package ws

import (
	"strings"
	"testing"
	"time"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

// === SSE Registry Tests ===

func TestNewSSERegistry(t *testing.T) {
	reg := NewSSERegistry()
	assert.NotNil(t, reg)
	assert.NotNil(t, reg.channels)
	assert.NotNil(t, reg.accounts)
	assert.Equal(t, 0, reg.TotalChannelCount())
}

func TestSSERegistry_Subscribe(t *testing.T) {
	reg := NewSSERegistry()

	ch := reg.Subscribe("ch1", 1, 100)
	require.NotNil(t, ch)
	assert.Equal(t, "ch1", ch.ID)
	assert.Equal(t, uint(1), ch.AccountID)
	assert.Equal(t, uint(100), ch.UserID)
	assert.False(t, ch.Closed)
	assert.NotNil(t, ch.Events)
	assert.Equal(t, 1, reg.TotalChannelCount())
	assert.Equal(t, 1, reg.ChannelCount(1))
}

func TestSSERegistry_SubscribeMultipleAccounts(t *testing.T) {
	reg := NewSSERegistry()

	reg.Subscribe("ch1", 1, 100)
	reg.Subscribe("ch2", 2, 200)
	reg.Subscribe("ch3", 1, 300)

	assert.Equal(t, 3, reg.TotalChannelCount())
	assert.Equal(t, 2, reg.ChannelCount(1)) // ch1 and ch3
	assert.Equal(t, 1, reg.ChannelCount(2)) // ch2
}

func TestSSERegistry_Unsubscribe(t *testing.T) {
	reg := NewSSERegistry()

	ch := reg.Subscribe("ch1", 1, 100)
	require.NotNil(t, ch)

	reg.Unsubscribe("ch1")

	assert.True(t, ch.Closed)
	assert.Equal(t, 0, reg.TotalChannelCount())
	assert.Equal(t, 0, reg.ChannelCount(1))
}

func TestSSERegistry_UnsubscribeUnknownChannel(t *testing.T) {
	reg := NewSSERegistry()

	// Unsubscribing unknown channel should not panic
	reg.Unsubscribe("nonexistent")
	assert.Equal(t, 0, reg.TotalChannelCount())
}

func TestSSERegistry_SubscribeConversation(t *testing.T) {
	reg := NewSSERegistry()

	ch := reg.Subscribe("ch1", 1, 100)
	require.NotNil(t, ch)

	reg.SubscribeConversation("ch1", 42)
	assert.True(t, ch.ConversationIDs[42])

	reg.SubscribeConversation("ch1", 99)
	assert.True(t, ch.ConversationIDs[99])
}

func TestSSERegistry_UnsubscribeConversation(t *testing.T) {
	reg := NewSSERegistry()

	ch := reg.Subscribe("ch1", 1, 100)
	require.NotNil(t, ch)

	reg.SubscribeConversation("ch1", 42)
	assert.True(t, ch.ConversationIDs[42])

	reg.UnsubscribeConversation("ch1", 42)
	assert.False(t, ch.ConversationIDs[42])
}

func TestSSERegistry_SendToAccount(t *testing.T) {
	reg := NewSSERegistry()

	ch1 := reg.Subscribe("ch1", 1, 100)
	ch2 := reg.Subscribe("ch2", 1, 200)
	ch3 := reg.Subscribe("ch3", 2, 300) // different account

	require.NotNil(t, ch1)
	require.NotNil(t, ch2)
	require.NotNil(t, ch3)

	event := SSEEvent{
		Type:    EventMessageCreated,
		Payload: map[string]interface{}{"id": 1, "content": "hello"},
	}

	reg.SendToAccount(1, event)

	// ch1 and ch2 should receive the event (account 1)
	assertSSEEventReceived(t, ch1, event)
	assertSSEEventReceived(t, ch2, event)
	assertNoSSEEvent(t, ch3)
}

func TestSSERegistry_SendToAccount_NoSubscribers(t *testing.T) {
	reg := NewSSERegistry()

	event := SSEEvent{
		Type:    EventMessageCreated,
		Payload: map[string]interface{}{"id": 1},
	}

	// Send to account with no subscribers — should not panic
	reg.SendToAccount(999, event)
}

func TestSSERegistry_SendToConversation_AccountWide(t *testing.T) {
	reg := NewSSERegistry()

	// ch1 has no conversation filters (subscribes to all events for account)
	ch1 := reg.Subscribe("ch1", 1, 100)
	// ch2 has a conversation filter
	ch2 := reg.Subscribe("ch2", 1, 200)
	reg.SubscribeConversation("ch2", 42)

	require.NotNil(t, ch1)
	require.NotNil(t, ch2)

	event := SSEEvent{
		Type:    EventMessageCreated,
		Payload: map[string]interface{}{"id": 1},
	}

	// Send to conversation 42 in account 1
	reg.SendToConversation(1, 42, event)

	// ch1 (no conv filter) should receive
	assertSSEEventReceived(t, ch1, event)
	// ch2 (subscribed to conv 42) should receive
	assertSSEEventReceived(t, ch2, event)
}

func TestSSERegistry_SendToConversation_Filtered(t *testing.T) {
	reg := NewSSERegistry()

	// ch1 subscribes to conversation 42 only
	ch1 := reg.Subscribe("ch1", 1, 100)
	reg.SubscribeConversation("ch1", 42)
	// ch2 subscribes to conversation 99 only
	ch2 := reg.Subscribe("ch2", 1, 200)
	reg.SubscribeConversation("ch2", 99)

	require.NotNil(t, ch1)
	require.NotNil(t, ch2)

	event := SSEEvent{
		Type:    EventConversationTypingOn,
		Payload: map[string]interface{}{"conversation_id": 42},
	}

	// Send to conversation 42 — only ch1 should receive
	reg.SendToConversation(1, 42, event)

	assertSSEEventReceived(t, ch1, event)
	assertNoSSEEvent(t, ch2)
}

func TestSSERegistry_SendToAccount_SlowClientDrop(t *testing.T) {
	reg := NewSSERegistry()

	ch := reg.Subscribe("ch1", 1, 100)
	require.NotNil(t, ch)

	// Fill the buffer (64 capacity)
	for i := 0; i < 64; i++ {
		reg.SendToAccount(1, SSEEvent{
			Type:    EventMessageCreated,
			Payload: map[string]interface{}{"seq": i},
		})
	}

	// This event should be dropped because the buffer is full
	reg.SendToAccount(1, SSEEvent{
		Type:    EventMessageCreated,
		Payload: map[string]interface{}{"overflow": true},
	})

	// Drain events — should get exactly 64
	drainCount := 0
	timeout := time.After(2 * time.Second)
	for {
		select {
		case <-ch.Events:
			drainCount++
		case <-timeout:
			goto done
		default:
			if drainCount >= 64 {
				goto done
			}
		}
	}
done:
	assert.Equal(t, 64, drainCount)
}

func TestFormatSSE(t *testing.T) {
	event := SSEEvent{
		Type:    "message.created",
		Payload: map[string]interface{}{"id": 1, "content": "hello"},
	}

	formatted, err := FormatSSE(event)
	require.NoError(t, err)

	assert.True(t, strings.HasPrefix(formatted, "event: message.created\n"))
	assert.True(t, strings.Contains(formatted, "data: "))
	assert.True(t, strings.HasSuffix(formatted, "\n\n"))
}

func TestFormatSSE_ComplexPayload(t *testing.T) {
	event := SSEEvent{
		Type:    "conversation.updated",
		Payload: map[string]interface{}{
			"id":     42,
			"status": "resolved",
		},
	}

	formatted, err := FormatSSE(event)
	require.NoError(t, err)

	assert.True(t, strings.Contains(formatted, "event: conversation.updated\n"))
	assert.True(t, strings.Contains(formatted, "\"id\":42"))
	assert.True(t, strings.Contains(formatted, "\"status\":\"resolved\""))
}

func TestFormatSSE_AllEventTypes(t *testing.T) {
	eventTypes := []string{
		EventMessageCreated,
		EventMessageUpdated,
		EventMessageDeleted,
		EventConversationCreated,
		EventConversationUpdated,
		EventConversationStatusChanged,
		EventAssigneeChanged,
		EventTeamChanged,
		EventContactCreated,
		EventContactUpdated,
		EventContactDeleted,
		EventInboxCreated,
		EventInboxUpdated,
		EventInboxDeleted,
		EventNotificationCreated,
		EventNotificationUpdated,
	}

	for _, eventType := range eventTypes {
		event := SSEEvent{
			Type:    eventType,
			Payload: map[string]interface{}{"test": true},
		}
		formatted, err := FormatSSE(event)
		require.NoError(t, err, "FormatSSE failed for event type: %s", eventType)
		assert.True(t, strings.Contains(formatted, "event: "+eventType+"\n"),
			"expected event line for type: %s", eventType)
	}
}

// === Helper functions for SSE tests ===

func assertSSEEventReceived(t *testing.T, ch *SSEChannel, expected SSEEvent) {
	t.Helper()
	select {
	case event := <-ch.Events:
		assert.Equal(t, expected.Type, event.Type)
	case <-time.After(200 * time.Millisecond):
		t.Fatalf("expected SSE event on channel %s but none received", ch.ID)
	}
}

func assertNoSSEEvent(t *testing.T, ch *SSEChannel) {
	t.Helper()
	select {
	case <-ch.Events:
		t.Fatalf("unexpected SSE event received on channel %s", ch.ID)
	case <-time.After(50 * time.Millisecond):
		// Expected: no event received within the timeout
	}
}