package ws

import (
	"encoding/json"
	"fmt"
	"sync"
	"testing"
	"time"

	"git.saqut.com/saqut/mwse/internal/protocol"
	"git.saqut.com/saqut/mwse/internal/testutil"
)

// newTestClient builds a client backed by an in-memory connection and starts its
// writer pump, the way the real server does.
func newTestClient(id string) (*Client, *testutil.FakeConn) {
	fc := testutil.NewFakeConn()
	c := NewClient(fc, id)
	go c.writePump()
	return c, fc
}

// waitFor polls cond until it holds or the deadline passes.
func waitFor(t *testing.T, cond func() bool) {
	t.Helper()
	for i := 0; i < 500; i++ {
		if cond() {
			return
		}
		time.Sleep(time.Millisecond)
	}
	t.Fatal("condition not met within timeout")
}

// lastSignal decodes the most recent [payload, name] frame from fc.
func lastSignal(t *testing.T, fc *testutil.FakeConn) (string, map[string]any) {
	t.Helper()
	writes := fc.Writes()
	if len(writes) == 0 {
		t.Fatal("no frames written")
	}
	var arr []any
	if err := json.Unmarshal(writes[len(writes)-1], &arr); err != nil {
		t.Fatalf("decode frame: %v", err)
	}
	name, _ := arr[1].(string)
	payload, _ := arr[0].(map[string]any)
	return name, payload
}

func TestSendConcurrentWithClose(t *testing.T) {
	// The core safety property of the rewrite: sending to a client that is closing
	// must never panic or race, only drop. Run under -race.
	for trial := 0; trial < 30; trial++ {
		c, _ := newTestClient("x")
		var wg sync.WaitGroup
		for i := 0; i < 8; i++ {
			wg.Add(1)
			go func() {
				defer wg.Done()
				for j := 0; j < 100; j++ {
					c.Send(map[string]any{"j": j})
				}
			}()
		}
		go c.Close()
		wg.Wait()
	}
}

func TestSendAfterCloseDoesNotPanic(t *testing.T) {
	c, _ := newTestClient("x")
	c.Close()
	waitFor(t, func() bool {
		select {
		case <-c.Done():
			return true
		default:
			return false
		}
	})
	// Should return promptly and not panic.
	c.Send(map[string]any{"ignored": true})
}

func TestRoomBroadcastDelivers(t *testing.T) {
	hub := NewHub()
	room := NewRoom(hub)
	room.OwnerID = "o"
	room.NotifyActionJoined = false // keep frame counts clean
	room.Publish()

	a, fa := newTestClient("a")
	b, fb := newTestClient("b")
	hub.addClient(a)
	hub.addClient(b)
	room.Join(a)
	room.Join(b)

	room.Broadcast("pack/room", map[string]any{"hello": float64(1)}, "", nil)

	waitFor(t, func() bool { return fa.WriteCount() >= 1 && fb.WriteCount() >= 1 })

	name, payload := lastSignal(t, fa)
	if name != "pack/room" {
		t.Fatalf("signal name = %q, want pack/room", name)
	}
	if payload["hello"] != float64(1) {
		t.Fatalf("payload = %v", payload)
	}
}

func TestRoomBroadcastRespectsExceptAndFilter(t *testing.T) {
	hub := NewHub()
	room := NewRoom(hub)
	room.OwnerID = "o"
	room.NotifyActionJoined = false
	room.Publish()

	a, fa := newTestClient("a")
	b, fb := newTestClient("b")
	hub.addClient(a)
	hub.addClient(b)
	room.Join(a)
	room.Join(b)

	// b opts out of peer-info notifications; the filter must skip it.
	b.SetStore(flagNotifyPairInfo, false)

	room.Broadcast("x", map[string]any{"n": float64(1)}, "", (*Client).PeerInfoNotifiable)
	waitFor(t, func() bool { return fa.WriteCount() >= 1 })
	time.Sleep(20 * time.Millisecond) // give a wrong delivery a chance to show up

	if fb.WriteCount() != 0 {
		t.Fatalf("filtered-out client received %d frames", fb.WriteCount())
	}

	// exceptID must also be honoured.
	room.Broadcast("y", map[string]any{}, a.ID, nil)
	waitFor(t, func() bool { return fb.WriteCount() >= 1 })
	if name, _ := lastSignal(t, fa); name == "y" {
		t.Fatal("exceptID client should not have received the second broadcast")
	}
}

func TestRoomEmptyTriggersDown(t *testing.T) {
	hub := NewHub()
	room := NewRoom(hub)
	room.OwnerID = "a"
	room.Publish()

	a, _ := newTestClient("a")
	hub.addClient(a)
	room.Join(a)

	room.Eject(a)

	if _, ok := hub.Room(room.ID); ok {
		t.Fatal("room should be removed from hub when it empties")
	}
	if a.InRoom(room.ID) {
		t.Fatal("client should no longer reference a downed room")
	}
}

// TestLeaveWhileSendRace is the #22 regression: broadcasting to a room while
// members concurrently leave and rejoin. Under -race this catches any unguarded
// access to shared room/peer state — the exact failure the Node engine had.
func TestLeaveWhileSendRace(t *testing.T) {
	hub := NewHub()
	room := NewRoom(hub)
	room.OwnerID = "owner"
	room.Publish()

	const n = 30
	clients := make([]*Client, n)
	for i := 0; i < n; i++ {
		c, _ := newTestClient(fmt.Sprintf("c%d", i))
		clients[i] = c
		hub.addClient(c)
		room.Join(c)
	}

	var wg sync.WaitGroup

	// Broadcasters hammer the room.
	for g := 0; g < 4; g++ {
		wg.Add(1)
		go func() {
			defer wg.Done()
			for j := 0; j < 300; j++ {
				room.Broadcast("pack/room", map[string]any{"j": j}, "", nil)
			}
		}()
	}

	// Churn: members leave and rejoin repeatedly while broadcasts are in flight.
	for i := 0; i < n; i++ {
		wg.Add(1)
		go func(c *Client) {
			defer wg.Done()
			for k := 0; k < 100; k++ {
				room.Eject(c)
				room.Join(c)
			}
		}(clients[i])
	}

	wg.Wait()

	for _, c := range clients {
		c.Close()
	}
}

func TestHubRegistryConcurrency(t *testing.T) {
	hub := NewHub()
	hub.Register("noop", func(c *Client, m protocol.Message) any { return success() })

	var wg sync.WaitGroup
	for g := 0; g < 8; g++ {
		wg.Add(1)
		go func(g int) {
			defer wg.Done()
			for i := 0; i < 200; i++ {
				id := fmt.Sprintf("g%d-%d", g, i)
				c := NewClient(testutil.NewFakeConn(), id)
				hub.addClient(c)
				_, _ = hub.Client(id)
				_ = hub.Clients()
				_ = hub.ClientCount()
				hub.removeClient(id)
			}
		}(g)
	}
	wg.Wait()
}

// success mirrors the services helper so the hub test stays self-contained.
func success() map[string]any { return map[string]any{"status": "success"} }

func TestServerHandleRepliesToRequest(t *testing.T) {
	hub := NewHub()
	hub.Register("ping", func(c *Client, m protocol.Message) any {
		return map[string]any{"pong": true}
	})
	srv := NewServer(hub)

	fc := testutil.NewFakeConn()
	go srv.handle(fc)

	fc.Push([]byte(`[{"type":"ping"}, 5, "R"]`))
	waitFor(t, func() bool { return fc.WriteCount() >= 1 })

	writes := fc.Writes()
	var arr []any
	if err := json.Unmarshal(writes[len(writes)-1], &arr); err != nil {
		t.Fatalf("decode reply: %v", err)
	}
	// Expect [ {"pong":true}, 5, "E" ].
	if len(arr) != 3 {
		t.Fatalf("reply arity = %d, want 3", len(arr))
	}
	if arr[1] != float64(5) {
		t.Fatalf("reply id = %v, want 5", arr[1])
	}
	if arr[2] != protocol.FlagEnd {
		t.Fatalf("reply flag = %v, want E", arr[2])
	}
	fc.Close()
}