DeltaTV Server

local channel = "channel"
local videoDir = "/tv"

--Base64 api by LBPHacker
local lookup_V2C = {}
for ixChar = 65, 90 do lookup_V2C[ixChar - 65] = string.char(ixChar) end
for ixChar = 97, 122 do lookup_V2C[ixChar - 71] = string.char(ixChar) end
for ixChar = 48, 57 do lookup_V2C[ixChar + 4] = string.char(ixChar) end
lookup_V2C[62] = "+"
lookup_V2C[63] = "/"
local lookup_C2V = {}
for key, value in pairs(lookup_V2C) do lookup_C2V[value] = key end

function encode(data)
    local result = ""
    for ix = 1, #data, 3 do
        local all24 = data:sub(ix, ix):byte() * 65536 + (data:sub(ix + 1, ix + 1):byte() or 0) * 256 + (data:sub(ix + 2, ix + 2):byte() or 0)
        result = result .. lookup_V2C[bit.band(all24, 16515072) / 262144] .. lookup_V2C[bit.band(all24, 258048) / 4096] .. lookup_V2C[bit.band(all24, 4032) / 64] .. lookup_V2C[bit.band(all24, 63)]
    end
    local padding = (3 - data:len() % 3) % 3
    return result:sub(1, result:len() - padding) .. string.rep("=", padding)
end

function decode(data)
    local result = ""
    for ix = 1, #data, 4 do
        local all24 = lookup_C2V[data:sub(ix, ix)] * 262144 + (lookup_C2V[data:sub(ix + 1, ix + 1)] or 0) * 4096 + (lookup_C2V[data:sub(ix + 2, ix + 2)] or 0) * 64 + (lookup_C2V[data:sub(ix + 3, ix + 3)] or 0)
        result = result .. string.char(bit.band(all24, 16711680) / 65536) .. string.char(bit.band(all24, 65280) / 256) .. string.char(bit.band(all24, 255))
    end
    return result:sub(1, result:len() - #data:match("^.-(=*)$"))
end




-- BNTP api below

local b = peripheral.find("bitnet_tower") or peripheral.find("bitnet_antenna")

local function ebn()
 if not b then
  error("No bitnet found!", 0)
 end
end

function sendMessage(message, useBase)
 useBase = useBase or false
 if type(useBase) ~= "boolean" then
  useBase = false
 end

 ebn()
 if type(message) == "table" and useBase == true then
  message = "t.bntp::"..encode(textutils.serialize(message))
 elseif type(message) ~= "table" and useBase == true then
  message = "bntp::"..encode(message)
 end

 b.transmit(message)
end


function receive()
 ebn()
 local e,s,m,d = os.pullEvent("bitnet_message")
 if m == nil then m = "nil" end
 if m:sub(1,6) == "bntp::" then
  m = decode(m:sub(7))
 elseif m:sub(1,8) == "t.bntp::" then
  m = textutils.unserialize( decode(m:sub(9)) )
 end
 return m,d
end

-- BNTP api ends

ebn()


local function fetch(program)
    v = program
    if fs.exists(videoDir.."/"..v) and not fs.isDir(videoDir.."/"..v) then
        local file = fs.open(videoDir.."/"..v, "r")
        local thing = textutils.unserialize(file.readAll())
        file.close()
        return thing
    end
    return nil
end


local function fetchList()
    local ls = {}
    local b = {}
    for k,v in pairs(fs.list(videoDir)) do
        if fs.exists(videoDir.."/"..v) and not fs.isDir(videoDir.."/"..v) then
            local thing = fetch(v)
            b = {thing[name], v}
            table.insert(b)
        end
    end
    return ls
end



while true do

    local mes, d = receive()

    if type(mes) ~= "table" then mes = {} end

    if mes.sType == "dtv.ping" then
        sendMessage({sType="dtv.pong", uid=mes.uid, channel=channel}, false)
    elseif mes.sType == "dtv.list" then
        sendMessage({sType="dtv.listPong", uid=mes.uid, channel=channel, data=fetchList()}, false)
    elseif mes.sType == "dtv.dl" then
        sendMessage({sType="dtv.listPong", uid=mes.uid, channel=channel, data=fetch(mes.program)}, false)
    end

end