-- our coroutine-with-mailbox thing.  badly needs renaming.

declare("current_threadinfo")

active_threads = {}

function CreateThread(threadfunc, ...)
  local fsm = coroutine.create(threadfunc)
  local threadinfo = {fsm=fsm, queued_triggers={}}
  
  local prev_threadinfo = current_threadinfo
  current_threadinfo = threadinfo
  local ok, err = coroutine.resume(fsm, threadinfo, unpack(arg)) -- start the fsm
  current_threadinfo = prev_threadinfo
  if not ok then
    log.error("CreateThread(): "..err)
    return nil, err
  end

  if coroutine.status(fsm) ~= "dead" then
    active_threads[threadinfo] = true
  end
  
  return threadinfo
end

function trigger_fsm(threadinfo,eventname, topts)
  if threadinfo == nil then log.error("nil threadinfo.") return end
  local fsm = threadinfo.fsm
  if fsm == nil or type(fsm) ~= "thread" then 
    log.error("trigger_fsm(...,"..eventname..","..StrTable(topts)..
      ") on non-thread?!\nthreadinfo="..StrTable(threadinfo))
    return 
  end

  if coroutine.status(fsm) == "running" then 
    log.error('trigger_fsm: trying to resume already running coroutine!')
    return
  end
  if coroutine.status(fsm) ~= "suspended" then return end

  local prev_threadinfo = current_threadinfo
  current_threadinfo = threadinfo
  local success, err = coroutine.resume(fsm, eventname, topts)
  current_threadinfo = prev_threadinfo

  if coroutine.status(fsm) == "dead" then
    active_threads[threadinfo] = nil
  end

  if not success then
    log.error("trigger_fsm("..tostring(eventname).."): "..err)
    if threadinfo.abort then threadinfo:abort() end
    return
  end
  return err
end

function get_queued_triggers(threadinfo)
  if table.getn(threadinfo.queued_triggers) > 0 then
    local t = table.remove(threadinfo.queued_triggers, 1)
    return t[1], t[2]
  end
end

function check_for_queued_triggers(threadinfo, triggers)
  local k,v, k2, v2
  for k,v in ipairs(threadinfo.queued_triggers) do
    for k2,v2 in ipairs(triggers) do
      if v[1] == v2 then
        table.remove(threadinfo.queued_triggers, k)
        return v[1], v[2]
      end
    end
  end
end

function check_for_queued_trigger(threadinfo, trigger)
  local k,v
  for k,v in ipairs(threadinfo.queued_triggers) do
    if v[1] == trigger then
      table.remove(threadinfo.queued_triggers, k)
      return v[1], v[2]
    end
  end
end

-- returns the trigger options
function WaitForSingleTrigger(threadinfo, trigger)
--  log.print("Waiting for '"..trigger.."' trigger.")
  if not threadinfo then log.error('nil thread info') return end
  local incomingtrigger, topts = check_for_queued_trigger(threadinfo, trigger)
  if incomingtrigger then return topts end
  while true do
    incomingtrigger, topts = coroutine.yield()
    if incomingtrigger == trigger then break end
    log.print("WaitForSingleTrigger NOTE: queuing "..incomingtrigger..", waiting for "..trigger)
--    if incomingtrigger == "LogOff" then
--      log.error('XXX ERROR: queueing a logoff while waiting for a '..trigger)
--    end
    table.insert(threadinfo.queued_triggers, {incomingtrigger, topts} )
  end
  return topts
end

-- returns which trigger and its options
function WaitForMultipleTriggers(threadinfo, triggers)
--  log.print("Waiting for multiple triggers: {")
--  for k,v in pairs(triggers) do log.print("      '"..v.."'") end
--  log.print("      }")
  local incomingtrigger, topts = check_for_queued_triggers(threadinfo, triggers)
  if incomingtrigger then return incomingtrigger, topts end
  while true do
    incomingtrigger, topts = coroutine.yield()
    for k,v in pairs(triggers) do
      if v == incomingtrigger then
        return incomingtrigger, topts
      end
    end
    log.print("WaitForMultipleTriggers NOTE: queuing "..incomingtrigger..", waiting for "..StrTable(triggers))
--    if incomingtrigger == "LogOff" then
--      printtable(triggers)
--      log.error(debug.traceback('XXX ERROR: queueing a logoff while waiting for above triggers'))
--    end
    table.insert(threadinfo.queued_triggers, {incomingtrigger, topts} )
  end
  return incomingtrigger, topts
end

-- returns which trigger and its options
function WaitForAnyTrigger(threadinfo)
--  log.print("Waiting for any trigger.")
  local incomingtrigger, topts = get_queued_triggers(threadinfo)
  if not incomingtrigger then
    incomingtrigger, topts = coroutine.yield()
  end
  -- log.print("WaitForAnyTrigger: Got "..incomingtrigger)
  return incomingtrigger, topts
end

local condition_waits = {}
function cond_wait(cond)
  condition_waits[cond] = condition_waits[cond] or {}
  table.insert(condition_waits[cond], current_threadinfo)
  WaitForSingleTrigger(current_threadinfo, cond)
end

function cond_signal(cond)
  local t = condition_waits[cond]
  condition_waits[cond] = nil
  if not t then return end
  for _,fsm in ipairs(t) do
    trigger_fsm(fsm, cond)
  end
end