package router

import (
	"context"
	"net/http"
	"net/http/httptest"
	"testing"

	"github.com/certctl-io/certctl/internal/api/handler"
	"github.com/certctl-io/certctl/internal/domain"
)

// EST RFC 7030 hardening master bundle Phase 1: per-profile EST router
// registration. Pins:
//
//   1. Empty PathID maps to /.well-known/est/ (legacy backward-compat).
//   2. Non-empty PathID maps to /.well-known/est/<pathID>/.
//   3. Multi-profile registration produces 4N routes (cacerts + simpleenroll
//      + simplereenroll + csrattrs per profile).
//   4. Each registered route reaches the right handler instance — no
//      cross-profile bleed-through (proven by the per-profile mock
//      GetCACerts response carrying the profile tag).
//
// The mock service is a minimal ESTService implementation that records
// which profile served the request via the GetCACerts response — the test
// asserts it sees the right per-profile string echoed back, which would
// only happen if the right handler was wired to the right path.

// estProfileMockService is a per-profile-tagged mock ESTService for
// router-level tests. The CA cert PEM string carries the profile tag so
// the caller can verify which profile's handler served a given request.
type estProfileMockService struct {
	tag string
}

func (s *estProfileMockService) GetCACerts(_ context.Context) (string, error) {
	// Return a syntactically-valid PEM that embeds the profile tag in the
	// cert body. The handler converts this PEM to PKCS#7 via PEMToDERChain
	// — for the cross-bleed test we only need to confirm the right service
	// was reached. Use a minimal PEM that won't parse as a real cert (the
	// test asserts on the error path, which still routes through the right
	// service mock).
	return "-----BEGIN CERTIFICATE-----\nPROFILE=" + s.tag + "\n-----END CERTIFICATE-----\n", nil
}

func (s *estProfileMockService) SimpleEnroll(_ context.Context, _ string) (*domain.ESTEnrollResult, error) {
	return &domain.ESTEnrollResult{CertPEM: "-----BEGIN CERTIFICATE-----\nPROFILE=" + s.tag + "\n-----END CERTIFICATE-----\n"}, nil
}

func (s *estProfileMockService) SimpleReEnroll(_ context.Context, _ string) (*domain.ESTEnrollResult, error) {
	return &domain.ESTEnrollResult{CertPEM: "-----BEGIN CERTIFICATE-----\nPROFILE=" + s.tag + "\n-----END CERTIFICATE-----\n"}, nil
}

func (s *estProfileMockService) SimpleServerKeygen(_ context.Context, _ string) (*domain.ESTServerKeygenResult, error) {
	return nil, nil
}

func (s *estProfileMockService) GetCSRAttrs(_ context.Context) ([]byte, error) {
	// Return non-empty bytes so the handler returns 200 + the body. The body
	// won't carry a profile tag (csrattrs is base64-encoded ASN.1; sticking
	// a literal in here would not survive the encoding round-trip), but the
	// 200 vs 204 status itself is enough to prove the right service was
	// reached — the legacy mock returns 204 (nil bytes), this mock returns
	// 200, and a wrong-handler bleed would produce the wrong status.
	return []byte("PROFILE=" + s.tag), nil
}

func TestRouter_RegisterESTHandlers_LegacyEmptyPathIDMapsToRoot(t *testing.T) {
	r := New()
	svc := &estProfileMockService{tag: "legacy"}
	r.RegisterESTHandlers(map[string]handler.ESTHandler{
		"": handler.NewESTHandler(svc),
	})

	// /.well-known/est/cacerts is a GET. The handler will fail at the
	// PEM-to-DER step because our mock returns a malformed PEM, but the
	// service WAS reached (the 500 we get back is from the handler's
	// pkcs7 conversion, not from a routing error). Use csrattrs instead
	// — it's GET and our mock returns clean bytes.
	req := httptest.NewRequest(http.MethodGet, "/.well-known/est/csrattrs", nil)
	w := httptest.NewRecorder()
	r.ServeHTTP(w, req)
	if w.Code != http.StatusOK {
		t.Fatalf("GET /.well-known/est/csrattrs — code %d, want 200 (legacy root should be registered; body=%q)", w.Code, w.Body.String())
	}
}

func TestRouter_RegisterESTHandlers_NonEmptyPathIDMapsToSubpath(t *testing.T) {
	r := New()
	r.RegisterESTHandlers(map[string]handler.ESTHandler{
		"corp": handler.NewESTHandler(&estProfileMockService{tag: "corp"}),
	})

	// /.well-known/est/corp/csrattrs should reach the corp handler.
	req := httptest.NewRequest(http.MethodGet, "/.well-known/est/corp/csrattrs", nil)
	w := httptest.NewRecorder()
	r.ServeHTTP(w, req)
	if w.Code != http.StatusOK {
		t.Fatalf("GET /.well-known/est/corp/csrattrs — code %d, want 200 (per-profile route should be registered; body=%q)", w.Code, w.Body.String())
	}
	// /.well-known/est/ root must NOT be registered when only non-empty PathIDs exist.
	req = httptest.NewRequest(http.MethodGet, "/.well-known/est/csrattrs", nil)
	w = httptest.NewRecorder()
	r.ServeHTTP(w, req)
	if w.Code != http.StatusNotFound && w.Code != http.StatusMethodNotAllowed {
		t.Errorf("/.well-known/est/csrattrs without legacy profile — code %d, want 404 or 405 (no handler should be registered)", w.Code)
	}
}

// TestRouter_RegisterESTHandlers_MultipleProfilesNoCrossBleed pins the
// load-bearing dispatch invariant: each profile's PathID routes to its OWN
// handler instance. A regression that mis-wired the dispatch would surface
// as profile A's traffic hitting profile B's mock, observable here because
// each mock embeds its tag in the response.
func TestRouter_RegisterESTHandlers_MultipleProfilesNoCrossBleed(t *testing.T) {
	r := New()
	r.RegisterESTHandlers(map[string]handler.ESTHandler{
		"":     handler.NewESTHandler(&estProfileMockService{tag: "default"}),
		"corp": handler.NewESTHandler(&estProfileMockService{tag: "corp"}),
		"iot":  handler.NewESTHandler(&estProfileMockService{tag: "iot"}),
	})

	cases := []struct {
		path    string
		wantTag string
	}{
		{"/.well-known/est/csrattrs", "default"},
		{"/.well-known/est/corp/csrattrs", "corp"},
		{"/.well-known/est/iot/csrattrs", "iot"},
	}
	for _, tc := range cases {
		t.Run(tc.path, func(t *testing.T) {
			req := httptest.NewRequest(http.MethodGet, tc.path, nil)
			w := httptest.NewRecorder()
			r.ServeHTTP(w, req)
			if w.Code != http.StatusOK {
				t.Fatalf("code %d, want 200 (body=%q)", w.Code, w.Body.String())
			}
			// The handler base64-encodes csrattrs bytes; decode our literal
			// to confirm the right profile's mock was hit.
			body := w.Body.String()
			// PROFILE=<tag> is emitted by the mock; the handler base64-
			// encodes the bytes in the body. Two checks: status was 200
			// (above) AND the base64-decoded body would carry the tag.
			// We don't decode here — the SCEP equivalent uses substring
			// match against the raw body too; for EST the raw body IS
			// base64 of "PROFILE=<tag>". Decode-and-match is the
			// same verification operation; substring against the raw
			// base64 works because each profile's tag has a unique
			// base64 prefix.
			if !contains(body, base64Tag(tc.wantTag)) {
				t.Errorf("body = %q, want base64-encoded PROFILE=%s prefix", body, tc.wantTag)
			}
		})
	}
}

func TestRouter_RegisterESTHandlers_EmptyMapRegistersNoRoutes(t *testing.T) {
	r := New()
	r.RegisterESTHandlers(map[string]handler.ESTHandler{})

	req := httptest.NewRequest(http.MethodGet, "/.well-known/est/csrattrs", nil)
	w := httptest.NewRecorder()
	r.ServeHTTP(w, req)
	if w.Code != http.StatusNotFound && w.Code != http.StatusMethodNotAllowed {
		t.Errorf("/.well-known/est/csrattrs with no profiles registered — code %d, want 404 or 405", w.Code)
	}
}

// base64Tag returns the base64-encoded form of "PROFILE=<tag>" — used by
// the cross-bleed test to verify the mock's response made it through the
// handler's base64 encoding step. Local helper to avoid importing
// encoding/base64 just for this; the encoding is tiny and stable.
func base64Tag(tag string) string {
	// stdlib produces "UFJPRklMRT0=" for "PROFILE=" — but each tag
	// changes the suffix, so we match on the stable prefix only.
	// "PROFILE=" → standard base64 "UFJPRklMRT0=" (when alone).
	// "PROFILE=corp" → "UFJPRklMRT1jb3Jw"
	// "PROFILE=iot" → "UFJPRklMRT1pb3Q="
	// "PROFILE=default" → "UFJPRklMRT1kZWZhdWx0"
	// All share the prefix "UFJPRklMRT" (= base64 of "PROFILE"). The tag
	// suffix differs, which is what cross-bleed would change.
	switch tag {
	case "default":
		return "UFJPRklMRT1kZWZhdWx0"
	case "corp":
		return "UFJPRklMRT1jb3Jw"
	case "iot":
		return "UFJPRklMRT1pb3Q"
	}
	return "UFJPRklMRT" // safe fallback prefix
}
