local tArgs = {...}
if #tArgs < 1 or (tArgs[1] ~= "m" and tArgs[1] ~= "s") then error("Usage channelMaster <mode>\nMode: m/s = master/slave") end
local masterMode = (tArgs[1]=="m")
local commChannel = rednet.CHANNEL_BROADCAST-1
local masterModemCount = 0
local slaves = {}
local mySlaveChannel = os.computerID()*3
local dynamicChannels = {}
local dynMax = 0
local rangeIndex = 0
local openDynChannels = 0

local modems = {}
for k,v in pairs(rs.getSides()) do
    if peripheral.getType(v) == "modem" then
        table.insert(modems,{per=peripheral.wrap(v),openChannels=0})

    end
end

for k,v in pairs(modems) do
    v.per.closeAll()
end

if masterMode then
    print("Master Mode\nListening on: "..commChannel.." & " .. rednet.CHANNEL_BROADCAST)
    modems[1].per.open(commChannel)
    modems[1].per.open(rednet.CHANNEL_BROADCAST)
    modems[1].openChannels = 2
else
    print("Slave Mode\nListening on: "..commChannel.." & "..mySlaveChannel)
    modems[1].per.open(commChannel)
    modems[1].per.open(mySlaveChannel)
    modems[1].openChannels = 2
end

dynMax = (#modems * 128)-2

print("Found "..#modems.. " modems")

if masterMode then
    print("Ready to search...") os.pullEvent("key")
    term.clear()
    term.setCursorPos(1,1)
    print("Waiting for clients...")
    modems[1].per.transmit(commChannel,commChannel,"RPPING")
    while true do
        local args = {os.pullEvent()}
        local cmd = table.remove(args,1)
        if cmd == "key" then
            if args[1] == keys.enter then
                break
            end
        elseif cmd == "modem_message" then
            local p = textutils.unserialize(args[4])
            if type(p) == "table" and type(p.mType) == "string" and p.mType == "RPANSWER" and type(p.modemCount) == "number" and type(p.channelCount) == "number" then
                table.insert(slaves,{args[3],p.channelCount})
                masterModemCount = masterModemCount + p.modemCount
            end
        end
    end
    print("Found " .. #slaves .. " slaves with a total of "..masterModemCount .. " modems.") os.pullEvent("key")
else
    print("Listening")
    while true do
        local ev,side,chan,replchan,msg,dist = os.pullEvent("modem_message")
        if chan == commChannel and msg == "RPPING" then
            modems[1].per.transmit(commChannel,mySlaveChannel,textutils.serialize({mType = "RPANSWER",modemCount=#modems,channelCount=dynMax}))
            break
        end
    end
end

local maxDynChannelRange = masterModemCount + dynMax

function closeAllChannels()
    for k,v in pairs(dynamicChannels) do
        modems[v].per.close(k)

    end
    for k,v in pairs(modems) do
        v.openChannels = 0
    end
    modems[1].openChannels = 2
    dynamicChannels = {}
    openDynChannels = 0
end

function openRange(rStart,rWidth)
    print("Opening "..rStart .. "=>"..(rStart+rWidth-1))
    local modemI = 1
    for i=rStart,rStart+(rWidth-1),1 do

        if modems[modemI].openChannels == 128 then

            modemI = modemI+1
            print("Changing to modem #"..modemI)
        end
        dynamicChannels[i] = modemI
        modems[modemI].openChannels = modems[modemI].openChannels + 1
        modems[modemI].per.open(i)
    end
end

function masterListenRange(nR)
    closeAllChannels()
    rangeIndex = nR
    local cChan = (rangeIndex * maxDynChannelRange)

    openRange(cChan,dynMax)
    cChan = cChan + dynMax
    for k,v in pairs(slaves) do

        modems[1].per.transmit(commChannel,v[1],textutils.serialize({mType = "RPLRANGE",sChan = cChan,sWidth = v[2]}))
        cChan = cChan + v[2]
    end
end

if masterMode then
    sleep(2)
    masterListenRange(0)
end

function logMsg(chan,replchan,msg)
    print(chan.."=>"..replchan.."//"..msg)
end
print("Listening...")
while true do

    local ev,side,chan,replchan,msg,dist = os.pullEvent()

    if ev == "modem_message" then
        local pp = textutils.unserialize(msg)
        if ((not masterMode) and chan == commChannel and replchan == mySlaveChannel and type(pp) == "table" and pp.mType == "RPLRANGE") then
            closeAllChannels()
            openRange(pp.sChan,pp.sWidth)
        else
            if not masterMode then
                if chan ~= commChannel then
                    print("INTERCEPT")
                    logMsg(chan,replchan,msg)
                    modems[1].per.transmit(commChannel,mySlaveChannel,textutils.serialize({mType = "RPINTERCEPT", ["chan"]=chan,["replchan"]=replchan,["msg"]=msg }))
                end
            else
                if type(pp) == "table" and type(pp.mType) == "string" and pp.mType == "RPINTERCEPT" then
                    logMsg(pp.chan,pp.replchan,pp.msg)
                else
                    logMsg(chan,replchan,msg)
                end
            end
        end
    elseif ev == "key" then
        if side == keys.left then
            masterListenRange(math.max(rangeIndex-1,0))
        elseif side == keys.right then
            masterListenRange(rangeIndex+1)
        end
    end

end