Mail Utility

-- THIS IS FREEWARE!!!
-- Written and designed by PaymentOption (Grim Reaper)

-- Messages must be written to files with two \n's at the end of the message, just to ensure that the whole message is split when reading.

-- Parallel concept application:
-- Every 5 seconds update the contacts with a timer.
-- os.startTimer( 5 )
-- function UpdateContacts()
--[[
    while true do
        -- Wait for an event.
        local event = os.pullEvent()

        -- If the timer triggered.
        if event == "timer" then
            -- Reload the contacts and restart the timer.
            LoadContacts()
            os.starTimer(5)
        end
    end
   end

   ...

   while true do
    parallel.waitForAny( UpdateContacts, RunShell, etc. )
   end
]]--

-- Simple mail system addition to shell.
-- Concept Top Down Design:
-- Establish a program that will listen for incoming rednet activity and check if said activity meets the email format.
-- If the rednet message is an email, alert the user.
-- Use a directory for stored mail.
-- Console based commands:
-- mail send <ID> would trigger a prompt that said something like: "Please type your message below."
-- Get as many lines as necessary with the limit read function designed earlier.

-- Format for an email:
-- !GRIM_REAPER_MAIL_SYSTEM_2012_!MESSAGE

-- Additional features:
-- Contacts:
--  Stored in a table: tContacts[n] = { Name, ID }
--  Function to read in contacts from a specified directory (probably mail/contacts/)

-- Variables --
-- Globals --
sMailFormat = "!jdf#0dfj!" -- This will be the string at the beginning of each mail message the signifies it as a mail message.

tContacts = {}
nContactUpdateTime = 3 -- The amount of seconds before updating the contacts table in during "parallel" execution.
sMailDirectory = "mail" -- Feel free to change this directory for your needs.
sContactsDirectory = sMailDirectory .. "/contacts" -- Feel free to change this too.
-------------
-- IMPORTANT: the contacts directory string contains the full path of the contacts directory. To get the name of the directory, use fs.getName()
---------------

-- BORROWED FUNCTIONS --
-- Borrowed from: http://lua-users.org/wiki/SplitJoin
-- Compatibility: Lua-5.1
function split(str, pat)
   local t = {}  -- NOTE: use {n = 0} in Lua-5.0
   local fpat = "(.-)" .. pat
   local last_end = 1
   local s, e, cap = str:find(fpat, 1)
   while s do
      if s ~= 1 or cap ~= "" then
     table.insert(t,cap)
      end
      last_end = e+1
      s, e, cap = str:find(fpat, last_end)
   end
   if last_end <= #str then
      cap = str:sub(last_end)
      table.insert(t, cap)
   end
   return t
end
------------------------

-- Existance Checks (Check for existing directories, create directories if not, etc.) --

-- CheckAllDirectories()
-- Checks if all the directories that need to exist, exit.
-- If a directory isn't found then it is created.
-- !WARNING! If a directory already exists but isn't the right one, then the function will try to catch it, but it might cause problems later!
-- The catch will be checking if the contacts directory exists within the mail directory. Also, if any directories within the contacts directory
-- will throw errors.
function CheckAllDirectories()
    local bMail_Check = false -- If the mail directory is setup properly.
    local bContacts_Check = false -- If the contacts directory is setup properly.

    -- First check if the mail directory is setup properly.
    if fs.exists( sMailDirectory ) and fs.isDir( sMailDirectory ) then
        local tMailDir_Contents = fs.list( sMailDirectory ) -- Get the contents of the mail directory so we can check its contents for the contacts directory.

        -- Go through the contents of the mail directory and try to find the contacts directory.
        for fileNumber,fileName in ipairs( tMailDir_Contents ) do
            -- If we found the contacts directory, break out of the loop.
            if fileName == fs.getName( sContactsDirectory ) then
                bMail_Check = true
                break
            end
        end

        -- If the mail directory is setup improperly.
        if not bMail_Check then
            -- Report the failure to the user.
            error( "Mail directory checking failed.\nDelete " .. sMailDirectory .. " and try again." )
        end
    -- If the mail directory doesn't appear to exist, or is not a directory.
    else
        -- Attempt to create the directory so we can continue the program.
        fs.makeDir( sMailDirectory )
    end

    -- Next check if the contacts directory is setup properly.
    if fs.exists( sContactsDirectory ) and fs.isDir( sContactsDirectory ) then
        local tContactDir_Contents = fs.list( sContactsDirectory ) -- Get the contents of the contacts directory to check for directories in it.

        -- Go through the contents of the contacts directory and look for directories.
        for fileIndex, fileName in ipairs( tContactDir_Contents ) do
            -- If we find a directory then the contacts check failed; break out of the loop.
            if fs.isDir( sContactsDirectory .. "/" .. fileName ) then
                bContacts_Check = false
                break
            end

            -- After every iteration, if there was no exception then the loop won't be terminated, so the check is true until false.
            bContacts_Check = true
        end

        -- If the contacts directory is setup improperly.
        if not bContacts_Check then
            -- Report the failure to the user.
            error( "Contacts directory checking failed.\nDelete " .. sContactsDirectory .. " and try again." )
        end
    else
        -- Assuming that the mail directory check passed.
        fs.makeDir( sContactsDirectory )
    end
end

-- CheckIfContactExists( sContactName )
-- Checks if the contact name entered matches an ID in the contacts table so we can send
-- the message to the correct ID.
-- RETURNS:
-- True and the ID if the name exists in the contacts table.
-- False and nil if the name does not exist in the contacts table.
function CheckIfContactExists_Name( sContactName )
    -- Check if the ID exists within the contacts table.
    for contactIndex,contactSubtable in ipairs( tContacts ) do
        -- If we found a match in the contacts table with the contact name given.
        if contactSubtable.Name == sContactName then
            -- Return true and the ID of the contact given.
            return true, contactSubtable.ID
        end
    end

    -- If the loop completed checking and found no results, then
    -- the contact probably doesn't exist in our table.
    return false, nil
end

function CheckIfContactExists_ID( nContactID )
    if nContactID and type( nContactID ) == "number" then
        -- Run through all of the contacts in the contacts table.
        for i=1, #tContacts do
            if tContacts[i].ID == nContactID then
                return true, tContacts[i].Name
            end
        end

        return false, nil
    else
        return false, nil
    end
end

-- CheckIfMessageIsMail( sMessage )
-- Checks if the given string is in the mail format.
-- RETURNS:
-- True and the mail without the formatting if the message is mail.
-- False and nil and if the message is not mail.
function CheckIfReceivedMessageIsMail( sMessage )
    -- Check if the mail format string is in only in the begging of the message,
    -- just in case it shows up in other places in the message.
    if string.find( sMessage, sMailFormat, 1, string.len( sMailFormat ) ) then
        -- Return true and the message without the formatting.
        local sMessage_Unformatted = string.sub( sMessage, 1, string.len( sMailFormat ) )
        return true, sMessage_Unformatted
    -- If the mail format was not found in the message at the begging onf the message.
    else
        -- Report the lack of mail formatting; this message is just a regular rednet message.
        return false,  nil
    end
end
--------------------

-- Loading Methods (load information from files) --

-- LoadContacts()
-- Loads all of the contact information from the contact directory into the following formatted table:
-- tContacts[n] = { Name, ID }
-- EXAMPLE:
-- tContacts[3] = { Name = "Bob", ID = 45 }
function LoadContacts()
    -- Get the contents of the contacts directory and clear the contacts table.
    local tContactDir_Contents = fs.list( sContactsDirectory )
    local contactFile = nil
    local contactNumber = 0
    tContacts = {}

    -- Go through the contacts directory contens and read the information. Filename = Name, Contents = ID
    for fileIndex,fileName in ipairs( tContactDir_Contents ) do
        -- Open the next contact file in the loop, read the id from it, then close it.
        contactFile = fs.open( sContactsDirectory .. "/" .. fileName, "r" )
        contactNumber = contactFile.readLine()
        contactFile.close()

        -- Add the new contact in a record.
        tContacts[#tContacts+1] = { Name = fileName, ID = tonumber( contactNumber ) }
    end
end

-- UpdateContacts()
-- Every 3 seconds a timer will be triggered and the event will be caught by this function whilst in parallel with the shell and other functions.
-- The function will reload the contacts to make sure any changes are saved.
function UpdateContacts()
    while true do
        local event = os.pullEvent()

        if event == "timer" then
            -- Restart the timer for contacts updating and reload the contacts.
            LoadContacts()
            os.startTimer( nContactUpdateTime )
        end
    end
end

-- ReadMail( sMessageName )
-- NOTE:
--[[
    Mail is written to files with the ID of the sender on the first line.
]]--
-- Prints out the contents of a message and scrolls if it is too long.
-- Finds the name of the mssage and checks if it exists, then gets the contents.
-- It determines the length of the message against how much space is left on the screen.
function ReadMail( sMessageName )
    local cursorPosX, cursorPosY = term.getCursorPos()
    local messageFile = nil
    local nScreenWidth, nScreenHeight = term.getSize()

    -- Check if the message really exsists in the mail directory.
    if fs.exists( sMailDirectory .. "/" .. sMessageName ) then
        local bCutOffMessage = false -- Whether or not we'll have to cut the message short so we can scroll.
        local nLinesLeft_ToPrint = 0 -- If the message is cut off, this will be how many lines we have left to print.

        -- Get the message into a string that we can print.
        messageFile = fs.open( sMailDirectory .. "/" .. sMessageName, "r" )
        local sMessageContents = messageFile.readAll()
        messageFile.close()

        -- Calculate the amount of lines we have to print on, just in case we need to "Press any key to continue" things.
        local nLinesLeft_OnScreen = nScreenHeight - cursorPosY - 1 -- Subtract 1 to compensate for "Press any key to continue"
        local nLinesInMessage = 0
        local tLines = {}
        local nFromID = 0
        local sFromName_Contact = ""
        local bFromContact = false

        -- Fill the lines tabel with every occurence of the endline marker "\n".
        tLines = split( sMessageContents, "\n" )
        nFromID = tonumber( tLines[1] ); table.remove( tLines, 1 ); table.remove( tLines, #tLines )
        nLinesInMessage = #tLines
        bFromContact, sFromName_Contact = CheckIfContactExists_ID( nFromID )


        -- Check if the amount of lines in the message is greater than the amount of lines left to print on.
        if nLinesInMessage > nLinesLeft_OnScreen then
            bCutOffMessage = true
            nLinesLeft_ToPrint = nLinesInMessage - nLinesLeft_OnScreen
        end

        -- Continue to draw the lines until there are no more; stop as many times as necessary.
        if bFromContact then
            print( "From: " .. sFromName_Contact )
            print( "------" .. string.rep( "-", string.len( sFromName_Contact ) ) )
        else
            print( "From: " .. nFromID )
            print( "------" .. string.rep( "-", string.len( tostring( nFromID ) ) ) )
        end

        local nLine = 1
        while nLine ~= nLinesInMessage do
            nLine = nLine + textutils.pagedPrint( tLines[nLine], ( nScreenHeight - 3 ) - nLine )
        end
    end
end

-- WriteMessage( nFromID, sMessage )
-- Creates a new message file in the mail directory and writes the message contents
-- to the file in proper format under the name message#. # = The amount of messages + 1
function WriteMail( nFromID, sMessage )
    -- Get the amount of messages so we can calculate the name of the newest message.
    local nMessageCount = #( fs.list( sMailDirectory ) ) - 1 -- Subtract 1 to compensate for the contacts directory.
    local sMessageName = "message" .. nMessageCount + 1

    -- Open the file and write the message contents.
    local messageFile = fs.open( sMailDirectory .. "/" .. sMessageName, "w" )
    messageFile.writeLine( nFromID .. "\n" .. sMessage .. "\n" .. [[\n]] .. "\n" .. [[\n]] )
    messageFile.close()

    return sMessageName
end
-------------------

-- Listening Methods (Listen for messages) --
-- Parallel functions:
-- To be ran in parallel with the shell.
function ListenForMail()
    -- Open the nearest modem.
    local tSides = rs.getSides()
    for index,side in ipairs( tSides ) do
        if peripheral.isPresent( side ) and peripheral.getType( side ) == "modem" then
            rednet.open( side )
        end
    end

    while true do
        local event, sender, message = os.pullEvent()

        if event == "rednet_message" then
            if CheckIfReceivedMessageIsMail( message ) then
                local sMessage = string.sub( message, string.len( sMailFormat ) + 1, string.len( message ) )
                local sMessageName = WriteMail( sender, sMessage )

                local xPos, yPos = term.getCursorPos()
                term.setCursorPos( 1, yPos + 1 )
                print( "Received and saved mail as " .. sMailDirectory .. "/" .. sMessageName )
                term.setCursorPos( xPos, yPos )
            end
        end
    end
end

function RunShell()
    while true do
        shell.run( "shell" )
    end
end

function MainLoop()
    while true do
        parallel.waitForAny( ListenForMail, UpdateContacts, RunShell )
    end
end
----------------------

CheckAllDirectories()
LoadContacts()
term.clear(); term.setCursorPos( 1,1 )
print( "Mail utility started." )
sleep( 1 )
term.clear(); term.setCursorPos( 1,1 )
MainLoop()