local mt = {}

mt.newPool = function()
	local pool = {}
	pool.threads = {} -- indexed by coroutines, contains their metadata
	pool.namedThreads = {} -- indexed by coroutine names, contains their metadata also.
	-- coroutines are named if their metadata has a name field.
	pool.threadcount = 0 -- used for detecting when all things in a pool are depleted
	
	pool.clear = function()
		pool.threads = {}
		pool.namedThreads = {}
		pool.threadcount = 0
	end
	
	pool.add = function(fn, options)
		options = options or {}
		options.co = coroutine.create(fn)
		pool.threads[options.co] = options
		if options.name then
			pool.namedThreads[options.name] = options
		end
		pool.threadcount = pool.threadcount + 1
		os.queueEvent("pool_fn_added",options,pool)
		return options.co
	end
	
	pool.rm = function(name)
		if not pool.namedThreads[name] then
			return false
		end
		pool.threads[pool.namedThreads[name].co] = nil
		pool.namedThreads[name] = nil
		pool.threadcount = pool.threadcount - 1
		return true
	end
	
	pool.addFile = function(filename, options)
		pool.add(function()
			dofile(filename)
		end,options)
	end
	
	pool.run = function(terminable)
		terminable = terminable or true -- if false, terminate events will be echoed to coroutines instead of 
		-- terminating this pool
		while true do
			local event = {coroutine.yield()}
			if event[1] == "terminate" and terminable then
				return
			end
			for thread, options in pairs(pool.threads) do
				if coroutine.status(thread) ~= "dead" then
					if event[1] == options.filter or options.filter == nil then
						local x,e,y = pcall(coroutine.resume,thread,unpack(event))
						options.filter = y
						if not x then
							os.queueEvent("pool_fn_crash",e,options,pool)
							pool.threadcount = pool.threadcount - 1
						end
					end
				else
					os.queueEvent("pool_fn_end",options,pool)
					pool.threadcount = pool.threadcount - 1
					pool.threads[thread] = nil
				end
			end
			if pool.threadcount == 0 then return end
		end
	end
	
	return pool
end

return mt