server

term.clear()
term.setCursorPos(1,1)

--os.loadAPI("/sha")
--os.loadAPI("/AES")

for _, side in pairs(redstone.getSides()) do
  if peripheral.getType(side) == "modem" then
    rednet.open(side)
  end
end

if not rednet.isOpen() then
  print("No rednet modem found")
  return
end

local function generateKey()
  return math.floor(os.time()*os.getComputerID()/12)
end

print("Rednet open")

rednet.host("ebay_server", "main_server")

local running = true
local quit = false

local servers = {}

local function contains(tbl, val)
  for i = 1, #tbl do
    if tbl[i] == val then
      return true, i
    end
  end
end

local function check(clientid)
  if #servers == 0 then
    rednet.send(clientid, "$no_servers")
    return false
  end
  return true
end

local function request(req)
  local rem = {}
  for i = 1, #servers do
    rednet.send(servers[i], req, "ebay_server")
    local id, mes = rednet.receive("ebay_server_"..servers[i], 3)
    if not id then
      print("Removing ".. servers[i] ..": Outdated server or offline")
      table.insert(rem, i)
    else
      return true, mes
    end
  end
  if #rem ~= 0 then
    for i = 1, #rem do
      table.remove(servers, rem[i])
    end
  end
  return false
end

local function good(mes)
  term.setTextColour(colours.green)
  print("["..textutils.formatTime(os.time()).."] [GOOD] "..mes)
end

local function info(mes)
  term.setTextColour(colours.white)
  print("["..textutils.formatTime(os.time()).."] [INFO] "..mes)
end

local function sev(mes)
  term.setTextColour(colours.red)
  print("["..textutils.formatTime(os.time()).."] [SEVR] "..mes)
end

local function split(str, sep)
  local t = {}
  local i = 1
  for str in string.gmatch(str, "([^"..sep.."]+)") do
    t[i] = str
    i = i + 1
  end
  return t
end

local function getUser(username, usrs)
  if #usrs == 0 then return nil end
  for i = 1, #usrs do
    if usrs[i].name == username then return users[i] end
  end
  return nil
end

local function beginsWith(str, bg)
  if #str < #bg then return false end
  if string.sub(str, 1, #bg) == bg then return true end
  return false
end

if not fs.exists("/disk/users") then
  local file = fs.open("/disk/users", "w")
  file.write("{}")
  file.close()
end

if not fs.exists("/disk/offers") then
  local file = fs.open("/disk/offers", "w")
  file.write("{}")
  file.close()
end

file = fs.open("/disk/users", "r")
local users = loadstring("return ".. file.readAll())()
file.close()

file = fs.open("/disk/offers", "r")
local offers = loadstring("return ".. file.readAll())()
file.close()

info(#users .. " users loaded")
info(#offers .. " offers loaded")

while running do

  local ev = { os.pullEvent() }

  if ev[1] == "key" then
    if ev[2] == keys.t and not quit then
      good("Press 'down' to quit")
      quit = true
    elseif ev[2] == keys.down and quit then
      good("Terminated")
      rednet.unhost("ebay_server", "main_server")
      for i = 1, #servers do
        rednet.send(servers[i], "$mainserver_shutdown", "ebay_server")
      end

      local offersF = fs.open("/disk/offers", "w")
      offersF.write(textutils.serialise(offers))
      offersF.close()

      local usersF = fs.open("/disk/users", "w")
      usersF.write(textutils.serialise(users))
      usersF.close()

      running = false
    else
      quit = false
    end
  end

  if ev[1] == "rednet_message" then
    if ev[4] == "ebay_server" then
      if ev[3] == "$boot_server_"..generateKey() then
        info("Registering server ".. ev[2])
        local cont, index = contains(servers, ev[2])
        if cont then table.remove(servers, index) end
        table.insert(servers, ev[2])
      elseif ev[3] == "$shutdown_server" then
        local cont, index = contains(servers, ev[2])
        if not cont then
          sev("Invalid shutdown post")
        else
          info("Removed ".. ev[2])
          table.remove(servers, index)
        end
      end
    elseif ev[4] == "ebay_client" then
      if ev[3] == "$get_status" then
        if #servers == 0 then
          rednet.send(ev[2], "$no_servers", "ebay_server")
        else
          rednet.send(ev[2], "$online", "ebay_server")
        end
      elseif ev[3] == "$get_offers" then
        if not fs.exists("/disk/offers") then
          sev("Database is gone!")
        else
          rednet.send(ev[2], textutils.serialise(offers), "ebay_server")
          good("Deliver offers to ".. ev[2] .. ": Success")
        end
      elseif string.sub(ev[3], 1, 9) == "$register" then
        info("Incoming register request")
        local rest = string.sub(ev[3], 10)
        local cred = split(rest, " ")

        if #cred ~= 2 then
          rednet.send(ev[2], "$err_bad_format")
          sev("Received invalid formatted register request from "..ev[2].." too many arguments: ".. #cred)
        else
          local usrname = cred[1]
          local pass = cred[2]
          --local pass = AES.decrypt("bananaserver", passenc)

          local user = getUser(usrname, users)
          if user then
            rednet.send(ev[2], "$err_username_used")
            info("Couldn't create user '".. usrname .."' because username was taken.")
          else
            local newuser = {
              name=usrname,
              password=sha.sha1(pass)
            }
            table.insert(users, newuser)
            rednet.send(ev[2], "$user_created")
            good("User '".. usrname .. "' created")
          end
        end
      elseif string.sub(ev[3],1,9) == "$addOffer" then
        info("Incoming add offer request")
        local rest = string.sub(ev[3], 10)
        local cred = split(rest, " ")
        if #cred ~= 3 or not tonumber(cred[1]) or not tonumber(cred[3]) then
          rednet.send(ev[2],"$err_bad_format")
          sev("Received invalid formatted add offer")
          print("'".. cred[1] .. "'")
          print("'".. cred[2] .. "'")
          print("'".. cred[3] .. "'")
        else
          local newOffer = {
             cost=tonumber(cred[1]),
             name=cred[2],
             stock=tonumber(cred[3])
          }
          table.insert(offers, newOffer)
          rednet.send(ev[2], "$offer_created")
          good("Offer created, creator ID: ".. ev[2])
        end
      end
    end
  end
end