-- mail.lua

--[[--
	Data structure for mail files:
	{
		["sender"] = (string),
		["receivers"] = (table) {
			[1] = (string),
			[2] = (string),
			etc.
		},
		["subject"] = (string),
		["message"] = (string),
	}

	Printer page size: 25x21
--]]--

--(( Settings ))--

local filename = "mail.dat"
local drivePath = "drive_1"
local printerPath = "printer_2"

--(( Variables ))--

err = {
	missing_item = "No item inside the disk drive!",
	invalid_item = "The received item is not valid!",
	missing_data = "No data found on the received disk!",
	invalid_data = "The data on the received disk is either corrupt or invalid!",
}

local printer = peripheral.wrap(printerPath)
or error("Unable to wrap printer!")

local drive = peripheral.wrap(drivePath)
or error("Unable to wrap disk drive!")

--(( Functions ))--

-- get the message from the disk drive
function readMail()
	if not drive.isDiskPresent() then
		return {err="missing_item"}
	end
	
	if not drive.hasData() then
		return {err="invalid_item"}
	end
	
	-- Get file path
	local path = drive.getMountPath()
	path = fs.combine(path, filename)
	
	if not fs.exists(path) then
		return {err="missing_data"}
	end
	
	-- Read data
	local file = fs.open(path,"r")
	local rawData = file.readAll()
	
	if type(rawData) ~= "string" then
		return {err="invalid_data"}
	end
	
	-- Unserialize it
	local data = textutils.unserialize(rawData)
	
	if type(data) ~= "table"
	or type(data.sender) ~= "string"
	or type(data.receivers) ~= "table"
	or type(data.message) ~= "string"
	then
		return {err="invalid_data"}
	end
	
	-- Prepare message
	local mail = {
		sender = data.sender,
		receivers = {},
		subject = data.subject,
		message = data.message,
	}
	
	-- validate the receivers
	for _,receiver in pairs(data.receivers) do
		if type(receiver) ~= "string" then
			return {err="invalid_data"}
		end

		table.insert(mail.receivers,receiver)
	end
	
	if #mail.receivers == 0 then
		return {err="invalid_data"}
	end
	
	return mail
end

-- write a letter
function writeMail(mail)
	for _,receiver in ipairs(mail.receivers) do

		local dir = inv.getDirection(receiver)
		if type(dir) == "string" then

			local rows = prepareMessage(mail)
			local pages = math.ceil(#rows/21) -- the pages are 21 high

			for page = 1,pages do
				if not printer.newPage() then
					error("Unable to start new page!")
				end

				local title = '"'
				util.wordwrap(mail.subject, function(row) title=title..row end, 32, 0)
				title = title .. '" from '
				util.wordwrap(mail.sender, function(row) title=title..row end, 32, 0)

				if pages > 1 then
					title = title .. " (page " .. page .. " of " .. pages .. ")"
				end

				printer.setPageTitle(title)

				local rows = prepareMessage(mail)
				for i,row in ipairs(rows) do
					if row == 666 then
						row = "[ Page " .. page .. " / " .. pages .. " ]--"
						row = string.rep("-",25-#row)..row

						printer.setCursorPos(1,21)
					else
						printer.setCursorPos(1,i-(page-1)*21)
					end

					printer.write(row)
				end

				if not printer.endPage() then
					error("Unable to end page!")
				end

				sleep(.5)
				inv.emptyDropper(dir)
			end

		else
			print("No mailbox for \"" .. receiver .. "\"!")
		end
	end
end

-- prepare the mail for writing
function prepareMessage(mail)
	local w,h = 25,21 -- size of page
	local rows = {}
	local message = mail.message
	local offset = 0

	repeat
		util.wordwrap("From: "..mail.sender, rows, w, 0)
		util.wordwrap("Subject: "..mail.subject, rows, w, 1)
		table.insert(rows, string.rep("-",w))
		message = util.wordwrap(message, rows, w, h - #rows - 2 + offset)
		table.insert(rows,666)

		offset = #rows
	until message == nil

	return rows
end

function getDrive()
	return drive
end

function getPrinter()
	return printer
end

-- eof