ComputerCraft OS

term.clear()
writepos, writecol, multchar, max, min, compare_coord, fill_color, render_folder, render_popup, render_time = table.unpack(require "os_library")

local function blue_screen(msg)
    local w,h = term.getSize()
    term.setBackgroundColor(colors.blue)
    term.setTextColor(colors.white)
    term.clear()
    writepos(2,2,":( An unexpected error has occurred!")
    writepos(2,3,"We are working on fixing the problem.")
    writepos(2,5,"Error: "..msg)

    writepos(2,7,"\aOpen shell")
    writepos(2,8,"\aRestart OS")
    writepos(2,9,"\aShutdown")
    local e, btn, cx, cy
    repeat
        e, btn, cx, cy = os.pullEvent("mouse_click")
    until cy>=7 and cy<=9

    term.setCursorPos(1,h)
    if cy==7 then
        term.setBackgroundColor(colors.black)
        term.clearLine()
    elseif cy==8 then
        shell.run("reboot")
    elseif cy==9 then
        shell.run("shutdown")
    end
end

local function is_lua_script(name)
    local afterdot = string.match(name, "%.(.*)")
    return afterdot == "lua" or afterdot == nil
end
local args = {...}
local folder = args[1]==nil and "" or args[1]
local shift = 1
local last_click = {0,0}

local function main()
    while true do
        render_folder(folder,shift)
        local event = {os.pullEvent()}
        local w,h = term.getSize()
        if event[1] == "timer" then
            render_time()
        elseif event[1] == "mouse_click" then
            if event[2] == 1 then
                if event[3] == w then
                    if event[4] == h then
                        shift = min(shift + 1,#fs.list(folder)-h+3)
                    elseif event[4] == 1 then
                        shift = max(shift-1,1)
                    elseif event[4] == 3 and term.isColour() then
                        shell.run("fg shell")
                    elseif event[4] == math.floor(h/2) then
                        if folder~="" then folder = fs.combine(folder,"..") end
                        shift = 1
                        term.clear()
                    elseif event[4] == math.floor(h/2)-1 then
                        folder = "/UserFiles"
                        shift = 1
                        term.clear()
                    elseif event[4] == 2 then
                        shift = 1
                    elseif event[4] == h-1 then
                        shift = max(#fs.list(folder)-h+3,1)
                    elseif event[4] == h-2 then
                        local x,y = render_popup(3,"Create",true)
                        local is_folder = false
                        writepos(x,y,"\aFile")
                        writepos(x,y+1,"\aFolder")
                        local e, btn, cx, cy
                        repeat
                            e, btn, cx, cy = os.pullEvent("mouse_click")
                        until cy == y or cy == y+1 or cy == y-1
                        if cy == y then
                            writecol(x,y,"\aFile",colors.cyan,colors.white)
                        elseif cy == y+1 then
                            writecol(x,y+1,"\aFolder",colors.cyan,colors.white)
                            is_folder = true
                        end
                        if cy ~= y-1 then
                            term.setCursorPos(x,y+2)
                            write("> ")
                            local rd = read()
                            if not is_folder and rd~="" then fs.open(fs.combine(folder,rd),"w").close() else fs.makeDir(fs.combine(folder,rd)) end
                        end
                        term.clear()
                    end
                elseif compare_coord({event[3],event[4]},{1,h}) then
                    term.setCursorPos(1,h)
                    term.setBackgroundColor(colors.gray)
                    term.clearLine()
                    write("> ")
                    shell.setDir(folder)
                    shell.run(read())
                    shell.setDir("/")
                    term.setCursorPos(1,h)
                    write("Execution finished, press to continue")
                    os.pullEvent("mouse_click")
                    term.setBackgroundColor(colors.black)
                    term.clear()
                else
                    if compare_coord({event[3],event[4]},last_click) then
                        last_click = {0,0}
                        local sel = fs.list(folder)[event[4]+shift-2]
                        if sel ~= nil and event[4] ~= 1 and event[4] ~= h then
                            if sel ~= nil then
                                local x,y = render_popup(7,sel,true)
                                if not fs.isDir(fs.combine(folder,sel)) then
                                    writepos(x,y,"\aExecute")
                                    writepos(x,y+1,"\aEdit")
                                else
                                    writepos(x,y,"(Folder)")
                                    writepos(x,y+1,"(No op.)")
                                end
                                writepos(x,y+2,"\aRename")
                                writepos(x,y+3,"\aDelete")
                                writepos(x,y+4,"\aCopy as..")
                                writepos(x,y+5,"\aMove to..")
                                local e, btn, cx, cy
                                repeat
                                    e, btn, cx, cy = os.pullEvent("mouse_click")
                                until cy>=y-1 and cy<=y+4
                                if cy==y and not fs.isDir(fs.combine(folder,sel)) then
                                    term.clear()
                                    render_folder(folder,shift)
                                    fill_color(1,h,w-1,h,colors.gray)
                                    term.setBackgroundColor(colors.gray)
                                    term.setCursorPos(1,h)
                                    shell.setDir(folder)
                                    shell.run(sel)
                                    shell.setDir("/")
                                    term.setCursorPos(1,h)
                                    write("Execution finished, press to continue")
                                    os.pullEvent("mouse_click")
                                    term.setBackgroundColor(colors.black)
                                    term.clear()
                                elseif cy==y+1 then
                                    shell.run("edit "..fs.combine(folder,sel))
                                elseif cy==y+2 then
                                    writecol(x,y+2,"\aRename",colors.cyan,colors.white)
                                    term.setCursorPos(x,y+6)
                                    write("> ")
                                    local newname = read()
                                    if newname ~= "" and newname ~= sel then
                                        fs.copy(fs.combine(folder,sel),fs.combine(folder,newname))
                                        fs.delete(fs.combine(folder,sel))
                                    end
                                elseif cy==y+3 then
                                    writecol(x,y+3,"\aDelete",colors.cyan,colors.white)
                                    term.setCursorPos(x,y+6)
                                    write("Sure? Y/N ")
                                    if read() == "Y" then
                                        fs.delete(fs.combine(folder,sel))
                                    end
                                elseif cy==y+4 then
                                    writecol(x,y+4,"\aCopy as..",colors.cyan,colors.white)
                                    term.setCursorPos(x,y+6)
                                    write("> ")
                                    local newname = read()
                                    if newname ~= "" and newname ~= sel then
                                        fs.copy(fs.combine(folder,sel),fs.combine(folder,newname))
                                    end
                                elseif cy==y+5 then
                                    writecol(x,y+5,"\aMove to..",colors.cyan,colors.white)
                                    term.setCursorPos(x,y+6)
                                    write("> ")
                                    local newname = read()
                                    if newname ~= "" and fs.combine(folder,newname) ~= fs.combine(folder,sel) then
                                        fs.copy(fs.combine(folder,sel),fs.combine(folder,newname,sel))
                                        fs.delete(fs.combine(folder,sel))
                                    end
                                end
                                term.clear()
                            end
                        end
                    else
                        last_click = {event[3],event[4]}
                    end
                end
            end
        elseif event[1] == "mouse_scroll" then
            shift = max(shift+event[2],1)
            if shift+h-3>#fs.list(folder) then shift = max(#fs.list(folder)-h+3,1) end
        elseif event[1] == "term_resize" or event[1] == "disk_eject" or event[1] == "disk" then
            term.clear()
        end
    end
end

local success, msg = pcall(main)
if not success then blue_screen(msg) end