local DOMAIN_FILE = "/.Domain_ID"
local CACHED_USERS = "/disk/cached_users"

-- Connect to Domain Controller
local function connectToDomainController()
    if fs.exists(DOMAIN_FILE) then
        local file = fs.open(DOMAIN_FILE, "r")
        local domainID = file.readLine()
        file.close()
        return domainID
    else
        return nil
    end
end

-- Fetch user data from the domain controller
local function fetchUserData(domainID)
    rednet.open("top") -- Adjust as per modem side
    rednet.send(domainID, textutils.serialize({type = "fetch_users"}))
    local _, message = rednet.receive()
    local userData = textutils.unserialize(message)
    rednet.close()

    -- Cache user data locally
    local file = fs.open(CACHED_USERS, "w")
    file.write(textutils.serialize(userData))
    file.close()
end

-- Validate login credentials
local function validateCredentials(domainID, username, password)
    rednet.open("top")
    rednet.send(domainID, textutils.serialize({type = "authenticate", username = username, password = password}))
    local _, message = rednet.receive()
    rednet.close()

    local response = textutils.unserialize(message)
    return response.success, response.roles
end

-- Login process
local function login()
    local domainID = connectToDomainController()
    if not domainID then
        print("Domain controller not found.")
        return
    end

    if not fs.exists(CACHED_USERS) then
        print("Fetching user data from the domain controller...")
        fetchUserData(domainID)
    end

    local file = fs.open(CACHED_USERS, "r")
    local cachedUsers = textutils.unserialize(file.readAll())
    file.close()

    print("Enter username:")
    local username = read()
    if not cachedUsers[username] then
        print("User not found.")
        return
    end

    print("Enter password:")
    local password = read("*")
    local success, roles = validateCredentials(domainID, username, password)

    if success then
        print("Login successful!")
        print("Roles: " .. table.concat(roles, ", "))
        -- Proceed to GUI or other functionality
    else
        print("Invalid credentials.")
    end
end

login()