function send(account, to, email)
    local message = ("@EMX~"..to.."~"..account.."~"..email)
    local file = fs.open("EMX/emails/"..to, "a")
    file.writeLine(message)
    file.close()
end

function getNumberOfEnters(data, string)
    local n = 0
    for i,v in ipairs(data) do
        if v == string then
            n = n + 1
        end
    end
    return n
end

function getAllEmails(account)
    if idExists(account) then
        local data = {}
        local temp = {}
        local cur = 1
        local file = fs.open("EMX/emails/account", "r")
        local line = file.readLine()
        while line ~= nil do
            local sender = getMessage(line)
            sender = getSender(sender)
            local n = getNumberOfEnters(temp, sender)
            n = n + 1
            data[cur] = sender.." ["..n.."]"
            temp[cur] = sender
            cur = cur + 1
            line = file.readLine()
        end
        file.close()
        return data
    else
        return nil
    end
end

function returnEmail(account, name)
    if idExists(account) then
        local email = nil
        local temp = {}
        local cur = 1
        local file = fs.open("EMX/emails/account", "r")
        local line = file.readLine()
        while line ~= nil do
            local msg = getMessage(line)
            local sender = getSender(msg)
            local n = getNumberOfEnters(temp, sender)
            n = n + 1
            local curname = sender..":"..n
            if curname == name then
                email = line
            end
            temp[cur] = sender
            cur = cur + 1
            line = file.readLine()
        end
        file.close()
        return email
    else
        return nil
    end
end

function joinTables(t1, t2)
    for k,v in ipairs(t2) do table.insert(t1, v) end return t1
end

function readEmail(broadcast, id)
    if isEmail(broadcast) then
        local msg = getMessage(broadcast)
        local mid = getID(msg)
        if mid == id then
            local email = getEmail(msg)
            local sender = getSender(msg)
            local sendername = getNickname(sender)
            local toname = getNickname(id)
            if toname ~= nil and sendername ~= nil then
                local start = {"From:"..sendername, "To:"..toname}
                local split = string.split(email, "}")
                local data = joinTables(start, split)
                return data
            else
                local data = {"NOT A VALID EMAIL", "CANNOT READ EMAIL"}
                return data
            end

        else
            local data = {"NOT A VALID USER", "CANNOT READ EMAIL"}
            return data
        end
    end
end

function startUp()
    fs.makeDir("EMX")
    fs.makeDir("EMX/data")
    fs.makeDir("EMX/emails")
    local file = fs.open("EMX/data/ids", "a")
    file.close()
end

function getSender(message)
    if isEmail(message) then
        message = getMessage(message)
    end
    local id = string.sub(message, 6, 9)
    return id
end

function isEmail(broadcast)
    if starts(broadcast, "@EMX~") then
        return true
    else
        return false
    end
end

function getID(message)
    if isEmail(message) then
        message = getMessage(message)
    end
    local id = string.sub(message, 1, 4)
    return id
end

function getEmail(message)
    if isEmail(message) then
        message = getMessage(message)
    end
    local msg = string.sub(message, 10, -1)
    return msg
end

function getMessage(broadcast)
    if isEmail(broadcast) then
        local s = string.sub(broadcast, 6, -1)
        return s
    else
        return nil
    end
end

function starts(String,Start)
   return string.sub(String,1,string.len(Start))==Start
end







function idExists(id)
    local ok = true
    local file = fs.open("EMX/data/ids", "r")
    local line = file.readLine()
    while line ~= nil do
        local cid = string.sub(line,1,4)
        if cid == id then
            ok = false
        end
        line = file.readLine()
    end
    file.close()
    return ok
end

function nicknameExists(nickname)
    local ok = true
    local file = fs.open("EMX/data/ids", "r")
    local line = file.readLine()
    while line ~= nil do
        local name = string.sub(line,6,-1)
        if name == nickname then
            ok = false
        end
        line = file.readLine()
    end
    file.close()
    return ok
end

function newAccount(nickname, password)
    if nicknameExists(nickname) then
        return "nonick"
    else
        local id = math.random(1000, 9999)
        local max = 0
        while idExists == false and max < 9999 do
            id = math.random(1000, 9999)
            max = max + 1
        end

        if max >= 9999 then
            return "noid"
        else
            local file = fs.open("EMX/data/ids", "a")
            local temp = fs.open("EMX/emails/"..id, "a")
            file.writeLine(id.."~"..nickname.."~"..password)
            file.close()
            temp.close()
            return "ok"
        end
    end
end

function getTrueId(nickname)
    local tid = nil
    local file = fs.open("EMX/data/ids", "r")
    local line = file.readLine()
    while line ~= nil do
        local name = string.sub(line,6,-1)
        if name == nickname then
            local id = string.sub(line,1,4)
            tid = id
        end
        line = file.readLine()
    end
    file.close()
    return tid
end

function matchPassword(id, password)
    local ok = false
    local file = fs.open("EMX/data/ids", "r")
    local line = file.readLine()
    while line ~= nil do
        local cid = string.sub(line,1,4)
        if cid == id then
            local name = string.sub(line,6,-1)
            local split = string.split(name, "~")
            local pass = split[2]
            if pass == password then
                ok = true
            end
        end
        line = file.readLine()
    end
    file.close()
    return ok
end

function getNickname(id)
    local nname = nil
    local file = fs.open("EMX/data/ids", "r")
    local line = file.readLine()
    while line ~= nil do
        local cid = string.sub(line,1,4)
        if cid == id then
            local name = string.sub(line,6,-1)
            local split = string.split(name, "~")
            nname = split[1]
        end
        line = file.readLine()
    end
    file.close()
    return nname
end