-- Function to log connections
local function logConnection(id, message)
    local logFile = "dns_log.txt"
    local file = fs.open(logFile, "a")
    file.writeLine("ID: " .. id .. " - " .. message .. " - " .. textutils.formatTime(os.time(), true))
    file.close()
end

-- Function to check if an ID is blocked
local function isBlocked(id)
    local blockFile = "/blocked/" .. tostring(id) .. ".txt"
    return fs.exists(blockFile)
end

-- Function to block an ID
local function blockID(id)
    local blockFile = "/blocked/" .. tostring(id) .. ".txt"
    local file = fs.open(blockFile, "w")
    file.write("Blocked")
    file.close()
end

-- Function to unblock an ID
local function unblockID(id)
    local blockFile = "/blocked/" .. tostring(id) .. ".txt"
    if fs.exists(blockFile) then
        fs.delete(blockFile)
    end
end

-- Function to load website IP from file
local function loadWebsiteIP(url)
    local filePath = "/DNS/" .. url
    if not fs.exists(filePath) then
        return nil
    end
    local file = fs.open(filePath, "r")
    local ip = file.readAll()
    file.close()
    return ip
end

-- Function to add a website to the DNS
local function addWebsite(url, ip)
    local filePath = "/DNS/" .. url
    local file = fs.open(filePath, "w")
    file.write(ip)
    file.close()
end

-- Function to remove a website from the DNS
local function removeWebsite(url)
    local filePath = "/DNS/" .. url
    if fs.exists(filePath) then
        fs.delete(filePath)
    end
end

-- Open modem
local modemSide = "top"  -- Change to the side your modem is connected to
rednet.open(modemSide)

local function drawMenu()
    term.clear()
    term.setCursorPos(1, 1)
    print("DNS Server Control Panel")
    print("1. View Logs")
    print("2. Block ID")
    print("3. Unblock ID")
    print("4. Add Website")
    print("5. Remove Website")
    print("6. Exit")
    print("Select an option:")
end

local function viewLogs()
    term.clear()
    term.setCursorPos(1, 1)
    print("Logs:")
    if fs.exists("dns_log.txt") then
        local file = fs.open("dns_log.txt", "r")
        while true do
            local line = file.readLine()
            if line == nil then break end
            print(line)
        end
        file.close()
    else
        print("No logs found.")
    end
    print("\nPress any key to return to the menu...")
    os.pullEvent("key")
end

local function blockUser()
    term.clear()
    term.setCursorPos(1, 1)
    print("Enter the ID to block:")
    local id = read()
    blockID(id)
    print("Blocked ID: " .. id)
    print("\nPress any key to return to the menu...")
    os.pullEvent("key")
end

local function unblockUser()
    term.clear()
    term.setCursorPos(1, 1)
    print("Enter the ID to unblock:")
    local id = read()
    unblockID(id)
    print("Unblocked ID: " .. id)
    print("\nPress any key to return to the menu...")
    os.pullEvent("key")
end

local function addWebsiteUI()
    term.clear()
    term.setCursorPos(1, 1)
    print("Enter the URL to add:")
    local url = read()
    print("Enter the IP for " .. url .. ":")
    local ip = read()
    addWebsite(url, ip)
    print("Added website: " .. url .. " with IP: " .. ip)
    print("\nPress any key to return to the menu...")
    os.pullEvent("key")
end

local function removeWebsiteUI()
    term.clear()
    term.setCursorPos(1, 1)
    print("Enter the URL to remove:")
    local url = read()
    removeWebsite(url)
    print("Removed website: " .. url)
    print("\nPress any key to return to the menu...")
    os.pullEvent("key")
end

-- Main control loop for UI
local function controlPanel()
    while true do
        drawMenu()
        local choice = read()
        if choice == "1" then
            viewLogs()
        elseif choice == "2" then
            blockUser()
        elseif choice == "3" then
            unblockUser()
        elseif choice == "4" then
            addWebsiteUI()
        elseif choice == "5" then
            removeWebsiteUI()
        elseif choice == "6" then
            break
        else
            print("Invalid option, try again.")
        end
    end
end

-- Run DNS server in parallel with control panel
local function dnsServer()
    print("DNS server is running...")
    while true do
        -- Wait for a DNS request
        local senderID, url = rednet.receive()
        logConnection(senderID, "Requested URL: " .. url)

        -- Check if the sender is blocked
        if isBlocked(senderID) then
            rednet.send(senderID, "ERROR 403: Your IP address has been blocked from this DNS Network")
            logConnection(senderID, "Blocked")
        else
            -- Look up the IP address for the requested URL
            local ip = loadWebsiteIP(url)
            if ip then
                rednet.send(senderID, ip)
                logConnection(senderID, "Sent IP: " .. ip)
            else
                rednet.send(senderID, "404_NOT_FOUND")
                logConnection(senderID, "URL not found")
            end
        end
    end
end

-- Run the DNS server and UI in parallel
parallel.waitForAny(dnsServer, controlPanel)