-- Open a rednet connection
peripheral.find("modem", rednet.open)

-- A function to make a cool terminal window
function makeScreen(lines)
    term.clear()
    term.setCursorPos(1, 1)
    
    for i = 1, #lines do
        print(lines[i])
    end

    print("\nCakeHUD")
end

-- Gets power level from the block below the computer
function getPowerLevel()
    local block = peripheral.wrap("bottom")
    
    return {
        power = block.getEnergyStored(),
        maxPower = block.getEnergyCapacity()
    }
end

-- Gets the server's TPS
function getTPS()
    local game_time_start = os.epoch "utc"
    
    sleep(0.1)

    local game_time_end = os.epoch "utc"
    local game_time_diff = game_time_end - game_time_start
    local utc_elapsed_seconds = game_time_diff / 100

    return 20 / utc_elapsed_seconds
end

function getReactorStatus()
    -- wait for a message on the cakehud_reactor channel
    local senderId, message, protocol = rednet.receive("cakehud_reactor")
    
    -- true if the reactor is charging, false if it's discharging
    return message == "reactor_charging"
end

local todo = {}
-- open the todo file
if fs.exists("todo.txt") then
    local file = fs.open("todo.txt", "r")
    todo = textutils.unserialize(file.readAll())
    file.close()
end

function waitForTodo()
    -- wait for a message on the cakehud_todo channel
    local senderId, message, protocol = rednet.receive("cakehud_todo")
    print("Received todo message: " .. message)

    -- deserialize the message
    local data = textutils.unserialize(message)

    -- add the data to the todo list
    if data.type == "add" then
        table.insert(todo, data.text)
        print("Added todo item: " .. data.text)
    end

    -- remove the data from the todo list
    if data.type == "delete" then
        -- find the index of the todo item
        if todo[data.id] then
            table.remove(todo, data.id)
        end
    end
    
    -- write the todo to file
    local file = fs.open("todo.txt", "w")
    file.write(textutils.serialize(todo))
    file.close()
end

-- Main loop
function processData()
    -- Run the functions asynchronously
    local powerLevel = getPowerLevel()
    local tps = getTPS()
    local reactorStatus = getReactorStatus()

    -- Make the screen
    makeScreen({
        "TPS: " .. math.floor(tps),
        "Power: " .. powerLevel.power .. "/" .. powerLevel.maxPower,
        "Reactor status: " .. (reactorStatus and "charging" or "discharging")
    })

    -- Transmit the data
    rednet.broadcast(textutils.serialize({
        power = powerLevel,
        tps = tps,
        reactorStatus = reactorStatus,
        todo = todo
    }), "cakehud")

    -- Wait
    sleep(0.25)
end

-- Run the main loop
while true do
    parallel.waitForAny(processData, waitForTodo)
end