package mcp

import (
	"sync"
	"testing"
	"time"
)

func TestNewSession(t *testing.T) {
	session, err := NewSession()
	if err != nil {
		t.Fatalf("Failed to create session: %v", err)
	}

	if session.ID == "" {
		t.Error("Session ID should not be empty")
	}
	if len(session.ID) != 32 {
		t.Errorf("Session ID should be 32 hex chars, got %d", len(session.ID))
	}
	if session.Initialized {
		t.Error("New session should not be initialized")
	}
}

func TestSessionTouch(t *testing.T) {
	session, _ := NewSession()
	originalActivity := session.LastActivity

	time.Sleep(10 * time.Millisecond)
	session.Touch()

	if !session.LastActivity.After(originalActivity) {
		t.Error("Touch should update LastActivity")
	}
}

func TestSessionInitialized(t *testing.T) {
	session, _ := NewSession()

	if session.IsInitialized() {
		t.Error("New session should not be initialized")
	}

	session.SetInitialized()

	if !session.IsInitialized() {
		t.Error("Session should be initialized after SetInitialized")
	}
}

func TestSessionNotifications(t *testing.T) {
	session, _ := NewSession()
	defer session.Close()

	notification := &Response{JSONRPC: "2.0", ID: 1}

	if !session.SendNotification(notification) {
		t.Error("SendNotification should return true on success")
	}

	select {
	case received := <-session.Notifications():
		if received.ID != notification.ID {
			t.Error("Received notification should match sent")
		}
	case <-time.After(100 * time.Millisecond):
		t.Error("Should receive notification")
	}
}

func TestSessionStoreCreate(t *testing.T) {
	store := NewSessionStore(30 * time.Minute)
	defer store.Stop()

	session, err := store.Create()
	if err != nil {
		t.Fatalf("Failed to create session: %v", err)
	}

	if store.Count() != 1 {
		t.Errorf("Store should have 1 session, got %d", store.Count())
	}

	// Verify we can retrieve it
	retrieved := store.Get(session.ID)
	if retrieved == nil {
		t.Fatal("Should be able to retrieve created session")
	}
	if retrieved.ID != session.ID {
		t.Error("Retrieved session ID should match")
	}
}

func TestSessionStoreGet(t *testing.T) {
	store := NewSessionStore(30 * time.Minute)
	defer store.Stop()

	// Get non-existent session
	if store.Get("nonexistent") != nil {
		t.Error("Should return nil for non-existent session")
	}

	// Create and retrieve
	session, _ := store.Create()
	retrieved := store.Get(session.ID)
	if retrieved == nil {
		t.Error("Should find created session")
	}
}

func TestSessionStoreDelete(t *testing.T) {
	store := NewSessionStore(30 * time.Minute)
	defer store.Stop()

	session, _ := store.Create()
	if store.Count() != 1 {
		t.Error("Should have 1 session after create")
	}

	if !store.Delete(session.ID) {
		t.Error("Delete should return true for existing session")
	}

	if store.Count() != 0 {
		t.Error("Should have 0 sessions after delete")
	}

	if store.Delete(session.ID) {
		t.Error("Delete should return false for non-existent session")
	}
}

func TestSessionStoreTTLExpiration(t *testing.T) {
	ttl := 50 * time.Millisecond
	store := NewSessionStore(ttl)
	defer store.Stop()

	session, _ := store.Create()

	// Should be retrievable immediately
	if store.Get(session.ID) == nil {
		t.Error("Session should be retrievable immediately")
	}

	// Wait for expiration
	time.Sleep(ttl + 10*time.Millisecond)

	// Should not be retrievable after TTL
	if store.Get(session.ID) != nil {
		t.Error("Expired session should not be retrievable")
	}
}

func TestSessionStoreTTLRefresh(t *testing.T) {
	ttl := 100 * time.Millisecond
	store := NewSessionStore(ttl)
	defer store.Stop()

	session, _ := store.Create()

	// Touch the session before TTL expires
	time.Sleep(60 * time.Millisecond)
	session.Touch()

	// Wait past original TTL but not past refreshed TTL
	time.Sleep(60 * time.Millisecond)

	// Should still be retrievable because we touched it
	if store.Get(session.ID) == nil {
		t.Error("Touched session should still be retrievable")
	}
}

func TestSessionStoreCleanup(t *testing.T) {
	ttl := 50 * time.Millisecond
	store := NewSessionStore(ttl)
	defer store.Stop()

	// Create multiple sessions
	for i := 0; i < 5; i++ {
		store.Create()
	}

	if store.Count() != 5 {
		t.Errorf("Should have 5 sessions, got %d", store.Count())
	}

	// Wait for cleanup to run (runs at ttl/2 intervals)
	time.Sleep(ttl + ttl/2 + 10*time.Millisecond)

	// All sessions should be cleaned up
	if store.Count() != 0 {
		t.Errorf("All sessions should be cleaned up, got %d", store.Count())
	}
}

func TestSessionStoreConcurrency(t *testing.T) {
	store := NewSessionStore(30 * time.Minute)
	defer store.Stop()

	var wg sync.WaitGroup
	sessionIDs := make(chan string, 100)

	// Create sessions concurrently
	for i := 0; i < 50; i++ {
		wg.Add(1)
		go func() {
			defer wg.Done()
			session, err := store.Create()
			if err != nil {
				t.Errorf("Failed to create session: %v", err)
				return
			}
			sessionIDs <- session.ID
		}()
	}

	wg.Wait()
	close(sessionIDs)

	// Verify all sessions were created
	if store.Count() != 50 {
		t.Errorf("Should have 50 sessions, got %d", store.Count())
	}

	// Read and delete concurrently
	var ids []string
	for id := range sessionIDs {
		ids = append(ids, id)
	}

	for _, id := range ids {
		wg.Add(2)
		go func(id string) {
			defer wg.Done()
			store.Get(id)
		}(id)
		go func(id string) {
			defer wg.Done()
			store.Delete(id)
		}(id)
	}

	wg.Wait()
}

func TestSessionStoreMaxSessions(t *testing.T) {
	maxSessions := 5
	store := NewSessionStoreWithLimit(30*time.Minute, maxSessions)
	defer store.Stop()

	// Create sessions up to limit
	for i := 0; i < maxSessions; i++ {
		_, err := store.Create()
		if err != nil {
			t.Fatalf("Failed to create session %d: %v", i, err)
		}
	}

	if store.Count() != maxSessions {
		t.Errorf("Expected %d sessions, got %d", maxSessions, store.Count())
	}

	// Try to create one more - should fail
	_, err := store.Create()
	if err != ErrTooManySessions {
		t.Errorf("Expected ErrTooManySessions, got %v", err)
	}

	// Count should still be at max
	if store.Count() != maxSessions {
		t.Errorf("Expected %d sessions after failed create, got %d", maxSessions, store.Count())
	}
}

func TestSessionStoreMaxSessionsWithDeletion(t *testing.T) {
	maxSessions := 3
	store := NewSessionStoreWithLimit(30*time.Minute, maxSessions)
	defer store.Stop()

	// Fill up the store
	sessions := make([]*Session, maxSessions)
	for i := 0; i < maxSessions; i++ {
		s, err := store.Create()
		if err != nil {
			t.Fatalf("Failed to create session: %v", err)
		}
		sessions[i] = s
	}

	// Should be full
	_, err := store.Create()
	if err != ErrTooManySessions {
		t.Error("Expected ErrTooManySessions when full")
	}

	// Delete one session
	store.Delete(sessions[0].ID)

	// Should be able to create again
	_, err = store.Create()
	if err != nil {
		t.Errorf("Should be able to create after deletion: %v", err)
	}
}

func TestSessionStoreDefaultMaxSessions(t *testing.T) {
	store := NewSessionStore(30 * time.Minute)
	defer store.Stop()

	// Just verify it uses the default (don't create 10000 sessions)
	if store.maxSessions != DefaultMaxSessions {
		t.Errorf("Expected default max sessions %d, got %d", DefaultMaxSessions, store.maxSessions)
	}
}

func TestGenerateSessionID(t *testing.T) {
	ids := make(map[string]bool)

	// Generate 1000 IDs and ensure uniqueness
	for i := 0; i < 1000; i++ {
		id, err := generateSessionID()
		if err != nil {
			t.Fatalf("Failed to generate session ID: %v", err)
		}

		if len(id) != 32 {
			t.Errorf("Session ID should be 32 hex chars, got %d", len(id))
		}

		if ids[id] {
			t.Error("Generated duplicate session ID")
		}
		ids[id] = true
	}
}