package boardwalk

import (
	"io/fs"
	"net/http"
	"net/http/httptest"
	"path"
	"regexp"
	"strings"
	"testing"
	"testing/fstest"
)

const testPrefix = "/acme-admin"

var (
	assetRef  = regexp.MustCompile(`(?:src|href)="([^"]+)"`)
	scriptTag = regexp.MustCompile(`<script\b[^>]*>`)
)

type apiSpy struct{ calls int }

func (s *apiSpy) ServeHTTP(w http.ResponseWriter, _ *http.Request) {
	s.calls++
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(http.StatusNotFound)
	_, _ = w.Write([]byte(`{"error":{"code":"not_found","message":"Not found","details":{}}}`))
}

func newTestHandler(t *testing.T) (http.Handler, *apiSpy) {
	t.Helper()
	spy := &apiSpy{}
	h, err := Handler(testPrefix, spy)
	if err != nil {
		t.Fatal(err)
	}
	return h, spy
}

func get(h http.Handler, target string) *httptest.ResponseRecorder {
	rec := httptest.NewRecorder()
	h.ServeHTTP(rec, httptest.NewRequest(http.MethodGet, target, nil))
	return rec
}

func TestIndexRewrite(t *testing.T) {
	h, _ := newTestHandler(t)
	for _, target := range []string{testPrefix, testPrefix + "/", testPrefix + "/index.html"} {
		rec := get(h, target)
		body := rec.Body.String()
		if rec.Code != http.StatusOK {
			t.Fatalf("%s status=%d", target, rec.Code)
		}
		if !strings.Contains(body, `<meta name="summer-admin-base" content="`+testPrefix+`"`) {
			t.Fatalf("%s index has no injected base: %s", target, body)
		}
		if strings.Contains(body, BaseToken) || strings.Contains(body, `="./`) {
			t.Fatalf("%s index was not rewritten: %s", target, body)
		}
		if !strings.Contains(body, `src="`+testPrefix+`/assets/`) {
			t.Fatalf("%s index script is not under the prefix: %s", target, body)
		}
	}
}

func TestRewriteIndexRequiresToken(t *testing.T) {
	if _, err := RewriteIndex([]byte(`<html><script src="./assets/a.js"></script></html>`), testPrefix); err == nil {
		t.Fatal("index without the base token was accepted")
	}
	root := fstest.MapFS{"index.html": &fstest.MapFile{Data: []byte("<html></html>")}}
	if _, err := newHandler(root, testPrefix, &apiSpy{}); err == nil || !strings.Contains(err.Error(), BaseToken) {
		t.Fatalf("stale dist accepted: %v", err)
	}
	if _, err := newHandler(fstest.MapFS{}, testPrefix, &apiSpy{}); err == nil {
		t.Fatal("dist without index.html accepted")
	}
	if _, err := Handler(testPrefix, nil); err == nil {
		t.Fatal("nil API not-found handler accepted")
	}
	if _, err := Handler("acme-admin", &apiSpy{}); err == nil {
		t.Fatal("prefix without a leading slash accepted")
	}
}

func TestRewriteIndexEscapesPrefix(t *testing.T) {
	out, err := RewriteIndex([]byte(`<meta content="`+BaseToken+`"><script src="./a.js"></script>`), `/a"b`)
	if err != nil {
		t.Fatal(err)
	}
	if strings.Contains(string(out), `"/a"b`) || !strings.Contains(string(out), `/a&#34;b`) {
		t.Fatalf("prefix not escaped: %s", out)
	}
}

func TestEveryReferencedAssetIsEmbedded(t *testing.T) {
	root, err := Dist()
	if err != nil {
		t.Fatal(err)
	}
	raw, err := fs.ReadFile(root, "index.html")
	if err != nil {
		t.Fatal(err)
	}
	index, err := RewriteIndex(raw, testPrefix)
	if err != nil {
		t.Fatal(err)
	}
	refs := assetRef.FindAllStringSubmatch(string(index), -1)
	if len(refs) == 0 {
		t.Fatal("index references no assets")
	}
	h, _ := newTestHandler(t)
	for _, ref := range refs {
		target := ref[1]
		if !strings.HasPrefix(target, testPrefix+"/") {
			t.Fatalf("reference %q is not under the prefix", target)
		}
		name := strings.TrimPrefix(target, testPrefix+"/")
		if _, err := fs.Stat(root, name); err != nil {
			t.Fatalf("index references %s, missing from the embedded dist: %v", name, err)
		}
		if rec := get(h, target); rec.Code != http.StatusOK {
			t.Fatalf("GET %s status=%d", target, rec.Code)
		}
	}
}

func TestNoInlineScript(t *testing.T) {
	root, err := Dist()
	if err != nil {
		t.Fatal(err)
	}
	raw, err := fs.ReadFile(root, "index.html")
	if err != nil {
		t.Fatal(err)
	}
	tags := scriptTag.FindAllString(string(raw), -1)
	if len(tags) == 0 {
		t.Fatal("index has no module script")
	}
	for _, tag := range tags {
		if !strings.Contains(tag, " src=") {
			t.Fatalf("inline script in index.html: %s", tag)
		}
	}
	if strings.Contains(strings.ToLower(string(raw)), "javascript:") {
		t.Fatal("index.html contains a javascript: URL")
	}
}

func TestAPIPathsAreDelegated(t *testing.T) {
	h, spy := newTestHandler(t)
	for _, target := range []string{testPrefix + "/api", testPrefix + "/api/", testPrefix + "/api/v1/nope", testPrefix + "/api/v1/auth/login"} {
		before := spy.calls
		rec := get(h, target)
		if spy.calls != before+1 || rec.Code != http.StatusNotFound || strings.Contains(rec.Body.String(), "<html") {
			t.Fatalf("%s was not delegated: status=%d body=%s", target, rec.Code, rec.Body.String())
		}
	}
	before := spy.calls
	if rec := get(h, testPrefix+"/apiary"); rec.Code != http.StatusOK || spy.calls != before {
		t.Fatalf("/apiary is a client route, status=%d", rec.Code)
	}
}

func TestMissingFileWithExtensionIs404(t *testing.T) {
	h, _ := newTestHandler(t)
	for _, target := range []string{testPrefix + "/assets/missing.js", testPrefix + "/favicon.ico", testPrefix + "/golem/missing.css"} {
		rec := get(h, target)
		if rec.Code != http.StatusNotFound || strings.Contains(rec.Body.String(), "summer-admin-base") {
			t.Fatalf("%s status=%d body=%s", target, rec.Code, rec.Body.String())
		}
	}
	for _, target := range []string{testPrefix + "/acme/demo/widgets", testPrefix + "/acme/demo/widgets/12", testPrefix + "/login"} {
		rec := get(h, target)
		if rec.Code != http.StatusOK || !strings.Contains(rec.Body.String(), "summer-admin-base") {
			t.Fatalf("client route %s status=%d", target, rec.Code)
		}
	}
}

func TestTraversalIsCleaned(t *testing.T) {
	root := fstest.MapFS{
		"index.html":    &fstest.MapFile{Data: []byte(`<meta content="` + BaseToken + `">`)},
		"assets/app.js": &fstest.MapFile{Data: []byte("console.log(1)")},
	}
	h, err := newHandler(root, testPrefix, &apiSpy{})
	if err != nil {
		t.Fatal(err)
	}
	for _, target := range []string{
		testPrefix + "/../../../go.mod",
		testPrefix + "/assets/../../boardwalk.go",
		testPrefix + "/%2e%2e/%2e%2e/etc/passwd.txt",
	} {
		req := httptest.NewRequest(http.MethodGet, "/", nil)
		req.URL.Path = target
		rec := httptest.NewRecorder()
		h.ServeHTTP(rec, req)
		if rec.Code != http.StatusNotFound || strings.Contains(rec.Body.String(), "module ") || strings.Contains(rec.Body.String(), "package ") {
			t.Fatalf("%s status=%d body=%s", target, rec.Code, rec.Body.String())
		}
	}
	req := httptest.NewRequest(http.MethodGet, "/", nil)
	req.URL.Path = testPrefix + "/assets/../index.html"
	rec := httptest.NewRecorder()
	h.ServeHTTP(rec, req)
	if rec.Code != http.StatusOK || strings.Contains(rec.Body.String(), BaseToken) {
		t.Fatalf("cleaned index path served the raw index: %d %s", rec.Code, rec.Body.String())
	}
}

func TestDirectoryIsNeverListed(t *testing.T) {
	h, _ := newTestHandler(t)
	root, err := Dist()
	if err != nil {
		t.Fatal(err)
	}
	entries, err := fs.ReadDir(root, "assets")
	if err != nil || len(entries) == 0 {
		t.Fatalf("embedded assets: %v", err)
	}
	for _, target := range []string{testPrefix + "/assets", testPrefix + "/assets/"} {
		rec := get(h, target)
		body := rec.Body.String()
		if strings.Contains(body, entries[0].Name()) || !strings.Contains(body, "summer-admin-base") {
			t.Fatalf("%s listed the directory or skipped the shell: %s", target, body)
		}
	}
}

func TestContentTypesAndCaching(t *testing.T) {
	h, _ := newTestHandler(t)
	root, err := Dist()
	if err != nil {
		t.Fatal(err)
	}
	want := map[string]string{
		".js":    "text/javascript; charset=utf-8",
		".css":   "text/css; charset=utf-8",
		".woff2": "font/woff2",
		".woff":  "font/woff",
	}
	seen := map[string]bool{}
	err = fs.WalkDir(root, "assets", func(name string, d fs.DirEntry, err error) error {
		if err != nil || d.IsDir() {
			return err
		}
		ext := path.Ext(name)
		ct, ok := want[ext]
		if !ok || seen[ext] {
			return nil
		}
		seen[ext] = true
		rec := get(h, testPrefix+"/"+name)
		if rec.Code != http.StatusOK || rec.Header().Get("Content-Type") != ct {
			t.Fatalf("%s status=%d type=%q, want %q", name, rec.Code, rec.Header().Get("Content-Type"), ct)
		}
		if cc := rec.Header().Get("Cache-Control"); cc != "public, max-age=31536000, immutable" {
			t.Fatalf("%s Cache-Control=%q", name, cc)
		}
		return nil
	})
	if err != nil {
		t.Fatal(err)
	}
	for ext := range want {
		if !seen[ext] {
			t.Fatalf("embedded dist has no %s asset", ext)
		}
	}
	index := get(h, testPrefix)
	if index.Header().Get("Cache-Control") != "no-store" || !strings.HasPrefix(index.Header().Get("Content-Type"), "text/html") {
		t.Fatalf("index headers = %v", index.Header())
	}
	if got := ContentType("x.svg"); got != "image/svg+xml" {
		t.Fatalf("svg type %q", got)
	}
	if got := ContentType("x.json"); got != "application/json" {
		t.Fatalf("json type %q", got)
	}
	if got := ContentType("x.unknown-ext"); got != "application/octet-stream" {
		t.Fatalf("unknown type %q", got)
	}
}

func TestSecurityHeadersOnEveryResponse(t *testing.T) {
	h, _ := newTestHandler(t)
	root, err := Dist()
	if err != nil {
		t.Fatal(err)
	}
	entries, err := fs.ReadDir(root, "assets")
	if err != nil || len(entries) == 0 {
		t.Fatalf("embedded assets: %v", err)
	}
	for _, target := range []string{
		testPrefix,
		testPrefix + "/acme/demo/widgets",
		testPrefix + "/assets/" + entries[0].Name(),
		testPrefix + "/missing.js",
		testPrefix + "/api/v1/nope",
	} {
		rec := get(h, target)
		for header, want := range map[string]string{
			"X-Content-Type-Options":  "nosniff",
			"Referrer-Policy":         "same-origin",
			"X-Frame-Options":         "DENY",
			"Content-Security-Policy": "frame-ancestors 'none'; base-uri 'none'; object-src 'none'; script-src 'self'",
			"X-Robots-Tag":            "noindex, nofollow",
		} {
			if got := rec.Header().Get(header); got != want {
				t.Fatalf("%s %s=%q, want %q", target, header, got, want)
			}
		}
	}
}

// TestPhase10BoardwalkServing covers the remaining serving branches: HEAD,
// query strings, encoded traversal, the index requested by name, a nested
// prefix, deep client routes, MIME fallback for unknown extensions and the
// constructor's error paths.
func TestPhase10BoardwalkServing(t *testing.T) {
	h, spy := newTestHandler(t)

	t.Run("HEAD answers headers without a body", func(t *testing.T) {
		for _, target := range []string{testPrefix, testPrefix + "/acme/demo/widgets"} {
			rec := httptest.NewRecorder()
			h.ServeHTTP(rec, httptest.NewRequest(http.MethodHead, target, nil))
			if rec.Code != http.StatusOK || rec.Body.Len() != 0 || !strings.HasPrefix(rec.Header().Get("Content-Type"), "text/html") {
				t.Fatalf("HEAD %s: status=%d len=%d type=%q", target, rec.Code, rec.Body.Len(), rec.Header().Get("Content-Type"))
			}
			if rec.Header().Get("Content-Length") == "" || rec.Header().Get("X-Frame-Options") != "DENY" {
				t.Fatalf("HEAD %s headers = %v", target, rec.Header())
			}
		}
	})

	t.Run("query strings do not change what is served", func(t *testing.T) {
		root, err := Dist()
		if err != nil {
			t.Fatal(err)
		}
		entries, err := fs.ReadDir(root, "assets")
		if err != nil || len(entries) == 0 {
			t.Fatalf("assets: %v", err)
		}
		asset := get(h, testPrefix+"/assets/"+entries[0].Name()+"?v=2")
		if asset.Code != http.StatusOK || asset.Header().Get("Cache-Control") != "public, max-age=31536000, immutable" {
			t.Fatalf("asset with query: status=%d headers=%v", asset.Code, asset.Header())
		}
		route := get(h, testPrefix+"/acme/demo/widgets?search=blue&page=2")
		if route.Code != http.StatusOK || !strings.Contains(route.Body.String(), "summer-admin-base") {
			t.Fatalf("client route with query: status=%d", route.Code)
		}
		before := spy.calls
		if rec := get(h, testPrefix+"/api/v1/nope?x=1"); rec.Code != http.StatusNotFound || spy.calls != before+1 {
			t.Fatalf("api with query not delegated: %d", rec.Code)
		}
	})

	t.Run("encoded traversal never escapes the build", func(t *testing.T) {
		for _, target := range []string{
			testPrefix + "/%2e%2e/%2e%2e/go.mod",
			testPrefix + "/assets/..%2f..%2fboardwalk.go",
			testPrefix + "/%2E%2E%2F%2E%2E%2Fgo.sum",
		} {
			rec := get(h, target)
			body := rec.Body.String()
			if rec.Code != http.StatusNotFound || strings.Contains(body, "module ") || strings.Contains(body, "package boardwalk") {
				t.Fatalf("%s status=%d body=%.80s", target, rec.Code, body)
			}
		}
	})

	t.Run("index.html by name is the rewritten index", func(t *testing.T) {
		byName := get(h, testPrefix+"/index.html")
		root := get(h, testPrefix+"/")
		if byName.Code != http.StatusOK || byName.Body.String() != root.Body.String() {
			t.Fatalf("index.html differs from the root index")
		}
		if strings.Contains(byName.Body.String(), BaseToken) || byName.Header().Get("Cache-Control") != "no-store" {
			t.Fatalf("index.html served raw or cacheable: %v", byName.Header())
		}
	})

	t.Run("nested prefix with a trailing slash", func(t *testing.T) {
		nested, err := Handler("/ops/admin/", &apiSpy{})
		if err != nil {
			t.Fatal(err)
		}
		rec := get(nested, "/ops/admin/acme/demo/widgets/12")
		body := rec.Body.String()
		if rec.Code != http.StatusOK || !strings.Contains(body, `content="/ops/admin"`) || !strings.Contains(body, `src="/ops/admin/assets/`) {
			t.Fatalf("nested prefix index: %d %s", rec.Code, body)
		}
		if rec := get(nested, "/ops/admin/api/v1/x"); rec.Code != http.StatusNotFound || strings.Contains(rec.Body.String(), "<html") {
			t.Fatalf("nested prefix api not delegated: %d", rec.Code)
		}
	})

	t.Run("deep extensionless paths are client routes", func(t *testing.T) {
		for _, target := range []string{testPrefix + "/a/b/c/d/e/f", testPrefix + "/settings/mail", testPrefix + "/assets"} {
			rec := get(h, target)
			if rec.Code != http.StatusOK || !strings.Contains(rec.Body.String(), "summer-admin-base") {
				t.Fatalf("%s status=%d", target, rec.Code)
			}
		}
	})

	t.Run("unknown extensions fall back to the mime table, then octet-stream", func(t *testing.T) {
		root := fstest.MapFS{
			"index.html":         &fstest.MapFile{Data: []byte(`<meta content="` + BaseToken + `">`)},
			"robots.txt":         &fstest.MapFile{Data: []byte("User-agent: *\n")},
			"assets/logo.png":    &fstest.MapFile{Data: []byte("\x89PNG")},
			"assets/blob.zzzext": &fstest.MapFile{Data: []byte("x")},
		}
		mapped, err := newHandler(root, testPrefix, &apiSpy{})
		if err != nil {
			t.Fatal(err)
		}
		for target, want := range map[string]string{
			"/robots.txt":         "text/plain; charset=utf-8",
			"/assets/logo.png":    "image/png",
			"/assets/blob.zzzext": "application/octet-stream",
		} {
			rec := get(mapped, testPrefix+target)
			if rec.Code != http.StatusOK || rec.Header().Get("Content-Type") != want {
				t.Fatalf("%s type=%q, want %q", target, rec.Header().Get("Content-Type"), want)
			}
		}
		if cc := get(mapped, testPrefix+"/robots.txt").Header().Get("Cache-Control"); cc != "no-cache" {
			t.Fatalf("non-asset file Cache-Control=%q, want no-cache", cc)
		}
		if got := ContentType("UPPER.JS"); got != "text/javascript; charset=utf-8" {
			t.Fatalf("extension case: %q", got)
		}
	})

	t.Run("constructor rejects a nil API handler, a relative prefix and a build without index", func(t *testing.T) {
		if _, err := Handler(testPrefix, nil); err == nil {
			t.Fatal("nil notFoundAPI accepted")
		}
		if _, err := Handler("backend", &apiSpy{}); err == nil {
			t.Fatal("relative prefix accepted")
		}
		if _, err := newHandler(fstest.MapFS{}, testPrefix, &apiSpy{}); err == nil || !strings.Contains(err.Error(), "index.html") {
			t.Fatalf("missing index: %v", err)
		}
		stale := fstest.MapFS{"index.html": &fstest.MapFile{Data: []byte("<html></html>")}}
		if _, err := newHandler(stale, testPrefix, &apiSpy{}); err == nil || !strings.Contains(err.Error(), BaseToken) {
			t.Fatalf("stale index: %v", err)
		}
	})
}