package sessionpeermanager

import (
	"sync"
	"testing"

	"github.com/ipfs/go-bitswap/internal/testutil"
	peer "github.com/libp2p/go-libp2p-core/peer"
)

type fakePeerTagger struct {
	lk          sync.Mutex
	taggedPeers []peer.ID
	wait        sync.WaitGroup
}

func (fpt *fakePeerTagger) TagPeer(p peer.ID, tag string, n int) {
	fpt.wait.Add(1)

	fpt.lk.Lock()
	defer fpt.lk.Unlock()
	fpt.taggedPeers = append(fpt.taggedPeers, p)
}

func (fpt *fakePeerTagger) UntagPeer(p peer.ID, tag string) {
	defer fpt.wait.Done()

	fpt.lk.Lock()
	defer fpt.lk.Unlock()
	for i := 0; i < len(fpt.taggedPeers); i++ {
		if fpt.taggedPeers[i] == p {
			fpt.taggedPeers[i] = fpt.taggedPeers[len(fpt.taggedPeers)-1]
			fpt.taggedPeers = fpt.taggedPeers[:len(fpt.taggedPeers)-1]
			return
		}
	}
}

func TestAddPeers(t *testing.T) {
	peers := testutil.GeneratePeers(2)
	spm := New(1, &fakePeerTagger{})

	isNew := spm.AddPeer(peers[0])
	if !isNew {
		t.Fatal("Expected peer to be new")
	}

	isNew = spm.AddPeer(peers[0])
	if isNew {
		t.Fatal("Expected peer to no longer be new")
	}

	isNew = spm.AddPeer(peers[1])
	if !isNew {
		t.Fatal("Expected peer to be new")
	}
}

func TestRemovePeers(t *testing.T) {
	peers := testutil.GeneratePeers(2)
	spm := New(1, &fakePeerTagger{})

	existed := spm.RemovePeer(peers[0])
	if existed {
		t.Fatal("Expected peer not to exist")
	}

	spm.AddPeer(peers[0])
	spm.AddPeer(peers[1])

	existed = spm.RemovePeer(peers[0])
	if !existed {
		t.Fatal("Expected peer to exist")
	}
	existed = spm.RemovePeer(peers[1])
	if !existed {
		t.Fatal("Expected peer to exist")
	}
	existed = spm.RemovePeer(peers[0])
	if existed {
		t.Fatal("Expected peer not to have existed")
	}
}

func TestHasPeers(t *testing.T) {
	peers := testutil.GeneratePeers(2)
	spm := New(1, &fakePeerTagger{})

	if spm.HasPeers() {
		t.Fatal("Expected not to have peers yet")
	}

	spm.AddPeer(peers[0])
	if !spm.HasPeers() {
		t.Fatal("Expected to have peers")
	}

	spm.AddPeer(peers[1])
	if !spm.HasPeers() {
		t.Fatal("Expected to have peers")
	}

	spm.RemovePeer(peers[0])
	if !spm.HasPeers() {
		t.Fatal("Expected to have peers")
	}

	spm.RemovePeer(peers[1])
	if spm.HasPeers() {
		t.Fatal("Expected to no longer have peers")
	}
}

func TestHasPeer(t *testing.T) {
	peers := testutil.GeneratePeers(2)
	spm := New(1, &fakePeerTagger{})

	if spm.HasPeer(peers[0]) {
		t.Fatal("Expected not to have peer yet")
	}

	spm.AddPeer(peers[0])
	if !spm.HasPeer(peers[0]) {
		t.Fatal("Expected to have peer")
	}

	spm.AddPeer(peers[1])
	if !spm.HasPeer(peers[1]) {
		t.Fatal("Expected to have peer")
	}

	spm.RemovePeer(peers[0])
	if spm.HasPeer(peers[0]) {
		t.Fatal("Expected not to have peer")
	}

	if !spm.HasPeer(peers[1]) {
		t.Fatal("Expected to have peer")
	}
}

func TestPeers(t *testing.T) {
	peers := testutil.GeneratePeers(2)
	spm := New(1, &fakePeerTagger{})

	if len(spm.Peers()) > 0 {
		t.Fatal("Expected not to have peers yet")
	}

	spm.AddPeer(peers[0])
	if len(spm.Peers()) != 1 {
		t.Fatal("Expected to have one peer")
	}

	spm.AddPeer(peers[1])
	if len(spm.Peers()) != 2 {
		t.Fatal("Expected to have two peers")
	}

	spm.RemovePeer(peers[0])
	if len(spm.Peers()) != 1 {
		t.Fatal("Expected to have one peer")
	}
}

func TestPeersDiscovered(t *testing.T) {
	peers := testutil.GeneratePeers(2)
	spm := New(1, &fakePeerTagger{})

	if spm.PeersDiscovered() {
		t.Fatal("Expected not to have discovered peers yet")
	}

	spm.AddPeer(peers[0])
	if !spm.PeersDiscovered() {
		t.Fatal("Expected to have discovered peers")
	}

	spm.RemovePeer(peers[0])
	if !spm.PeersDiscovered() {
		t.Fatal("Expected to still have discovered peers")
	}
}

func TestPeerTagging(t *testing.T) {
	peers := testutil.GeneratePeers(2)
	fpt := &fakePeerTagger{}
	spm := New(1, fpt)

	spm.AddPeer(peers[0])
	if len(fpt.taggedPeers) != 1 {
		t.Fatal("Expected to have tagged one peer")
	}

	spm.AddPeer(peers[0])
	if len(fpt.taggedPeers) != 1 {
		t.Fatal("Expected to have tagged one peer")
	}

	spm.AddPeer(peers[1])
	if len(fpt.taggedPeers) != 2 {
		t.Fatal("Expected to have tagged two peers")
	}

	spm.RemovePeer(peers[1])
	if len(fpt.taggedPeers) != 1 {
		t.Fatal("Expected to have untagged peer")
	}
}

func TestShutdown(t *testing.T) {
	peers := testutil.GeneratePeers(2)
	fpt := &fakePeerTagger{}
	spm := New(1, fpt)

	spm.AddPeer(peers[0])
	spm.AddPeer(peers[1])
	if len(fpt.taggedPeers) != 2 {
		t.Fatal("Expected to have tagged two peers")
	}

	spm.Shutdown()

	if len(fpt.taggedPeers) != 0 {
		t.Fatal("Expected to have untagged all peers")
	}
}