th_interfaces-v0.0.1

-- ThunderNet - network interfaces.
-- (c) ProgramCrafter

-- Last patch: Stem support (06.04.2021)

local function err(msg)
  return function() error(msg) end
end

local NYIMSG = 'Not yet implemented'
local NULLMSG = 'Receiving data from /dev/null'
local NULLADDR = '00000000-0000-0000-0000-000000000000'

local evt = require 'event'

-- Event callbacks (`parsers`)
-- Input:     event
-- Output:    thundernet::data, answer_info (such as network card address)

local function parse_null(proxy)
  return function(event) end
end
local function parse_modem(proxy)
  -- Use this function only to create MODEM parsers!
  -- TUNNEL parsers are below in parse_tunnel.
  return function(event)
    -- Event format: modem_message(receiverAddress: string, senderAddress: string, port: number, distance: number, ...)
    if not event then return end
    if event[1] ~= 'modem_message' then return end
    if event[2] ~= proxy.address then return end
    if event[6] then
      return event[6], event[3]
    end
  end
end
local function parse_tunnel(proxy)
  return function(event)
    -- Event format: modem_message(receiverAddress: string, senderAddress: string, port: number, distance: number, ...)
    if not event then return end
    if event[1] ~= 'modem_message' then return end
    if event[2] ~= proxy.address then return end
    if event[6] then
      return event[6], event[3]
    end
  end
end

local stem_inited = false

return {
  ['null'] = function() return {
    send = function() end,      broadcast = function() end,
    recv = parse_null(),        addr = NULLADDR
  } end,

  ['modem'] = function(proxy) return {
    send = proxy.send,          broadcast = proxy.broadcast,
    recv = parse_modem(proxy),  addr = proxy.address
  } end,

  ['tunnel'] = function(proxy) return {
    send = err(NYIMSG),         broadcast = err(NYIMSG),
    recv = parse_tunnel(proxy), addr = proxy.address
  } end,

  ['internet'] = function(proxy, uid)
    local stem_installed, stem = pcall(require, 'stem')
    local stem_channel = 'thunderlib~06042021161759~'
    if stem_inited or not stem_installed then
      if not stem_installed then
        print('[Thunderlib interfaces] Install Stem library for connecting to Internet.')
      end
      return {send = parse_null(), broadcast = parse_null(),
              recv = parse_null(), addr = proxy.address}
    else
      stem_inited = true
      local server = stem.connect()
      server:subscribe(stem_channel)
      return {
        send = function(addr, port, msg)
          server:send(stem_channel, uid .. 'D' .. addr .. '\0' .. msg)
        end,
        broadcast = function(port, msg)
          server:send(stem_channel, uid .. 'B' .. msg)
        end,
        recv = function(event)
          if not event then return end
          if event[1] == 'stem_message' then
            local d = event[3]

            local sender = d:sub(1, #uid)
            local _type = d:sub(#uid + 1, #uid + 1)
            if d:sub(#uid + 1, #uid + 1) == 'B' then
              return d:sub(#uid + 2), sender
            end

            if d:sub(#uid + 2, #uid * 2 + 1) ~= uid then return end
            return d:sub(#uid * 2 + 2), sender
          end
        end,
        stop = function() server:disconnect() end,
        addr = proxy.address
      }
    end
  end,

  ['combine'] = function(connections)
    return {
      send = function(routes, addr, ...)
        if not routes[addr] then return false end
        return routes[addr][1].send(routes[addr][2], ...)
      end,
      broadcast = function(...)
        for _, connection in pairs(connections) do
          connection.broadcast(...)
        end
      end,
      recv = function(is_timeout)
        is_timeout = is_timeout or function() end
        while not is_timeout() do
          local e = {evt.pull(0.05)}
          if e[1] then
            for _, connection in pairs(connections) do
              local flag, info = connection.recv(e)
              if flag then return {connection, info}, flag end
            end
          end
        end
      end
    }
  end
}