local drive = peripheral.find("tape_drive")
if not drive then
    printError("no tape drive found")
    printError("it's kinda required to play tapes, you know?")
    return
end

local running = true

local table_of_contents = {}

local function read32()
    local v = 0
    for i = 1, 4 do
        local b = drive.read()
        v = bit32.bor(bit32.lshift(v, 8), b)
    end
    return v
end

local function bytes2time(b)
    local s = math.floor(b / 6000)
    if s < 60 then return string.format("%ds", s) end
    return string.format("%dm, %ds", math.floor(s / 60), s % 60)
end

term.clear()
local screen_w, screen_h = term.getSize()

parallel.waitForAll(
function()
    while running do
        for i = 1, math.min(screen_h - 1, 48) do
            term.setCursorPos(1, i)
            term.clearLine()
            local song = table_of_contents[i]
            if song then
                term.write(string.format("#%2d %9s %s", i, bytes2time(song.length), song.title))
            end
        end
        term.setCursorPos(1, screen_h)
        term.clearLine()
        term.write(string.format("%s - %d", drive.getState(), drive.getPosition()))
        os.sleep(0.1)
    end
end,
function()
    while running do
        local evd = { os.pullEvent() }
        local ev, evd = table.remove(evd, 1), evd

        if ev == "mouse_click" then
            local x, y = table.unpack(evd, 2)
            if drive.isReady() and y <= #table_of_contents then
                drive.seek(-drive.getSize())
                drive.seek(table_of_contents[y].offset)
                drive.play()
            end
        elseif ev == "term_resize" then
            term.clear()
            screen_w, screen_h = term.getSize()
        elseif ev == "tape_present" then
            table_of_contents = {}
            if evd[1] then
                drive.stop()
                drive.seek(-drive.getSize())
                for i = 1, 48 do
                    local offset = read32()
                    local length = read32()
                    local title = drive.read(117):gsub("\x00", "")
                    if length > 0 then
                        table.insert(table_of_contents, {
                            title = title,
                            offset = offset,
                            length = length,
                            ending = offset + length
                        })
                    end
                end
            end
        end
    end
end,
function()
    local tape_was_present = nil
    local drive_old_state = nil
    while running do
        local tape_present = drive.isReady()
        if tape_present ~= tape_was_present then
            os.queueEvent("tape_present", tape_present)
            tape_was_present = tape_present
        end

        local drive_state = drive.getState()
        if drive_old_state ~= drive_state then
            os.queueEvent("drive_state", drive_state)
            drive_old_state = drive_state
        end

        os.sleep(0.25)
    end
end)