package workercluster

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

	rafthttp "github.com/CanonicalLtd/raft-http"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

// newLocalListener opens a TCP listener on the loopback interface
// using an ephemeral port. Used by transport and e2e tests.
func newLocalListener(t *testing.T) net.Listener {
	t.Helper()
	l, err := net.Listen("tcp", "127.0.0.1:0")
	require.NoError(t, err)
	return l
}

// TestTransport_Auth_RejectsMissingCreds verifies that a request
// without an Authorization header is rejected with 401.
func TestTransport_Auth_RejectsMissingCreds(t *testing.T) {
	h := rafthttp.NewHandler()
	wrapped := NewAuthHandler(h, HTTPCreds{Login: "alice", Password: "secret"}, nil)

	rec := httptest.NewRecorder()
	req := httptest.NewRequest("GET", "/raft", nil)
	wrapped.ServeHTTP(rec, req)

	assert.Equal(t, http.StatusUnauthorized, rec.Code)
	assert.Equal(t, `Basic realm="raft"`, rec.Header().Get("WWW-Authenticate"))
}

// TestTransport_Auth_RejectsWrongCreds verifies that a request with
// incorrect credentials is rejected with 401.
func TestTransport_Auth_RejectsWrongCreds(t *testing.T) {
	h := rafthttp.NewHandler()
	wrapped := NewAuthHandler(h, HTTPCreds{Login: "alice", Password: "secret"}, nil)

	rec := httptest.NewRecorder()
	req := httptest.NewRequest("GET", "/raft", nil)
	req.SetBasicAuth("alice", "wrong")
	wrapped.ServeHTTP(rec, req)

	assert.Equal(t, http.StatusUnauthorized, rec.Code)
}

// TestTransport_Auth_AcceptsCorrectCreds verifies that a request with
// matching credentials is forwarded to the inner rafthttp handler. The
// rafthttp GET path expects an Upgrade header; without one it returns
// 400, but the important point is that the auth wrapper does not block
// the request before reaching the inner handler.
func TestTransport_Auth_AcceptsCorrectCreds(t *testing.T) {
	h := rafthttp.NewHandler()
	wrapped := NewAuthHandler(h, HTTPCreds{Login: "alice", Password: "secret"}, nil)

	rec := httptest.NewRecorder()
	req := httptest.NewRequest("GET", "/raft", nil)
	req.SetBasicAuth("alice", "secret")
	wrapped.ServeHTTP(rec, req)

	assert.NotEqual(t, http.StatusUnauthorized, rec.Code, "auth wrapper should not block good credentials")
	assert.Equal(t, http.StatusBadRequest, rec.Code, "rafthttp expects Upgrade:raft header; with auth, 400 confirms we reached the inner handler")
}

// TestTransport_Auth_PanicsOnEmptyCreds verifies the wrapper refuses
// to construct without both login and password.
func TestTransport_Auth_PanicsOnEmptyCreds(t *testing.T) {
	assert.Panics(t, func() {
		NewAuthHandler(rafthttp.NewHandler(), HTTPCreds{Login: "", Password: ""}, nil)
	})
}

// TestTransport_Auth_TimingSafe verifies that the wrapper uses
// crypto/subtle.ConstantTimeCompare rather than ==. We assert this
// indirectly: with wrong creds the response is always 401 regardless of
// how close the password is to the real one.
func TestTransport_Auth_TimingSafe(t *testing.T) {
	h := rafthttp.NewHandler()
	wrapped := NewAuthHandler(h, HTTPCreds{Login: "alice", Password: "secret"}, nil)

	for _, pw := range []string{"s", "se", "sec", "secr", "secre", "secret", "secretX"} {
		rec := httptest.NewRecorder()
		req := httptest.NewRequest("GET", "/raft", nil)
		req.SetBasicAuth("alice", pw)
		wrapped.ServeHTTP(rec, req)
		if pw == "secret" {
			assert.NotEqual(t, http.StatusUnauthorized, rec.Code, "exact password should pass auth")
		} else {
			assert.Equal(t, http.StatusUnauthorized, rec.Code, "password %q should fail auth", pw)
		}
	}
}

// TestTransport_HTTPCreds_IsConfigured verifies the IsConfigured
// contract: both set, or neither.
func TestTransport_HTTPCreds_IsConfigured(t *testing.T) {
	cases := []struct {
		creds HTTPCreds
		want  bool
	}{
		{HTTPCreds{Login: "u", Password: "p"}, true},
		{HTTPCreds{Login: "u"}, false},
		{HTTPCreds{Password: "p"}, false},
		{HTTPCreds{}, false},
	}
	for _, tc := range cases {
		assert.Equal(t, tc.want, tc.creds.IsConfigured(), "%+v", tc.creds)
	}
}

// TestTransport_NewTransportRequiresArgs guards the constructor's
// invariants.
func TestTransport_NewTransportRequiresArgs(t *testing.T) {
	h := rafthttp.NewHandler()
	l := newLocalListener(t)

	_, _, err := NewTransport("", l, nil, nil, nil)
	require.Error(t, err)

	_, _, err = NewTransport("", nil, h, nil, nil)
	require.Error(t, err)

	layer, srv, err := NewTransport("/raft", l, h, nil, nil)
	require.NoError(t, err)
	require.NotNil(t, layer)
	require.NotNil(t, srv)
	require.NoError(t, srv.Close())
	require.NoError(t, l.Close())
}