local serialization = require("serialization")
local uuid = require("uuid")
local computer = require("computer")

local Version = {0, 1}

local Message = {
  Hello         = 0x48454c4f,
  Register      = 0x52454749,
  Deregister    = 0x44524547,
  NounRequest   = 0x4e524551,
  NounResponse  = 0x4e524553,
  VerbRequest   = 0x56524551,
  VerbResponse  = 0x56524553,
  ListenRequest = 0x4c524551,
  ListenNotify  = 0x4c4e4f54,
  ListenCancel  = 0x4c535450,
}

local query_param = {
  __call=function(self, v)
    return {ty=self.ty, v=v}
  end,
}
local Query = {
  Change        = {ty=0x434847},
  Rising        = {ty=0x524953},
  Falling       = {ty=0x46414c},
  Equals        = setmetatable({ty=0x455155, invalid=true}, query_param),
  Above         = setmetatable({ty=0x414256, invalid=true}, query_param),
  Below         = setmetatable({ty=0x424c4f, invalid=true}, query_param),
}

-- Network ---------------------------------------------------------------- {{{
local Network = {
  default_port = 0xBC00 | (Version[1] << 4) | Version[2],
}

function Network:new(modem, port)
  if type(modem) == "number" then
    port = modem
    modem = nil
  end
  local self = {
    modem = modem or require("component").modem,
    port = port or Network.default_port,
    event = require("event"),
  }
  setmetatable(self, {__index=Network})

  return self
end
setmetatable(Network, {__call=Network.new})

function Network:start(callback)
  self.modem.open(self.port)
  self.listener = function(_, addr_lo, addr_remote, port, _, msg)
    -- Filter everything we don't care about
    if addr_lo ~= self.modem.address then return end
    if port ~= self.port then return end
    callback(addr_remote, serialization.unserialize(msg))
  end
  self.event.listen("modem_message", self.listener)
end

function Network:send(addr, msg)
  self.modem.send(addr, self.port, serialization.serialize(msg))
end

function Network:broadcast(msg)
  self.modem.broadcast(self.port, serialization.serialize(msg))
end

function Network:pull(filter, timeout)
  local last_msg
  local ev = self.event.pullFiltered(timeout, function(ev, addr_lo, addr_remote, port, _, msg)
    if ev ~= "modem_message" then return false end
    if addr_lo ~= self.modem.address then return false end
    if port ~= self.port then return false end
    last_msg = serialization.unserialize(msg)
    return filter(addr_remote, last_msg)
  end)
  if ev ~= nil then
    return last_msg
  else
    return nil
  end
end

function Network:stop()
  self.event.ignore("modem_message", self.listener)
  self.modem.close(self.port)
end
-- }}}

-- BaseControl ------------------------------------------------------------ {{{
local BaseControl = {
  version = Version,
  Message = Message,
  Query = Query,
  Network = Network,
}

-- Lifecycle {{{
function BaseControl:new(network)
  local self = {
    local_nouns = {},
    local_verbs = {},
    remote_nouns = {},
    remote_verbs = {},
    listeners = {},

    live = false,
    network = network or Network:new(),
  }
  setmetatable(self, {__index=BaseControl, __call=BaseControl.new})

  self.network:start(function(remote, msg)
    self:_network_handler(remote, msg)
  end)
  self.network:broadcast{ty=Message.Hello}

  return self
end

function BaseControl:register(name, value)
  if self.live then
    error("can't register \""..name.."\" after finalizing")
  end

  if type(name) == "table" then
    -- Batch register
    for name, value in pairs(name) do
      self:register(name, value)
    end
  elseif type(value) == "function" then
    if self.local_verbs[name] ~= nil then
      error("\""..name.."\" already registered")
    else
      self.local_verbs[name] = value
    end
  else
    if self.local_nouns[name] ~= nil then
      error("\""..name.."\" already registered")
    else
      self.local_nouns[name] = value
    end
  end
end

function BaseControl:finalize(waits, timeout)
  if self == BaseControl then
    self = BaseControl:new()
  end

  -- Announce own nouns and verbs if this is the first
  -- call to finalize() and we have registered names
  if not self.live then
    local nouns, verbs = self:nouns(true), self:verbs(true)
    if #nouns > 0 or #verbs > 0 then
      self.network:broadcast{
        ty=Message.Register,
        nouns=nouns,
        verbs=verbs,
      }
    end
    self.live = true
  end

  if #(waits or {}) ~= 0 then
    -- Wait for requested names
    local remaining = {} -- Table with all remaining names as keys
    local num_remaining = 0  -- Number of remaining names
    for _, name in ipairs(waits) do
      if not self:has_noun(name) and not self:has_verb(name) then
        remaining[name] = true
        num_remaining = num_remaining + 1
      end
    end

    local tstart = computer.uptime()
    local timeout_remaining = timeout
    while num_remaining > 0 do
      if timeout ~= nil then
        timeout_remaining = timeout - (computer.uptime() - tstart)
        if timeout_remaining <= 0 then
          error("timeout")
        end
      end
      -- Wait until the next register arrives
      local msg = self.network:pull(function(remote, msg)
        return msg.ty == Message.Register
      end, timeout_remaining)
      if msg ~= nil then
        for _, noun in ipairs(msg.nouns or {}) do
          if remaining[noun] then
            num_remaining = num_remaining - 1
            remaining[noun] = nil
          end
        end
        for _, verb in ipairs(msg.verbs or {}) do
          if remaining[verb] then
            num_remaining = num_remaining - 1
            remaining[verb] = nil
          end
        end
      end
    end
  end

  return self
end

function BaseControl:close()
  if self.live == true then
    -- Deregister own nouns and verbs if we were live
    local nouns, verbs = self:nouns(true), self:verbs(true)
    if #nouns > 0 or #verbs > 0 then
      self.network:broadcast{
        ty=Message.Deregister,
        nouns=nouns,
        verbs=verbs,
      }
    end
  end

  self.network:stop()
  setmetatable(self, nil)
end
-- }}}

-- Nouns {{{
function BaseControl:has_noun(noun)
  return self.local_nouns[noun] ~= nil or self.remote_nouns[noun] ~= nil
end

function BaseControl:nouns(local_only)
  local nouns = {}
  for noun in pairs(self.local_nouns) do
    table.insert(nouns, noun)
  end
  if not local_only then
    for noun in pairs(self.remote_nouns) do
      table.insert(nouns, noun)
    end
  end
  return nouns
end

function BaseControl:get(noun, timeout)
  if self.local_nouns[noun] ~= nil then
    return self.local_nouns[noun]
  elseif self.local_verbs[noun] ~= nil then
    error("\""..noun.."\" is not a noun")
  elseif self.remote_nouns[noun] ~= nil then
    self.network:send(self.remote_nouns[noun], {
      ty=Message.NounRequest,
      noun=noun,
    })
    local answer = self.network:pull(function(remote, msg)
      if remote ~= self.remote_nouns[noun] then return false end
      if msg.ty ~= Message.NounResponse then return false end
      if msg.noun ~= noun then return false end
      return true
    end, timeout)
    if answer ~= nil then
      return answer.value
    else
      error("timeout")
    end
  else
    return error("unknown noun \""..noun.."\"")
  end
end

function BaseControl:set(name, value)
  if self.local_nouns[name] ~= nil then
    if type(value) == "function" then
      error("\""..name.."\" can't be cast into a verb")
    else
      local old = self.local_nouns[name]
      self.local_nouns[name] = value

      for id, l in pairs(self.listeners[name] or {}) do
        if   (l.query.ty == Query.Change.ty  and value ~= old)
          or (l.query.ty == Query.Rising.ty  and value > old)
          or (l.query.ty == Query.Falling.ty and value < old)
          or (l.query.ty == Query.Equals.ty  and value == l.query.v)
          or (l.query.ty == Query.Above.ty   and value > l.query.v)
          or (l.query.ty == Query.Below.ty   and value < l.query.v)
            then
          if l.callback ~= nil then
            l.callback(value)
          else
            self.network:send(l.addr, {
              ty=Message.ListenNotify,
              noun=name,
              id=id,
              value=value,
            })
          end
        end
      end
    end
  elseif self.local_verbs[name] ~= nil then
    if type(value) ~= "function" then
      error("\""..name.."\" can't be cast into a noun")
    else
      self.local_verbs[name] = value
    end
  else
    error("\""..name.."\" is not a local")
  end
end
-- }}}

-- Verbs {{{
function BaseControl:has_verb(verb)
  return self.local_verbs[verb] ~= nil or self.remote_verbs[verb] ~= nil
end

function BaseControl:verbs(local_only)
  local verbs = {}
  for verb in pairs(self.local_verbs) do
    table.insert(verbs, verb)
  end
  if not local_only then
    for verb in pairs(self.remote_verbs) do
      table.insert(verbs, verb)
    end
  end
  return verbs
end

function BaseControl:call(verb, ...)
  if self.local_verbs[verb] ~= nil then
    self.local_verbs[verb](...)
    return true
  elseif self.remote_verbs[verb] ~= nil then
    self.network:send(self.remote_verbs[verb], {
      ty=Message.VerbRequest,
      verb=verb,
      param={...},
    })
    return true
  else
    return false
  end
end

function BaseControl:call_sync(timeout, verb, ...)
  local param = {...}
  if type(timeout) ~= "number" then
    table.insert(param, 1, verb)
    timeout, verb = nil, timeout
  end
  if self.local_verbs[verb] ~= nil then
    return self.local_verbs[verb](table.unpack(param))
  elseif self.remote_verbs[verb] ~= nil then
    self.network:send(self.remote_verbs[verb], {
      ty=Message.VerbRequest,
      verb=verb,
      param=param,
      sync=true,
    })
    local answer = self.network:pull(function(remote, msg)
      if remote ~= self.remote_verbs[verb] then return false end
      if msg.ty ~= Message.VerbResponse then return false end
      if msg.verb ~= verb then return false end
      return true
    end, timeout)
    if answer ~= nil then
      return table.unpack(answer.ret)
    else
      error("timeout")
    end
  else
    error("unknown verb \""..verb.."\"")
  end
end
-- }}}

-- Listening {{{
function BaseControl:listen(noun, query, callback)
  if query.invalid then
    error("invalid query, forgot a parameter?")
  end
  if self.listeners[noun] == nil then
    self.listeners[noun] = {}
  end
  local id = uuid.next()
  self.listeners[noun][id] = {
    query=query,
    callback=callback,
  }
  if self.local_nouns[noun] ~= nil then
    return id, true
  elseif self.remote_nouns[noun] ~= nil then
    self.network:send(self.remote_nouns[noun], {
      ty=Message.ListenRequest,
      noun=noun,
      id=id,
      query=query,
    })
    return id, true
  else
    return id, false
  end
end

function BaseControl:cancel(noun, id)
  if self.listeners[noun] == nil or self.listeners[noun][id] == nil then
    error("can't cancel unknown listener on \""..noun.."\"")
  end
  if self.local_nouns[noun] == nil and self.remote_nouns[noun] ~= nil then
    self.network:send(self.remote_nouns[noun], {
      ty=Message.ListenCancel,
      noun=noun,
      id=id,
    })
  end
  self.listeners[noun][id] = nil
end
-- }}}

-- Network Handler {{{
function BaseControl:_network_handler(remote, msg)
  if msg.ty == Message.Hello then
    if self.live then
      -- If we are live already, answer with own nouns and verbs
      self.network:send(remote, {
        ty=Message.Register,
        nouns=self:nouns(true),
        verbs=self:verbs(true),
      })
    end
  elseif msg.ty == Message.Register then
    for _, noun in ipairs(msg.nouns or {}) do
      self.remote_nouns[noun] = remote
      for id, l in pairs(self.listeners[noun] or {}) do
        self.network:send(remote, {
          ty=Message.ListenRequest,
          noun=noun,
          id=id,
          query=l.query,
        })
      end
    end
    for _, verb in ipairs(msg.verbs or {}) do
      self.remote_verbs[verb] = remote
    end
  elseif msg.ty == Message.Deregister then
    for _, noun in ipairs(msg.nouns or {}) do
      if self.remote_nouns[noun] == remote then
        self.remote_nouns[noun] = nil
      end
    end
    for _, verb in ipairs(msg.verbs or {}) do
      if self.remote_verbs[verb] == remote then
        self.remote_verbs[verb] = nil
      end
    end
  elseif msg.ty == Message.NounRequest then
    self.network:send(remote, {
      ty=Message.NounResponse,
      noun=msg.noun,
      value=self.local_nouns[msg.noun],
    })
  elseif msg.ty == Message.NounResponse then
    -- Handled via pull
  elseif msg.ty == Message.VerbRequest then
    if self.local_verbs[msg.verb] ~= nil then
      local ret = table.pack(self.local_verbs[msg.verb](table.unpack(msg.param)))
      if msg.sync then
        self.network:send(remote, {
          ty=Message.VerbResponse,
          verb=msg.verb,
          ret=ret,
        })
      end
    end
  elseif msg.ty == Message.VerbResponse then
    -- Handled via pull
  elseif msg.ty == Message.ListenRequest then
    if self.local_nouns[msg.noun] ~= nil then
      if self.listeners[msg.noun] == nil then
        self.listeners[msg.noun] = {}
      end
      self.listeners[msg.noun][msg.id] = {
        query=msg.query,
        addr=remote,
      }
    end
  elseif msg.ty == Message.ListenNotify then
    if self.listeners[msg.noun][msg.id] ~= nil then
      self.listeners[msg.noun][msg.id].callback(msg.value)
    end
  elseif msg.ty == Message.ListenCancel then
    if self.listeners[msg.noun][msg.id] ~= nil then
      if self.listeners[msg.noun][msg.id].addr == remote then
        self.listeners[msg.noun][msg.id] = nil
      end
    end
  end
end
-- }}}
-- }}}

return setmetatable(BaseControl, {__call=BaseControl.new})