package handlers_test

import (
	"context"
	"crypto/tls"
	"net/http"
	"net/http/httptest"
	"regexp"
	"testing"

	"github.com/go-chi/chi"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
	"sneak.berlin/go/webhooker/internal/database"
	"sneak.berlin/go/webhooker/internal/handlers"
	"sneak.berlin/go/webhooker/internal/session"
)

// The only two schemes a rendered entrypoint URL may carry,
// whatever the request claimed.
const (
	schemeHTTPS = "https"
	schemeHTTP  = "http"
)

// entrypointURLPattern captures the entrypoint URL the source
// detail page renders, which is the operator-visible product of
// BaseURL. Asserting on the extracted string rather than on a
// substring of the page proves the raw header value cannot reach
// the scheme by any route.
var entrypointURLPattern = regexp.MustCompile(
	`<code id="entrypoint-url-[^"]*"[^>]*>([^<]*)</code>`,
)

// baseURLFixture is one started app plus the webhook whose
// entrypoint URL the BaseURL cases read.
type baseURLFixture struct {
	handlers *handlers.Handlers
	session  *session.Session
	webhook  string
	path     string
}

// newBaseURLFixture starts the app and seeds a webhook with one
// entrypoint.
func newBaseURLFixture(t *testing.T) *baseURLFixture {
	t.Helper()

	var (
		h    *handlers.Handlers
		sess *session.Session
		db   *database.Database
	)

	app := newTestApp(t, &h, &sess, &db)
	app.RequireStart()

	t.Cleanup(app.RequireStop)

	wh := seedWebhook(t, db)
	seedEntrypoint(t, db, wh.ID)

	return &baseURLFixture{
		handlers: h,
		session:  sess,
		webhook:  wh.ID,
		path:     "ep-" + wh.ID,
	}
}

// entrypointURL renders the source detail page for the fixture's
// webhook over a request the caller shapes, and returns the
// entrypoint URL as an operator would copy it.
func (f *baseURLFixture) entrypointURL(
	t *testing.T,
	host string,
	shape func(*http.Request),
) string {
	t.Helper()

	req := httptest.NewRequestWithContext(
		context.Background(),
		http.MethodGet,
		"/source/"+f.webhook,
		nil,
	)
	req.Host = host

	shape(req)

	for _, c := range authenticatedCookies(
		t, f.session, deleteTestUserID, deleteTestUsername,
	) {
		req.AddCookie(c)
	}

	rctx := chi.NewRouteContext()
	rctx.URLParams.Add(paramSourceID, f.webhook)
	req = req.WithContext(
		context.WithValue(
			req.Context(), chi.RouteCtxKey, rctx,
		),
	)

	w := httptest.NewRecorder()
	f.handlers.HandleSourceDetail().ServeHTTP(w, req)

	require.Equal(t, http.StatusOK, w.Code)

	match := entrypointURLPattern.FindStringSubmatch(w.Body.String())
	require.Len(
		t, match, 2,
		"the page must render exactly one entrypoint URL",
	)

	return match[1]
}

// forwardedProto returns a request shaper setting
// X-Forwarded-Proto, or leaving the request alone for "".
func forwardedProto(value string) func(*http.Request) {
	return func(r *http.Request) {
		if value == "" {
			return
		}

		r.Header.Set("X-Forwarded-Proto", value)
	}
}

// baseURLCase is one X-Forwarded-Proto spelling and the scheme
// the rendered entrypoint URL owes it.
type baseURLCase struct {
	name   string
	header string
	scheme string
	why    string
}

// baseURLCases enumerate the spellings a proxy really emits. The
// scheme is only ever http or https: the header value itself is
// never a scheme, however it is spelled.
func baseURLCases() []baseURLCase {
	return []baseURLCase{
		{
			name:   "lowercase",
			header: schemeHTTPS,
			scheme: schemeHTTPS,
			why:    "the ordinary spelling",
		},
		{
			name:   "uppercase",
			header: "HTTPS",
			scheme: schemeHTTPS,
			why: "the token is case-insensitive; the scheme " +
				"in a copyable URL is not",
		},
		{
			name:   "chain with plaintext inner hop",
			header: "https, http",
			scheme: schemeHTTPS,
			why: "a chained proxy appends its hop; the " +
				"leftmost element faces the client",
		},
		{
			name:   "chain of two TLS hops",
			header: "https,https",
			scheme: schemeHTTPS,
			why:    "appended chain with no space after the comma",
		},
		{
			name:   "trailing space",
			header: "https ",
			scheme: schemeHTTPS,
			why:    "whitespace is not part of the token",
		},
		{
			name:   "plaintext",
			header: schemeHTTP,
			scheme: schemeHTTP,
			why:    "the negative control: the proxy reports plaintext",
		},
		{
			name:   "no header",
			header: "",
			scheme: schemeHTTP,
			why:    "a plaintext request asserting nothing is http",
		},
		{
			name:   "garbage token",
			header: "javascript:alert(1)//",
			scheme: schemeHTTP,
			why: "anything that is not https is not TLS, and " +
				"the token never becomes the scheme",
		},
	}
}

// TestSourceDetailBaseURL_ForwardedProtoSpellings is the
// regression test for the entrypoint URL an operator pastes into
// the sending system: a header spelling that used to land in the
// scheme verbatim produced a URL no sender could deliver to.
func TestSourceDetailBaseURL_ForwardedProtoSpellings(t *testing.T) {
	t.Parallel()

	const host = "hooks.example.com"

	fixture := newBaseURLFixture(t)

	for _, tc := range baseURLCases() {
		t.Run(tc.name, func(t *testing.T) {
			t.Parallel()

			assert.Equal(
				t,
				tc.scheme+"://"+host+"/webhook/"+fixture.path,
				fixture.entrypointURL(
					t, host, forwardedProto(tc.header),
				),
				"X-Forwarded-Proto %q: %s", tc.header, tc.why,
			)
		})
	}
}

// TestSourceDetailBaseURL_DirectTLSBeatsPlaintextHeader pins the
// precedence the old code had backwards: it let any present
// header overwrite what the connection itself proved, so a
// direct-TLS request behind a proxy reporting http rendered an
// http URL.
func TestSourceDetailBaseURL_DirectTLSBeatsPlaintextHeader(
	t *testing.T,
) {
	t.Parallel()

	const host = "hooks.example.com"

	fixture := newBaseURLFixture(t)

	got := fixture.entrypointURL(t, host, func(r *http.Request) {
		r.TLS = &tls.ConnectionState{}
		r.Header.Set("X-Forwarded-Proto", "http")
	})

	assert.Equal(
		t,
		"https://"+host+"/webhook/"+fixture.path,
		got,
		"a connection this process terminated with TLS "+
			"outranks a header claiming plaintext",
	)
}

// TestSourceDetailBaseURL_KeepsHostAuthority pins the host half
// of the URL: it is taken from the request unchanged, so the
// deployments that do not sit on port 443 still get a URL that
// works. Constraining the host would break exactly these.
func TestSourceDetailBaseURL_KeepsHostAuthority(t *testing.T) {
	t.Parallel()

	fixture := newBaseURLFixture(t)

	hosts := []string{
		"hooks.example.com:8443",
		"[2001:db8::1]:8443",
		"internal-host",
	}

	for _, host := range hosts {
		t.Run(host, func(t *testing.T) {
			t.Parallel()

			assert.Equal(
				t,
				"https://"+host+"/webhook/"+fixture.path,
				fixture.entrypointURL(
					t, host, forwardedProto("HTTPS"),
				),
				"the authority must survive verbatim, port and all",
			)
		})
	}
}