// Copyright 2020 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package client

import (
	"math/rand"
	"testing"
	"time"

	"github.com/ethereum/go-ethereum/common/mclock"
	"github.com/ethereum/go-ethereum/p2p/enode"
	"github.com/ethereum/go-ethereum/p2p/enr"
	"github.com/ethereum/go-ethereum/p2p/nodestate"
)

type testIter struct {
	waitCh chan struct{}
	nodeCh chan *enode.Node
	node   *enode.Node
}

func (i *testIter) Next() bool {
	i.waitCh <- struct{}{}
	i.node = <-i.nodeCh
	return i.node != nil
}

func (i *testIter) Node() *enode.Node {
	return i.node
}

func (i *testIter) Close() {}

func (i *testIter) push() {
	var id enode.ID
	rand.Read(id[:])
	i.nodeCh <- enode.SignNull(new(enr.Record), id)
}

func (i *testIter) waiting(timeout time.Duration) bool {
	select {
	case <-i.waitCh:
		return true
	case <-time.After(timeout):
		return false
	}
}

func TestFillSet(t *testing.T) {
	ns := nodestate.NewNodeStateMachine(nil, nil, &mclock.Simulated{}, testSetup)
	iter := &testIter{
		waitCh: make(chan struct{}),
		nodeCh: make(chan *enode.Node),
	}
	fs := NewFillSet(ns, iter, sfTest1)
	ns.Start()

	expWaiting := func(i int, push bool) {
		for ; i > 0; i-- {
			if !iter.waiting(time.Second * 10) {
				t.Fatalf("FillSet not waiting for new nodes")
			}
			if push {
				iter.push()
			}
		}
	}

	expNotWaiting := func() {
		if iter.waiting(time.Millisecond * 100) {
			t.Fatalf("FillSet unexpectedly waiting for new nodes")
		}
	}

	expNotWaiting()
	fs.SetTarget(3)
	expWaiting(3, true)
	expNotWaiting()
	fs.SetTarget(100)
	expWaiting(2, true)
	expWaiting(1, false)
	// lower the target before the previous one has been filled up
	fs.SetTarget(0)
	iter.push()
	expNotWaiting()
	fs.SetTarget(10)
	expWaiting(4, true)
	expNotWaiting()
	// remove all previosly set flags
	ns.ForEach(sfTest1, nodestate.Flags{}, func(node *enode.Node, state nodestate.Flags) {
		ns.SetState(node, nodestate.Flags{}, sfTest1, 0)
	})
	// now expect FillSet to fill the set up again with 10 new nodes
	expWaiting(10, true)
	expNotWaiting()

	fs.Close()
	ns.Stop()
}