-- Remote Desktop System for ComputerCraft
-- Usage: Run "host" on the server computer, "client" on the controlling computer

local mode = ...
if not mode then
    print("Usage: remote <host|client>")
    return
end

-- Configuration
local PROTOCOL = "remote_desktop"
local REFRESH_RATE = 0.5

-- Host Mode - Computer being controlled
if mode == "host" then
    print("Starting Remote Desktop Host...")
    print("Opening rednet...")

    -- Find and open modem
    local modem = peripheral.find("modem")
    if not modem then
        print("Error: No modem found!")
        return
    end

    rednet.open(peripheral.getName(modem))
    rednet.host(PROTOCOL, "remote_host")

    print("Host ready! ID: " .. os.getComputerID())
    print("Waiting for client connection...")

    local clientID = nil
    local running = true

    -- Function to capture screen
    local function captureScreen()
        local w, h = term.getSize()
        local screen = {}
        local oldX, oldY = term.getCursorPos()

        for y = 1, h do
            screen[y] = {}
            for x = 1, w do
                term.setCursorPos(x, y)
                local char = term.read() or " "
                screen[y][x] = char:sub(1, 1)
            end
        end

        term.setCursorPos(oldX, oldY)
        return {content = screen, width = w, height = h, cursorX = oldX, cursorY = oldY}
    end

    -- Main loop
    while running do
        local event, p1, p2, p3 = os.pullEvent()

        if event == "rednet_message" then
            local senderID, message = p1, p2

            if type(message) == "table" then
                if message.type == "connect" then
                    clientID = senderID
                    print("Client connected: " .. clientID)
                    rednet.send(clientID, {type = "connect_ack"}, PROTOCOL)

                elseif message.type == "command" and senderID == clientID then
                    print("Executing: " .. message.cmd)
                    shell.run(message.cmd)

                elseif message.type == "text" and senderID == clientID then
                    term.write(message.content)

                elseif message.type == "screen_request" and senderID == clientID then
                    local screen = captureScreen()
                    rednet.send(clientID, {type = "screen_data", screen = screen}, PROTOCOL)

                elseif message.type == "disconnect" and senderID == clientID then
                    print("Client disconnected")
                    clientID = nil
                end
            end
        end
    end

-- Client Mode - Controlling computer
elseif mode == "client" then
    print("Starting Remote Desktop Client...")

    -- Find and open modem
    local modem = peripheral.find("modem")
    if not modem then
        print("Error: No modem found!")
        return
    end

    rednet.open(peripheral.getName(modem))

    -- Find host
    print("Looking for host...")
    local hostID = rednet.lookup(PROTOCOL, "remote_host")

    if not hostID then
        print("Error: No host found!")
        print("Make sure host is running.")
        return
    end

    print("Found host: " .. hostID)
    print("Connecting...")

    -- Connect to host
    rednet.send(hostID, {type = "connect"}, PROTOCOL)
    local id, msg = rednet.receive(PROTOCOL, 5)

    if not msg or msg.type ~= "connect_ack" then
        print("Connection failed!")
        return
    end

    print("Connected!")
    print("")
    print("Commands:")
    print("  cmd <command> - Run command on host")
    print("  text <text>   - Display text on host")
    print("  screen        - View host screen")
    print("  exit          - Disconnect")
    print("")

    -- Main client loop
    local running = true
    while running do
        write("> ")
        local input = read()
        local parts = {}
        for word in input:gmatch("%S+") do
            table.insert(parts, word)
        end

        if #parts == 0 then
            -- Empty input, continue
        elseif parts[1] == "cmd" then
            local cmd = input:match("cmd%s+(.+)")
            if cmd then
                rednet.send(hostID, {type = "command", cmd = cmd}, PROTOCOL)
                print("Command sent")
            else
                print("Usage: cmd <command>")
            end

        elseif parts[1] == "text" then
            local txt = input:match("text%s+(.+)")
            if txt then
                rednet.send(hostID, {type = "text", content = txt}, PROTOCOL)
                print("Text sent")
            else
                print("Usage: text <text>")
            end

        elseif parts[1] == "screen" then
            print("Requesting screen...")
            rednet.send(hostID, {type = "screen_request"}, PROTOCOL)

            local id, msg = rednet.receive(PROTOCOL, 5)
            if msg and msg.type == "screen_data" then
                term.clear()
                term.setCursorPos(1, 1)

                local screen = msg.screen
                for y = 1, screen.height do
                    term.setCursorPos(1, y)
                    for x = 1, screen.width do
                        term.write(screen.content[y][x])
                    end
                end

                print("")
                print("--- End of screen (Press any key) ---")
                os.pullEvent("key")
                term.clear()
                term.setCursorPos(1, 1)
            else
                print("Failed to receive screen data")
            end

        elseif parts[1] == "exit" then
            rednet.send(hostID, {type = "disconnect"}, PROTOCOL)
            print("Disconnected")
            running = false

        else
            print("Unknown command: " .. parts[1])
        end
    end

    rednet.close()
else
    print("Invalid mode. Use 'host' or 'client'")
end