// Copyright 2020 The Go Authors. All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file or at
// https://developers.google.com/open-source/licenses/bsd.

package main

import (
	"bufio"
	"fmt"
	"net/http"
	"net/http/httptest"
	"net/url"
	"strconv"
	"strings"
	"testing"

	"github.com/golang/gddo/gddo-server/dynconfig"
	"github.com/google/go-cmp/cmp"
)

func TestHandlePkgGoDevRedirect(t *testing.T) {
	for _, test := range []struct {
		name, url, wantLocationHeader, wantSetCookieHeader string
		wantStatusCode                                     int
		cookie                                             *http.Cookie
	}{
		{
			name:                "test pkggodev-redirect param is on",
			url:                 "http://godoc.org/net/http?redirect=on",
			wantLocationHeader:  "https://pkg.go.dev/net/http?utm_source=godoc",
			wantSetCookieHeader: "pkggodev-redirect=on; Path=/",
			wantStatusCode:      http.StatusFound,
		},
		{
			name:                "test pkggodev-redirect param is off",
			url:                 "http://godoc.org/net/http?redirect=off",
			wantLocationHeader:  "",
			wantSetCookieHeader: "pkggodev-redirect=; Path=/; Max-Age=0",
			wantStatusCode:      http.StatusOK,
		},
		{
			name:                "test pkggodev-redirect param is unset",
			url:                 "http://godoc.org/net/http",
			wantLocationHeader:  "",
			wantSetCookieHeader: "",
			wantStatusCode:      http.StatusOK,
		},
		{
			name:                "toggle enabled pkggodev-redirect cookie",
			url:                 "http://godoc.org/net/http?redirect=off",
			cookie:              &http.Cookie{Name: "pkggodev-redirect", Value: "true"},
			wantLocationHeader:  "",
			wantSetCookieHeader: "pkggodev-redirect=; Path=/; Max-Age=0",
			wantStatusCode:      http.StatusOK,
		},
		{
			name:                "pkggodev-redirect enabled cookie should redirect",
			url:                 "http://godoc.org/net/http",
			cookie:              &http.Cookie{Name: "pkggodev-redirect", Value: "on"},
			wantLocationHeader:  "https://pkg.go.dev/net/http?utm_source=godoc",
			wantSetCookieHeader: "",
			wantStatusCode:      http.StatusFound,
		},
		{
			name:           "do not redirect if user is returning from pkg.go.dev",
			url:            "http://godoc.org/net/http?utm_source=backtogodoc",
			cookie:         &http.Cookie{Name: "pkggodev-redirect", Value: "on"},
			wantStatusCode: http.StatusOK,
		},
	} {
		t.Run(test.name, func(t *testing.T) {
			req := httptest.NewRequest("GET", test.url, nil)
			if test.cookie != nil {
				req.AddCookie(test.cookie)
			}
			handler := pkgGoDevRedirectHandler(nil, func(w http.ResponseWriter, r *http.Request) error {
				return nil
			})

			w := httptest.NewRecorder()
			err := handler(w, req)
			if err != nil {
				t.Fatal(err)
			}
			resp := w.Result()

			if got, want := resp.Header.Get("Location"), test.wantLocationHeader; got != want {
				t.Errorf("Location header mismatch: got %q; want %q", got, want)
			}
			if got, want := resp.Header.Get("Set-Cookie"), test.wantSetCookieHeader; got != want {
				t.Errorf("Set-Cookie header mismatch: got %q; want %q", got, want)
			}
			if got, want := resp.StatusCode, test.wantStatusCode; got != want {
				t.Errorf("Status code mismatch: got %d; want %d", got, want)
			}
		})
	}
}

func TestPkgGoDevURL(t *testing.T) {
	testCases := []struct {
		from, to string
	}{
		{
			from: "https://godoc.org",
			to:   "https://pkg.go.dev?utm_source=godoc",
		},
		{
			from: "https://godoc.org/-/about",
			to:   "https://pkg.go.dev/about?utm_source=godoc",
		},
		{
			from: "https://godoc.org/-/go",
			to:   "https://pkg.go.dev/std?utm_source=godoc",
		},
		{
			from: "https://godoc.org/-/subrepo",
			to:   "https://pkg.go.dev/search?q=golang.org%2Fx&utm_source=godoc",
		},
		{
			from: "https://godoc.org/C",
			to:   "https://pkg.go.dev/C?utm_source=godoc",
		},
		{
			from: "https://godoc.org/?q=foo",
			to:   "https://pkg.go.dev/search?q=foo&utm_source=godoc",
		},
		{
			from: "https://godoc.org/cloud.google.com/go/storage",
			to:   "https://pkg.go.dev/cloud.google.com/go/storage?utm_source=godoc",
		},
		{
			from: "https://godoc.org/cloud.google.com/go/storage?imports",
			to:   "https://pkg.go.dev/cloud.google.com/go/storage?tab=imports&utm_source=godoc",
		},
		{
			from: "https://godoc.org/cloud.google.com/go/storage?importers",
			to:   "https://pkg.go.dev/cloud.google.com/go/storage?tab=importedby&utm_source=godoc",
		},
		{
			from: "https://godoc.org/cloud.google.com/go/storage?status.svg",
			to:   "https://pkg.go.dev/badge/cloud.google.com/go/storage?utm_source=godoc",
		},
		{
			from: "https://godoc.org/cloud.google.com/go/storage?status.png",
			to:   "https://pkg.go.dev/badge/cloud.google.com/go/storage?utm_source=godoc",
		},
		{
			from: "https://godoc.org/github.com/golang/go",
			to:   "https://pkg.go.dev/std?utm_source=godoc",
		},
		{
			from: "https://godoc.org/github.com/golang/go/src",
			to:   "https://pkg.go.dev/std?utm_source=godoc",
		},
		{
			from: "https://godoc.org/github.com/golang/go/src/cmd/vet",
			to:   "https://pkg.go.dev/cmd/vet?utm_source=godoc",
		},
		{
			from: "https://godoc.org/golang.org/x/vgo/vendor/cmd/go/internal/modfile",
			to:   "https://pkg.go.dev/?utm_source=godoc",
		},
		{
			from: "https://godoc.org/golang.org/x/vgo/vendor",
			to:   "https://pkg.go.dev/?utm_source=godoc",
		},
		{
			from: "https://godoc.org/cryptoscope.co/go/specialκ",
			to:   "https://golang.org/issue/43036",
		},
		{
			from: "https://godoc.org/github.com/google/go-containerregistry/",
			to:   "https://pkg.go.dev/github.com/google/go-containerregistry?utm_source=godoc",
		},
	}

	for _, tc := range testCases {
		t.Run(strings.ReplaceAll(tc.from, "/", " "), func(t *testing.T) {
			u, err := url.Parse(tc.from)
			if err != nil {
				t.Fatalf("url.Parse(%q): %v", tc.from, err)
			}
			to := pkgGoDevURL(u)
			if got, want := to.String(), tc.to; got != want {
				t.Errorf("pkgGoDevURL(%q) = %q; want %q", u, got, want)
			}
		})
	}
}

func TestNewGDDOEvent(t *testing.T) {
	for _, test := range []struct {
		name   string
		url    string
		cookie *http.Cookie
		want   *gddoEvent
	}{
		{
			name: "home page request",
			url:  "https://godoc.org",
			want: &gddoEvent{
				Host:        "godoc.org",
				Path:        "",
				UsePkgGoDev: false,
			},
		},
		{
			name:   "home page request with cookie on should redirect",
			url:    "https://godoc.org",
			cookie: &http.Cookie{Name: "pkggodev-redirect", Value: "on"},
			want: &gddoEvent{
				Host:        "godoc.org",
				Path:        "",
				UsePkgGoDev: true,
			},
		},
		{
			name: "about page request",
			url:  "https://godoc.org/-/about",
			want: &gddoEvent{
				Host:        "godoc.org",
				Path:        "/-/about",
				UsePkgGoDev: false,
			},
		},
		{
			name: "request with search query parameter",
			url:  "https://godoc.org/?q=test",
			want: &gddoEvent{
				Host:        "godoc.org",
				Path:        "/",
				UsePkgGoDev: false,
			},
		},
		{
			name: "package page request",
			url:  "https://godoc.org/net/http",
			want: &gddoEvent{
				Host:        "godoc.org",
				Path:        "/net/http",
				UsePkgGoDev: false,
			},
		},
		{
			name:   "package page request with wrong cookie on should not redirect",
			url:    "https://godoc.org/net/http",
			cookie: &http.Cookie{Name: "bogus-cookie", Value: "on"},
			want: &gddoEvent{
				Host:        "godoc.org",
				Path:        "/net/http",
				UsePkgGoDev: false,
			},
		},
		{
			name:   "package page request with query parameter off should not redirect",
			url:    "https://godoc.org/net/http?redirect=off",
			cookie: &http.Cookie{Name: "pkggodev-redirect", Value: "on"},
			want: &gddoEvent{
				Host:        "godoc.org",
				Path:        "/net/http",
				UsePkgGoDev: false,
			},
		},
		{
			name:   "package page request with cookie on should redirect",
			url:    "https://godoc.org/net/http",
			cookie: &http.Cookie{Name: "pkggodev-redirect", Value: "on"},
			want: &gddoEvent{
				Host:        "godoc.org",
				Path:        "/net/http",
				UsePkgGoDev: true,
			},
		},
		{
			name:   "package page request with query parameter on should redirect",
			url:    "https://godoc.org/net/http?redirect=on",
			cookie: &http.Cookie{Name: "pkggodev-redirect", Value: ""},
			want: &gddoEvent{
				Host:        "godoc.org",
				Path:        "/net/http",
				UsePkgGoDev: true,
			},
		},
		{
			name: "api request",
			url:  "https://api.godoc.org/imports/net/http",
			want: &gddoEvent{
				Host:        "api.godoc.org",
				Path:        "/imports/net/http",
				UsePkgGoDev: false,
			},
		},
		{
			name:   "api requests should never redirect, even with cookie on",
			url:    "https://api.godoc.org/imports/net/http",
			cookie: &http.Cookie{Name: "pkggodev-redirect", Value: "on"},
			want: &gddoEvent{
				Host:        "api.godoc.org",
				Path:        "/imports/net/http",
				UsePkgGoDev: false,
			},
		},
		{
			name:   "api requests should never redirect, even with query parameter on",
			url:    "https://api.godoc.org/imports/net/http?redirect=on",
			cookie: &http.Cookie{Name: "pkggodev-redirect", Value: ""},
			want: &gddoEvent{
				Host:        "api.godoc.org",
				Path:        "/imports/net/http",
				UsePkgGoDev: false,
			},
		},
	} {
		t.Run(test.name, func(t *testing.T) {
			want := test.want
			want.Latency = 100
			want.URL = test.url
			want.Header = http.Header{}
			want.IsRobot = true
			r := httptest.NewRequest("GET", test.url, nil)
			if test.cookie != nil {
				r.AddCookie(test.cookie)
				want.Header.Add("Cookie", test.cookie.String())
			}
			got := newGDDOEvent(r, want.Latency, want.IsRobot, http.StatusOK)
			want.Status = http.StatusOK
			if diff := cmp.Diff(want, got); diff != "" {
				t.Fatalf("mismatch (-want +got):\n%s", diff)
			}
		})
	}
}

func TestNewGDDOEventFromRequests(t *testing.T) {
	for _, test := range []struct {
		name       string
		requestURI string
		host       string
		want       *gddoEvent
	}{
		{
			name:       "absolute index path",
			requestURI: "https://godoc.org",
			host:       "godoc.org",
			want: &gddoEvent{
				Host: "godoc.org",
				Path: "",
				URL:  "https://godoc.org",
			},
		},
		{
			name:       "absolute index path with trailing slash",
			requestURI: "https://godoc.org/",
			host:       "godoc.org",
			want: &gddoEvent{
				Host: "godoc.org",
				Path: "/",
				URL:  "https://godoc.org/",
			},
		},
		{
			name:       "relative index path",
			requestURI: "/",
			host:       "godoc.org",
			want: &gddoEvent{
				Host: "godoc.org",
				Path: "/",
				URL:  "https://godoc.org/",
			},
		},
		{
			name:       "absolute about path",
			requestURI: "https://godoc.org/-/about",
			host:       "godoc.org",
			want: &gddoEvent{
				Host: "godoc.org",
				Path: "/-/about",
				URL:  "https://godoc.org/-/about",
			},
		},
		{
			name:       "relative about path",
			requestURI: "/-/about",
			host:       "godoc.org",
			want: &gddoEvent{
				Host: "godoc.org",
				Path: "/-/about",
				URL:  "https://godoc.org/-/about",
			},
		},
		{
			name:       "absolute package path",
			requestURI: "https://godoc.org/net/http",
			host:       "godoc.org",
			want: &gddoEvent{
				Host: "godoc.org",
				Path: "/net/http",
				URL:  "https://godoc.org/net/http",
			},
		},
		{
			name:       "relative package path",
			requestURI: "/net/http",
			host:       "godoc.org",
			want: &gddoEvent{
				Host: "godoc.org",
				Path: "/net/http",
				URL:  "https://godoc.org/net/http",
			},
		},
		{
			name:       "absolute path with query parameters",
			requestURI: "https://godoc.org/net/http?q=test",
			host:       "godoc.org",
			want: &gddoEvent{
				Host: "godoc.org",
				Path: "/net/http",
				URL:  "https://godoc.org/net/http?q=test",
			},
		},
		{
			name:       "relative path with query parameters",
			requestURI: "/net/http?q=test",
			host:       "godoc.org",
			want: &gddoEvent{
				Host: "godoc.org",
				Path: "/net/http",
				URL:  "https://godoc.org/net/http?q=test",
			},
		},
		{
			name:       "absolute api path",
			requestURI: "https://api.godoc.org/imports/net/http",
			host:       "api.godoc.org",
			want: &gddoEvent{
				Host: "api.godoc.org",
				Path: "/imports/net/http",
				URL:  "https://api.godoc.org/imports/net/http",
			},
		},
		{
			name:       "relative api path",
			requestURI: "/imports/net/http",
			host:       "api.godoc.org",
			want: &gddoEvent{
				Host: "api.godoc.org",
				Path: "/imports/net/http",
				URL:  "https://api.godoc.org/imports/net/http",
			},
		},
	} {
		t.Run(test.name, func(t *testing.T) {
			want := test.want
			want.Latency = 100
			want.Header = http.Header{}
			want.IsRobot = false
			requestLine := "GET " + test.requestURI + " HTTP/1.1\r\nHost: " + test.host + "\r\n\r\n"
			req, err := http.ReadRequest(bufio.NewReader(strings.NewReader(requestLine)))
			if err != nil {
				t.Fatal("invalid NewRequest arguments; " + err.Error())
			}
			got := newGDDOEvent(req, want.Latency, want.IsRobot, http.StatusOK)
			want.Status = http.StatusOK
			if diff := cmp.Diff(want, got); diff != "" {
				t.Fatalf("mismatch (-want +got):\n%s", diff)
			}
		})
	}
}

func TestShouldTeeRequest(t *testing.T) {
	for _, test := range []struct {
		urlPath string
		want    bool
	}{
		{"/", true},
		{"/-/about", true},
		{"/net/http", true},
		{"/_ah/ready", false},
		{"/_ah/warmup", false},
		{"/-/bootstrap.min.css", false},
		{"/-/bootstrap.min.js", false},
		{"/-/bot", false},
		{"/-/jquery-2.0.3.min.js", false},
		{"/-/refresh", false},
		{"/-/sidebar.css", false},
		{"/-/site.css", false},
		{"/-/site.js", false},
		{"/BingSiteAuth.xml", false},
		{"/google3d2f3cd4cc2bb44b.html", false},
		{"/humans.txt", false},
		{"/robots.txt", false},
		{"/third_party/jquery.timeago.js", false},
	} {
		if got := shouldTeeRequest(test.urlPath); got != test.want {
			t.Errorf("shouldTeeRequest(%q): %t; want %t", test.urlPath, got, test.want)
		}
	}
}

func TestShouldRedirectURLForSnapshot(t *testing.T) {
	var testRequests []*http.Request
	for _, tu := range []string{
		"https://api.godoc.org/-/about",
		"https://api.godoc.org/?q=http",
		"https://api.godoc.org/-/net/http",
		"https://godoc.org",
		"https://godoc.org/-/about",
		"https://godoc.org/-/aboutfoo",
		"https://godoc.org/-/about/foobar",
		"https://godoc.org/-/bot",
		"https://godoc.org/-/go",
		"https://godoc.org/-/subrepo",
		"https://godoc.org/?q=http",
		"https://godoc.org/cmd",
		"https://godoc.org/net/http",
		"https://godoc.org/cloud.google.com/go",
		"https://godoc.org/cloud.google.com/go/pubsub",
		"https://godoc.org/cloud.google.com/go/storage",
		"https://godoc.org/cloud.google.com/go/storage/internal",
		"https://godoc.org/github.com/my/module",
		"https://godoc.org/github.com/my/module/package",
	} {
		u, err := url.Parse(tu)
		if err != nil {
			t.Fatal(err)
		}
		req := httptest.NewRequest("GET", u.String(), nil)
		req.URL = u
		req.Form = u.Query()
		testRequests = append(testRequests, req)
	}

	for _, test := range []struct {
		name     string
		snapshot *dynconfig.DynamicConfig
		redirect map[string]bool
	}{
		{
			name: "redirect homepage",
			snapshot: &dynconfig.DynamicConfig{
				RedirectHomepage: true,
			},
			redirect: map[string]bool{"https://godoc.org": true},
		},
		{
			name: "redirect search page",
			snapshot: &dynconfig.DynamicConfig{
				RedirectSearch: true,
			},
			redirect: map[string]bool{"https://godoc.org/?q=http": true},
		},
		{
			name: "redirect static page",
			snapshot: &dynconfig.DynamicConfig{
				RedirectPaths: []string{"/-/about", "/-/subrepo", "/-/go"},
			},
			redirect: map[string]bool{
				"https://godoc.org/-/about":   true,
				"https://godoc.org/-/go":      true,
				"https://godoc.org/-/subrepo": true,
			},
		},
		{
			name: "redirect stdlib packages",
			snapshot: &dynconfig.DynamicConfig{
				RedirectStdlib: true,
			},
			redirect: map[string]bool{
				"https://godoc.org/net/http": true,
				"https://godoc.org/cmd":      true,
			},
		},
		{
			name: "redirect cloud.google.com/go",
			snapshot: &dynconfig.DynamicConfig{
				RedirectPaths: []string{"/cloud.google.com/go"},
			},
			redirect: map[string]bool{
				"https://godoc.org/cloud.google.com/go":                  true,
				"https://godoc.org/cloud.google.com/go/pubsub":           true,
				"https://godoc.org/cloud.google.com/go/storage":          true,
				"https://godoc.org/cloud.google.com/go/storage/internal": true,
			},
		},
	} {
		t.Run(test.name, func(t *testing.T) {
			for _, req := range testRequests {
				u := req.URL.String()
				got := shouldRedirectURLForSnapshot(req, test.snapshot)
				if test.redirect[u] && !got {
					t.Errorf("%q should redirect but didn't", u)
				}
				if !test.redirect[u] && got {
					t.Errorf("%q should not redirect and did", u)
				}
			}
		})
	}
}

func TestShouldRedirectURLForSnapshot_RolloutPercentage(t *testing.T) {
	checkRollout := func(t *testing.T, paths []string, rollout uint, want uint) {
		t.Helper()
		var inExperiment int
		for _, p := range paths {
			req, err := http.NewRequest("GET", "http://godoc.org/"+p, nil)
			if err != nil {
				t.Fatal(err)
			}
			snapshot := &dynconfig.DynamicConfig{RedirectRollout: rollout}
			if shouldRedirectURLForSnapshot(req, snapshot) {
				inExperiment++
			}
		}
		if rollout == 0 {
			if inExperiment != 0 {
				t.Fatalf("rollout is 0 and inExperiment = %d; want = 0", inExperiment)
			}
			return
		}
		got := uint(100 * inExperiment / len(paths))
		if got != want {
			t.Errorf("rollout = %d; want = %d", got, want)
		}
	}

	var paths []string
	for host := range vcsHostsWithThreeElementRepoName {
		for i := 0; i < 1000; i++ {
			p := host + "/" + strconv.Itoa(i) + "/foo"
			paths = append(paths, p)
		}
	}
	pathsWithCustomHost := paths
	for i := 0; i < 1000; i++ {
		pathsWithCustomHost = append(pathsWithCustomHost, "mymodule.com/"+strconv.Itoa(i))
	}
	for _, rollout := range []uint{0, 33, 47, 50, 53, 75, 100} {
		t.Run(fmt.Sprintf("%d", rollout), func(t *testing.T) {
			checkRollout(t, paths, rollout, rollout)
		})
		t.Run(fmt.Sprintf("customhost %d", rollout), func(t *testing.T) {
			// Map of rollout set to expected rollout percentage. Numbers are
			// skewed because all my.module.com/<i> paths are added, and they
			// will not be opted in.
			want := map[uint]uint{0: 0, 33: 28, 47: 40, 50: 42, 53: 45, 75: 64, 100: 100}[rollout]
			checkRollout(t, pathsWithCustomHost, rollout, want)
		})
	}
}