databaseWriter.lua

local databaseFile = "disk/patents.skydb"
local adminPassword = ""

local function save(tbl,name)
    local file = fs.open(name,"w")
    file.write(textutils.serialise(tbl))
    file.close()
end

local function load(name)
    local file = fs.open(name,"r")
    local data = file.readAll()
    file.close()
    return textutils.unserialise(data)
end

local function centerText(text,y)
    local x,_ = term.getSize()
    local x = math.floor(x/2) - math.floor(string.len(text)/2)
    term.setCursorPos(x,y)
    term.write(text)
end

database = load(databaseFile)
numData = #database
cpn = 1
dataWriting = false

local function checkCurNumber()
    if cpn > numData then cpn = numData end
    if cpn < 1 then cpn = 1 end
end

local function writeData()
    patentWriting = true
    newDataNum = numData + 1
    term.clear()
    term.setCursorPos(1,1)
    term.write("Owner: ")
    dOwner = read()
    term.setCursorPos(1,2)
    term.write("Name: ")
    dName = read()
    term.setCursorPos(1,3)
    term.write("Description: ")
    dDesc = read()

    database[newDataNum] = {owner = dOwner,name = dName,desc = dDesc}
    patentWriting = false
    save(database,patentFile)
    numData = #database
    term.clear()
end

local function deleteData(tbl,num)
    dataWriting = true
    term.clear()
    term.setCursorPos(1,1)
    term.write("Are you sure you want to delete this data? (y/n)")
    term.setCursorPos(1,2)
    acceptance = read()
    if acceptance == "y" then
        term.setCursorPos(1,3)
        term.write("Please enter the admin password: ")
        local password = read("*")
        if adminPassword == password then
            table.remove(tbl,num)
            term.setCursorPos(1,5)
            print("Data deleted. A copy is stored on the working disk, and a read only copy is stored on the backup disk.")
        else
            term.setCursorPos(1,5)
            print("Password incorrect, returning to data view")
        end
    sleep(1)
    numData = #database
    save(database,databaseFile)
    dataWriting = false
    term.clear()
    end
end

local function handleKeys()
    while true do
        _,key = os.pullEvent("key")
        if key == keys.q then cpn = cpn - 1 term.clear() end
        if key == keys.e then cpn = cpn + 1 term.clear() end
        if key == keys.p then writeData() end
        if key == keys.semiColon then deleteData(database,cpn) end
    end
end

local function main()
    while true do
        if not patentWriting then
            term.setCursorPos(1,1)
            term.clearLine()
            term.setTextColour(colours.white)
            centerText(tostring(cpn) .. "/" .. tostring(numData),1)
            checkCurNumber()
            if database[cpn] ~= nil then
                term.setTextColour(colours.red)
                centerText("Owner: "..database[cpn]["owner"],2)
                term.setTextColour(colours.yellow)
                centerText("Name: "..database[cpn]["name"],3)
                term.setTextColour(colours.white)
                term.setCursorPos(1,4)
                print(database[cpn]["desc"])
            else
                term.clear()
            end
        end
        sleep(0.1)
    end
end
term.clear()
parallel.waitForAny(handleKeys,main)