package shared

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

	"github.com/go-chi/chi/v5"
)

// Closes the audit's R-001 + R-007 mechanically once auth is wired
// per ADR-003. Tests cover: pass-through on empty config, token
// gate (401 on missing/wrong, 200 on correct), IP gate (403 on
// disallowed, 200 on allowed), /health bypass, both-layers when
// both configured, and constant-time comparison usage.

func mountWithAuth(cfg AuthConfig) http.Handler {
	r := chi.NewRouter()
	r.Get("/health", func(w http.ResponseWriter, _ *http.Request) {
		w.WriteHeader(http.StatusOK)
		_, _ = w.Write([]byte("ok"))
	})
	r.Group(func(authed chi.Router) {
		authed.Use(RequireAuth(cfg))
		authed.Get("/data", func(w http.ResponseWriter, _ *http.Request) {
			w.WriteHeader(http.StatusOK)
			_, _ = w.Write([]byte("private"))
		})
	})
	return r
}

func get(t *testing.T, srv *httptest.Server, path string, header string) (int, string) {
	t.Helper()
	req, err := http.NewRequest(http.MethodGet, srv.URL+path, nil)
	if err != nil {
		t.Fatalf("NewRequest: %v", err)
	}
	if header != "" {
		req.Header.Set("Authorization", header)
	}
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		t.Fatalf("Do: %v", err)
	}
	defer resp.Body.Close()
	buf := make([]byte, 1024)
	n, _ := resp.Body.Read(buf)
	return resp.StatusCode, string(buf[:n])
}

func TestRequireAuth_EmptyConfig_PassesThrough(t *testing.T) {
	srv := httptest.NewServer(mountWithAuth(AuthConfig{}))
	defer srv.Close()

	if status, _ := get(t, srv, "/data", ""); status != http.StatusOK {
		t.Errorf("empty config should pass through, got status %d", status)
	}
	if status, _ := get(t, srv, "/health", ""); status != http.StatusOK {
		t.Errorf("/health on empty config should pass, got %d", status)
	}
}

func TestRequireAuth_TokenSet_RejectsMissing(t *testing.T) {
	srv := httptest.NewServer(mountWithAuth(AuthConfig{Token: "secret123"}))
	defer srv.Close()

	if status, _ := get(t, srv, "/data", ""); status != http.StatusUnauthorized {
		t.Errorf("missing Authorization should return 401, got %d", status)
	}
}

func TestRequireAuth_TokenSet_RejectsWrong(t *testing.T) {
	srv := httptest.NewServer(mountWithAuth(AuthConfig{Token: "secret123"}))
	defer srv.Close()

	if status, _ := get(t, srv, "/data", "Bearer wrong-token"); status != http.StatusUnauthorized {
		t.Errorf("wrong token should return 401, got %d", status)
	}
}

func TestRequireAuth_TokenSet_AcceptsCorrect(t *testing.T) {
	srv := httptest.NewServer(mountWithAuth(AuthConfig{Token: "secret123"}))
	defer srv.Close()

	status, body := get(t, srv, "/data", "Bearer secret123")
	if status != http.StatusOK {
		t.Errorf("correct Bearer should return 200, got %d", status)
	}
	if body != "private" {
		t.Errorf("expected 'private' body, got %q", body)
	}
}

func TestRequireAuth_TokenSet_HealthRemainsPublic(t *testing.T) {
	srv := httptest.NewServer(mountWithAuth(AuthConfig{Token: "secret123"}))
	defer srv.Close()

	if status, _ := get(t, srv, "/health", ""); status != http.StatusOK {
		t.Errorf("/health must stay public when token is set, got %d", status)
	}
}

func TestRequireAuth_RejectsTokenAsRawNotBearer(t *testing.T) {
	srv := httptest.NewServer(mountWithAuth(AuthConfig{Token: "secret123"}))
	defer srv.Close()

	// "secret123" alone (without "Bearer " prefix) should NOT pass.
	if status, _ := get(t, srv, "/data", "secret123"); status != http.StatusUnauthorized {
		t.Errorf("raw-token without 'Bearer ' prefix must reject, got %d", status)
	}
}

func TestRequireAuth_IPAllowlist_AllowsLoopback(t *testing.T) {
	cfg := AuthConfig{AllowedIPs: []string{"127.0.0.0/8"}}
	srv := httptest.NewServer(mountWithAuth(cfg))
	defer srv.Close()

	// httptest.Server binds 127.0.0.1, so the test client always
	// connects from 127.0.0.1 → allowed.
	if status, _ := get(t, srv, "/data", ""); status != http.StatusOK {
		t.Errorf("loopback in allowed CIDR should pass, got %d", status)
	}
}

func TestRequireAuth_IPAllowlist_RejectsNonAllowed(t *testing.T) {
	// Allowlist excludes loopback — every test request from 127.x.x.x
	// gets rejected.
	cfg := AuthConfig{AllowedIPs: []string{"10.0.0.0/8"}}
	srv := httptest.NewServer(mountWithAuth(cfg))
	defer srv.Close()

	if status, _ := get(t, srv, "/data", ""); status != http.StatusForbidden {
		t.Errorf("non-allowed IP should return 403, got %d", status)
	}
}

func TestRequireAuth_BareIPInAllowlist(t *testing.T) {
	// Bare IP without /N suffix should be treated as /32.
	cfg := AuthConfig{AllowedIPs: []string{"127.0.0.1"}}
	srv := httptest.NewServer(mountWithAuth(cfg))
	defer srv.Close()

	if status, _ := get(t, srv, "/data", ""); status != http.StatusOK {
		t.Errorf("bare IP /32 should pass, got %d", status)
	}
}

func TestRequireAuth_BothLayers_RequiresBoth(t *testing.T) {
	cfg := AuthConfig{
		Token:      "secret123",
		AllowedIPs: []string{"127.0.0.0/8"},
	}
	srv := httptest.NewServer(mountWithAuth(cfg))
	defer srv.Close()

	// Missing token: 401 even from allowed IP.
	if status, _ := get(t, srv, "/data", ""); status != http.StatusUnauthorized {
		t.Errorf("allowed IP without token should still 401, got %d", status)
	}
	// Wrong token: 401.
	if status, _ := get(t, srv, "/data", "Bearer wrong"); status != http.StatusUnauthorized {
		t.Errorf("allowed IP + wrong token should 401, got %d", status)
	}
	// Right token: 200 (we're on loopback, IP allowed).
	if status, _ := get(t, srv, "/data", "Bearer secret123"); status != http.StatusOK {
		t.Errorf("allowed IP + correct token should 200, got %d", status)
	}
	// /health: 200 always.
	if status, _ := get(t, srv, "/health", ""); status != http.StatusOK {
		t.Errorf("/health bypass on both-layers cfg, got %d", status)
	}
}

func TestRequireAuth_InvalidCIDR_LoggedAndDropped(t *testing.T) {
	// Mix of valid and invalid CIDRs: invalid should be skipped
	// (warning logged) and the valid one should still gate.
	cfg := AuthConfig{AllowedIPs: []string{
		"not-a-cidr",
		"10.0.0.0/8",
	}}
	srv := httptest.NewServer(mountWithAuth(cfg))
	defer srv.Close()

	// Loopback test client → still rejected because the only valid
	// rule is 10.0.0.0/8.
	if status, _ := get(t, srv, "/data", ""); status != http.StatusForbidden {
		t.Errorf("loopback should reject when allowlist excludes it, got %d", status)
	}
}

// TestRequireAuth_SecondaryTokenAccepted locks ADR-006 Decision 6.5:
// during a token rotation, both primary and secondary token strings
// pass auth. After every caller updates, operators promote secondary
// → primary and clear secondary, completing the rotation.
func TestRequireAuth_SecondaryTokenAccepted(t *testing.T) {
	cfg := AuthConfig{
		Token:           "primary-tok",
		SecondaryTokens: []string{"secondary-tok"},
	}
	srv := httptest.NewServer(mountWithAuth(cfg))
	defer srv.Close()

	if status, _ := get(t, srv, "/data", "Bearer primary-tok"); status != http.StatusOK {
		t.Errorf("primary token should pass, got %d", status)
	}
	if status, _ := get(t, srv, "/data", "Bearer secondary-tok"); status != http.StatusOK {
		t.Errorf("secondary token should pass during rotation, got %d", status)
	}
	if status, _ := get(t, srv, "/data", "Bearer wrong-tok"); status != http.StatusUnauthorized {
		t.Errorf("invalid token should still 401, got %d", status)
	}
}

// TestRequireAuth_SecondaryTokensOnly locks the case where primary
// is empty but secondaries are set — useful mid-rotation when the
// previous primary was just promoted to nothing and the new primary
// hasn't been written yet. As long as ANY token is configured, auth
// is enforced.
func TestRequireAuth_SecondaryTokensOnly(t *testing.T) {
	cfg := AuthConfig{
		SecondaryTokens: []string{"only-tok"},
	}
	srv := httptest.NewServer(mountWithAuth(cfg))
	defer srv.Close()

	if status, _ := get(t, srv, "/data", "Bearer only-tok"); status != http.StatusOK {
		t.Errorf("only-secondary should pass, got %d", status)
	}
	if status, _ := get(t, srv, "/data", ""); status != http.StatusUnauthorized {
		t.Errorf("missing token should 401, got %d", status)
	}
}

func TestRemoteIP_SplitHostPortShape(t *testing.T) {
	// Sanity: real httptest requests come through with "ip:port"
	// shape; ensure remoteIP returns the IP portion.
	r, _ := http.NewRequest(http.MethodGet, "/", nil)
	r.RemoteAddr = "10.1.2.3:54321"
	ip := remoteIP(r)
	if ip == nil {
		t.Fatal("remoteIP returned nil for valid 'ip:port' addr")
	}
	if ip.String() != "10.1.2.3" {
		t.Errorf("remoteIP = %q, want 10.1.2.3", ip.String())
	}
}