w,h = term.getSize()
umail = { }
rmail = { }
slc = 1
serverid = 0
side = "top"

confirmmsg = ""
newmsg = ""
newto = 0

emidx = 1
emlist = { }

state = 1
states = {
  ["TOP"] = {
    id = 1,
    options = 6
  },
  ["COMPOSETEXT"] = {
    id = 2
  },
  ["COMPOSEMENU"] = {
    id = 3,
    options = 2
  },
  ["UNREAD"] = {
    id = 4,
    options = 2
  },
  ["ARCHIVE"] = {
    id = 5,
    options = 4
  },
  ["CONFIRM"] = {
    id = 6,
    options = 1
  },
  ["CHANGENAME"] = {
    id = 7
  }
}

-- Helper Functions --

function split(str, pattern)
  local t = { }
  local fpat = "(.-)" .. pattern
  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

-- Interface Drawing --

function printHeader()
  term.setCursorPos(1, 1)
  term.write("Lary's EMAIL CLIENT")
  printRight(1, "VERSION 1.0")
  term.setCursorPos(1, 2)
  term.write("Computer ID: "..os.getComputerID())
end

function printConfirm()
  local boxsize = 26
  local ok = "[ OK ]"
  printCentered(8, string.rep("*", boxsize))
  printCentered(9, "*"..string.rep(" ", boxsize-2).."*")
  local ws = (boxsize - #confirmmsg - 2)/2
  printCentered(10, "*"..string.rep(" ", ws)..confirmmsg..string.rep(" ", ws).."*")
  ws = (boxsize - #ok - 2)/2
  printCentered(11, "*"..string.rep(" ", ws)..ok..string.rep(" ", ws).."*")
  printCentered(12, "*"..string.rep(" ", boxsize-2).."*")
  printCentered(13, string.rep("*", boxsize))
end

function printChangeName()
  term.setCursorPos(4, 6)
  term.write("Enter new name: ")
end

function printStored()
  term.setCursorPos(1,4)
  term.write("From: "..emlist[emidx].from)
  term.setCursorPos(1,5)
  term.write("Sent at: "..textutils.formatTime(tonumber(emlist[emidx].time)))
  term.setCursorPos(1,6)
  term.write("--------------------")
  term.setCursorPos(1,7)
  print(emlist[emidx].body)
  term.setCursorPos(1,h-1)
  term.write("Reading Email "..emidx.." of "..table.getn(emlist))
end

function printArchiveMenu()
  local ws = string.rep(" ", 4)
  local pr, ba, de, ne
  if slc==1 then pr = "[ PREV ]" else pr = "  PREV  " end
  if slc==2 then ba = "[ BACK ]" else ba = "  BACK  " end
  if slc==3 then de = "[ DELETE ]" else de = "  DELETE  " end
  if slc==4 then ne = "[ NEXT ]" else ne = "  NEXT  " end
  term.setCursorPos(1,h)
  printCentered(h, ws..pr..ws..ba..ws..de..ws..ne)
end

function printUnreadMenu()
  local full = ""
  if slc==1 then full = "[ ARCHIVE ]       DELETE  "
            else full = "  ARCHIVE       [ DELETE ]"
  end
  printCentered(h, full)
end

function printCompose()
  term.setCursorPos(1,4)
  term.write("To:")
  term.setCursorPos(1,5)
  term.write("Body:")
  term.setCursorPos(1,h)
  term.write("Hit Enter twice to end the email.")
end

function printComposeMenu()
  term.setCursorPos(1,h)
  term.clearLine()
  local optionstr = ""
  if slc == 1 then
     optionstr = " [ SEND ]        DELETE   "
  else
     optionstr = "   SEND        [ DELETE ] "
  end
  printCentered(h, optionstr)
end

function printTopMenu()
  term.setCursorPos(1, h-1)
  term.write("Hi, "..os.getComputerLabel().."!")
  term.setCursorPos(1, h)
  term.write("You have "..table.getn(umail).." new message(s).")

  printCentered(4, "Select Option:")
  if slc == 1 then printCentered(7, " [ COMPOSE EMAIL ] ")
  else printCentered(7, "   COMPOSE EMAIL   ") end
  if slc == 2 then printCentered(8, " [ UNREAD EMAILS ] ")
  else printCentered(8, "   UNREAD EMAILS   ") end
  if slc == 3 then printCentered(9, "[ ARCHIVED EMAILS ]")
  else printCentered(9, "  ARCHIVED EMAILS  ") end
  if slc == 4 then printCentered(10, "  [ CHANGE NAME ]  ")
  else printCentered(10, "    CHANGE NAME    ") end
  if slc == 5 then printCentered(11, " [ REFRESH EMAIL ] ")
  else printCentered(11, "   REFRESH EMAIL   ") end
  if slc == 6 then printCentered(12, "     [ QUIT ]      ")
  else printCentered(12, "       QUIT        ") end
end

function printRight(height, value)
  local xpos = w - string.len(value)
  term.setCursorPos(xpos, height)
  term.write(value)
end

function printCentered(height, value)
  local xpos = w/2 - string.len(value)/2
  term.setCursorPos(xpos, height)
  term.write(value)
end

-- Email Tools --

function sendEmail()
  rednet.open(side)
  local newemail = "$EMAIL"..newto
                 .."!SP!"..os.getComputerLabel()
                 .."!SP!"..os.time().."!SP!"
                 ..newmsg
  rednet.send(serverid, newemail)
  if rednet.receive(5)~=nil then
    confirmmsg = "MESSAGE SENT"
  else
    confirmmsg = "ERROR OCCURRED"
  end
  rednet.close(side)
end

function readEmails()
  rednet.open(side)
  rednet.send(serverid, "$REQUEST")
  local id, mail = rednet.receive(5)
  if mail==nil then
    confirmmsg = "SERVER ERROR"
    rednet.close("left")
    return
  end
  mail = string.gsub(mail, "$RESPONSE", "")

  local t = split(mail, "!SP!")

  for i=1,table.getn(t),3 do
    table.insert(umail, {
      from = t[i],
      time = t[i+1],
      body = t[i+2]
    })
  end
  rednet.close(side)
end

function readFromArchive()
  if not fs.exists(shell.resolve(".").."/archive") then return end
  local file = io.open(shell.resolve(".").."/archive", "r")
  local fullstr = ""
  local fline = file:read()
  while fline do
    fullstr=fullstr..fline
    fline = file:read()
  end
  file:close()
  local t = split(fullstr, "!SP!")
  for i=1,#t,3 do
    table.insert(rmail, {
      from = t[i],
      time = t[i+1],
      body = t[i+2]
    })
  end
end

function writeToArchive()
  local file = io.open(shell.resolve(".").."/archive", "w")
  local arcstr = ""
  for i=1,#rmail do
    arcstr=arcstr.."!SP!"..rmail[i].from.."!SP!"..
                 rmail[i].time.."!SP!"..rmail[i].body
  end
  file:write(arcstr)
  file:close()
end

-- Interface Logic --

function runInterface()
  term.clear()
  while true do
    if state==states["TOP"].id then
      term.clear()
      printHeader()
      printTopMenu()
      local e,key = os.pullEvent("key")
      if key==200 and slc>1 then slc = slc-1
      elseif key==208 and slc<6 then slc=slc+1
      elseif key==28 then
        if slc==1 then
          state = states["COMPOSETEXT"].id
          newmsg = ""
        elseif slc==2 then
          if table.getn(umail)==0 then
            confirmmsg="No new mail."
            state=states["CONFIRM"].id
          else
            emidx=1
            emlist = umail
            state=states["UNREAD"].id
          end
        elseif slc==3 then
          if table.getn(rmail)==0 then
            confirmmsg="Archive Empty."
            state=states["CONFIRM"].id
          else
            emidx=1
            emlist = rmail
            state=states["ARCHIVE"].id
          end
        elseif slc==4 then
          state=states["CHANGENAME"].id
        elseif slc==5 then
          local ocount = table.getn(umail)
          readEmails()
          if ocount < table.getn(umail) then
            confirmmsg = "Messages Received!"
          else
            confirmmsg = "No new mail."
          end
          state = states["CONFIRM"].id
        elseif slc==6 then
          term.clear()
          term.setCursorPos(1,1)
          return
        end
      end
    elseif state==states["CHANGENAME"].id then
      term.clear()
      printHeader()
      printChangeName()
      local nname = io.read()
      if #nname>25 then
        nname = string.sub(nname, 1, 25)
      end
      os.setComputerLabel(nname)
      state=states["TOP"].id
    elseif state==states["COMPOSETEXT"].id then
      term.clear()
      printHeader()
      printCompose()
      term.setCursorPos(5, 4)
      newto = tonumber(io.read())
      term.setCursorPos(1, 6)
      local newmail=""
      repeat
        newmail = io.read().."\n"
        newmsg=newmsg..newmail.." "
      until newmail=="\n"
      state = states["COMPOSEMENU"].id
    elseif state==states["COMPOSEMENU"].id then
      printComposeMenu()
      local e, key = os.pullEvent("key")
      if key==203 and slc>1 then
        slc=slc-1
      elseif key==205 and slc<2 then
        slc=slc+1
      elseif key==28 then
        if slc==1 then
          sendEmail()
          state = states["CONFIRM"].id
        else
          state = states["TOP"].id
        end
      end
    elseif state==states["ARCHIVE"].id then
      term.clear()
      printHeader()
      printStored()
      printArchiveMenu()
      local e, key = os.pullEvent("key")
      if key==203 and slc>1 then
        slc=slc-1
      elseif key==205 and slc<4 then
        slc=slc+1
      elseif key==28 then
        if slc==1 and emidx>1 then emidx=emidx-1
        elseif slc==2 then state=states["TOP"].id
        elseif slc==3 then
          table.remove(rmail, emidx)
          writeToArchive()
          if #rmail==0 then
            confirmmsg= "Archive Empty."
            state=states["CONFIRM"].id
          end
          if emidx>#rmail then emidx=#rmail end
        elseif slc==4 and emidx<#rmail then
          emidx=emidx+1
        end
      end
    elseif state==states["UNREAD"].id then
      term.clear()
      printHeader()
      printStored()
      printUnreadMenu()
      local e, key = os.pullEvent("key")
      if key==203 and slc>1 then
        slc=slc-1
      elseif key==205 and slc<2 then
        slc=slc+1
      elseif key==28 then
        if slc==1 then
          table.insert(rmail, {
            from = emlist[emidx].from,
            time = emlist[emidx].time,
            body = emlist[emidx].body
           })
           writeToArchive()
        end
        table.remove(umail, emidx)
        emlist = umail
        if table.getn(umail)==0 then
          confirmmsg="Inbox Empty."
          state=states["CONFIRM"].id
        end
      end
    elseif state==states["CONFIRM"].id then
      printConfirm()
      local e, key = os.pullEvent("key")
      if key==28 then
        state = states["TOP"].id
      end
    end
  end
end

-- On Startup --

function getPrefs()
  local file = io.open(shell.resolve(".").."/pref")
  if not file then
    print("pref file not found! Make sure to include"
        .." it in your mail directory.")
    return false
  end
  local sidl = file:read()
  sidl = string.gsub(sidl, "serverid=", "")
  print(sidl)
  sidl = tonumber(sidl)
  if sidl==0 then
    print("Client prefs not initialized- check readme for detals.")
    return false
  end
  serverid = sidl
  sidl = file:read()
  sidl = string.gsub(sidl, "side=", "")
  side = sidl
  return true
end

if not getPrefs() then return end
readFromArchive()
rednet.broadcast("Computer: "..os.getComputerID().." is now on network.")
if os.getComputerLabel() == nil then
  os.setComputerLabel("New User")
end

runInterface()