server

--[[
    CC-Bank
    Copyright © 2012  Yingtong Li

    CC-Bank is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    CC-Bank is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with CC-Bank.  If not, see <http://www.gnu.org/licenses/>.
--]]

os.loadAPI("crypt")

local modemSide = "left"
local version = "CC-Bank-0.2.0-Compatible"

local function log(level, info)
    local severity = "?"
    if level == 1 then  severity = "INFO"   end
    if level == 2 then  severity = "WARNING"    end
    if level == 3 then  severity = "ERROR"  end
    print("[" .. severity .. "] " .. textutils.formatTime(os.time()) .. " - " .. info)
end

local function serve()
    rednet.open(modemSide)
    local senderId, message = rednet.receive()

    if string.len(message) >= string.len(version) then
        if string.sub(message, 1, string.len(version)) == version then
            local bits = textutils.unserialize(string.sub(message, string.len(version) + 1))
            local command = bits[1]
            local acc = bits[2]
            local pass = bits[3]

            log (1, command .. " from " .. acc)

            if command == "BALANCE" then
                if fs.exists("acc/" .. acc .. ".txt") then
                    local file = fs.open("acc/" .. acc .. ".txt", "r")
                    local passC = file.readLine()
                    local bal = file.readLine()
                    file.close()

                    if crypt.checkPassword(pass, passC) then
                        rednet.send(senderId, bal)
                        return
                    end
                end
            elseif command == "TRANSFER" then
                local dest = bits[4]
                local amt = tonumber(bits[5])
                if fs.exists("acc/" .. acc .. ".txt") and fs.exists("acc/" .. dest .. ".txt") then
                    local fileFrom = fs.open("acc/" .. acc .. ".txt", "r")
                    local passC = fileFrom.readLine()
                    local bal = tonumber(fileFrom.readLine())
                    fileFrom.close()

                    local fileTo = fs.open("acc/" .. dest .. ".txt", "r")
                    local passT = fileTo.readLine()
                    local balT = tonumber(fileTo.readLine())
                    fileTo.close()

                    if crypt.checkPassword(pass, passC) and bal >= amt then
                        fileFrom = fs.open("acc/" .. acc .. ".txt", "w")
                        fileTo = fs.open("acc/" .. dest .. ".txt", "w")

                        fileFrom.writeLine(passC)
                        fileFrom.writeLine(bal - amt)
                        fileFrom.close()

                        fileTo.writeLine(passT)
                        fileTo.writeLine(balT + amt)
                        fileTo.close()

                        log (1, "Transferred " .. amt .. " from " .. acc .. " to " .. dest)

                        rednet.send(senderId, "+")
                        return
                    end
                end
            elseif command == "WITHDRAW" then
                local amt = tonumber(bits[4])
                if fs.exists("acc/" .. acc .. ".txt") then
                    local file = fs.open("acc/" .. acc .. ".txt", "r")
                    local passC = file.readLine()
                    local bal = tonumber(file.readLine())
                    file.close()

                    if crypt.checkPassword(pass, passC) and bal >= amt then
                        file = fs.open("acc/" .. acc .. ".txt", "w")

                        file.writeLine(passC)
                        file.writeLine(bal - amt)
                        file.close()

                        log (1, "Withdrew " .. amt .. " from " .. acc)

                        rednet.send(senderId, "+")
                        return
                    end
                end
            end
        end
        log (2, "Request denied")
        rednet.send(senderId, "-")
    end
end

while true do
    serve()
end