Server DOS

-- Server Program

-- Function to find and return the modem peripheral
local function findModem()
    for _, side in ipairs(peripheral.getNames()) do
        if peripheral.getType(side) == "modem" then
            return side
        end
    end
    return nil
end

local modemSide = findModem()
if not modemSide then
    print("Error: No modem found. Please attach a modem.")
    return
end

rednet.open(modemSide)

local saveDirectory = "DGOS"
local serverID = os.getComputerID()

-- Create save directory if it doesn't exist
if not fs.exists(saveDirectory) then
    fs.makeDir(saveDirectory)
end

-- Function to display advanced GUI on the monitor
local function drawGUI()
    local monitor = peripheral.wrap("right")
    monitor.setTextScale(0.5)
    monitor.setBackgroundColor(colors.black)
    monitor.clear()

    -- Header
    monitor.setCursorPos(1, 1)
    monitor.setTextColor(colors.white)
    monitor.write("Server ID: " .. tostring(serverID))

    -- Status area
    monitor.setCursorPos(1, 3)
    monitor.setBackgroundColor(colors.gray)
    monitor.clearLine()
    monitor.write("Status: ")

    -- Logs area
    monitor.setCursorPos(1, 5)
    monitor.setBackgroundColor(colors.gray)
    monitor.clearLine()
    monitor.write("Logs:")
end

-- Function to update status in GUI
local function updateStatus(status)
    local monitor = peripheral.wrap("right")
    monitor.setCursorPos(9, 3)
    monitor.setBackgroundColor(colors.gray)
    monitor.clearLine()
    monitor.write(status)
end

-- Function to log file transfer in GUI
local function logTransfer(fileName, success)
    local monitor = peripheral.wrap("right")
    monitor.setCursorPos(1, 7)
    monitor.setTextColor(colors.white)
    monitor.setBackgroundColor(colors.black)
    monitor.clearLine()
    monitor.write(string.format("File: %s | Status: %s", fileName, success and "Success" or "Failure"))
end

-- Function to display file details and await confirmation
local function confirmFileTransfer(fileName, fileContent)
    local monitor = peripheral.wrap("right")
    monitor.clear()
    monitor.setCursorPos(1, 1)
    monitor.write("Incoming file:")
    monitor.setCursorPos(1, 3)
    monitor.write("Name: " .. fileName)
    monitor.setCursorPos(1, 4)
    monitor.write("Size: " .. string.len(fileContent) .. " bytes")
    monitor.setCursorPos(1, 5)
    monitor.write("[Confirm]")
    monitor.setCursorPos(1, 6)
    monitor.write("[Decline]")

    while true do
        local event, side, x, y = os.pullEvent("monitor_touch")
        if y == 5 then
            return true
        elseif y == 6 then
            return false
        end
    end
end

-- Function to handle displaying critical information
local function displayCriticalInformation(criticalMessage)
    print("Critical Error: " .. criticalMessage)
    local monitor = peripheral.wrap("right")
    monitor.setCursorPos(1, 9)
    monitor.setBackgroundColor(colors.red)
    monitor.clearLine()
    monitor.setTextColor(colors.white)
    monitor.write("Critical: " .. criticalMessage)
end

-- Initialize GUI
drawGUI()

-- Main loop to receive messages
while true do
    local senderID, message, protocol = rednet.receive()

    if protocol == "file_transfer" then
        print("Received file from ID: " .. senderID)

        if type(message) == "table" and message.fileName and message.fileContent then
            -- Display file details and wait for confirmation
            local confirmed = confirmFileTransfer(message.fileName, message.fileContent)

            if confirmed then
                -- Save file if confirmed
                local filePath = fs.combine(saveDirectory, message.fileName)
                local file = fs.open(filePath, "w")
                file.write(message.fileContent)
                file.close()

                print("File saved as " .. message.fileName)

                -- Update GUI
                updateStatus("File received")
                logTransfer(message.fileName, true)
                sleep(2)
                drawGUI()

                -- Send confirmation to client
                rednet.send(senderID, { status = "Accepted" }, "confirmation")
            else
                print("File transfer declined.")
                logTransfer(message.fileName, false)
                updateStatus("File declined")
                sleep(2)
                drawGUI()

                -- Send confirmation to client
                rednet.send(senderID, { status = "Declined" }, "confirmation")
            end
        else
            print("Invalid message received.")
            displayCriticalInformation("Invalid file transfer request.")
        end
    else
        -- Assuming other protocols indicate critical information
        displayCriticalInformation(message)
    end
end