package middleware

import (
	"bytes"
	"context"
	"fmt"
	"io"
	"net"
	"net/http"
	"net/http/httptest"
	"net/url"
	"regexp"
	"sync"
	"testing"
	"time"

	"github.com/labstack/echo/v4"
	"github.com/stretchr/testify/assert"
)

// Assert expected with url.EscapedPath method to obtain the path.
func TestProxy(t *testing.T) {
	// Setup
	t1 := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		fmt.Fprint(w, "target 1")
	}))
	defer t1.Close()
	url1, _ := url.Parse(t1.URL)
	t2 := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		fmt.Fprint(w, "target 2")
	}))
	defer t2.Close()
	url2, _ := url.Parse(t2.URL)
	targets := []*ProxyTarget{
		{
			Name: "target 1",
			URL:  url1,
		},
		{
			Name: "target 2",
			URL:  url2,
		},
	}
	rb := NewRandomBalancer(nil)
	// must add targets:
	for _, target := range targets {
		assert.True(t, rb.AddTarget(target))
	}

	// must ignore duplicates:
	for _, target := range targets {
		assert.False(t, rb.AddTarget(target))
	}

	// Random
	e := echo.New()
	e.Use(Proxy(rb))
	req := httptest.NewRequest(http.MethodGet, "/", nil)
	rec := httptest.NewRecorder()
	e.ServeHTTP(rec, req)
	body := rec.Body.String()
	expected := map[string]bool{
		"target 1": true,
		"target 2": true,
	}
	assert.Condition(t, func() bool {
		return expected[body]
	})

	for _, target := range targets {
		assert.True(t, rb.RemoveTarget(target.Name))
	}

	assert.False(t, rb.RemoveTarget("unknown target"))

	// Round-robin
	rrb := NewRoundRobinBalancer(targets)
	e = echo.New()
	e.Use(Proxy(rrb))

	rec = httptest.NewRecorder()
	e.ServeHTTP(rec, req)
	body = rec.Body.String()
	assert.Equal(t, "target 1", body)

	rec = httptest.NewRecorder()
	e.ServeHTTP(rec, req)
	body = rec.Body.String()
	assert.Equal(t, "target 2", body)

	// ModifyResponse
	e = echo.New()
	e.Use(ProxyWithConfig(ProxyConfig{
		Balancer: rrb,
		ModifyResponse: func(res *http.Response) error {
			res.Body = io.NopCloser(bytes.NewBuffer([]byte("modified")))
			res.Header.Set("X-Modified", "1")
			return nil
		},
	}))

	rec = httptest.NewRecorder()
	e.ServeHTTP(rec, req)
	assert.Equal(t, "modified", rec.Body.String())
	assert.Equal(t, "1", rec.Header().Get("X-Modified"))

	// ProxyTarget is set in context
	contextObserver := func(next echo.HandlerFunc) echo.HandlerFunc {
		return func(c echo.Context) (err error) {
			next(c)
			assert.Contains(t, targets, c.Get("target"), "target is not set in context")
			return nil
		}
	}
	rrb1 := NewRoundRobinBalancer(targets)

	e = echo.New()
	e.Use(contextObserver)
	e.Use(Proxy(rrb1))
	rec = httptest.NewRecorder()
	e.ServeHTTP(rec, req)
}

type testProvider struct {
	*commonBalancer
	target *ProxyTarget
	err    error
}

func (p *testProvider) Next(c echo.Context) *ProxyTarget {
	return &ProxyTarget{}
}

func (p *testProvider) NextTarget(c echo.Context) (*ProxyTarget, error) {
	return p.target, p.err
}

func TestTargetProvider(t *testing.T) {
	t1 := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		fmt.Fprint(w, "target 1")
	}))
	defer t1.Close()
	url1, _ := url.Parse(t1.URL)

	e := echo.New()
	tp := &testProvider{commonBalancer: new(commonBalancer)}
	tp.target = &ProxyTarget{Name: "target 1", URL: url1}
	e.Use(Proxy(tp))
	rec := httptest.NewRecorder()
	req := httptest.NewRequest(http.MethodGet, "/", nil)
	e.ServeHTTP(rec, req)
	body := rec.Body.String()
	assert.Equal(t, "target 1", body)
}

func TestFailNextTarget(t *testing.T) {
	url1, err := url.Parse("http://dummy:8080")
	assert.Nil(t, err)

	e := echo.New()
	tp := &testProvider{commonBalancer: new(commonBalancer)}
	tp.target = &ProxyTarget{Name: "target 1", URL: url1}
	tp.err = echo.NewHTTPError(http.StatusInternalServerError, "method could not select target")

	e.Use(Proxy(tp))
	rec := httptest.NewRecorder()
	req := httptest.NewRequest(http.MethodGet, "/", nil)
	e.ServeHTTP(rec, req)
	body := rec.Body.String()
	assert.Equal(t, "{\"message\":\"method could not select target\"}\n", body)
}

func TestProxyRealIPHeader(t *testing.T) {
	// Setup
	upstream := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {}))
	defer upstream.Close()
	url, _ := url.Parse(upstream.URL)
	rrb := NewRoundRobinBalancer([]*ProxyTarget{{Name: "upstream", URL: url}})
	e := echo.New()
	e.Use(Proxy(rrb))
	req := httptest.NewRequest(http.MethodGet, "/", nil)
	rec := httptest.NewRecorder()

	remoteAddrIP, _, _ := net.SplitHostPort(req.RemoteAddr)
	realIPHeaderIP := "203.0.113.1"
	extractedRealIP := "203.0.113.10"
	tests := []*struct {
		hasRealIPheader bool
		hasIPExtractor  bool
		extectedXRealIP string
	}{
		{false, false, remoteAddrIP},
		{false, true, extractedRealIP},
		{true, false, realIPHeaderIP},
		{true, true, extractedRealIP},
	}

	for _, tt := range tests {
		if tt.hasRealIPheader {
			req.Header.Set(echo.HeaderXRealIP, realIPHeaderIP)
		} else {
			req.Header.Del(echo.HeaderXRealIP)
		}
		if tt.hasIPExtractor {
			e.IPExtractor = func(*http.Request) string {
				return extractedRealIP
			}
		} else {
			e.IPExtractor = nil
		}
		e.ServeHTTP(rec, req)
		assert.Equal(t, tt.extectedXRealIP, req.Header.Get(echo.HeaderXRealIP), "hasRealIPheader: %t / hasIPExtractor: %t", tt.hasRealIPheader, tt.hasIPExtractor)
	}
}

func TestProxyRewrite(t *testing.T) {
	var testCases = []struct {
		whenPath         string
		expectProxiedURI string
		expectStatus     int
	}{
		{
			whenPath:         "/api/users",
			expectProxiedURI: "/users",
			expectStatus:     http.StatusOK,
		},
		{
			whenPath:         "/js/main.js",
			expectProxiedURI: "/public/javascripts/main.js",
			expectStatus:     http.StatusOK,
		},
		{
			whenPath:         "/old",
			expectProxiedURI: "/new",
			expectStatus:     http.StatusOK,
		},
		{
			whenPath:         "/users/jack/orders/1",
			expectProxiedURI: "/user/jack/order/1",
			expectStatus:     http.StatusOK,
		},
		{
			whenPath:         "/user/jill/order/T%2FcO4lW%2Ft%2FVp%2F",
			expectProxiedURI: "/user/jill/order/T%2FcO4lW%2Ft%2FVp%2F",
			expectStatus:     http.StatusOK,
		},
		{ // ` ` (space) is encoded by httpClient to `%20` when doing request to Echo. `%20` should not be double escaped when proxying request
			whenPath:         "/api/new users",
			expectProxiedURI: "/new%20users",
			expectStatus:     http.StatusOK,
		},
		{ // query params should be proxied and not be modified
			whenPath:         "/api/users?limit=10",
			expectProxiedURI: "/users?limit=10",
			expectStatus:     http.StatusOK,
		},
	}

	for _, tc := range testCases {
		t.Run(tc.whenPath, func(t *testing.T) {
			receivedRequestURI := make(chan string, 1)
			upstream := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
				// RequestURI is the unmodified request-target of the Request-Line (RFC 7230, Section 3.1.1) as sent by the client to a server
				// we need unmodified target to see if we are encoding/decoding the url in addition to rewrite/replace logic
				// if original request had `%2F` we should not magically decode it to `/` as it would change what was requested
				receivedRequestURI <- r.RequestURI
			}))
			defer upstream.Close()
			serverURL, _ := url.Parse(upstream.URL)
			rrb := NewRoundRobinBalancer([]*ProxyTarget{{Name: "upstream", URL: serverURL}})

			// Rewrite
			e := echo.New()
			e.Use(ProxyWithConfig(ProxyConfig{
				Balancer: rrb,
				Rewrite: map[string]string{
					"/old":              "/new",
					"/api/*":            "/$1",
					"/js/*":             "/public/javascripts/$1",
					"/users/*/orders/*": "/user/$1/order/$2",
				},
			}))

			targetURL, _ := serverURL.Parse(tc.whenPath)
			req := httptest.NewRequest(http.MethodGet, targetURL.String(), nil)
			rec := httptest.NewRecorder()

			e.ServeHTTP(rec, req)

			assert.Equal(t, tc.expectStatus, rec.Code)
			actualRequestURI := <-receivedRequestURI
			assert.Equal(t, tc.expectProxiedURI, actualRequestURI)
		})
	}
}

func TestProxyRewriteRegex(t *testing.T) {
	// Setup
	receivedRequestURI := make(chan string, 1)
	upstream := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		// RequestURI is the unmodified request-target of the Request-Line (RFC 7230, Section 3.1.1) as sent by the client to a server
		// we need unmodified target to see if we are encoding/decoding the url in addition to rewrite/replace logic
		// if original request had `%2F` we should not magically decode it to `/` as it would change what was requested
		receivedRequestURI <- r.RequestURI
	}))
	defer upstream.Close()
	tmpUrL, _ := url.Parse(upstream.URL)
	rrb := NewRoundRobinBalancer([]*ProxyTarget{{Name: "upstream", URL: tmpUrL}})

	// Rewrite
	e := echo.New()
	e.Use(ProxyWithConfig(ProxyConfig{
		Balancer: rrb,
		Rewrite: map[string]string{
			"^/a/*":     "/v1/$1",
			"^/b/*/c/*": "/v2/$2/$1",
			"^/c/*/*":   "/v3/$2",
		},
		RegexRewrite: map[*regexp.Regexp]string{
			regexp.MustCompile("^/x/.+?/(.*)"):   "/v4/$1",
			regexp.MustCompile("^/y/(.+?)/(.*)"): "/v5/$2/$1",
		},
	}))

	testCases := []struct {
		requestPath string
		statusCode  int
		expectPath  string
	}{
		{"/unmatched", http.StatusOK, "/unmatched"},
		{"/a/test", http.StatusOK, "/v1/test"},
		{"/b/foo/c/bar/baz", http.StatusOK, "/v2/bar/baz/foo"},
		{"/c/ignore/test", http.StatusOK, "/v3/test"},
		{"/c/ignore1/test/this", http.StatusOK, "/v3/test/this"},
		{"/x/ignore/test", http.StatusOK, "/v4/test"},
		{"/y/foo/bar", http.StatusOK, "/v5/bar/foo"},
		// NB: fragment is not added by golang httputil.NewSingleHostReverseProxy implementation
		// $2 = `bar?q=1#frag`, $1 = `foo`. replaced uri = `/v5/bar?q=1#frag/foo` but httputil.NewSingleHostReverseProxy does not send `#frag/foo` (currently)
		{"/y/foo/bar?q=1#frag", http.StatusOK, "/v5/bar?q=1"},
	}

	for _, tc := range testCases {
		t.Run(tc.requestPath, func(t *testing.T) {
			targetURL, _ := url.Parse(tc.requestPath)
			req := httptest.NewRequest(http.MethodGet, targetURL.String(), nil)
			rec := httptest.NewRecorder()

			e.ServeHTTP(rec, req)

			actualRequestURI := <-receivedRequestURI
			assert.Equal(t, tc.expectPath, actualRequestURI)
			assert.Equal(t, tc.statusCode, rec.Code)
		})
	}
}

func TestProxyError(t *testing.T) {
	// Setup
	url1, _ := url.Parse("http://127.0.0.1:27121")
	url2, _ := url.Parse("http://127.0.0.1:27122")

	targets := []*ProxyTarget{
		{
			Name: "target 1",
			URL:  url1,
		},
		{
			Name: "target 2",
			URL:  url2,
		},
	}
	rb := NewRandomBalancer(nil)
	// must add targets:
	for _, target := range targets {
		assert.True(t, rb.AddTarget(target))
	}

	// must ignore duplicates:
	for _, target := range targets {
		assert.False(t, rb.AddTarget(target))
	}

	// Random
	e := echo.New()
	e.Use(Proxy(rb))
	req := httptest.NewRequest(http.MethodGet, "/", nil)

	// Remote unreachable
	rec := httptest.NewRecorder()
	req.URL.Path = "/api/users"
	e.ServeHTTP(rec, req)
	assert.Equal(t, "/api/users", req.URL.Path)
	assert.Equal(t, http.StatusBadGateway, rec.Code)
}

func TestClientCancelConnectionResultsHTTPCode499(t *testing.T) {
	var timeoutStop sync.WaitGroup
	timeoutStop.Add(1)
	HTTPTarget := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		timeoutStop.Wait() // wait until we have canceled the request
		w.WriteHeader(http.StatusOK)
	}))
	defer HTTPTarget.Close()
	targetURL, _ := url.Parse(HTTPTarget.URL)
	target := &ProxyTarget{
		Name: "target",
		URL:  targetURL,
	}
	rb := NewRandomBalancer(nil)
	assert.True(t, rb.AddTarget(target))
	e := echo.New()
	e.Use(Proxy(rb))
	rec := httptest.NewRecorder()
	req := httptest.NewRequest(http.MethodGet, "/", nil)
	ctx, cancel := context.WithCancel(req.Context())
	req = req.WithContext(ctx)
	go func() {
		time.Sleep(10 * time.Millisecond)
		cancel()
	}()
	e.ServeHTTP(rec, req)
	timeoutStop.Done()
	assert.Equal(t, 499, rec.Code)
}