package floodsub

import (
	"bytes"
	"context"
	"fmt"
	"math/rand"
	"testing"
	"time"

	host "github.com/libp2p/go-libp2p/p2p/host"
	netutil "github.com/libp2p/go-libp2p/p2p/test/util"
)

func getNetHosts(t *testing.T, ctx context.Context, n int) []host.Host {
	var out []host.Host

	for i := 0; i < n; i++ {
		h := netutil.GenHostSwarm(t, ctx)
		out = append(out, h)
	}

	return out
}

func connect(t *testing.T, a, b host.Host) {
	pinfo := a.Peerstore().PeerInfo(a.ID())
	err := b.Connect(context.Background(), pinfo)
	if err != nil {
		t.Fatal(err)
	}
}

func sparseConnect(t *testing.T, hosts []host.Host) {
	for i, a := range hosts {
		for j := 0; j < 3; j++ {
			n := rand.Intn(len(hosts))
			if n == i {
				j--
				continue
			}

			b := hosts[n]

			connect(t, a, b)
		}
	}
}

func connectAll(t *testing.T, hosts []host.Host) {
	for i, a := range hosts {
		for j, b := range hosts {
			if i == j {
				continue
			}

			connect(t, a, b)
		}
	}
}

func getPubsubs(ctx context.Context, hs []host.Host) []*PubSub {
	var psubs []*PubSub
	for _, h := range hs {
		psubs = append(psubs, NewFloodSub(ctx, h))
	}
	return psubs
}

func TestBasicFloodsub(t *testing.T) {
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()
	hosts := getNetHosts(t, ctx, 20)

	psubs := getPubsubs(ctx, hosts)

	var msgs []<-chan *Message
	for _, ps := range psubs {
		subch, err := ps.Subscribe("foobar")
		if err != nil {
			t.Fatal(err)
		}

		msgs = append(msgs, subch)
	}

	//connectAll(t, hosts)
	sparseConnect(t, hosts)

	time.Sleep(time.Millisecond * 100)

	for i := 0; i < 100; i++ {
		msg := []byte(fmt.Sprintf("%d the flooooooood %d", i, i))

		owner := rand.Intn(len(psubs))

		psubs[owner].Publish("foobar", msg)

		for _, resp := range msgs {
			got := <-resp
			if !bytes.Equal(msg, got.Data) {
				t.Fatal("got wrong message!")
			}
		}
	}

}

func TestMultihops(t *testing.T) {
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	hosts := getNetHosts(t, ctx, 6)

	psubs := getPubsubs(ctx, hosts)

	connect(t, hosts[0], hosts[1])
	connect(t, hosts[1], hosts[2])
	connect(t, hosts[2], hosts[3])
	connect(t, hosts[3], hosts[4])
	connect(t, hosts[4], hosts[5])

	var msgChs []<-chan *Message
	for i := 1; i < 6; i++ {
		ch, err := psubs[i].Subscribe("foobar")
		if err != nil {
			t.Fatal(err)
		}
		msgChs = append(msgChs, ch)
	}

	time.Sleep(time.Millisecond * 100)

	msg := []byte("i like cats")
	err := psubs[0].Publish("foobar", msg)
	if err != nil {
		t.Fatal(err)
	}

	// last node in the chain should get the message
	select {
	case out := <-msgChs[4]:
		if !bytes.Equal(out.GetData(), msg) {
			t.Fatal("got wrong data")
		}
	case <-time.After(time.Second * 5):
		t.Fatal("timed out waiting for message")
	}
}

func TestReconnects(t *testing.T) {
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	hosts := getNetHosts(t, ctx, 10)

	psubs := getPubsubs(ctx, hosts)

	connect(t, hosts[0], hosts[1])
	connect(t, hosts[0], hosts[2])

	A, err := psubs[1].Subscribe("cats")
	if err != nil {
		t.Fatal(err)
	}

	B, err := psubs[2].Subscribe("cats")
	if err != nil {
		t.Fatal(err)
	}

	time.Sleep(time.Millisecond * 100)

	msg := []byte("apples and oranges")
	err = psubs[0].Publish("cats", msg)
	if err != nil {
		t.Fatal(err)
	}

	assertReceive(t, A, msg)
	assertReceive(t, B, msg)

	hosts[2].Close()

	msg2 := []byte("potato")
	err = psubs[0].Publish("cats", msg2)
	if err != nil {
		t.Fatal(err)
	}

	assertReceive(t, A, msg2)

	time.Sleep(time.Millisecond * 50)
	_, ok := psubs[0].peers[hosts[2].ID()]
	if ok {
		t.Fatal("shouldnt have this peer anymore")
	}
}

func assertReceive(t *testing.T, ch <-chan *Message, exp []byte) {
	select {
	case msg := <-ch:
		if !bytes.Equal(msg.GetData(), exp) {
			t.Fatalf("got wrong message, expected %s but got %s", string(exp), string(msg.GetData()))
		}
	case <-time.After(time.Second * 5):
		t.Fatal("timed out waiting for message of: ", exp)
	}
}