package server

import (
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"log/slog"
	"mime"
	"mime/multipart"
	"net/http"
	"net/http/httptest"
	"net/url"
	"os"
	"path/filepath"
	"regexp"
	"slices"
	"strings"
	"testing"
	"time"

	"send/internal/auth"
	"send/internal/config"
	"send/internal/store"
)

// clock is the fixed instant tests start from; s.now is swapped so expiry can
// be exercised without sleeping.
var clock = time.Date(2026, 9, 12, 10, 0, 0, 0, time.UTC)

type harness struct {
	*Server
	ts    *httptest.Server
	dir   string
	now   time.Time
	token string // a token allowing vanity names
	admin string
}

func newHarness(t *testing.T, tweak func(*config.Config)) *harness {
	t.Helper()
	dir := t.TempDir()

	cfg := config.Config{}
	fs := config.NewSet("test", "SEND_TEST_")
	cfg.Register(fs)
	if err := fs.Parse(nil); err != nil {
		t.Fatal(err)
	}
	cfg.DataDir = dir
	cfg.MaxSize = 1 << 20
	cfg.MaxExpiry = 72 * time.Hour
	cfg.DefaultExpiry = 72 * time.Hour
	cfg.MinFreeBytes = 0
	cfg.UploadRate = 100000
	cfg.UploadBurst = 100000
	if tweak != nil {
		tweak(&cfg)
	}
	if err := cfg.Normalise(); err != nil {
		t.Fatal(err)
	}

	st, err := store.Open(cfg.DataDir)
	if err != nil {
		t.Fatal(err)
	}
	tokens, err := auth.Load(cfg.TokensPath)
	if err != nil {
		t.Fatal(err)
	}

	h := &harness{dir: dir, now: clock}
	for _, spec := range []struct {
		name  string
		admin bool
		dst   *string
	}{{"friend", false, &h.token}, {"boss", true, &h.admin}} {
		secret, err := store.NewSecret()
		if err != nil {
			t.Fatal(err)
		}
		if err := tokens.Add(&auth.Token{
			Name: spec.name, Hash: auth.HashSecret(secret),
			AllowVanity: true, Admin: spec.admin,
		}); err != nil {
			t.Fatal(err)
		}
		*spec.dst = secret
	}

	log := slog.New(slog.NewTextHandler(io.Discard, nil))
	srv, err := New(&cfg, st, tokens, log)
	if err != nil {
		t.Fatal(err)
	}
	srv.now = func() time.Time { return h.now }

	h.Server = srv
	h.ts = httptest.NewServer(srv)
	t.Cleanup(h.ts.Close)
	return h
}

// upload posts a raw body, the way curl does.
func (h *harness) upload(t *testing.T, body []byte, headers map[string]string) *http.Response {
	t.Helper()
	return h.uploadReader(t, bytes.NewReader(body), headers)
}

func (h *harness) uploadReader(t *testing.T, body io.Reader, headers map[string]string) *http.Response {
	t.Helper()
	req, err := http.NewRequest("POST", h.ts.URL+"/api/upload", body)
	if err != nil {
		t.Fatal(err)
	}
	req.Header.Set("Accept", "application/json")
	for k, v := range headers {
		req.Header.Set(k, v)
	}
	resp, err := h.ts.Client().Do(req)
	if err != nil {
		t.Fatal(err)
	}
	return resp
}

func decode[T any](t *testing.T, resp *http.Response) T {
	t.Helper()
	defer resp.Body.Close()
	var v T
	if err := json.NewDecoder(resp.Body).Decode(&v); err != nil {
		t.Fatalf("decoding %s response: %v", resp.Status, err)
	}
	return v
}

func TestRoundTrip(t *testing.T) {
	h := newHarness(t, nil)
	payload := bytes.Repeat([]byte("godot"), 4096)

	resp := h.upload(t, payload, map[string]string{
		"Content-Disposition": `attachment; filename="MyGame.zip"`,
	})
	if resp.StatusCode != http.StatusCreated {
		t.Fatalf("upload status = %s", resp.Status)
	}
	res := decode[uploadResult](t, resp)

	if res.Filename != "MyGame.zip" {
		t.Errorf("filename = %q, want MyGame.zip", res.Filename)
	}
	if res.Size != int64(len(payload)) {
		t.Errorf("size = %d, want %d", res.Size, len(payload))
	}
	if res.DeleteToken == "" {
		t.Error("no delete token returned")
	}

	get, err := h.ts.Client().Get(h.ts.URL + "/d/" + res.ID)
	if err != nil {
		t.Fatal(err)
	}
	defer get.Body.Close()
	got, _ := io.ReadAll(get.Body)
	if !bytes.Equal(got, payload) {
		t.Errorf("downloaded %d bytes, want %d", len(got), len(payload))
	}

	// An uploaded file must never come back as something a browser will run.
	if ct := get.Header.Get("Content-Type"); ct != "application/octet-stream" {
		t.Errorf("Content-Type = %q", ct)
	}
	if get.Header.Get("X-Content-Type-Options") != "nosniff" {
		t.Error("missing nosniff")
	}
	if !strings.Contains(get.Header.Get("Content-Security-Policy"), "sandbox") {
		t.Errorf("CSP = %q", get.Header.Get("Content-Security-Policy"))
	}
	disp, params, err := mime.ParseMediaType(get.Header.Get("Content-Disposition"))
	if err != nil || disp != "attachment" || params["filename"] != "MyGame.zip" {
		t.Errorf("Content-Disposition = %q (%v)", get.Header.Get("Content-Disposition"), err)
	}
}

func TestHTMLUploadIsServedInert(t *testing.T) {
	h := newHarness(t, nil)
	resp := h.upload(t, []byte("<script>alert(1)</script>"), map[string]string{
		"Content-Disposition": `attachment; filename="evil.html"`,
	})
	res := decode[uploadResult](t, resp)

	get, err := h.ts.Client().Get(h.ts.URL + "/d/" + res.ID)
	if err != nil {
		t.Fatal(err)
	}
	defer get.Body.Close()
	if ct := get.Header.Get("Content-Type"); ct != "application/octet-stream" {
		t.Errorf("HTML served as %q; it must never be text/html", ct)
	}
	if !strings.HasPrefix(get.Header.Get("Content-Disposition"), "attachment") {
		t.Error("HTML was not served as an attachment")
	}
}

func TestRangeRequest(t *testing.T) {
	h := newHarness(t, nil)
	payload := bytes.Repeat([]byte("abcdefgh"), 1024)
	res := decode[uploadResult](t, h.upload(t, payload, nil))

	req, _ := http.NewRequest("GET", h.ts.URL+"/d/"+res.ID, nil)
	req.Header.Set("Range", "bytes=0-1023")
	get, err := h.ts.Client().Do(req)
	if err != nil {
		t.Fatal(err)
	}
	defer get.Body.Close()
	if get.StatusCode != http.StatusPartialContent {
		t.Fatalf("status = %s, want 206", get.Status)
	}
	body, _ := io.ReadAll(get.Body)
	if len(body) != 1024 || !bytes.Equal(body, payload[:1024]) {
		t.Errorf("got %d bytes, want the first 1024", len(body))
	}
	if cr := get.Header.Get("Content-Range"); cr != fmt.Sprintf("bytes 0-1023/%d", len(payload)) {
		t.Errorf("Content-Range = %q", cr)
	}
}

// An oversized body must be refused on bytes actually written, never on a
// declared length. This sends a chunked body, so there is no Content-Length to
// consult even if the code wanted to.
func TestOversizeChunkedUploadIsRefused(t *testing.T) {
	h := newHarness(t, func(c *config.Config) { c.MaxSize = 4096 })

	// A plain io.Reader (not a *bytes.Buffer) makes the client use chunked
	// encoding with no declared length.
	body := io.LimitReader(zeroes{}, 1<<20)
	resp := h.uploadReader(t, struct{ io.Reader }{body}, nil)
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusRequestEntityTooLarge {
		t.Fatalf("status = %s, want 413", resp.Status)
	}
	if n := h.store.Count(); n != 0 {
		t.Errorf("%d objects stored after a refused upload", n)
	}
	assertNoDebris(t, h.dir)
}

// A body one byte over the cap is refused; exactly at the cap is accepted.
func TestSizeLimitBoundary(t *testing.T) {
	h := newHarness(t, func(c *config.Config) { c.MaxSize = 1000 })

	resp := h.upload(t, bytes.Repeat([]byte("x"), 1000), nil)
	if resp.StatusCode != http.StatusCreated {
		t.Fatalf("exactly at the limit: status = %s, want 201", resp.Status)
	}
	resp.Body.Close()

	resp = h.upload(t, bytes.Repeat([]byte("x"), 1001), nil)
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusRequestEntityTooLarge {
		t.Fatalf("one byte over: status = %s, want 413", resp.Status)
	}
}

type zeroes struct{}

func (zeroes) Read(p []byte) (int, error) { return len(p), nil }

func TestAnonymousCannotClaimVanity(t *testing.T) {
	h := newHarness(t, nil)
	resp := h.upload(t, []byte("hi"), map[string]string{"Vanity": "my-file"})
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusForbidden {
		t.Fatalf("status = %s, want 403", resp.Status)
	}
	if h.store.Exists("my-file") {
		t.Error("the name was claimed despite the refusal")
	}
}

func TestVanityCollision(t *testing.T) {
	h := newHarness(t, nil)
	hdr := map[string]string{
		"Vanity":        "my-file",
		"Authorization": "Bearer " + h.token,
	}
	resp := h.upload(t, []byte("first"), hdr)
	if resp.StatusCode != http.StatusCreated {
		t.Fatalf("first upload: status = %s", resp.Status)
	}
	resp.Body.Close()

	resp = h.upload(t, []byte("second"), hdr)
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusConflict {
		t.Fatalf("second upload: status = %s, want 409", resp.Status)
	}

	// The first object must be untouched.
	get, err := h.ts.Client().Get(h.ts.URL + "/d/my-file")
	if err != nil {
		t.Fatal(err)
	}
	defer get.Body.Close()
	body, _ := io.ReadAll(get.Body)
	if string(body) != "first" {
		t.Errorf("content = %q, want %q", body, "first")
	}
}

func TestUnknownTokenIsRejected(t *testing.T) {
	h := newHarness(t, nil)
	resp := h.upload(t, []byte("hi"), map[string]string{"Authorization": "Bearer nope"})
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusUnauthorized {
		t.Fatalf("status = %s, want 401", resp.Status)
	}
}

// Expiry is enforced on read, not only by the sweeper, which never runs here.
func TestExpiryIsCheckedOnRead(t *testing.T) {
	h := newHarness(t, nil)
	res := decode[uploadResult](t, h.upload(t, []byte("ephemeral"), map[string]string{
		"Expiry": "1h",
	}))

	status := func(when time.Duration) int {
		h.now = clock.Add(when)
		get, err := h.ts.Client().Get(h.ts.URL + "/d/" + res.ID)
		if err != nil {
			t.Fatal(err)
		}
		get.Body.Close()
		return get.StatusCode
	}

	if got := status(59 * time.Minute); got != http.StatusOK {
		t.Fatalf("before expiry: status = %d, want 200", got)
	}
	if got := status(61 * time.Minute); got != http.StatusNotFound {
		t.Fatalf("after expiry: status = %d, want 404", got)
	}
	// The read path also reclaims the space.
	if _, err := os.Stat(filepath.Join(h.dir, "objects", res.ID)); !os.IsNotExist(err) {
		t.Error("expired object was not removed on read")
	}
}

func TestExpiryBeyondLimitIsRefused(t *testing.T) {
	h := newHarness(t, nil) // max 72h for anonymous
	for _, req := range []string{"30d", "never"} {
		resp := h.upload(t, []byte("hi"), map[string]string{"Expiry": req})
		if resp.StatusCode != http.StatusBadRequest {
			t.Errorf("Expiry: %s => status %s, want 400", req, resp.Status)
		}
		resp.Body.Close()
	}
}

func TestTokenMayOutliveTheAnonymousLimit(t *testing.T) {
	h := newHarness(t, nil)
	forever := "never"
	if err := h.tokens.Remove("friend"); err != nil {
		t.Fatal(err)
	}
	secret, _ := store.NewSecret()
	if err := h.tokens.Add(&auth.Token{
		Name: "friend", Hash: auth.HashSecret(secret),
		MaxExpiry: &forever, DefaultExpiry: &forever, AllowVanity: true,
	}); err != nil {
		t.Fatal(err)
	}
	res := decode[uploadResult](t, h.upload(t, []byte("keep me"), map[string]string{
		"Authorization": "Bearer " + secret,
		"Expiry":        "never",
	}))
	if res.Expires != "" {
		t.Errorf("expires = %q, want empty (never)", res.Expires)
	}
}

func TestPathTraversalIsRejected(t *testing.T) {
	h := newHarness(t, nil)

	// As a requested vanity name.
	for _, name := range []string{"../etc/passwd", "..", ".", "/absolute", "a/b", `a\b`, "ok..name"} {
		resp := h.upload(t, []byte("x"), map[string]string{
			"Vanity":        name,
			"Authorization": "Bearer " + h.token,
		})
		if resp.StatusCode == http.StatusCreated {
			t.Errorf("vanity %q was accepted", name)
		}
		resp.Body.Close()
	}

	// As a download path. Some of these are normalised away into a redirect to
	// the index, which is harmless; what matters is that no stored bytes are
	// ever served, so the check is for an object response rather than a status.
	for _, path := range []string{
		"/d/..%2f..%2fetc%2fpasswd", "/d/.", "/d/..", "/d/%2e%2e",
		"/d/../tokens.json", "/d/%2e%2e%2ftokens.json", "/d/objects",
	} {
		get, err := h.ts.Client().Get(h.ts.URL + path)
		if err != nil {
			continue // the client itself may refuse to send it, which is fine
		}
		get.Body.Close()
		if get.Header.Get("Content-Disposition") != "" {
			t.Errorf("GET %s served an object", path)
		}
	}
}

func TestReservedNamesAreRejected(t *testing.T) {
	h := newHarness(t, nil)
	for _, name := range []string{"api", "static", "d", "i", "robots.txt"} {
		resp := h.upload(t, []byte("x"), map[string]string{
			"Vanity":        name,
			"Authorization": "Bearer " + h.token,
		})
		if resp.StatusCode != http.StatusBadRequest {
			t.Errorf("vanity %q => %s, want 400", name, resp.Status)
		}
		resp.Body.Close()
	}
}

func TestDeleteRequiresTheRightToken(t *testing.T) {
	h := newHarness(t, nil)
	res := decode[uploadResult](t, h.upload(t, []byte("delete me"), nil))

	del := func(token string) int {
		form := strings.NewReader("token=" + token)
		req, _ := http.NewRequest("POST", h.ts.URL+"/api/d/"+res.ID+"/delete", form)
		req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
		req.Header.Set("Accept", "application/json")
		resp, err := h.ts.Client().Do(req)
		if err != nil {
			t.Fatal(err)
		}
		resp.Body.Close()
		return resp.StatusCode
	}

	if got := del("wrong-token"); got != http.StatusForbidden {
		t.Errorf("wrong token => %d, want 403", got)
	}
	if got := del(h.token); got != http.StatusForbidden {
		t.Errorf("a non-owning, non-admin token => %d, want 403", got)
	}
	if got := del(res.DeleteToken); got != http.StatusOK {
		t.Errorf("correct token => %d, want 200", got)
	}
	// The token is single-use because the object it names is gone.
	if got := del(res.DeleteToken); got != http.StatusNotFound {
		t.Errorf("reused token => %d, want 404", got)
	}
	assertNoDebris(t, h.dir)
}

func TestAdminMayDeleteAnything(t *testing.T) {
	h := newHarness(t, nil)
	res := decode[uploadResult](t, h.upload(t, []byte("someone else's"), nil))

	req, _ := http.NewRequest("POST", h.ts.URL+"/api/d/"+res.ID+"/delete", nil)
	req.Header.Set("Authorization", "Bearer "+h.admin)
	req.Header.Set("Accept", "application/json")
	resp, err := h.ts.Client().Do(req)
	if err != nil {
		t.Fatal(err)
	}
	resp.Body.Close()
	if resp.StatusCode != http.StatusOK {
		t.Fatalf("admin delete => %s, want 200", resp.Status)
	}
}

func TestMultipartUpload(t *testing.T) {
	h := newHarness(t, nil)

	var body bytes.Buffer
	mw := multipart.NewWriter(&body)
	// Order matters: the server needs these before the file part arrives.
	mw.WriteField("token", h.token)
	mw.WriteField("expiry", "2h")
	mw.WriteField("vanity", "from-the-form")
	fw, err := mw.CreateFormFile("file", "notes (draft).txt")
	if err != nil {
		t.Fatal(err)
	}
	fw.Write([]byte("hello from a browser"))
	mw.Close()

	req, _ := http.NewRequest("POST", h.ts.URL+"/api/upload", &body)
	req.Header.Set("Content-Type", mw.FormDataContentType())
	req.Header.Set("Accept", "application/json")
	resp, err := h.ts.Client().Do(req)
	if err != nil {
		t.Fatal(err)
	}
	if resp.StatusCode != http.StatusCreated {
		t.Fatalf("status = %s", resp.Status)
	}
	res := decode[uploadResult](t, resp)
	if res.ID != "from-the-form" {
		t.Errorf("id = %q, want from-the-form", res.ID)
	}
	if res.Filename != "notes (draft).txt" {
		t.Errorf("filename = %q", res.Filename)
	}
}

// A form post with no Accept: application/json gets the HTML success page, so
// the no-JS path works.
func TestFormPostRendersHTML(t *testing.T) {
	h := newHarness(t, nil)
	var body bytes.Buffer
	mw := multipart.NewWriter(&body)
	fw, _ := mw.CreateFormFile("file", "thing.bin")
	fw.Write([]byte("data"))
	mw.Close()

	req, _ := http.NewRequest("POST", h.ts.URL+"/api/upload", &body)
	req.Header.Set("Content-Type", mw.FormDataContentType())
	req.Header.Set("Accept", "text/html,application/xhtml+xml")
	resp, err := h.ts.Client().Do(req)
	if err != nil {
		t.Fatal(err)
	}
	defer resp.Body.Close()
	if ct := resp.Header.Get("Content-Type"); !strings.HasPrefix(ct, "text/html") {
		t.Fatalf("Content-Type = %q, want HTML", ct)
	}
	page, _ := io.ReadAll(resp.Body)
	if !strings.Contains(string(page), "Delete token") {
		t.Error("the success page does not show the delete token")
	}
}

func TestBasePathMounting(t *testing.T) {
	h := newHarness(t, func(c *config.Config) { c.BasePath = "/send" })

	get, err := h.ts.Client().Get(h.ts.URL + "/send/")
	if err != nil {
		t.Fatal(err)
	}
	defer get.Body.Close()
	if get.StatusCode != http.StatusOK {
		t.Fatalf("GET /send/ => %s", get.Status)
	}
	page, _ := io.ReadAll(get.Body)
	if !strings.Contains(string(page), `href="/send/static/style.css"`) {
		t.Error("page links do not carry the base path")
	}

	// The bare prefix redirects to the slashed form.
	noRedirect := *h.ts.Client()
	noRedirect.CheckRedirect = func(*http.Request, []*http.Request) error {
		return http.ErrUseLastResponse
	}
	resp, err := noRedirect.Get(h.ts.URL + "/send")
	if err != nil {
		t.Fatal(err)
	}
	resp.Body.Close()
	if resp.StatusCode != http.StatusMovedPermanently {
		t.Errorf("GET /send => %s, want 301", resp.Status)
	}
}

// An upload that dies mid-flight must leave nothing visible behind, and the
// sweeper must eventually reclaim the directory.
func TestAbandonedUploadIsInvisibleAndSwept(t *testing.T) {
	h := newHarness(t, nil)

	up, err := h.store.Reserve("half-done")
	if err != nil {
		t.Fatal(err)
	}
	up.Write([]byte("partial"))
	// Deliberately no Commit and no Abort: this is what a killed process leaves.

	get, err := h.ts.Client().Get(h.ts.URL + "/d/half-done")
	if err != nil {
		t.Fatal(err)
	}
	get.Body.Close()
	if get.StatusCode != http.StatusNotFound {
		t.Errorf("an uncommitted object was visible: %s", get.Status)
	}

	dir := filepath.Join(h.dir, "objects", "half-done")
	old := clock.Add(-48 * time.Hour)
	if err := os.Chtimes(dir, old, old); err != nil {
		t.Fatal(err)
	}
	h.store.Sweep(clock)
	if _, err := os.Stat(dir); !os.IsNotExist(err) {
		t.Error("abandoned upload directory was not swept")
	}
}

func TestQuotaRefusesUploads(t *testing.T) {
	h := newHarness(t, func(c *config.Config) { c.MaxTotalBytes = 100 })

	resp := h.upload(t, bytes.Repeat([]byte("x"), 80), nil)
	if resp.StatusCode != http.StatusCreated {
		t.Fatalf("first upload => %s", resp.Status)
	}
	resp.Body.Close()

	// Only 20 bytes of quota remain, so this is truncated to the remainder and
	// refused rather than allowed to overshoot.
	resp = h.upload(t, bytes.Repeat([]byte("x"), 80), nil)
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusRequestEntityTooLarge {
		t.Fatalf("over quota => %s, want 413", resp.Status)
	}
}

func TestRateLimit(t *testing.T) {
	h := newHarness(t, func(c *config.Config) {
		c.UploadRate = 1
		c.UploadBurst = 2
	})
	var last *http.Response
	for range 3 {
		if last != nil {
			last.Body.Close()
		}
		last = h.upload(t, []byte("x"), nil)
	}
	defer last.Body.Close()
	if last.StatusCode != http.StatusTooManyRequests {
		t.Fatalf("third upload => %s, want 429", last.Status)
	}
}

// assertNoDebris checks that no object directory was left behind.
func assertNoDebris(t *testing.T, dir string) {
	t.Helper()
	entries, err := os.ReadDir(filepath.Join(dir, "objects"))
	if err != nil {
		t.Fatal(err)
	}
	for _, e := range entries {
		t.Errorf("leftover object directory: %s", e.Name())
	}
}

// --- remembered tokens ---------------------------------------------------

// Logging in is what stores a token; uploading never touches the cookie.
func TestLoginStoresTheToken(t *testing.T) {
	h := newHarness(t, nil)

	resp := h.postForm(t, "/login", url.Values{"token": {h.token}, "persist": {"1"}}, nil)
	resp.Body.Close()
	if resp.StatusCode != http.StatusSeeOther {
		t.Fatalf("status = %s, want 303", resp.Status)
	}
	if loc := resp.Header.Get("Location"); loc != "/" {
		t.Errorf("Location = %q, want /", loc)
	}

	cookie := findCookie(resp, tokenCookie)
	if cookie == nil {
		t.Fatal("logging in set no cookie")
	}
	if cookie.Value != h.token {
		t.Error("the cookie does not hold the token")
	}
	if !cookie.HttpOnly {
		t.Error("the session cookie is readable by scripts")
	}
	if cookie.SameSite != http.SameSiteStrictMode {
		t.Error("the session cookie is not SameSite=Strict, so it is CSRF-exposed")
	}
	if cookie.MaxAge <= 0 {
		t.Error("'stay logged in' did not persist the cookie")
	}

	// The session alone is now enough to claim a custom name.
	req, _ := http.NewRequest("POST", h.ts.URL+"/api/upload", strings.NewReader("two"))
	req.Header.Set("Accept", "application/json")
	req.Header.Set("Vanity", "session-upload")
	req.AddCookie(cookie)
	up, err := h.ts.Client().Do(req)
	if err != nil {
		t.Fatal(err)
	}
	if up.StatusCode != http.StatusCreated {
		t.Fatalf("upload with only the session: status = %s", up.Status)
	}
	if res := decode[uploadResult](t, up); res.ID != "session-upload" {
		t.Errorf("id = %q, want session-upload", res.ID)
	}
}

// Without "stay logged in" the cookie must die with the browser.
func TestLoginWithoutPersistIsASessionCookie(t *testing.T) {
	h := newHarness(t, nil)
	resp := h.postForm(t, "/login", url.Values{"token": {h.token}}, nil)
	resp.Body.Close()
	c := findCookie(resp, tokenCookie)
	if c == nil {
		t.Fatal("no cookie was set")
	}
	if c.MaxAge != 0 || !c.Expires.IsZero() {
		t.Errorf("cookie carries a lifetime (MaxAge=%d), want a session cookie", c.MaxAge)
	}
}

func TestLoginRejectsAnUnknownToken(t *testing.T) {
	h := newHarness(t, nil)
	resp := h.postForm(t, "/login", url.Values{"token": {"not-a-token"}}, nil)
	raw, _ := io.ReadAll(resp.Body)
	resp.Body.Close()

	if resp.StatusCode != http.StatusUnauthorized {
		t.Fatalf("status = %s, want 401", resp.Status)
	}
	if findCookie(resp, tokenCookie) != nil {
		t.Error("a rejected login still set a cookie")
	}
	if !strings.Contains(string(raw), "not recognised") {
		t.Error("the login page does not say what went wrong")
	}
}

// Guessing a token at the login form is throttled; a correct one is not.
func TestFailedLoginsAreThrottled(t *testing.T) {
	h := newHarness(t, nil)
	h.authLimiter = newLimiter(1, 3)

	var last *http.Response
	for range 5 {
		if last != nil {
			last.Body.Close()
		}
		last = h.postForm(t, "/login", url.Values{"token": {"guess"}}, nil)
	}
	if last.StatusCode != http.StatusTooManyRequests {
		t.Fatalf("repeated guesses => %s, want 429", last.Status)
	}
	last.Body.Close()

	resp := h.postForm(t, "/login", url.Values{"token": {h.token}}, nil)
	resp.Body.Close()
	if resp.StatusCode != http.StatusSeeOther {
		t.Fatalf("a correct token was throttled: %s", resp.Status)
	}
}

// The post-login destination is an allowlisted page name, never a URL, so it
// cannot be turned into an open redirect.
func TestLoginRedirectIsAllowlisted(t *testing.T) {
	h := newHarness(t, nil)
	for _, c := range []struct{ next, want string }{
		{"admin", "/admin"},
		{"", "/"},
		{"https://evil.example.com", "/"},
		{"//evil.example.com", "/"},
		{"../../etc", "/"},
	} {
		resp := h.postForm(t, "/login", url.Values{"token": {h.admin}, "next": {c.next}}, nil)
		resp.Body.Close()
		if loc := resp.Header.Get("Location"); loc != c.want {
			t.Errorf("next=%q => Location %q, want %q", c.next, loc, c.want)
		}
	}
}

func TestLogoutEndsTheSession(t *testing.T) {
	h := newHarness(t, nil)
	resp := h.postForm(t, "/logout", url.Values{}, &http.Cookie{Name: tokenCookie, Value: h.token})
	resp.Body.Close()

	if resp.StatusCode != http.StatusSeeOther {
		t.Fatalf("status = %s, want 303", resp.Status)
	}
	c := findCookie(resp, tokenCookie)
	if c == nil || c.MaxAge >= 0 || c.Value != "" {
		t.Fatalf("the session cookie was not cleared: %v", c)
	}
}

// Uploading must never change the session, in either direction.
func TestUploadNeverTouchesTheSession(t *testing.T) {
	h := newHarness(t, nil)

	resp := h.formUpload(t, map[string]string{"token": h.token}, "a.bin", "one")
	resp.Body.Close()
	if c := findCookie(resp, tokenCookie); c != nil {
		t.Errorf("an upload with a one-off token set a session cookie: %v", c)
	}

	resp = h.formUploadWith(t, &http.Cookie{Name: tokenCookie, Value: h.token},
		map[string]string{}, "b.bin", "two")
	resp.Body.Close()
	if c := findCookie(resp, tokenCookie); c != nil {
		t.Errorf("an upload cleared the session: %v", c)
	}
}

// A one-off token on the form wins over the logged-in session.
func TestExplicitTokenBeatsTheCookie(t *testing.T) {
	h := newHarness(t, nil)
	cookie := &http.Cookie{Name: tokenCookie, Value: h.token}

	resp := h.formUploadWith(t, cookie, map[string]string{"token": h.admin}, "b.bin", "y")
	defer resp.Body.Close()
	res := decode[uploadResult](t, resp)

	m, err := h.store.Get(res.ID, h.now)
	if err != nil {
		t.Fatal(err)
	}
	if m.Owner != "boss" {
		t.Errorf("owner = %q, want boss: the session shadowed the one-off token", m.Owner)
	}
}

// A session whose token has since been revoked must not wedge the page.
func TestStaleCookieIsDropped(t *testing.T) {
	h := newHarness(t, nil)
	req, _ := http.NewRequest("GET", h.ts.URL+"/", nil)
	req.AddCookie(&http.Cookie{Name: tokenCookie, Value: "a-token-that-was-revoked"})
	resp, err := h.ts.Client().Do(req)
	if err != nil {
		t.Fatal(err)
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusOK {
		t.Fatalf("status = %s, want the page to still render", resp.Status)
	}
	if c := findCookie(resp, tokenCookie); c == nil || c.MaxAge >= 0 {
		t.Error("a stale cookie was not dropped")
	}
	page, _ := io.ReadAll(resp.Body)
	if !strings.Contains(string(page), "no longer valid") {
		t.Error("the page does not explain that the session ended")
	}
	if !strings.Contains(string(page), "<em>anonymous</em>") {
		t.Error("the page claims an identity it could not resolve")
	}
}

// The session is resolved server-side, so every page agrees about who you are
// even though the cookie is unreadable by script.
func TestIndexShowsWhoIsLoggedIn(t *testing.T) {
	h := newHarness(t, nil)
	req, _ := http.NewRequest("GET", h.ts.URL+"/", nil)
	req.AddCookie(&http.Cookie{Name: tokenCookie, Value: h.token})
	resp, err := h.ts.Client().Do(req)
	if err != nil {
		t.Fatal(err)
	}
	defer resp.Body.Close()
	page, _ := io.ReadAll(resp.Body)
	if !strings.Contains(string(page), ">friend<") {
		t.Error("the page does not show who is logged in")
	}
	if strings.Contains(string(page), h.token) {
		t.Error("the page echoes the token back into the HTML")
	}
}

// The per-object delete token must still work when a cookie is also present.
func TestCookieDoesNotShadowTheDeleteToken(t *testing.T) {
	h := newHarness(t, nil)
	// Uploaded anonymously, so the logged-in token owns nothing here.
	res := decode[uploadResult](t, h.upload(t, []byte("x"), nil))

	form := strings.NewReader("token=" + res.DeleteToken)
	req, _ := http.NewRequest("POST", h.ts.URL+"/api/d/"+res.ID+"/delete", form)
	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	req.Header.Set("Accept", "application/json")
	req.AddCookie(&http.Cookie{Name: tokenCookie, Value: h.token})
	resp, err := h.ts.Client().Do(req)
	if err != nil {
		t.Fatal(err)
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusOK {
		t.Fatalf("status = %s, want 200: the cookie shadowed the delete token", resp.Status)
	}
}

func findCookie(resp *http.Response, name string) *http.Cookie {
	for _, c := range resp.Cookies() {
		if c.Name == name {
			return c
		}
	}
	return nil
}

// formUpload posts the multipart form the browser would, with fields ordered
// ahead of the file part.
func (h *harness) formUpload(t *testing.T, fields map[string]string, filename, content string) *http.Response {
	t.Helper()
	return h.formUploadWith(t, nil, fields, filename, content)
}

func (h *harness) formUploadWith(t *testing.T, cookie *http.Cookie, fields map[string]string, filename, content string) *http.Response {
	t.Helper()
	var body bytes.Buffer
	mw := multipart.NewWriter(&body)
	for k, v := range fields {
		mw.WriteField(k, v)
	}
	fw, err := mw.CreateFormFile("file", filename)
	if err != nil {
		t.Fatal(err)
	}
	fw.Write([]byte(content))
	mw.Close()

	req, _ := http.NewRequest("POST", h.ts.URL+"/api/upload", &body)
	req.Header.Set("Content-Type", mw.FormDataContentType())
	req.Header.Set("Accept", "application/json")
	if cookie != nil {
		req.AddCookie(cookie)
	}
	resp, err := h.ts.Client().Do(req)
	if err != nil {
		t.Fatal(err)
	}
	return resp
}

// --- content security policy ---------------------------------------------

// The page's own behaviour and its CSP have to agree, and nothing in a Go test
// or a curl invocation enforces CSP — only a browser does. This reads the
// script that is actually shipped, works out which fetch directives the page
// needs, and checks the policy grants them.
//
// It exists because omitting connect-src once made the browser block every
// upload while every server-side test still passed.
func TestAppCSPAllowsWhatThePageDoes(t *testing.T) {
	h := newHarness(t, nil)

	resp, err := h.ts.Client().Get(h.ts.URL + "/static/app.js")
	if err != nil {
		t.Fatal(err)
	}
	defer resp.Body.Close()
	script, err := io.ReadAll(resp.Body)
	if err != nil {
		t.Fatal(err)
	}

	// Which directive each capability the script might use depends on. Every
	// fetch directive falls back to default-src when unlisted, and default-src
	// here is 'none', so anything the script does must be granted explicitly.
	needs := []struct {
		directive string
		used      bool
		because   string
	}{
		{"connect-src", bytes.Contains(script, []byte("XMLHttpRequest")) ||
			bytes.Contains(script, []byte("fetch(")), "the page makes XHR or fetch calls"},
		{"script-src", true, "the page loads an external script"},
		{"style-src", true, "the page loads an external stylesheet"},
		{"form-action", true, "the page posts a form"},
	}

	page, err := h.ts.Client().Get(h.ts.URL + "/")
	if err != nil {
		t.Fatal(err)
	}
	page.Body.Close()
	csp := page.Header.Get("Content-Security-Policy")
	if csp == "" {
		t.Fatal("the upload page carries no Content-Security-Policy")
	}

	directives := map[string]string{}
	for _, d := range strings.Split(csp, ";") {
		name, value, _ := strings.Cut(strings.TrimSpace(d), " ")
		directives[strings.ToLower(name)] = strings.TrimSpace(value)
	}
	if directives["default-src"] != "'none'" {
		t.Errorf("default-src = %q, want 'none': the checks below assume it denies by default",
			directives["default-src"])
	}

	for _, n := range needs {
		if !n.used {
			continue
		}
		value, ok := directives[n.directive]
		if !ok {
			t.Errorf("CSP has no %s, but %s; the browser will fall back to default-src and block it",
				n.directive, n.because)
			continue
		}
		if !strings.Contains(value, "'self'") {
			t.Errorf("CSP %s = %q, which does not allow this origin, but %s",
				n.directive, value, n.because)
		}
	}
}

// The download policy is the opposite case: it must stay maximally restrictive,
// since it governs bytes a stranger uploaded.
func TestDownloadCSPStaysInert(t *testing.T) {
	h := newHarness(t, nil)
	res := decode[uploadResult](t, h.upload(t, []byte("<script>alert(1)</script>"), nil))

	get, err := h.ts.Client().Get(h.ts.URL + "/d/" + res.ID)
	if err != nil {
		t.Fatal(err)
	}
	get.Body.Close()

	csp := get.Header.Get("Content-Security-Policy")
	if !strings.Contains(csp, "default-src 'none'") || !strings.Contains(csp, "sandbox") {
		t.Errorf("download CSP = %q, want default-src 'none' and sandbox", csp)
	}
	for _, forbidden := range []string{"connect-src", "script-src 'self'", "'unsafe-inline'"} {
		if strings.Contains(csp, forbidden) {
			t.Errorf("download CSP contains %q; uploaded bytes must be granted nothing", forbidden)
		}
	}
}

// The result page is the only place a link to the info page is ever offered,
// so losing it strands that page with no way to discover it.
func TestResultPageOffersBothLinksAndAWayBack(t *testing.T) {
	h := newHarness(t, nil)

	var body bytes.Buffer
	mw := multipart.NewWriter(&body)
	fw, _ := mw.CreateFormFile("file", "thing.bin")
	fw.Write([]byte("data"))
	mw.Close()

	req, _ := http.NewRequest("POST", h.ts.URL+"/api/upload", &body)
	req.Header.Set("Content-Type", mw.FormDataContentType())
	req.Header.Set("Accept", "text/html")
	resp, err := h.ts.Client().Do(req)
	if err != nil {
		t.Fatal(err)
	}
	defer resp.Body.Close()
	raw, _ := io.ReadAll(resp.Body)
	page := string(raw)

	id := h.store.List()[0].ID
	for _, want := range []struct{ what, fragment string }{
		{"the info page link", "/i/" + id},
		{"the direct download link", "/d/" + id},
		{"a way to upload another file", `href="/">Upload another file`},
		{"the script that enables the copy buttons", "static/app.js"},
	} {
		if !strings.Contains(page, want.fragment) {
			t.Errorf("the result page is missing %s (%q)", want.what, want.fragment)
		}
	}

	// Copy buttons ship hidden, so a reader without JavaScript never sees a
	// button that does nothing.
	if strings.Count(page, `class="copy"`) != strings.Count(page, `hidden>Copy<`) {
		t.Error("a copy button is not hidden by default")
	}
}

// The JSON reply has to carry the same two links, since the script builds the
// result card from it alone.
func TestUploadJSONCarriesBothLinks(t *testing.T) {
	h := newHarness(t, nil)
	res := decode[uploadResult](t, h.upload(t, []byte("x"), nil))

	if res.URL == "" || !strings.Contains(res.URL, "/d/"+res.ID) {
		t.Errorf("url = %q, want the direct download", res.URL)
	}
	if res.InfoURL == "" || !strings.Contains(res.InfoURL, "/i/"+res.ID) {
		t.Errorf("info_url = %q, want the info page", res.InfoURL)
	}
	// Both must actually resolve.
	for _, u := range []string{res.URL, res.InfoURL} {
		get, err := h.ts.Client().Get(u)
		if err != nil {
			t.Fatal(err)
		}
		get.Body.Close()
		if get.StatusCode != http.StatusOK {
			t.Errorf("GET %s => %s", u, get.Status)
		}
	}
}

// --- administration ------------------------------------------------------

func (h *harness) get(t *testing.T, path, token string) *http.Response {
	t.Helper()
	req, _ := http.NewRequest("GET", h.ts.URL+path, nil)
	if token != "" {
		req.Header.Set("Authorization", "Bearer "+token)
	}
	resp, err := h.ts.Client().Do(req)
	if err != nil {
		t.Fatal(err)
	}
	return resp
}

// The admin page shows every stored file, so who may open it is the whole
// security story for this feature.
func TestAdminPageAccessControl(t *testing.T) {
	h := newHarness(t, nil)
	cases := []struct {
		who   string
		token string
		want  int
	}{
		{"anonymous", "", http.StatusUnauthorized},
		{"an unknown token", "not-a-token", http.StatusUnauthorized},
		{"a non-admin token", h.token, http.StatusForbidden},
		{"an admin token", h.admin, http.StatusOK},
	}
	for _, c := range cases {
		resp := h.get(t, "/admin", c.token)
		resp.Body.Close()
		if resp.StatusCode != c.want {
			t.Errorf("GET /admin as %s => %s, want %d", c.who, resp.Status, c.want)
		}
	}
}

// The cookie is the credential a browser actually uses for this page.
func TestAdminPageAcceptsTheSession(t *testing.T) {
	h := newHarness(t, nil)
	req, _ := http.NewRequest("GET", h.ts.URL+"/admin", nil)
	req.AddCookie(&http.Cookie{Name: tokenCookie, Value: h.admin})
	resp, err := h.ts.Client().Do(req)
	if err != nil {
		t.Fatal(err)
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusOK {
		t.Fatalf("GET /admin with an admin cookie => %s", resp.Status)
	}
}

func TestAdminPageListsEveryoneAndHidesExpired(t *testing.T) {
	h := newHarness(t, nil)

	// One anonymous, one owned, one that will have expired by the time the
	// page is rendered.
	h.upload(t, []byte("anon"), map[string]string{
		"Content-Disposition": `attachment; filename="anonymous.bin"`}).Body.Close()
	h.upload(t, []byte("owned"), map[string]string{
		"Authorization":       "Bearer " + h.token,
		"Vanity":              "friends-file",
		"Content-Disposition": `attachment; filename="owned.bin"`}).Body.Close()
	h.upload(t, []byte("gone"), map[string]string{
		"Expiry":              "1h",
		"Content-Disposition": `attachment; filename="expired.bin"`}).Body.Close()

	h.now = clock.Add(2 * time.Hour)
	resp := h.get(t, "/admin", h.admin)
	defer resp.Body.Close()
	raw, _ := io.ReadAll(resp.Body)
	page := string(raw)

	for _, want := range []string{"anonymous.bin", "owned.bin", "friends-file", "friend"} {
		if !strings.Contains(page, want) {
			t.Errorf("the admin page does not list %q", want)
		}
	}
	if strings.Contains(page, "expired.bin") {
		t.Error("the admin page lists an expired file as though it were still stored")
	}
	// Token names and limits are shown; nothing secret is.
	if !strings.Contains(page, "boss") {
		t.Error("the token table does not list the tokens")
	}
	for _, secret := range []string{h.admin, h.token} {
		if strings.Contains(page, secret) {
			t.Error("the admin page echoes a token secret")
		}
		if strings.Contains(page, auth.HashSecret(secret)) {
			t.Error("the admin page exposes a token hash")
		}
	}
}

func TestAdminSortIsRestrictedToKnownColumns(t *testing.T) {
	h := newHarness(t, nil)
	h.upload(t, []byte("x"), nil).Body.Close()

	for _, sort := range []string{"size", "created", "expires", "name", "owner", "", "../../etc", "nonsense"} {
		resp := h.get(t, "/admin?sort="+url.QueryEscape(sort), h.admin)
		resp.Body.Close()
		if resp.StatusCode != http.StatusOK {
			t.Errorf("sort=%q => %s", sort, resp.Status)
		}
	}
}

// Deleting from the table returns to the table rather than to a dead end.
func TestAdminDeleteReturnsToTheTable(t *testing.T) {
	h := newHarness(t, nil)
	res := decode[uploadResult](t, h.upload(t, []byte("someone else's"), nil))

	client := *h.ts.Client()
	client.CheckRedirect = func(*http.Request, []*http.Request) error { return http.ErrUseLastResponse }

	form := strings.NewReader("from=admin")
	req, _ := http.NewRequest("POST", h.ts.URL+"/api/d/"+res.ID+"/delete", form)
	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	req.Header.Set("Accept", "text/html")
	req.AddCookie(&http.Cookie{Name: tokenCookie, Value: h.admin})
	resp, err := client.Do(req)
	if err != nil {
		t.Fatal(err)
	}
	resp.Body.Close()

	if resp.StatusCode != http.StatusSeeOther {
		t.Fatalf("status = %s, want 303", resp.Status)
	}
	if loc := resp.Header.Get("Location"); loc != "/admin" {
		t.Errorf("Location = %q, want /admin", loc)
	}
	if _, err := h.store.Get(res.ID, h.now); err == nil {
		t.Error("the file was not deleted")
	}
}

// A non-admin must not be able to delete someone else's file from that form.
func TestAdminDeleteStillRequiresAdmin(t *testing.T) {
	h := newHarness(t, nil)
	res := decode[uploadResult](t, h.upload(t, []byte("not yours"), nil))

	form := strings.NewReader("from=admin")
	req, _ := http.NewRequest("POST", h.ts.URL+"/api/d/"+res.ID+"/delete", form)
	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	req.Header.Set("Accept", "application/json")
	req.AddCookie(&http.Cookie{Name: tokenCookie, Value: h.token})
	resp, err := h.ts.Client().Do(req)
	if err != nil {
		t.Fatal(err)
	}
	resp.Body.Close()
	if resp.StatusCode != http.StatusForbidden {
		t.Fatalf("status = %s, want 403", resp.Status)
	}
}

// The header link is the only way to discover the page, so it must appear for
// an admin and never for anyone else.
func TestAdminLinkIsShownOnlyToAdmins(t *testing.T) {
	h := newHarness(t, nil)
	for _, c := range []struct {
		who   string
		token string
		want  bool
	}{
		{"anonymous", "", false},
		{"a non-admin token", h.token, false},
		{"an admin token", h.admin, true},
	} {
		req, _ := http.NewRequest("GET", h.ts.URL+"/", nil)
		if c.token != "" {
			req.AddCookie(&http.Cookie{Name: tokenCookie, Value: c.token})
		}
		resp, err := h.ts.Client().Do(req)
		if err != nil {
			t.Fatal(err)
		}
		raw, _ := io.ReadAll(resp.Body)
		resp.Body.Close()
		if got := strings.Contains(string(raw), `href="/admin"`); got != c.want {
			t.Errorf("admin link shown to %s = %v, want %v", c.who, got, c.want)
		}
	}
}

// Mixing the two request shapes — a multipart body with the headers the raw
// shape uses — must not silently discard the options. Being handed a UUID when
// you asked for a name is worse than being told no.
func TestMultipartHonoursTheHeaderForm(t *testing.T) {
	h := newHarness(t, nil)

	var body bytes.Buffer
	mw := multipart.NewWriter(&body)
	fw, _ := mw.CreateFormFile("file", "build.zip")
	fw.Write([]byte("payload"))
	mw.Close()

	req, _ := http.NewRequest("POST", h.ts.URL+"/api/upload", &body)
	req.Header.Set("Content-Type", mw.FormDataContentType())
	req.Header.Set("Accept", "application/json")
	req.Header.Set("Authorization", "Bearer "+h.token)
	req.Header.Set("Vanity", "friends-build")
	req.Header.Set("Expiry", "1h")
	resp, err := h.ts.Client().Do(req)
	if err != nil {
		t.Fatal(err)
	}
	if resp.StatusCode != http.StatusCreated {
		t.Fatalf("status = %s", resp.Status)
	}
	res := decode[uploadResult](t, resp)
	if res.ID != "friends-build" {
		t.Errorf("id = %q, want friends-build: the Vanity header was ignored", res.ID)
	}
	if want := clock.Add(time.Hour).UTC().Format(time.RFC3339); res.Expires != want {
		t.Errorf("expires = %q, want %q: the Expiry header was ignored", res.Expires, want)
	}
}

// A form field still wins, so the browser's own controls stay authoritative.
func TestFormFieldsOverrideTheHeaders(t *testing.T) {
	h := newHarness(t, nil)

	var body bytes.Buffer
	mw := multipart.NewWriter(&body)
	mw.WriteField("vanity", "from-the-form")
	mw.WriteField("expiry", "")
	fw, _ := mw.CreateFormFile("file", "build.zip")
	fw.Write([]byte("payload"))
	mw.Close()

	req, _ := http.NewRequest("POST", h.ts.URL+"/api/upload", &body)
	req.Header.Set("Content-Type", mw.FormDataContentType())
	req.Header.Set("Accept", "application/json")
	req.Header.Set("Authorization", "Bearer "+h.token)
	req.Header.Set("Vanity", "from-the-header")
	resp, err := h.ts.Client().Do(req)
	if err != nil {
		t.Fatal(err)
	}
	res := decode[uploadResult](t, resp)
	if res.ID != "from-the-form" {
		t.Errorf("id = %q, want the form field to win", res.ID)
	}
}

// --- deleting from the info page -----------------------------------------

// postForm submits a form the way a browser would, without following the
// redirect: where these posts send you, and what they set on the way, is
// usually the thing under test.
func (h *harness) postForm(t *testing.T, path string, form url.Values, cookie *http.Cookie) *http.Response {
	t.Helper()
	req, _ := http.NewRequest("POST", h.ts.URL+path, strings.NewReader(form.Encode()))
	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	req.Header.Set("Accept", "text/html")
	if cookie != nil {
		req.AddCookie(cookie)
	}
	client := *h.ts.Client()
	client.CheckRedirect = func(*http.Request, []*http.Request) error {
		return http.ErrUseLastResponse
	}
	resp, err := client.Do(req)
	if err != nil {
		t.Fatal(err)
	}
	return resp
}

// The delete token is shown once and then has to be usable somewhere. The info
// page is the link an uploader would have kept, so the form lives there.
func TestInfoPageAcceptsTheDeleteToken(t *testing.T) {
	h := newHarness(t, nil)
	res := decode[uploadResult](t, h.upload(t, []byte("x"), nil))

	info := h.get(t, "/i/"+res.ID, "")
	raw, _ := io.ReadAll(info.Body)
	info.Body.Close()
	page := string(raw)

	if !strings.Contains(page, "Remove this file") {
		t.Error("the info page offers no way to use a delete token")
	}
	if !strings.Contains(page, `name="token"`) {
		t.Error("the info page has no field for the delete token")
	}
	if strings.Contains(page, res.DeleteToken) {
		t.Fatal("the info page leaks the delete token to anyone holding the link")
	}

	resp := h.postForm(t, "/api/d/"+res.ID+"/delete",
		url.Values{"from": {"info"}, "token": {res.DeleteToken}}, nil)
	resp.Body.Close()
	if resp.StatusCode != http.StatusOK {
		t.Fatalf("deleting with the right token => %s", resp.Status)
	}
	if _, err := h.store.Get(res.ID, h.now); err == nil {
		t.Error("the file was not deleted")
	}
}

// A mistyped token must land back on the file's page with the reason, not on a
// generic error page that has thrown the form away.
func TestWrongDeleteTokenReturnsToTheInfoPage(t *testing.T) {
	h := newHarness(t, nil)
	res := decode[uploadResult](t, h.upload(t, []byte("x"), map[string]string{
		"Content-Disposition": `attachment; filename="keepme.bin"`}))

	resp := h.postForm(t, "/api/d/"+res.ID+"/delete",
		url.Values{"from": {"info"}, "token": {"wrong"}}, nil)
	raw, _ := io.ReadAll(resp.Body)
	resp.Body.Close()
	page := string(raw)

	if resp.StatusCode != http.StatusForbidden {
		t.Errorf("status = %s, want 403", resp.Status)
	}
	if !strings.Contains(page, "keepme.bin") {
		t.Error("the response is not the file's own page")
	}
	if !strings.Contains(page, "not correct") {
		t.Error("the page does not say what went wrong")
	}
	if !strings.Contains(page, "<details open>") {
		t.Error("the delete section is collapsed, hiding the error")
	}
	if _, err := h.store.Get(res.ID, h.now); err != nil {
		t.Error("the file was deleted despite a wrong token")
	}
}

// Someone whose own token already authorises removal gets a button, not a
// field asking for a token they do not have.
func TestInfoPageOffersADirectButtonToAnOwner(t *testing.T) {
	h := newHarness(t, nil)
	res := decode[uploadResult](t, h.upload(t, []byte("x"), map[string]string{
		"Authorization": "Bearer " + h.token}))

	for _, c := range []struct {
		who       string
		token     string
		expectBtn bool
	}{
		{"the owner", h.token, true},
		{"an admin", h.admin, true},
		{"a stranger", "", false},
	} {
		req, _ := http.NewRequest("GET", h.ts.URL+"/i/"+res.ID, nil)
		if c.token != "" {
			req.AddCookie(&http.Cookie{Name: tokenCookie, Value: c.token})
		}
		resp, err := h.ts.Client().Do(req)
		if err != nil {
			t.Fatal(err)
		}
		raw, _ := io.ReadAll(resp.Body)
		resp.Body.Close()
		got := strings.Contains(string(raw), "Your token can remove this file")
		if got != c.expectBtn {
			t.Errorf("direct delete button shown to %s = %v, want %v", c.who, got, c.expectBtn)
		}
	}

	// And that button actually works with no token field at all.
	resp := h.postForm(t, "/api/d/"+res.ID+"/delete",
		url.Values{"from": {"info"}}, &http.Cookie{Name: tokenCookie, Value: h.token})
	resp.Body.Close()
	if resp.StatusCode != http.StatusOK {
		t.Fatalf("owner delete => %s", resp.Status)
	}
}

// Guessing is throttled, but only the guessing: a correct token is never
// delayed by someone else's failed attempts.
func TestFailedDeletesAreThrottledAndSuccessIsNot(t *testing.T) {
	h := newHarness(t, nil)
	h.authLimiter = newLimiter(1, 3)

	res := decode[uploadResult](t, h.upload(t, []byte("x"), nil))

	var last *http.Response
	for range 5 {
		if last != nil {
			last.Body.Close()
		}
		last = h.postForm(t, "/api/d/"+res.ID+"/delete",
			url.Values{"from": {"info"}, "token": {"guess"}}, nil)
	}
	if last.StatusCode != http.StatusTooManyRequests {
		t.Fatalf("repeated guesses => %s, want 429", last.Status)
	}
	last.Body.Close()

	// The real token still works, having consumed nothing from the bucket.
	resp := h.postForm(t, "/api/d/"+res.ID+"/delete",
		url.Values{"from": {"info"}, "token": {res.DeleteToken}}, nil)
	resp.Body.Close()
	if resp.StatusCode != http.StatusOK {
		t.Fatalf("the correct token was throttled: %s", resp.Status)
	}
}

// --- cross-site posts ----------------------------------------------------

// A login form needs no cookie to submit, so SameSite does not cover it: a
// hostile page could otherwise sign a visitor into an account it controls and
// collect whatever they upload next. Browsers label their own requests, and
// those labels are checked on every state-changing route.
func TestCrossOriginPostsAreRejected(t *testing.T) {
	h := newHarness(t, nil)

	paths := []string{"/login", "/logout", "/api/upload", "/api/d/anything/delete"}
	hostile := []map[string]string{
		{"Origin": "https://evil.example.com"},
		{"Sec-Fetch-Site": "cross-site"},
		{"Sec-Fetch-Site": "same-site"},
	}
	for _, path := range paths {
		for _, headers := range hostile {
			req, _ := http.NewRequest("POST", h.ts.URL+path, strings.NewReader("token=x"))
			req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
			req.Header.Set("Accept", "application/json")
			for k, v := range headers {
				req.Header.Set(k, v)
			}
			resp, err := h.ts.Client().Do(req)
			if err != nil {
				t.Fatal(err)
			}
			resp.Body.Close()
			if resp.StatusCode != http.StatusForbidden {
				t.Errorf("POST %s with %v => %s, want 403", path, headers, resp.Status)
			}
		}
	}
}

// The page's own posts, and API clients that label nothing, must still work.
func TestSameOriginAndUnlabelledPostsAreAccepted(t *testing.T) {
	h := newHarness(t, nil)
	for _, headers := range []map[string]string{
		{},                                // curl and friends
		{"Sec-Fetch-Site": "same-origin"}, // the page itself
		{"Sec-Fetch-Site": "none"},        // typed into the bar
		{"Origin": "http://" + strings.TrimPrefix(h.ts.URL, "http://")}, // older browser
	} {
		req, _ := http.NewRequest("POST", h.ts.URL+"/login",
			strings.NewReader(url.Values{"token": {h.token}}.Encode()))
		req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
		req.Header.Set("Accept", "application/json")
		for k, v := range headers {
			req.Header.Set(k, v)
		}
		resp, err := h.ts.Client().Do(req)
		if err != nil {
			t.Fatal(err)
		}
		resp.Body.Close()
		if resp.StatusCode != http.StatusOK {
			t.Errorf("POST /login with %v => %s, want 200", headers, resp.Status)
		}
	}
}

// The header is the only navigation there is, so it has to tell the truth
// about the session on every page.
func TestHeaderReflectsTheSession(t *testing.T) {
	h := newHarness(t, nil)

	for _, c := range []struct {
		who     string
		token   string
		present []string
		absent  []string
	}{
		{"anonymous", "", []string{`href="/login"`}, []string{`action="/logout"`, `href="/admin"`}},
		{"a plain token", h.token, []string{`action="/logout"`, ">friend<"}, []string{`href="/login"`, `href="/admin"`}},
		{"an admin token", h.admin, []string{`action="/logout"`, `href="/admin"`, ">boss<"}, []string{`href="/login"`}},
	} {
		for _, path := range []string{"/", "/login"} {
			req, _ := http.NewRequest("GET", h.ts.URL+path, nil)
			if c.token != "" {
				req.AddCookie(&http.Cookie{Name: tokenCookie, Value: c.token})
			}
			resp, err := h.ts.Client().Do(req)
			if err != nil {
				t.Fatal(err)
			}
			raw, _ := io.ReadAll(resp.Body)
			resp.Body.Close()
			page := string(raw)

			for _, want := range c.present {
				if !strings.Contains(page, want) {
					t.Errorf("GET %s as %s: missing %q", path, c.who, want)
				}
			}
			for _, unwanted := range c.absent {
				if strings.Contains(page, unwanted) {
					t.Errorf("GET %s as %s: unexpectedly offers %q", path, c.who, unwanted)
				}
			}
		}
	}
}

// The upload form keeps a one-off token field, so a quick upload under another
// token does not require logging in and out.
func TestUploadPageKeepsTheOneOffTokenField(t *testing.T) {
	h := newHarness(t, nil)
	resp := h.get(t, "/", "")
	raw, _ := io.ReadAll(resp.Body)
	resp.Body.Close()
	page := string(raw)

	if !strings.Contains(page, `name="token"`) {
		t.Error("the upload form has no one-off token field")
	}
	if !strings.Contains(page, "does not log you in") {
		t.Error("the form does not explain that the field is one-off")
	}
	// The limits are rendered, not fetched, so no script is needed to show them.
	if !strings.Contains(page, `data-max-size="1048576"`) {
		t.Error("the form does not carry the server-rendered size limit")
	}
}

// A chosen passphrase has to work everywhere a generated token does: at the
// login form, on an upload, and as a session.
func TestChosenPassphraseWorksEndToEnd(t *testing.T) {
	h := newHarness(t, nil)
	const passphrase = "godot-friends-2026"

	tok, err := auth.NewChosen("memorable", passphrase)
	if err != nil {
		t.Fatal(err)
	}
	tok.AllowVanity = true
	if err := h.tokens.Add(tok); err != nil {
		t.Fatal(err)
	}

	resp := h.postForm(t, "/login", url.Values{"token": {passphrase}, "persist": {"1"}}, nil)
	resp.Body.Close()
	if resp.StatusCode != http.StatusSeeOther {
		t.Fatalf("login with a passphrase => %s", resp.Status)
	}
	cookie := findCookie(resp, tokenCookie)
	if cookie == nil {
		t.Fatal("no session was started")
	}

	req, _ := http.NewRequest("POST", h.ts.URL+"/api/upload", strings.NewReader("x"))
	req.Header.Set("Accept", "application/json")
	req.Header.Set("Vanity", "chosen-upload")
	req.AddCookie(cookie)
	up, err := h.ts.Client().Do(req)
	if err != nil {
		t.Fatal(err)
	}
	if up.StatusCode != http.StatusCreated {
		t.Fatalf("upload with a passphrase session => %s", up.Status)
	}
	if res := decode[uploadResult](t, up); res.ID != "chosen-upload" {
		t.Errorf("id = %q, want chosen-upload", res.ID)
	}
}

// Deriving a passphrase is expensive by design, which makes an unverified
// credential an amplifier unless the work is charged for. Junk must not be
// able to buy unlimited derivations.
func TestUnverifiedCredentialsCannotForceUnlimitedDerivations(t *testing.T) {
	h := newHarness(t, nil)
	tok, err := auth.NewChosen("memorable", "a-chosen-passphrase")
	if err != nil {
		t.Fatal(err)
	}
	if err := h.tokens.Add(tok); err != nil {
		t.Fatal(err)
	}
	h.authLimiter = newLimiter(1, 3)

	// Distinct junk on every request, so the memo never answers.
	for i := range 6 {
		req, _ := http.NewRequest("GET", h.ts.URL+"/", nil)
		req.AddCookie(&http.Cookie{Name: tokenCookie, Value: fmt.Sprintf("junk-%d", i)})
		resp, err := h.ts.Client().Do(req)
		if err != nil {
			t.Fatal(err)
		}
		resp.Body.Close()
		// The page still renders; it just renders as anonymous.
		if resp.StatusCode != http.StatusOK {
			t.Fatalf("page %d => %s", i, resp.Status)
		}
	}
	if h.tokens.Resolved("junk-5") {
		t.Error("a derivation ran past the budget")
	}
}

// The memo means a live session pays the derivation once, not per request.
func TestPassphraseSessionsAreMemoised(t *testing.T) {
	h := newHarness(t, nil)
	const passphrase = "a-chosen-passphrase"
	tok, err := auth.NewChosen("memorable", passphrase)
	if err != nil {
		t.Fatal(err)
	}
	if err := h.tokens.Add(tok); err != nil {
		t.Fatal(err)
	}

	if h.tokens.Resolved(passphrase) {
		t.Fatal("resolved before anything verified it")
	}
	resp := h.get(t, "/", "")
	resp.Body.Close()

	req, _ := http.NewRequest("GET", h.ts.URL+"/", nil)
	req.AddCookie(&http.Cookie{Name: tokenCookie, Value: passphrase})
	first, err := h.ts.Client().Do(req)
	if err != nil {
		t.Fatal(err)
	}
	first.Body.Close()

	if !h.tokens.Resolved(passphrase) {
		t.Error("the session was not memoised, so every request would derive again")
	}
}

// Rotating a secret has to end the sessions that were using it, or rotation
// would not actually revoke anything.
func TestRotationEndsLiveSessions(t *testing.T) {
	h := newHarness(t, nil)

	// A logged-in browser, and a page render proving the session works.
	session := &http.Cookie{Name: tokenCookie, Value: h.token}
	req, _ := http.NewRequest("GET", h.ts.URL+"/", nil)
	req.AddCookie(session)
	resp, err := h.ts.Client().Do(req)
	if err != nil {
		t.Fatal(err)
	}
	raw, _ := io.ReadAll(resp.Body)
	resp.Body.Close()
	if !strings.Contains(string(raw), ">friend<") {
		t.Fatal("setup: the session is not logged in")
	}

	var replacement string
	if err := h.tokens.Update("friend", func(tok *auth.Token) error {
		s, err := tok.SetGenerated()
		replacement = s
		return err
	}); err != nil {
		t.Fatal(err)
	}

	// The old cookie is now just a string.
	req, _ = http.NewRequest("GET", h.ts.URL+"/", nil)
	req.AddCookie(session)
	resp, err = h.ts.Client().Do(req)
	if err != nil {
		t.Fatal(err)
	}
	raw, _ = io.ReadAll(resp.Body)
	resp.Body.Close()
	if strings.Contains(string(raw), ">friend<") {
		t.Error("a rotated-away secret still authenticates a session")
	}
	if !strings.Contains(string(raw), "no longer valid") {
		t.Error("the page does not explain that the session ended")
	}

	// Uploading with the old secret is refused; the new one works.
	old := h.upload(t, []byte("x"), map[string]string{"Authorization": "Bearer " + h.token})
	old.Body.Close()
	if old.StatusCode != http.StatusUnauthorized {
		t.Errorf("upload with the old secret => %s, want 401", old.Status)
	}
	fresh := h.upload(t, []byte("x"), map[string]string{
		"Authorization": "Bearer " + replacement,
		"Vanity":        "after-rotation",
	})
	if fresh.StatusCode != http.StatusCreated {
		t.Fatalf("upload with the rotated secret => %s", fresh.Status)
	}
	if res := decode[uploadResult](t, fresh); res.ID != "after-rotation" {
		t.Errorf("id = %q: the rotated token lost its vanity permission", res.ID)
	}
}

// Sorting has to compare the underlying values, not their rendered form: two
// uploads in the same minute render identically but are not equal.
func TestAdminSortOrdersByValue(t *testing.T) {
	h := newHarness(t, nil)

	// Three files, distinct in every sortable dimension.
	type spec struct {
		name   string
		size   int
		expiry string
	}
	for i, s := range []spec{
		{"big", 300, "3h"},
		{"small", 10, "1h"},
		{"medium", 100, "2h"},
	} {
		h.now = clock.Add(time.Duration(i) * time.Second) // same minute, distinct instants
		resp := h.upload(t, bytes.Repeat([]byte("x"), s.size), map[string]string{
			"Authorization":       "Bearer " + h.token,
			"Vanity":              s.name,
			"Expiry":              s.expiry,
			"Content-Disposition": `attachment; filename="` + s.name + `.bin"`,
		})
		resp.Body.Close()
	}
	h.now = clock

	order := func(sortBy string) []string {
		resp := h.get(t, "/admin?sort="+sortBy, h.admin)
		raw, _ := io.ReadAll(resp.Body)
		resp.Body.Close()
		var ids []string
		for _, m := range regexp.MustCompile(`class="id mono">([a-z]+)`).FindAllStringSubmatch(string(raw), -1) {
			ids = append(ids, m[1])
		}
		return ids
	}

	for _, c := range []struct {
		sortBy string
		want   []string
	}{
		{"size", []string{"big", "medium", "small"}},    // largest first
		{"expires", []string{"small", "medium", "big"}}, // soonest first
		{"created", []string{"medium", "small", "big"}}, // newest first
		{"name", []string{"big", "medium", "small"}},    // by filename
	} {
		got := order(c.sortBy)
		if !slices.Equal(got, c.want) {
			t.Errorf("sort=%s gave %v, want %v", c.sortBy, got, c.want)
		}
	}
}

// The listing is a table, and a table needs more room than a form. It also has
// to stop being a table on a narrow screen rather than grow a scrollbar.
func TestAdminPageIsLaidOutForATable(t *testing.T) {
	h := newHarness(t, nil)
	h.upload(t, []byte("x"), nil).Body.Close()

	resp := h.get(t, "/admin", h.admin)
	raw, _ := io.ReadAll(resp.Body)
	resp.Body.Close()
	page := string(raw)

	if !strings.Contains(page, `class="wide"`) {
		t.Error("the listing renders at the narrow reading measure meant for forms")
	}
	// Every cell needs its label for the stacked layout, where the header row
	// is hidden.
	for _, label := range []string{"Size", "Owner", "Uploaded", "Expires"} {
		if !strings.Contains(page, `data-label="`+label+`"`) {
			t.Errorf("cells carry no %q label, so the stacked layout loses its headings", label)
		}
	}

	css := h.get(t, "/static/style.css", "")
	cssRaw, _ := io.ReadAll(css.Body)
	css.Body.Close()
	style := string(cssRaw)

	if !strings.Contains(style, "body.wide") {
		t.Error("no wide layout is defined")
	}
	if !strings.Contains(style, "@media (max-width: 46rem)") {
		t.Error("no narrow-screen rule, so the table will scroll sideways on a phone")
	}
	if strings.Contains(style, "overflow-x: auto") && strings.Contains(page, "tablewrap") {
		t.Error("the listing still relies on a horizontal scroll container")
	}
}