startup

--This is a router
rednet.open('top')
term.clear()
term.setCursorPos(1,1)
print('This is computer #',os.getComputerID())

local function numbersOnly(pre,limit)-- Works like read(), except only accepts numbers. Writes a desired prefix and can accept a max number length
    term.setCursorBlink(true)
    local x,y=term.getCursorPos()
    local num=''
    while true do
        if pre then write(pre) end
        write(num)
        local event,key=os.pullEvent()
        if event=='char' and tonumber(key) then
            if #num<limit then
                num=num..key
            end
        elseif event=='key' then
            if key==14 then
                num=string.sub(num, 1, -2)
            elseif key==28 then
                print()
                term.setCursorBlink(false)
                return tonumber(num)
            end
        end
        term.setCursorPos(x,y)
        term.clearLine()
    end
end

local function checkId(id)--Checks for id in file ids, returns true if present, false if not
    if fs.exists("ids") then
        local f = fs.open("ids", "r")
        for line in f.readLine do
            if line:find(id) then
                return true
            end
        end
        return false
    end
end

local function saveId(id)-- Saves an id to file id
    if not checkId(id) then
        local f=fs.open('ids','a')
        f.writeLine(id..'')
        f.close()
        return true
    else
        return false
    end
end

local function receiveMessage()-- Same as rednet.receive(), but returns true if sending was successful, false if not
    local id,msg,d=rednet.receive()
    rednet.send(id,true)
    return id,msg,d
end

local function sendMessage(id,msg)-- Same as rednet.send(), but sends confirmation of received message
    rednet.send(id,msg,5)
    local tid,tmsg,td=rednet.receive(5)
    if tid==id and tmsg then
        return true
    else
        return false
    end
end

local function createFile(name)--Creates a file with filename 'name'
    if not fs.exists(name) then
        f=fs.open(name,'w')
        f.writeLine('{}')
        f.close()
    end
end

local function checkId(id)
    if fs.exists("ids") then
        local f = fs.open("ids", "r")
        for line in f.readLine do
            if line:find(id) then
                return true
            end
        end
        return false
    end
end

local function saveId(id)
    if not checkId(id) then
        local f=fs.open('ids','a')
        f.writeLine(id..'')
        f.close()
        return true
    else
        return false
    end
end

local function loadFromFile(variable,file)
    local file_path=fs.open(file,'r')
    local values=textutils.unserialize(file_path.readLine())
    for i,v in pairs(values) do
        if i==variable then
            file_path.close()
            return v
        end
    end
    file_path.close()
    return nil
end

local function saveToFile(variable,value,file)
    local file=file or 'config'
    createFile(file)
    local file_path=fs.open(file,'r')
    local values=textutils.unserialize(file_path.readLine())
    values[variable]=value
    file_path.close()

    local file_path=fs.open(file,'w')
    file_path.writeLine(textutils.serialize(values))
    file_path.close()
end

local function getParentId()
    parent_id=loadFromFile('parent_id','config')
    if not parent_id then
        while true do
            local parent_id=numbersOnly('Please give the id of the parent router: ',3)
            local msg=textutils.serialize({action='registerRouter',id=os.getComputerID()})
            if sendMessage(parent_id,msg) then
                saveToFile('parent_id',parent_id,'config')
                break
            else
                print('The requested router could not be found. Please check its availability, or try another id.')
            end
            sleep(0.01)
        end
    end
    return parent_id
end

createFile('ids')
createFile('config')
local parent_id=getParentId()
print('Parent id: '..tostring(parent_id))

while true do
    local id,msg,d=receiveMessage()
    print('got message')
    local values=textutils.unserialize(msg)
    print('unserialized')

    if values['action']=='registerComputer' then
        if not checkId(values['id']) then
            saveId(values['id'])
            print('Adding computer ID # '..tostring(values['id'])..' to the id list')
        end
        local msg=textutils.serialize({id=os.getComputerID(),action='computerAdded'})
        sendMessage(values['id'],msg)
    elseif values['action']=='registerRouter' then
        if not loadFromFile('router_ids','config') then
            saveToFile('router_ids',{values['id']},'config')
        else
            local exists=false
            for _,v in ipairs(loadFromFile('router_ids','config')) do
                if v==values['id'] then
                    exists=true
                end
            end
            if not exists then
                local tmp=loadFromFile('router_ids','config')
                table.insert(tmp,actions['id'])
                saveToFile('router_ids',tmp,'config')
            end
        end
    elseif values['action']=='return' then
        if checkId(values['id']) then
            sendMessage(values['id'],msg)
        else
            for _,v in ipairs(loadFromFile('router_ids','config')) do
                sendMessage(v,msg)
            end
        end
    else
        if sendMessage(parent_id,msg) then
            print('Router Id: '..tostring(parent_id)..' reception of message confirmed.')
        else
            print('Message send to Router Id: '..tostring(parent_id)..' failed.')
        end
    end
end