /home/student
Test: find assignment.c -> /home/student/assignment.c
Test: size home -> 6656 (2048+512+4096)
Test: rm temp.txt from tmp, then ls tmp -> (empty)
Test: save and load, verify tree is identical

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HANDWRITTEN DESIGN DOCUMENT (Required)
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Submit on paper:
1. Draw the tree structure for the test scenario above
2. Explain your choice of child-sibling representation
3. Trace the pwd function call from /home/student
4. Trace the find function searching for "data.csv"
5. Explain how rm handles recursive deletion

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GRADING RUBRIC
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| Component                    | Marks |
|------------------------------|-------|
| Data structure design        |   10  |
| mkdir, touch, ls             |   15  |
| cd, pwd                      |   15  |
| find, rm                     |   15  |
| tree display                 |   10  |
| size calculation             |    5  |
| save/load                    |   10  |
| Menu interface & error handling|  5  |
| Handwritten design document  |   15  |
| Total                        |  100  |

Viva Demonstration: Required (multiplier: 0 or 1)
- You must run the program and explain your code
- Be prepared to add a new feature on the spot

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VIVA QUESTIONS:
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1. Why did you use child-sibling representation?
2. What is the time complexity of your find operation?
3. How does your cd handle invalid paths?
4. Add a "mv" (move) command that moves a file to another directory (live).
5. How would you implement file permissions?
6. What would change if you used a BST instead of a general tree?

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