package proxy

import (
	"crypto/tls"
	"io"
	"net"
	"net/http"
	"net/http/httptest"
	"os"
	"strings"
	"testing"
	"time"

	"github.com/gofiber/fiber/v3"
	clientpkg "github.com/gofiber/fiber/v3/client"
	"github.com/stretchr/testify/require"

	"github.com/gofiber/fiber/v3/internal/tlstest"
	"github.com/valyala/fasthttp"
)

func startServer(app *fiber.App, ln net.Listener) {
	go func() {
		err := app.Listener(ln, fiber.ListenConfig{
			DisableStartupMessage: true,
		})
		if err != nil {
			panic(err)
		}
	}()
}

func createProxyTestServer(t *testing.T, handler fiber.Handler, network, address string) (target *fiber.App, addr string) { //nolint:nonamedreturns // gocritic unnamedResult prefers naming returned target app and address for readability
	t.Helper()

	target = fiber.New()
	target.Get("/", handler)

	ln, err := net.Listen(network, address)
	require.NoError(t, err)

	addr = ln.Addr().String()

	startServer(target, ln)

	return target, addr
}

func createProxyTestServerIPv4(t *testing.T, handler fiber.Handler) (target *fiber.App, addr string) { //nolint:nonamedreturns // gocritic unnamedResult prefers naming returned target app and address for readability
	t.Helper()
	return createProxyTestServer(t, handler, fiber.NetworkTCP4, "127.0.0.1:0")
}

func createProxyTestServerIPv6(t *testing.T, handler fiber.Handler) (target *fiber.App, addr string) { //nolint:nonamedreturns // gocritic unnamedResult prefers naming returned target app and address for readability
	t.Helper()
	return createProxyTestServer(t, handler, fiber.NetworkTCP6, "[::1]:0")
}

func createRedirectServer(t *testing.T) string {
	t.Helper()
	app := fiber.New()

	var addr string
	app.Get("/", func(c fiber.Ctx) error {
		c.Location("http://" + addr + "/final")
		return c.Status(fiber.StatusMovedPermanently).SendString("redirect")
	})
	app.Get("/final", func(c fiber.Ctx) error {
		return c.SendString("final")
	})

	ln, err := net.Listen(fiber.NetworkTCP4, "127.0.0.1:0")
	require.NoError(t, err)
	t.Cleanup(func() {
		ln.Close() //nolint:errcheck // It is fine to ignore the error here
	})
	addr = ln.Addr().String()

	startServer(app, ln)

	return addr
}

// go test -run Test_Proxy_Empty_Host
func Test_Proxy_Empty_Upstream_Servers(t *testing.T) {
	t.Parallel()

	defer func() {
		if r := recover(); r != nil {
			if r != "Servers cannot be empty" {
				panic(r)
			}
		}
	}()
	app := fiber.New()
	app.Use(Balancer(Config{Servers: []string{}}))
}

// go test -run Test_Proxy_Empty_Config
func Test_Proxy_Empty_Config(t *testing.T) {
	t.Parallel()

	defer func() {
		if r := recover(); r != nil {
			if r != "Servers cannot be empty" {
				panic(r)
			}
		}
	}()
	app := fiber.New()
	app.Use(Balancer(Config{}))
}

// go test -run Test_Proxy_Next
func Test_Proxy_Next(t *testing.T) {
	t.Parallel()

	app := fiber.New()
	app.Use(Balancer(Config{
		Servers: []string{"127.0.0.1"},
		Next: func(_ fiber.Ctx) bool {
			return true
		},
	}))

	resp, err := app.Test(httptest.NewRequest(fiber.MethodGet, "/", http.NoBody))
	require.NoError(t, err)
	require.Equal(t, fiber.StatusNotFound, resp.StatusCode)
}

// go test -run Test_Proxy
func Test_Proxy(t *testing.T) {
	t.Parallel()

	target, addr := createProxyTestServerIPv4(t, func(c fiber.Ctx) error {
		return c.SendStatus(fiber.StatusTeapot)
	})

	resp, err := target.Test(httptest.NewRequest(fiber.MethodGet, "/", http.NoBody), fiber.TestConfig{
		Timeout:       2 * time.Second,
		FailOnTimeout: true,
	})
	require.NoError(t, err)
	require.Equal(t, fiber.StatusTeapot, resp.StatusCode)

	app := fiber.New()

	app.Use(Balancer(Config{Servers: []string{addr}}))

	req := httptest.NewRequest(fiber.MethodGet, "/", http.NoBody)
	req.Host = addr
	resp, err = app.Test(req)
	require.NoError(t, err)
	require.Equal(t, fiber.StatusTeapot, resp.StatusCode)
}

// go test -run Test_Proxy_Balancer_WithTlsConfig
func Test_Proxy_Balancer_WithTlsConfig(t *testing.T) {
	t.Parallel()

	serverTLSConf, _, err := tlstest.GetTLSConfigs()
	require.NoError(t, err)

	ln, err := net.Listen(fiber.NetworkTCP4, "127.0.0.1:0")
	require.NoError(t, err)

	ln = tls.NewListener(ln, serverTLSConf)

	app := fiber.New()

	app.Get("/tlsbalancer", func(c fiber.Ctx) error {
		return c.SendString("tls balancer")
	})

	addr := ln.Addr().String()
	clientTLSConf := &tls.Config{InsecureSkipVerify: true} //nolint:gosec // We're in a test func, so this is fine

	// disable certificate verification in Balancer
	app.Use(Balancer(Config{
		Servers:   []string{addr},
		TLSConfig: clientTLSConf,
	}))

	startServer(app, ln)

	client := clientpkg.New()
	client.SetTLSConfig(clientTLSConf)

	resp, err := client.Get("https://" + addr + "/tlsbalancer")
	require.NoError(t, err)
	require.Equal(t, fiber.StatusOK, resp.StatusCode())
	require.Equal(t, "tls balancer", string(resp.Body()))
	resp.Close()
}

// go test -run Test_Proxy_Balancer_IPv6_Upstream
func Test_Proxy_Balancer_IPv6_Upstream(t *testing.T) {
	t.Parallel()

	target, addr := createProxyTestServerIPv6(t, func(c fiber.Ctx) error {
		return c.SendStatus(fiber.StatusTeapot)
	})

	resp, err := target.Test(httptest.NewRequest(fiber.MethodGet, "/", http.NoBody), fiber.TestConfig{
		Timeout:       2 * time.Second,
		FailOnTimeout: true,
	})
	require.NoError(t, err)
	require.Equal(t, fiber.StatusTeapot, resp.StatusCode)

	app := fiber.New()

	app.Use(Balancer(Config{Servers: []string{addr}}))

	req := httptest.NewRequest(fiber.MethodGet, "/", http.NoBody)
	req.Host = addr
	resp, err = app.Test(req)
	require.NoError(t, err)
	require.Equal(t, fiber.StatusInternalServerError, resp.StatusCode)
}

// go test -run Test_Proxy_Balancer_IPv6_Upstream
func Test_Proxy_Balancer_IPv6_Upstream_With_DialDualStack(t *testing.T) {
	t.Parallel()

	target, addr := createProxyTestServerIPv6(t, func(c fiber.Ctx) error {
		return c.SendStatus(fiber.StatusTeapot)
	})

	resp, err := target.Test(httptest.NewRequest(fiber.MethodGet, "/", http.NoBody), fiber.TestConfig{
		Timeout:       2 * time.Second,
		FailOnTimeout: true,
	})
	require.NoError(t, err)
	require.Equal(t, fiber.StatusTeapot, resp.StatusCode)

	app := fiber.New()

	app.Use(Balancer(Config{
		Servers:       []string{addr},
		DialDualStack: true,
	}))

	req := httptest.NewRequest(fiber.MethodGet, "/", http.NoBody)
	req.Host = addr
	resp, err = app.Test(req)
	require.NoError(t, err)
	require.Equal(t, fiber.StatusTeapot, resp.StatusCode)
}

// go test -run Test_Proxy_Balancer_IPv6_Upstream
func Test_Proxy_Balancer_IPv4_Upstream_With_DialDualStack(t *testing.T) {
	t.Parallel()

	target, addr := createProxyTestServerIPv4(t, func(c fiber.Ctx) error {
		return c.SendStatus(fiber.StatusTeapot)
	})

	resp, err := target.Test(httptest.NewRequest(fiber.MethodGet, "/", http.NoBody), fiber.TestConfig{
		Timeout:       2 * time.Second,
		FailOnTimeout: true,
	})
	require.NoError(t, err)
	require.Equal(t, fiber.StatusTeapot, resp.StatusCode)

	app := fiber.New()

	app.Use(Balancer(Config{
		Servers:       []string{addr},
		DialDualStack: true,
	}))

	req := httptest.NewRequest(fiber.MethodGet, "/", http.NoBody)
	req.Host = addr
	resp, err = app.Test(req)
	require.NoError(t, err)
	require.Equal(t, fiber.StatusTeapot, resp.StatusCode)
}

// go test -run Test_Proxy_Forward_WithTlsConfig_To_Http
func Test_Proxy_Forward_WithTlsConfig_To_Http(t *testing.T) {
	t.Parallel()

	_, targetAddr := createProxyTestServerIPv4(t, func(c fiber.Ctx) error {
		return c.SendString("hello from target")
	})

	proxyServerTLSConf, _, err := tlstest.GetTLSConfigs()
	require.NoError(t, err)

	proxyServerLn, err := net.Listen(fiber.NetworkTCP4, "127.0.0.1:0")
	require.NoError(t, err)

	proxyServerLn = tls.NewListener(proxyServerLn, proxyServerTLSConf)
	proxyAddr := proxyServerLn.Addr().String()

	app := fiber.New()
	app.Use(Forward("http://" + targetAddr))
	startServer(app, proxyServerLn)

	client := clientpkg.New()
	client.SetTimeout(5 * time.Second)
	client.TLSConfig().InsecureSkipVerify = true

	resp, err := client.Get("https://" + proxyAddr)
	require.NoError(t, err)
	require.Equal(t, fiber.StatusOK, resp.StatusCode())
	require.Equal(t, "hello from target", string(resp.Body()))
	resp.Close()
}

// go test -run Test_Proxy_Forward
func Test_Proxy_Forward(t *testing.T) {
	t.Parallel()

	app := fiber.New()

	_, addr := createProxyTestServerIPv4(t, func(c fiber.Ctx) error {
		return c.SendString("forwarded")
	})

	app.Use(Forward("http://" + addr))

	resp, err := app.Test(httptest.NewRequest(fiber.MethodGet, "/", http.NoBody))
	require.NoError(t, err)
	require.Equal(t, fiber.StatusOK, resp.StatusCode)

	b, err := io.ReadAll(resp.Body)
	require.NoError(t, err)
	require.Equal(t, "forwarded", string(b))
}

// go test -run Test_Proxy_Forward_WithClient_TLSConfig
func Test_Proxy_Forward_WithClient_TLSConfig(t *testing.T) {
	t.Parallel()

	serverTLSConf, _, err := tlstest.GetTLSConfigs()
	require.NoError(t, err)

	ln, err := net.Listen(fiber.NetworkTCP4, "127.0.0.1:0")
	require.NoError(t, err)

	ln = tls.NewListener(ln, serverTLSConf)

	app := fiber.New()

	app.Get("/tlsfwd", func(c fiber.Ctx) error {
		return c.SendString("tls forward")
	})

	addr := ln.Addr().String()
	clientTLSConf := &tls.Config{InsecureSkipVerify: true} //nolint:gosec // We're in a test func, so this is fine

	// disable certificate verification
	WithClient(&fasthttp.Client{
		TLSConfig: clientTLSConf,
	})
	app.Use(Forward("https://" + addr + "/tlsfwd"))

	startServer(app, ln)

	client := clientpkg.New()
	client.SetTLSConfig(clientTLSConf)

	resp, err := client.Get("https://" + addr)
	require.NoError(t, err)
	require.Equal(t, fiber.StatusOK, resp.StatusCode())
	require.Equal(t, "tls forward", string(resp.Body()))
	resp.Close()
}

// go test -run Test_Proxy_Modify_Response
func Test_Proxy_Modify_Response(t *testing.T) {
	t.Parallel()

	_, addr := createProxyTestServerIPv4(t, func(c fiber.Ctx) error {
		return c.Status(500).SendString("not modified")
	})

	app := fiber.New()
	app.Use(Balancer(Config{
		Servers: []string{addr},
		ModifyResponse: func(c fiber.Ctx) error {
			c.Response().SetStatusCode(fiber.StatusOK)
			return c.SendString("modified response")
		},
	}))

	resp, err := app.Test(httptest.NewRequest(fiber.MethodGet, "/", http.NoBody))
	require.NoError(t, err)
	require.Equal(t, fiber.StatusOK, resp.StatusCode)

	b, err := io.ReadAll(resp.Body)
	require.NoError(t, err)
	require.Equal(t, "modified response", string(b))
}

// go test -run Test_Proxy_Modify_Request
func Test_Proxy_Modify_Request(t *testing.T) {
	t.Parallel()

	_, addr := createProxyTestServerIPv4(t, func(c fiber.Ctx) error {
		b := c.Request().Body()
		return c.SendString(string(b))
	})

	app := fiber.New()
	app.Use(Balancer(Config{
		Servers: []string{addr},
		ModifyRequest: func(c fiber.Ctx) error {
			c.Request().SetBody([]byte("modified request"))
			return nil
		},
	}))

	resp, err := app.Test(httptest.NewRequest(fiber.MethodGet, "/", http.NoBody))
	require.NoError(t, err)
	require.Equal(t, fiber.StatusOK, resp.StatusCode)

	b, err := io.ReadAll(resp.Body)
	require.NoError(t, err)
	require.Equal(t, "modified request", string(b))
}

// go test -run Test_Proxy_Timeout_Slow_Server
func Test_Proxy_Timeout_Slow_Server(t *testing.T) {
	t.Parallel()

	_, addr := createProxyTestServerIPv4(t, func(c fiber.Ctx) error {
		time.Sleep(300 * time.Millisecond)
		return c.SendString("fiber is awesome")
	})

	app := fiber.New()
	app.Use(Balancer(Config{
		Servers: []string{addr},
		Timeout: 600 * time.Millisecond,
	}))

	resp, err := app.Test(httptest.NewRequest(fiber.MethodGet, "/", http.NoBody), fiber.TestConfig{
		Timeout:       2 * time.Second,
		FailOnTimeout: true,
	})
	require.NoError(t, err)
	require.Equal(t, fiber.StatusOK, resp.StatusCode)

	b, err := io.ReadAll(resp.Body)
	require.NoError(t, err)
	require.Equal(t, "fiber is awesome", string(b))
}

// go test -run Test_Proxy_With_Timeout
func Test_Proxy_With_Timeout(t *testing.T) {
	t.Parallel()

	_, addr := createProxyTestServerIPv4(t, func(c fiber.Ctx) error {
		time.Sleep(1 * time.Second)
		return c.SendString("fiber is awesome")
	})

	app := fiber.New()
	app.Use(Balancer(Config{
		Servers: []string{addr},
		Timeout: 100 * time.Millisecond,
	}))

	resp, err := app.Test(httptest.NewRequest(fiber.MethodGet, "/", http.NoBody), fiber.TestConfig{
		Timeout:       2 * time.Second,
		FailOnTimeout: true,
	})
	require.NoError(t, err)
	require.Equal(t, fiber.StatusInternalServerError, resp.StatusCode)

	b, err := io.ReadAll(resp.Body)
	require.NoError(t, err)
	require.Equal(t, "timeout", string(b))
}

// go test -run Test_Proxy_Buffer_Size_Response
func Test_Proxy_Buffer_Size_Response(t *testing.T) {
	t.Parallel()

	_, addr := createProxyTestServerIPv4(t, func(c fiber.Ctx) error {
		long := strings.Join(make([]string, 5000), "-")
		c.Set("Very-Long-Header", long)
		return c.SendString("ok")
	})

	app := fiber.New()
	app.Use(Balancer(Config{Servers: []string{addr}, KeepConnectionHeader: true}))

	resp, err := app.Test(httptest.NewRequest(fiber.MethodGet, "/", http.NoBody))
	require.NoError(t, err)
	require.Equal(t, fiber.StatusInternalServerError, resp.StatusCode)

	app = fiber.New()
	app.Use(Balancer(Config{
		Servers:        []string{addr},
		ReadBufferSize: 1024 * 8,
	}))

	resp, err = app.Test(httptest.NewRequest(fiber.MethodGet, "/", http.NoBody))
	require.NoError(t, err)
	require.Equal(t, fiber.StatusOK, resp.StatusCode)
}

// go test -race -run Test_Proxy_Do_RestoreOriginalURL
func Test_Proxy_Do_RestoreOriginalURL(t *testing.T) {
	t.Parallel()
	_, addr := createProxyTestServerIPv4(t, func(c fiber.Ctx) error {
		return c.SendString("proxied")
	})

	app := fiber.New()
	app.Get("/test", func(c fiber.Ctx) error {
		return Do(c, "http://"+addr)
	})
	resp, err1 := app.Test(httptest.NewRequest(fiber.MethodGet, "/test", http.NoBody))
	require.NoError(t, err1)
	require.Equal(t, "/test", resp.Request.URL.String())
	require.Equal(t, fiber.StatusOK, resp.StatusCode)
	body, err := io.ReadAll(resp.Body)
	require.NoError(t, err)
	require.Equal(t, "proxied", string(body))
}

// go test -race -run Test_Proxy_Do_WithRealURL
func Test_Proxy_Do_WithRealURL(t *testing.T) {
	t.Parallel()

	_, addr := createProxyTestServerIPv4(t, func(c fiber.Ctx) error {
		return c.SendString("real url")
	})

	app := fiber.New()
	app.Get("/test", func(c fiber.Ctx) error {
		return Do(c, "http://"+addr)
	})

	resp, err1 := app.Test(httptest.NewRequest(fiber.MethodGet, "/test", http.NoBody), fiber.TestConfig{
		Timeout:       2 * time.Second,
		FailOnTimeout: true,
	})
	require.NoError(t, err1)
	require.Equal(t, fiber.StatusOK, resp.StatusCode)
	require.Equal(t, "/test", resp.Request.URL.String())
	body, err := io.ReadAll(resp.Body)
	require.NoError(t, err)
	require.Equal(t, "real url", string(body))
}

// go test -race -run Test_Proxy_Do_WithRedirect
func Test_Proxy_Do_WithRedirect(t *testing.T) {
	t.Parallel()

	addr := createRedirectServer(t)
	app := fiber.New()
	app.Get("/test", func(c fiber.Ctx) error {
		return Do(c, "http://"+addr)
	})

	resp, err1 := app.Test(httptest.NewRequest(fiber.MethodGet, "/test", http.NoBody), fiber.TestConfig{
		Timeout:       2 * time.Second,
		FailOnTimeout: true,
	})
	require.NoError(t, err1)
	body, err := io.ReadAll(resp.Body)
	require.NoError(t, err)
	require.Equal(t, "redirect", string(body))
	require.Equal(t, fiber.StatusMovedPermanently, resp.StatusCode)
}

// go test -race -run Test_Proxy_DoRedirects_RestoreOriginalURL
func Test_Proxy_DoRedirects_RestoreOriginalURL(t *testing.T) {
	t.Parallel()

	addr := createRedirectServer(t)
	app := fiber.New()
	app.Get("/test", func(c fiber.Ctx) error {
		return DoRedirects(c, "http://"+addr, 1)
	})

	resp, err1 := app.Test(httptest.NewRequest(fiber.MethodGet, "/test", http.NoBody), fiber.TestConfig{
		Timeout:       2 * time.Second,
		FailOnTimeout: true,
	})
	require.NoError(t, err1)
	body, err := io.ReadAll(resp.Body)
	require.NoError(t, err)
	require.Equal(t, "final", string(body))
	require.Equal(t, fiber.StatusOK, resp.StatusCode)
	require.Equal(t, "/test", resp.Request.URL.String())
}

// go test -race -run Test_Proxy_DoRedirects_TooManyRedirects
func Test_Proxy_DoRedirects_TooManyRedirects(t *testing.T) {
	t.Parallel()

	addr := createRedirectServer(t)
	app := fiber.New()
	app.Get("/test", func(c fiber.Ctx) error {
		return DoRedirects(c, "http://"+addr, 0)
	})

	resp, err1 := app.Test(httptest.NewRequest(fiber.MethodGet, "/test", http.NoBody), fiber.TestConfig{
		Timeout:       2 * time.Second,
		FailOnTimeout: true,
	})
	require.NoError(t, err1)
	body, err := io.ReadAll(resp.Body)
	require.NoError(t, err)
	require.Equal(t, "too many redirects detected when doing the request", string(body))
	require.Equal(t, fiber.StatusInternalServerError, resp.StatusCode)
	require.Equal(t, "/test", resp.Request.URL.String())
}

// go test -race -run Test_Proxy_DoTimeout_RestoreOriginalURL
func Test_Proxy_DoTimeout_RestoreOriginalURL(t *testing.T) {
	t.Parallel()

	_, addr := createProxyTestServerIPv4(t, func(c fiber.Ctx) error {
		return c.SendString("proxied")
	})

	app := fiber.New()
	app.Get("/test", func(c fiber.Ctx) error {
		return DoTimeout(c, "http://"+addr, time.Second)
	})

	resp, err1 := app.Test(httptest.NewRequest(fiber.MethodGet, "/test", http.NoBody), fiber.TestConfig{
		Timeout:       2 * time.Second,
		FailOnTimeout: true,
	})
	require.NoError(t, err1)
	body, err := io.ReadAll(resp.Body)
	require.NoError(t, err)
	require.Equal(t, "proxied", string(body))
	require.Equal(t, fiber.StatusOK, resp.StatusCode)
	require.Equal(t, "/test", resp.Request.URL.String())
}

// go test -race -run Test_Proxy_DoTimeout_Timeout
func Test_Proxy_DoTimeout_Timeout(t *testing.T) {
	_, addr := createProxyTestServerIPv4(t, func(c fiber.Ctx) error {
		time.Sleep(time.Second * 5)
		return c.SendString("proxied")
	})

	app := fiber.New()
	app.Get("/test", func(c fiber.Ctx) error {
		return DoTimeout(c, "http://"+addr, time.Second)
	})

	resp, err := app.Test(httptest.NewRequest(fiber.MethodGet, "/test", http.NoBody), fiber.TestConfig{
		Timeout:       2 * time.Second,
		FailOnTimeout: true,
	})
	require.NoError(t, err)
	body, err := io.ReadAll(resp.Body)
	require.NoError(t, err)

	require.Equal(t, "timeout", string(body))
	require.Equal(t, fiber.StatusInternalServerError, resp.StatusCode)
	require.Equal(t, "/test", resp.Request.URL.String())
}

// go test -race -run Test_Proxy_DoDeadline_RestoreOriginalURL
func Test_Proxy_DoDeadline_RestoreOriginalURL(t *testing.T) {
	t.Parallel()

	_, addr := createProxyTestServerIPv4(t, func(c fiber.Ctx) error {
		return c.SendString("proxied")
	})

	app := fiber.New()
	app.Get("/test", func(c fiber.Ctx) error {
		return DoDeadline(c, "http://"+addr, time.Now().Add(time.Second))
	})

	resp, err1 := app.Test(httptest.NewRequest(fiber.MethodGet, "/test", http.NoBody))
	require.NoError(t, err1)
	body, err := io.ReadAll(resp.Body)
	require.NoError(t, err)
	require.Equal(t, "proxied", string(body))
	require.Equal(t, fiber.StatusOK, resp.StatusCode)
	require.Equal(t, "/test", resp.Request.URL.String())
}

// go test -race -run Test_Proxy_DoDeadline_PastDeadline
func Test_Proxy_DoDeadline_PastDeadline(t *testing.T) {
	_, addr := createProxyTestServerIPv4(t, func(c fiber.Ctx) error {
		time.Sleep(time.Second * 5)
		return c.SendString("proxied")
	})

	app := fiber.New()
	app.Get("/test", func(c fiber.Ctx) error {
		return DoDeadline(c, "http://"+addr, time.Now().Add(2*time.Second))
	})

	_, err1 := app.Test(httptest.NewRequest(fiber.MethodGet, "/test", http.NoBody), fiber.TestConfig{
		Timeout:       1 * time.Second,
		FailOnTimeout: true,
	})
	require.Equal(t, os.ErrDeadlineExceeded, err1)
}

// go test -race -run Test_Proxy_Do_HTTP_Prefix_URL
func Test_Proxy_Do_HTTP_Prefix_URL(t *testing.T) {
	t.Parallel()

	_, addr := createProxyTestServerIPv4(t, func(c fiber.Ctx) error {
		return c.SendString("hello world")
	})

	app := fiber.New()
	app.Get("/*", func(c fiber.Ctx) error {
		path := c.OriginalURL()
		url := strings.TrimPrefix(path, "/")

		require.Equal(t, "http://"+addr, url)
		if err := Do(c, url); err != nil {
			return err
		}
		c.Response().Header.Del(fiber.HeaderServer)
		return nil
	})

	resp, err := app.Test(httptest.NewRequest(fiber.MethodGet, "/http://"+addr, http.NoBody))
	require.NoError(t, err)
	s, err := io.ReadAll(resp.Body)
	require.NoError(t, err)
	require.Equal(t, "hello world", string(s))
}

// go test -race -run Test_Proxy_Forward_Global_Client
func Test_Proxy_Forward_Global_Client(t *testing.T) {
	t.Parallel()
	ln, err := net.Listen(fiber.NetworkTCP4, "127.0.0.1:0")
	require.NoError(t, err)
	WithClient(&fasthttp.Client{
		NoDefaultUserAgentHeader: true,
		DisablePathNormalizing:   true,
	})
	app := fiber.New()
	app.Get("/test_global_client", func(c fiber.Ctx) error {
		return c.SendString("test_global_client")
	})

	addr := ln.Addr().String()
	app.Use(Forward("http://" + addr + "/test_global_client"))
	startServer(app, ln)

	client := clientpkg.New()
	resp, err := client.Get("http://" + addr)
	require.NoError(t, err)
	require.Equal(t, fiber.StatusOK, resp.StatusCode())
	require.Equal(t, "test_global_client", string(resp.Body()))
	resp.Close()
}

// go test -race -run Test_Proxy_Forward_Local_Client
func Test_Proxy_Forward_Local_Client(t *testing.T) {
	t.Parallel()
	ln, err := net.Listen(fiber.NetworkTCP4, "127.0.0.1:0")
	require.NoError(t, err)
	app := fiber.New()
	app.Get("/test_local_client", func(c fiber.Ctx) error {
		return c.SendString("test_local_client")
	})

	addr := ln.Addr().String()
	app.Use(Forward("http://"+addr+"/test_local_client", &fasthttp.Client{
		NoDefaultUserAgentHeader: true,
		DisablePathNormalizing:   true,

		Dial: fasthttp.Dial,
	}))
	startServer(app, ln)

	client := clientpkg.New()
	resp, err := client.Get("http://" + addr)
	require.NoError(t, err)
	require.Equal(t, fiber.StatusOK, resp.StatusCode())
	require.Equal(t, "test_local_client", string(resp.Body()))
	resp.Close()
}

// go test -run Test_Proxy_WithClient_Nil_Panics
func Test_Proxy_WithClient_Nil_Panics(t *testing.T) {
	t.Parallel()

	require.PanicsWithValue(t, "proxy: WithClient requires a non-nil *fasthttp.Client", func() {
		WithClient(nil)
	})
}

// go test -run Test_Proxy_Do_NilClientOverride
func Test_Proxy_Do_NilClientOverride(t *testing.T) {
	t.Parallel()

	_, addr := createProxyTestServerIPv4(t, func(c fiber.Ctx) error {
		return c.SendString("proxied")
	})

	app := fiber.New()
	app.Get("/test", func(c fiber.Ctx) error {
		return Do(c, "http://"+addr, nil)
	})

	resp, err := app.Test(httptest.NewRequest(fiber.MethodGet, "/test", http.NoBody))
	require.NoError(t, err)
	require.Equal(t, fiber.StatusInternalServerError, resp.StatusCode)

	body, err := io.ReadAll(resp.Body)
	require.NoError(t, err)
	require.Equal(t, errNilProxyClientOverride.Error(), string(body))
}

// go test -run Test_Proxy_Do_NonNilClientOverride
func Test_Proxy_Do_NonNilClientOverride(t *testing.T) {
	t.Parallel()

	_, addr := createProxyTestServerIPv4(t, func(c fiber.Ctx) error {
		return c.SendString("proxied")
	})

	app := fiber.New()
	app.Get("/test", func(c fiber.Ctx) error {
		return Do(c, "http://"+addr, &fasthttp.Client{
			NoDefaultUserAgentHeader: true,
			DisablePathNormalizing:   true,
		})
	})

	resp, err := app.Test(httptest.NewRequest(fiber.MethodGet, "/test", http.NoBody), fiber.TestConfig{
		Timeout:       2 * time.Second,
		FailOnTimeout: true,
	})
	require.NoError(t, err)
	require.Equal(t, fiber.StatusOK, resp.StatusCode)

	body, err := io.ReadAll(resp.Body)
	require.NoError(t, err)
	require.Equal(t, "proxied", string(body))
}

// go test -run Test_Proxy_SelectClient_NilGlobal
func Test_Proxy_SelectClient_NilGlobal(t *testing.T) {
	t.Parallel()

	selectedClient, err := selectClient(nil)
	require.ErrorIs(t, err, errNilGlobalProxyClient)
	require.Nil(t, selectedClient)
}

// go test -run Test_Proxy_NilClientOverride_AcrossHelpers
func Test_Proxy_NilClientOverride_AcrossHelpers(t *testing.T) {
	t.Parallel()

	_, addr := createProxyTestServerIPv4(t, func(c fiber.Ctx) error {
		return c.SendString("proxied")
	})

	tests := map[string]func(c fiber.Ctx) error{
		"DoRedirects": func(c fiber.Ctx) error {
			return DoRedirects(c, "http://"+addr, 1, nil)
		},
		"DoDeadline": func(c fiber.Ctx) error {
			return DoDeadline(c, "http://"+addr, time.Now().Add(time.Second), nil)
		},
		"DoTimeout": func(c fiber.Ctx) error {
			return DoTimeout(c, "http://"+addr, time.Second, nil)
		},
	}

	for name, run := range tests {
		t.Run(name, func(t *testing.T) {
			t.Parallel()

			app := fiber.New()
			app.Get("/test", run)

			resp, err := app.Test(httptest.NewRequest(fiber.MethodGet, "/test", http.NoBody))
			require.NoError(t, err)
			require.Equal(t, fiber.StatusInternalServerError, resp.StatusCode)

			body, err := io.ReadAll(resp.Body)
			require.NoError(t, err)
			require.Equal(t, errNilProxyClientOverride.Error(), string(body))
		})
	}
}

// go test -run Test_ProxyBalancer_Custom_Client
func Test_ProxyBalancer_Custom_Client(t *testing.T) {
	t.Parallel()

	target, addr := createProxyTestServerIPv4(t, func(c fiber.Ctx) error {
		return c.SendStatus(fiber.StatusTeapot)
	})

	resp, err := target.Test(httptest.NewRequest(fiber.MethodGet, "/", http.NoBody), fiber.TestConfig{
		Timeout:       2 * time.Second,
		FailOnTimeout: true,
	})
	require.NoError(t, err)
	require.Equal(t, fiber.StatusTeapot, resp.StatusCode)

	app := fiber.New()

	app.Use(Balancer(Config{Client: &fasthttp.LBClient{
		Clients: []fasthttp.BalancingClient{
			&fasthttp.HostClient{
				NoDefaultUserAgentHeader: true,
				DisablePathNormalizing:   true,
				Addr:                     addr,
			},
		},
		Timeout: time.Second,
	}}))

	req := httptest.NewRequest(fiber.MethodGet, "/", http.NoBody)
	req.Host = addr
	resp, err = app.Test(req)
	require.NoError(t, err)
	require.Equal(t, fiber.StatusTeapot, resp.StatusCode)
}

// go test -run Test_Proxy_Domain_Forward_Local
func Test_Proxy_Domain_Forward_Local(t *testing.T) {
	t.Parallel()
	ln, err := net.Listen(fiber.NetworkTCP4, "127.0.0.1:0")
	require.NoError(t, err)
	app := fiber.New()

	// target server
	ln1, err := net.Listen(fiber.NetworkTCP4, "127.0.0.1:0")
	require.NoError(t, err)
	app1 := fiber.New()

	app1.Get("/test", func(c fiber.Ctx) error {
		return c.SendString("test_local_client:" + c.Query("query_test"))
	})

	proxyAddr := ln.Addr().String()
	targetAddr := ln1.Addr().String()
	localDomain := strings.Replace(proxyAddr, "127.0.0.1", "localhost", 1)
	app.Use(DomainForward(localDomain, "http://"+targetAddr, &fasthttp.Client{
		NoDefaultUserAgentHeader: true,
		DisablePathNormalizing:   true,

		Dial: fasthttp.Dial,
	}))
	startServer(app, ln)
	startServer(app1, ln1)

	client := clientpkg.New()
	resp, err := client.Get("http://" + localDomain + "/test?query_test=true")
	require.NoError(t, err)
	require.Equal(t, fiber.StatusOK, resp.StatusCode())
	require.Equal(t, "test_local_client:true", string(resp.Body()))
	resp.Close()
}

// go test -run Test_Proxy_Balancer_Forward_Local
func Test_Proxy_Balancer_Forward_Local(t *testing.T) {
	t.Parallel()

	app := fiber.New()

	_, addr := createProxyTestServerIPv4(t, func(c fiber.Ctx) error {
		return c.SendString("forwarded")
	})

	app.Use(BalancerForward([]string{addr}))

	resp, err := app.Test(httptest.NewRequest(fiber.MethodGet, "/", http.NoBody))
	require.NoError(t, err)
	require.Equal(t, fiber.StatusOK, resp.StatusCode)

	b, err := io.ReadAll(resp.Body)
	require.NoError(t, err)

	require.Equal(t, "forwarded", string(b))
}

func Test_Proxy_Balancer_Forward_OverwritesXRealIP(t *testing.T) {
	t.Parallel()

	const (
		spoofedIP       = "10.0.0.1"
		appTestClientIP = "0.0.0.0"
	)

	_, addr := createProxyTestServerIPv4(t, func(c fiber.Ctx) error {
		value := c.Get("X-Real-IP")
		require.Equal(t, appTestClientIP, value)
		require.NotEqual(t, spoofedIP, value)
		return c.SendStatus(fiber.StatusOK)
	})

	app := fiber.New()
	app.Use(BalancerForward([]string{addr}))

	req := httptest.NewRequest(fiber.MethodGet, "/", http.NoBody)
	req.Header.Set("X-Real-IP", spoofedIP)

	resp, err := app.Test(req)
	require.NoError(t, err)
	require.Equal(t, fiber.StatusOK, resp.StatusCode)
}

func Test_Proxy_Immutable(t *testing.T) {
	t.Parallel()

	target, addr := createProxyTestServerIPv4(t, func(c fiber.Ctx) error {
		return c.SendStatus(fiber.StatusTeapot)
	})

	resp, err := target.Test(httptest.NewRequest(fiber.MethodGet, "/", http.NoBody), fiber.TestConfig{
		Timeout:       2 * time.Second,
		FailOnTimeout: true,
	})
	require.NoError(t, err)
	require.Equal(t, fiber.StatusTeapot, resp.StatusCode)

	app := fiber.New(fiber.Config{Immutable: true})

	app.Use(Balancer(Config{Servers: []string{addr}}))

	req := httptest.NewRequest(fiber.MethodGet, "/", http.NoBody)
	req.Host = addr
	resp, err = app.Test(req)
	require.NoError(t, err)
	require.Equal(t, fiber.StatusTeapot, resp.StatusCode)
}

func Test_Proxy_KeepConnectionHeader(t *testing.T) {
	t.Parallel()

	_, addr := createProxyTestServerIPv4(t, func(c fiber.Ctx) error {
		c.Set(fiber.HeaderConnection, "backend")
		return c.SendString("ok")
	})

	app := fiber.New()
	app.Use(Balancer(Config{Servers: []string{addr}, KeepConnectionHeader: true}))

	req := httptest.NewRequest(fiber.MethodGet, "/", http.NoBody)
	req.Host = addr
	req.Header.Set(fiber.HeaderConnection, "keep-alive")

	resp, err := app.Test(req)
	require.NoError(t, err)
	require.Equal(t, "backend", resp.Header.Get(fiber.HeaderConnection))
}

func Test_Proxy_DropConnectionHeader(t *testing.T) {
	t.Parallel()

	_, addr := createProxyTestServerIPv4(t, func(c fiber.Ctx) error {
		c.Set(fiber.HeaderConnection, "backend")
		return c.SendString("ok")
	})

	app := fiber.New()
	app.Use(Balancer(Config{Servers: []string{addr}}))

	req := httptest.NewRequest(fiber.MethodGet, "/", http.NoBody)
	req.Host = addr
	req.Header.Set(fiber.HeaderConnection, "keep-alive")

	resp, err := app.Test(req)
	require.NoError(t, err)
	require.Empty(t, resp.Header.Get(fiber.HeaderConnection))
}

func Test_Proxy_Forward_OverwritesXRealIP(t *testing.T) {
	t.Parallel()

	const spoofedIP = "10.0.0.1"
	// app.Test injects 0.0.0.0 as the remote address, so c.IP() returns IPv4zero.
	appTestClientIP := net.IPv4zero.String()

	_, addr := createProxyTestServerIPv4(t, func(c fiber.Ctx) error {
		require.Equal(t, appTestClientIP, c.Get("X-Real-IP"))
		return c.SendStatus(fiber.StatusOK)
	})

	app := fiber.New()
	app.Use(Forward("http://" + addr))

	req := httptest.NewRequest(fiber.MethodGet, "/", http.NoBody)
	req.Header.Set("X-Real-IP", spoofedIP)

	resp, err := app.Test(req)
	require.NoError(t, err)
	require.Equal(t, fiber.StatusOK, resp.StatusCode)
}

func Test_Proxy_DomainForward_OverwritesXRealIP(t *testing.T) {
	t.Parallel()

	const (
		spoofedIP    = "10.0.0.1"
		testHostname = "example.com"
	)
	// app.Test injects 0.0.0.0 as the remote address, so c.IP() returns IPv4zero.
	appTestClientIP := net.IPv4zero.String()

	_, addr := createProxyTestServerIPv4(t, func(c fiber.Ctx) error {
		require.Equal(t, appTestClientIP, c.Get("X-Real-IP"))
		return c.SendStatus(fiber.StatusOK)
	})

	app := fiber.New()
	app.Use(DomainForward(testHostname, "http://"+addr))

	req := httptest.NewRequest(fiber.MethodGet, "/", http.NoBody)
	req.Host = testHostname
	req.Header.Set("X-Real-IP", spoofedIP)

	resp, err := app.Test(req)
	require.NoError(t, err)
	require.Equal(t, fiber.StatusOK, resp.StatusCode)
}
