-- SimpleOS v1.0 (English Version)
-- For ComputerCraft: Tweaked

local function drawTitle()
    term.clear()
    term.setCursorPos(1, 1)
    print("=== SimpleOS 1.0 ===")
    print("")
end

local function drawMenu()
    drawTitle()
    print("[1] List all files")
    print("[2] Edit a file")
    print("[3] Run a program")
    print("[4] Open native shell")
    print("[5] Shutdown computer")
    print("")
    write("Enter option number: ")
end

local function listFiles()
    drawTitle()
    print("Files in root directory:")
    local files = fs.list("/")
    for i = 1, #files do
        if fs.isDir(files[i]) then
            print("[DIR]  " .. files[i])
        else
            print("[FILE] " .. files[i])
        end
    end
    print("")
    write("Press any key to return...")
    os.pullEvent("key")
end

local function editFile()
    drawTitle()
    write("Enter filename to edit: ")
    local filename = read()
    if filename ~= "" then
        shell.run("edit " .. filename)
    end
end

local function runProgram()
    drawTitle()
    write("Enter program name to run: ")
    local prog = read()
    if prog ~= "" then
        shell.run(prog)
        print("")
        write("Press any key to return...")
        os.pullEvent("key")
    end
end

-- Main loop (safe, no yield error)
while true do
    drawMenu()
    local input = read()
    
    if input == "1" then
        listFiles()
    elseif input == "2" then
        editFile()
    elseif input == "3" then
        runProgram()
    elseif input == "4" then
        drawTitle()
        print("Entered native shell. Type 'exit' to return.")
        shell.run("shell")
    elseif input == "5" then
        term.clear()
        term.setCursorPos(1, 1)
        print("Shutting down...")
        sleep(0.5)
        os.shutdown()
    else
        print("Invalid option, please try again")
        sleep(0.8)
    end
end