ndisk server migration

-- migrate_to_ndisk.lua
-- Script to migrate data from local disk "students/" folder to NDisk

local ndisk = require("ndisk_api")
local disk = peripheral.find("drive")
if not disk then
    print("Error: No disk drive found. Cannot read source data.")
    return
end

local diskMount = disk.getMountPath()
if not diskMount then
    print("Error: No disk inserted.")
    return
end

if not fs.exists(diskMount .. "/students") then
    print("Error: 'students' directory not found on disk.")
    return
end

print("Initializing NDisk...")
ndisk.init()
print("Starting migration...")

local successCount = 0
local failCount = 0

local function migrateFile(localPath, ndiskPath)
    print("Migrating: " .. ndiskPath)
    local file = fs.open(localPath, "r")
    local content = file.readAll()
    file.close()

    local success, err = ndisk.write(ndiskPath, content)
    if success then
        -- Verify
        local readBack, readErr = ndisk.read(ndiskPath)
        if readBack == content then
            print("  [OK]")
            successCount = successCount + 1
        else
            print("  [FAIL] Verification mismatch: " .. (readErr or "Content differs"))
            failCount = failCount + 1
        end
    else
        print("  [FAIL] Write error: " .. (err or "matches"))
        failCount = failCount + 1
    end
end

local function traverse(path, relativePath)
    local list = fs.list(path)
    for _, item in ipairs(list) do
        local fullPath = fs.combine(path, item)
        local newRelPath = relativePath == "" and item or (relativePath .. "/" .. item)

        if fs.isDir(fullPath) then
            traverse(fullPath, newRelPath)
        else
            -- Check if it's a student file?
            -- path starts with diskMount .. "/students"
            -- relPath starts with "students/..." if we pass that?
            -- Actually, we want keys in NDisk to be "students/ID/file.txt"
            -- So if we iterate inside "diskMount/students", relativePath is "ID/file.txt"
            -- We want to prepend "students/"

            local ndiskKey = "students/" .. newRelPath
            migrateFile(fullPath, ndiskKey)
        end
    end
end

traverse(diskMount .. "/students", "")

print("Migration Complete.")
print("Success: " .. successCount)
print("Failed: " .. failCount)
print("You can verify manually via 'ndisk_api' or running the server.")