package module

import (
	"errors"
	"strconv"
	"tunnel/pkg/server/env"
	"tunnel/pkg/server/opts"
	"tunnel/pkg/server/queue"
)

const splitDefaultSize = 1024

var errBadSize = errors.New("bad size value")

type splitModule struct {
	size int
}

func (m *splitModule) Send(rq, wq queue.Q) error {
	for b := range rq {
		var upto int

		for n := 0; n < len(b); n = upto {
			upto += m.size

			if upto > len(b) {
				upto = len(b)
			}

			wq <- b[n:upto]
		}
	}

	return nil
}

func (m *splitModule) Open(env.Env) (interface{}, error) {
	return m, nil
}

func newSplitModule(opts opts.Opts, env env.Env) (module, error) {
	size := splitDefaultSize

	if s, ok := opts["size"]; ok {
		var err error

		if size, err = strconv.Atoi(s); err != nil || size <= 0 {
			return nil, errBadSize
		}
	}

	return &splitModule{size: size}, nil
}

func init() {
	register("split", newSplitModule)
}