package httpapi_test

import (
	"context"
	"encoding/json"
	"io"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"

	"github.com/urpi/go-bananas/internal/auth"
	"github.com/urpi/go-bananas/internal/config"
	"github.com/urpi/go-bananas/internal/domain"
	"github.com/urpi/go-bananas/internal/httpapi"
	"github.com/urpi/go-bananas/internal/logging"
	"github.com/urpi/go-bananas/internal/seed"
	"github.com/urpi/go-bananas/internal/store"
)

// These tests cover the routing posture of the HTTP surface, which is the part
// that cannot be verified by testing handlers in isolation. A handler that behaves
// correctly but is mounted on the wrong side of the authentication middleware is
// still a vulnerability, and no amount of handler testing would catch it.
//
// The split being asserted is:
//   - /rt/v1 and session discovery are reachable without a session;
//   - everything else under /api/v1 requires one;
//   - the two exceptions are the only exceptions.

// testConfig builds a minimal development configuration.
func testConfig(t *testing.T) config.Config {
	t.Helper()
	cfg := config.Config{
		Environment:        "test",
		AuthMode:           config.AuthModeNone,
		PublicBaseURL:      "http://localhost:8080",
		SessionSecret:      "0123456789abcdef0123456789abcdef",
		SessionSameSite:    "Lax",
		DatabasePath:       ":memory:",
		DatabaseMaxConns:   4,
		RateLimitPerMinute: 600,
	}
	if err := cfg.Validate(); err != nil {
		t.Fatalf("test config is invalid: %v", err)
	}
	return cfg
}

// newTestRouter builds a router over an in-memory database with authentication
// disabled.
//
// AUTH_MODE=none is not the same as "anonymous": it is a deliberate deployment
// choice to grant every caller admin, so it is the right fixture for exercising
// unauthenticated *routing* (probes, the runtime API, the 404 handler) but not
// authentication itself.
func newTestRouter(t *testing.T) http.Handler {
	t.Helper()
	cfg := testConfig(t)
	cfg.AuthMode = config.AuthModeNone
	return buildRouter(t, cfg, nil)
}

// newUnauthenticatedRouter builds a router in OIDC mode with no session.
//
// This is the fixture for the authentication tests: every request arrives
// anonymous and must be rejected, which is exactly the state a signed-out browser
// is in. The resolver is a stub so that no identity provider is contacted.
func newUnauthenticatedRouter(t *testing.T) http.Handler {
	t.Helper()
	cfg := testConfig(t)
	cfg.AuthMode = config.AuthModeOIDC
	cfg.OIDCIssuer = "https://auth.lcl-urpi.be/realms/urpi"
	cfg.OIDCClientID = "go-bananas"
	cfg.OIDCClientSecret = "test-client-secret"
	cfg.SessionSecure = false
	return buildRouter(t, cfg, rejectingResolver{})
}

// newRuntimeRouter builds a router whose store has the built-in themes seeded, which
// is what the runtime endpoints need in order to have anything to serve.
func newRuntimeRouter(t *testing.T) http.Handler {
	t.Helper()
	h, st := buildRouterWithStore(t, testConfig(t), nil)
	if _, _, err := st.Seed(context.Background(), seed.Themes()); err != nil {
		t.Fatalf("seed built-in themes: %v", err)
	}
	return h
}

// buildRouter wires a router for a configuration and an optional resolver.
func buildRouter(t *testing.T, cfg config.Config, resolver auth.Resolver) http.Handler {
	t.Helper()
	h, _ := buildRouterWithStore(t, cfg, resolver)
	return h
}

// buildRouterWithStore wires a router and hands back its store, so a test can seed
// or assert against the same database the handlers read.
func buildRouterWithStore(t *testing.T, cfg config.Config, resolver auth.Resolver) (http.Handler, *store.Store) {
	t.Helper()

	st, err := store.Open(context.Background(), store.Options{Path: ":memory:"})
	if err != nil {
		t.Fatalf("open store: %v", err)
	}
	t.Cleanup(func() { _ = st.Close() })

	// The logger discards its output: these tests assert on HTTP status codes, and
	// a passing run would otherwise fill the test log with request lines.
	log := logging.New(logging.Options{Level: "error", Writer: io.Discard})

	authenticator, err := auth.New(cfg, resolver, nil)
	if err != nil {
		t.Fatalf("new authenticator: %v", err)
	}

	return httpapi.NewRouter(httpapi.Deps{
		Config:        cfg,
		Store:         st,
		Cache:         httpapi.NewThemeCache(),
		Authenticator: authenticator,
		Log:           log,
		Version:       "test",
		RuntimeDefaults: func() (string, domain.Appearance) {
			return "", ""
		},
	}), st
}

// get performs a request and returns the recorder.
func get(t *testing.T, h http.Handler, path string) *httptest.ResponseRecorder {
	t.Helper()
	rec := httptest.NewRecorder()
	h.ServeHTTP(rec, httptest.NewRequestWithContext(t.Context(), http.MethodGet, path, nil))
	return rec
}

// TestSessionEndpointsAreReachableWithoutASession is the regression test for the
// mistake that made the admin UI unable to start a login: session introspection sat
// inside the authenticated subtree, so the UI received 401 for the one request it
// needs in order to discover that it is not logged in.
func TestSessionEndpointsAreReachableWithoutASession(t *testing.T) {
	router := newUnauthenticatedRouter(t)

	for _, path := range []string{"/api/v1/auth/me", "/api/v1/auth/config"} {
		t.Run(path, func(t *testing.T) {
			rec := get(t, router, path)
			if rec.Code != http.StatusOK {
				t.Fatalf("got %d, want 200: %s", rec.Code, rec.Body.String())
			}

			var body map[string]any
			if err := json.Unmarshal(rec.Body.Bytes(), &body); err != nil {
				t.Fatalf("response is not JSON: %v", err)
			}
			if _, ok := body["mode"]; !ok {
				t.Error("response does not report the auth mode")
			}
		})
	}
}

// TestMeReportsAnonymityRatherThanFailing checks that an absent session is a 200
// with an explicit flag, not an error status. The UI treats this as the normal
// first-load state.
func TestMeReportsAnonymityRatherThanFailing(t *testing.T) {
	rec := get(t, newUnauthenticatedRouter(t), "/api/v1/auth/me")
	if rec.Code != http.StatusOK {
		t.Fatalf("got %d, want 200", rec.Code)
	}

	var body struct {
		Authenticated bool   `json:"authenticated"`
		Mode          string `json:"mode"`
	}
	if err := json.Unmarshal(rec.Body.Bytes(), &body); err != nil {
		t.Fatalf("decode: %v", err)
	}
	if body.Authenticated {
		t.Error("anonymous request reported as authenticated")
	}
	if body.Mode == "" {
		t.Error("auth mode is empty")
	}
}

// TestAdminAPIRequiresASession is the other half of the contract: moving the two
// session endpoints out of the guarded subtree must not have opened the rest of
// /api/v1. Each route is checked individually, because a single unguarded route is
// the whole vulnerability and testing the group as a whole would not localise it.
func TestAdminAPIRequiresASession(t *testing.T) {
	router := newUnauthenticatedRouter(t)

	protected := []struct {
		method string
		path   string
	}{
		{http.MethodGet, "/api/v1/meta"},
		{http.MethodGet, "/api/v1/stats"},
		{http.MethodGet, "/api/v1/themes"},
		{http.MethodGet, "/api/v1/themes/midnight"},
		{http.MethodGet, "/api/v1/themes/midnight/export"},
		{http.MethodGet, "/api/v1/themes/midnight/versions"},
		{http.MethodGet, "/api/v1/themes/midnight/diff"},
		{http.MethodPost, "/api/v1/themes"},
		{http.MethodPost, "/api/v1/tokens/validate"},
		{http.MethodGet, "/api/v1/tokens/schema"},
		{http.MethodGet, "/api/v1/keys"},
		{http.MethodGet, "/api/v1/admin/users"},
		{http.MethodGet, "/api/v1/admin/audit"},
		{http.MethodGet, "/api/v1/admin/settings"},
	}

	for _, tc := range protected {
		t.Run(tc.method+" "+tc.path, func(t *testing.T) {
			rec := httptest.NewRecorder()
			router.ServeHTTP(rec, httptest.NewRequestWithContext(t.Context(), tc.method, tc.path, nil))
			if rec.Code != http.StatusUnauthorized {
				t.Errorf("got %d, want 401: %s", rec.Code, rec.Body.String())
			}
		})
	}
}

// TestRuntimeIsPublic checks that the runtime API is not behind authentication. A
// theme is a public asset by design: the whole point is that a browser can link to
// it with no credentials, which is also why it has its own rate limiter.
//
// The assertion is deliberately "not 401" rather than "200". With no published
// theme these endpoints legitimately answer 400 or 404, and both are fine here —
// what would not be fine is a 401, which would mean the request never reached the
// handler. Checking for the absence of the failure mode rather than the presence of
// a success keeps the test meaningful whether or not a theme exists.
func TestRuntimeIsPublic(t *testing.T) {
	router := newTestRouter(t)

	for _, path := range []string{
		"/rt/v1/manifest.json",
		"/rt/v1/theme.css",
		"/rt/v1/theme.json",
		"/rt/v1/embed",
		"/rt/v1/themes/midnight/theme.css",
	} {
		t.Run(path, func(t *testing.T) {
			rec := get(t, router, path)
			if rec.Code == http.StatusUnauthorized {
				t.Errorf("runtime endpoint demanded authentication: %s", rec.Body.String())
			}
			if rec.Code == http.StatusNotFound && strings.Contains(rec.Body.String(), "endpoint") {
				t.Errorf("runtime route is not registered: %s", rec.Body.String())
			}
		})
	}
}

// TestRuntimeIsReadableCrossOrigin checks that a consuming application on another
// host can read the styling contract.
//
// This is not a hypothetical: every sibling application is on its own host, so in a
// real deployment all of them read this tree cross-origin, and two of those reads are
// enforced by the platform rather than negotiated. An ES module <script> is always
// fetched under CORS rules, and fetch() from another origin needs the header. The
// failure this guards against is silent and total: the control renders as an empty
// box and reports no palettes, while every same-origin test still passes.
func TestRuntimeIsReadableCrossOrigin(t *testing.T) {
	router := newTestRouter(t)

	for _, path := range []string{
		"/rt/v1/contract.json",
		"/rt/v1/contract.css",
		"/rt/v1/components.js",
		"/rt/v1/manifest.json",
	} {
		t.Run(path, func(t *testing.T) {
			// The Origin header is what makes this a cross-origin read at all. Without
			// it the middleware deliberately adds nothing, so a test that omits it is
			// not testing the policy — it is testing the same-origin path under a
			// misleading name.
			req := httptest.NewRequestWithContext(context.Background(), http.MethodGet, path, nil)
			req.Header.Set("Origin", "https://tell.lcl-urpi.be")
			rec := httptest.NewRecorder()
			router.ServeHTTP(rec, req)

			if got := rec.Header().Get("Access-Control-Allow-Origin"); got != "*" {
				t.Errorf("Access-Control-Allow-Origin = %q, want \"*\" so another host can read it", got)
			}
			if !strings.Contains(rec.Header().Get("Vary"), "Origin") {
				t.Error("Vary must include Origin, or a shared cache can serve one caller's entry to another")
			}
			if got := rec.Header().Get("Access-Control-Allow-Credentials"); got != "" {
				// Browsers reject a credentialed wildcard, and the runtime needs no
				// credentials: the SDK sends credentials:'omit'.
				t.Errorf("Access-Control-Allow-Credentials = %q, want it absent alongside a wildcard", got)
			}
		})
	}
}

// TestAdminAPIIsNotOpenedByTheRuntimePolicy is the counterpart to the test above.
//
// Opening the runtime tree to any origin is only safe because that tree is public
// styling. The admin API sits on the same router and is per-user and credentialed, so
// it must stay on the allow-list. A fix that simply sent "*" everywhere would make the
// runtime work and quietly expose the admin API, and the runtime tests alone would
// still pass.
//
// The router in this test has no configured origins, which is the default deployment
// shape, so the expectation is that nothing is allowed.
func TestAdminAPIIsNotOpenedByTheRuntimePolicy(t *testing.T) {
	router := newTestRouter(t)

	for _, path := range []string{"/api/v1/session", "/api/v1/themes"} {
		t.Run(path, func(t *testing.T) {
			req := httptest.NewRequestWithContext(t.Context(), http.MethodGet, path, nil)
			req.Header.Set("Origin", "https://tell.lcl-urpi.be")
			rec := httptest.NewRecorder()
			router.ServeHTTP(rec, req)

			if got := rec.Header().Get("Access-Control-Allow-Origin"); got != "" {
				t.Errorf("Access-Control-Allow-Origin = %q on %s, want none: the admin API is per-user and must stay restricted", got, path)
			}
		})
	}
}

// TestAdminAPIAllowsAConfiguredOrigin checks that the restriction is an allow-list and
// not a blanket refusal: an operator who configures an origin for their own tooling
// should get it working, otherwise the safe default becomes permanent breakage with no
// way out.
func TestAdminAPIAllowsAConfiguredOrigin(t *testing.T) {
	cfg := testConfig(t)
	cfg.AuthMode = config.AuthModeNone
	cfg.CORSAllowedOrigins = []string{"https://admin.example"}
	router := buildRouter(t, cfg, nil)

	req := httptest.NewRequestWithContext(t.Context(), http.MethodGet, "/api/v1/session", nil)
	req.Header.Set("Origin", "https://admin.example")
	rec := httptest.NewRecorder()
	router.ServeHTTP(rec, req)

	if got := rec.Header().Get("Access-Control-Allow-Origin"); got != "https://admin.example" {
		t.Errorf("Access-Control-Allow-Origin = %q, want the configured origin echoed back", got)
	}
	if got := rec.Header().Get("Access-Control-Allow-Credentials"); got != "true" {
		t.Errorf("Access-Control-Allow-Credentials = %q, want \"true\" for a credentialed allow-listed origin", got)
	}
}

// TestRuntimeAnswersPreflight checks the OPTIONS branch. The runtime is read-only, so
// no consumer needs a preflight today; answering it is still correct, and refusing it
// would be a confusing way to express that.
//
// It goes through the router rather than the middleware directly because the router is
// what a real preflight arrives at, and the branch could be mounted wrongly without
// that ever showing up in a unit test of the middleware alone.
func TestRuntimeAnswersPreflight(t *testing.T) {
	req := httptest.NewRequestWithContext(
		context.Background(), http.MethodOptions, "/rt/v1/contract.json", nil)
	req.Header.Set("Origin", "https://tell.lcl-urpi.be")
	// A real preflight names the method it wants to use. Without this header the
	// request is not a preflight, and asserting 204 on it would be asserting on a
	// case no browser ever sends — which is how this test passed against a 405.
	req.Header.Set("Access-Control-Request-Method", "GET")
	rec := httptest.NewRecorder()
	newTestRouter(t).ServeHTTP(rec, req)

	if rec.Code != http.StatusNoContent {
		t.Errorf("status %d, want %d", rec.Code, http.StatusNoContent)
	}
	if got := rec.Header().Get("Access-Control-Allow-Origin"); got != "*" {
		t.Errorf("Access-Control-Allow-Origin = %q on the preflight, want \"*\"", got)
	}
}

// TestUnknownAPIEndpointIsJSONNotTheSPA checks that a typo under /api/v1 returns a
// machine-readable error. Falling through to the single-page app there would hand
// an HTML document to a fetch() call, and the client would report a JSON parse
// error instead of the 404 that actually happened.
func TestUnknownAPIEndpointIsJSONNotTheSPA(t *testing.T) {
	rec := get(t, newTestRouter(t), "/api/v1/does-not-exist")
	if rec.Code != http.StatusNotFound {
		t.Fatalf("got %d, want 404", rec.Code)
	}
	if ct := rec.Header().Get("Content-Type"); ct != "application/json; charset=utf-8" {
		t.Errorf("content type %q, want JSON", ct)
	}
}

// TestProbesArePublic checks the health endpoints, which a kubelet must be able to
// reach without credentials or they would restart a healthy pod forever.
func TestProbesArePublic(t *testing.T) {
	router := newTestRouter(t)
	for _, path := range []string{"/healthz", "/livez", "/readyz"} {
		t.Run(path, func(t *testing.T) {
			if rec := get(t, router, path); rec.Code != http.StatusOK {
				t.Errorf("got %d, want 200: %s", rec.Code, rec.Body.String())
			}
		})
	}
}

// rejectingResolver is an OIDC resolver that authenticates nobody.
//
// It exists so the router can be built in OIDC mode without contacting a real
// provider: New refuses to start in OIDC mode without a resolver, and the
// authentication tests need a mode where a missing session is actually rejected.
type rejectingResolver struct{}

func (rejectingResolver) Begin(context.Context, *http.Request, http.ResponseWriter, string) error {
	return nil
}

func (rejectingResolver) Complete(context.Context, *http.Request) (*auth.Login, error) {
	return nil, auth.ErrNoSession
}

func (rejectingResolver) End(context.Context, string) string { return "" }
func (rejectingResolver) Enabled() bool                      { return true }
func (rejectingResolver) ClearState(http.ResponseWriter)     {}
func (rejectingResolver) LogoutURL(string) string            { return "" }