package starssh

import (
	"errors"
	"io"
	"sync/atomic"
	"testing"
	"time"

	"golang.org/x/crypto/ssh"
	sshagent "golang.org/x/crypto/ssh/agent"
)

type testCloser struct {
	closed atomic.Int32
}

func (c *testCloser) Close() error {
	c.closed.Add(1)
	return nil
}

func TestNewExecSessionEnablesAgentForwardingOnce(t *testing.T) {
	oldNewSSHSession := newSSHSession
	oldNewSSHAgentForwarder := newSSHAgentForwarder
	oldRouteSSHAgentForwarding := routeSSHAgentForwarding
	oldRequestSSHAgentForwarding := requestSSHAgentForwarding
	oldCloseSSHClient := closeSSHClient
	t.Cleanup(func() {
		newSSHSession = oldNewSSHSession
		newSSHAgentForwarder = oldNewSSHAgentForwarder
		routeSSHAgentForwarding = oldRouteSSHAgentForwarding
		requestSSHAgentForwarding = oldRequestSSHAgentForwarding
		closeSSHClient = oldCloseSSHClient
	})

	baseClient := &ssh.Client{}
	star := &StarSSH{
		LoginInfo: LoginInput{
			ForwardSSHAgent: true,
			Timeout:         time.Second,
		},
	}
	star.setTransport(baseClient, nil)

	newSSHSession = func(client *ssh.Client) (*ssh.Session, error) {
		if client != baseClient {
			t.Fatalf("unexpected ssh client %p", client)
		}
		return &ssh.Session{}, nil
	}

	var agentInitCalls atomic.Int32
	closer := &testCloser{}
	newSSHAgentForwarder = func(timeout time.Duration) (sshagent.Agent, io.Closer, error) {
		agentInitCalls.Add(1)
		if timeout != time.Second {
			t.Fatalf("unexpected forwarding timeout: %v", timeout)
		}
		return sshagent.NewKeyring(), closer, nil
	}

	var routeCalls atomic.Int32
	routeSSHAgentForwarding = func(client *ssh.Client, keyring sshagent.Agent) error {
		routeCalls.Add(1)
		if client != baseClient {
			t.Fatalf("unexpected routed client %p", client)
		}
		if keyring == nil {
			t.Fatal("expected non-nil forwarded agent keyring")
		}
		return nil
	}

	var requestCalls atomic.Int32
	requestSSHAgentForwarding = func(session *ssh.Session) error {
		requestCalls.Add(1)
		if session == nil {
			t.Fatal("expected non-nil ssh session")
		}
		return nil
	}

	if _, err := star.NewExecSession(); err != nil {
		t.Fatalf("first exec session: %v", err)
	}
	if _, err := star.NewExecSession(); err != nil {
		t.Fatalf("second exec session: %v", err)
	}

	if agentInitCalls.Load() != 1 {
		t.Fatalf("expected one agent forwarder init, got %d", agentInitCalls.Load())
	}
	if routeCalls.Load() != 1 {
		t.Fatalf("expected one agent route registration, got %d", routeCalls.Load())
	}
	if requestCalls.Load() != 2 {
		t.Fatalf("expected agent forwarding request on each session, got %d", requestCalls.Load())
	}

	closeSSHClient = func(client sshClientRequester) error { return nil }
	if err := star.Close(); err != nil {
		t.Fatalf("close starssh: %v", err)
	}
	if closer.closed.Load() != 1 {
		t.Fatalf("expected forwarded agent closer to run once, got %d", closer.closed.Load())
	}
}

func TestNewPTYSessionEnablesAgentForwardingWhenConfigured(t *testing.T) {
	oldNewSSHSession := newSSHSession
	oldRequestSessionPTY := requestSessionPTY
	oldNewSSHAgentForwarder := newSSHAgentForwarder
	oldRouteSSHAgentForwarding := routeSSHAgentForwarding
	oldRequestSSHAgentForwarding := requestSSHAgentForwarding
	t.Cleanup(func() {
		newSSHSession = oldNewSSHSession
		requestSessionPTY = oldRequestSessionPTY
		newSSHAgentForwarder = oldNewSSHAgentForwarder
		routeSSHAgentForwarding = oldRouteSSHAgentForwarding
		requestSSHAgentForwarding = oldRequestSSHAgentForwarding
	})

	star := &StarSSH{
		LoginInfo: LoginInput{
			ForwardSSHAgent: true,
		},
	}
	star.setTransport(&ssh.Client{}, nil)

	newSSHSession = func(client *ssh.Client) (*ssh.Session, error) {
		return &ssh.Session{}, nil
	}

	var ptyCalls atomic.Int32
	requestSessionPTY = func(session *ssh.Session, config TerminalConfig) error {
		ptyCalls.Add(1)
		return nil
	}

	newSSHAgentForwarder = func(timeout time.Duration) (sshagent.Agent, io.Closer, error) {
		return sshagent.NewKeyring(), &testCloser{}, nil
	}
	routeSSHAgentForwarding = func(client *ssh.Client, keyring sshagent.Agent) error { return nil }

	var requestCalls atomic.Int32
	requestSSHAgentForwarding = func(session *ssh.Session) error {
		requestCalls.Add(1)
		return nil
	}

	if _, err := star.NewPTYSession(nil); err != nil {
		t.Fatalf("new pty session: %v", err)
	}
	if ptyCalls.Load() != 1 {
		t.Fatalf("expected one PTY request, got %d", ptyCalls.Load())
	}
	if requestCalls.Load() != 1 {
		t.Fatalf("expected one agent forwarding request, got %d", requestCalls.Load())
	}
}

func TestNewExecSessionSkipsAgentForwardingWhenDisabled(t *testing.T) {
	oldNewSSHSession := newSSHSession
	oldNewSSHAgentForwarder := newSSHAgentForwarder
	oldRequestSSHAgentForwarding := requestSSHAgentForwarding
	t.Cleanup(func() {
		newSSHSession = oldNewSSHSession
		newSSHAgentForwarder = oldNewSSHAgentForwarder
		requestSSHAgentForwarding = oldRequestSSHAgentForwarding
	})

	star := &StarSSH{}
	star.setTransport(&ssh.Client{}, nil)

	newSSHSession = func(client *ssh.Client) (*ssh.Session, error) {
		return &ssh.Session{}, nil
	}
	newSSHAgentForwarder = func(timeout time.Duration) (sshagent.Agent, io.Closer, error) {
		t.Fatal("agent forwarder should not initialize when disabled")
		return nil, nil, nil
	}
	requestSSHAgentForwarding = func(session *ssh.Session) error {
		t.Fatal("agent forwarding should not be requested when disabled")
		return nil
	}

	if _, err := star.NewExecSession(); err != nil {
		t.Fatalf("new exec session without forwarding: %v", err)
	}
}

func TestRequestAgentForwardingReturnsUnavailableError(t *testing.T) {
	oldNewSSHAgentForwarder := newSSHAgentForwarder
	oldRequestSSHAgentForwarding := requestSSHAgentForwarding
	t.Cleanup(func() {
		newSSHAgentForwarder = oldNewSSHAgentForwarder
		requestSSHAgentForwarding = oldRequestSSHAgentForwarding
	})

	star := &StarSSH{}
	star.setTransport(&ssh.Client{}, nil)

	newSSHAgentForwarder = func(timeout time.Duration) (sshagent.Agent, io.Closer, error) {
		return nil, nil, errors.New("ssh-agent forwarding unavailable: ssh-agent unavailable")
	}
	requestSSHAgentForwarding = func(session *ssh.Session) error {
		t.Fatal("session request should not run when agent forwarder init fails")
		return nil
	}

	err := star.RequestAgentForwarding(&ssh.Session{})
	if err == nil {
		t.Fatal("expected agent forwarding init error")
	}
}

func TestRequestAgentForwardingWrapsSetupErrorAsUnavailable(t *testing.T) {
	oldNewSSHAgentForwarder := newSSHAgentForwarder
	t.Cleanup(func() {
		newSSHAgentForwarder = oldNewSSHAgentForwarder
	})

	star := &StarSSH{}
	star.setTransport(&ssh.Client{}, nil)

	newSSHAgentForwarder = func(timeout time.Duration) (sshagent.Agent, io.Closer, error) {
		return nil, nil, errors.New("dial unix /tmp/ssh-broken.sock: connect: permission denied")
	}

	err := star.RequestAgentForwarding(&ssh.Session{})
	if !isSSHAgentForwardingUnavailableError(err) {
		t.Fatalf("expected unavailable error, got %v", err)
	}
}

func TestRequestAgentForwardingReturnsDeniedError(t *testing.T) {
	oldNewSSHAgentForwarder := newSSHAgentForwarder
	oldRouteSSHAgentForwarding := routeSSHAgentForwarding
	oldRequestSSHAgentForwarding := requestSSHAgentForwarding
	t.Cleanup(func() {
		newSSHAgentForwarder = oldNewSSHAgentForwarder
		routeSSHAgentForwarding = oldRouteSSHAgentForwarding
		requestSSHAgentForwarding = oldRequestSSHAgentForwarding
	})

	star := &StarSSH{}
	star.setTransport(&ssh.Client{}, nil)

	newSSHAgentForwarder = func(timeout time.Duration) (sshagent.Agent, io.Closer, error) {
		return sshagent.NewKeyring(), &testCloser{}, nil
	}
	routeSSHAgentForwarding = func(client *ssh.Client, keyring sshagent.Agent) error { return nil }
	requestSSHAgentForwarding = func(session *ssh.Session) error {
		return errors.New("forwarding request denied")
	}

	err := star.RequestAgentForwarding(&ssh.Session{})
	if !isSSHAgentForwardingDeniedError(err) {
		t.Fatalf("expected forwarding denied error, got %v", err)
	}
}

func TestNewExecSessionIgnoresAgentForwardingDenied(t *testing.T) {
	oldNewSSHSession := newSSHSession
	oldNewSSHAgentForwarder := newSSHAgentForwarder
	oldRouteSSHAgentForwarding := routeSSHAgentForwarding
	oldRequestSSHAgentForwarding := requestSSHAgentForwarding
	t.Cleanup(func() {
		newSSHSession = oldNewSSHSession
		newSSHAgentForwarder = oldNewSSHAgentForwarder
		routeSSHAgentForwarding = oldRouteSSHAgentForwarding
		requestSSHAgentForwarding = oldRequestSSHAgentForwarding
	})

	star := &StarSSH{
		LoginInfo: LoginInput{
			ForwardSSHAgent: true,
		},
	}
	star.setTransport(&ssh.Client{}, nil)

	newSSHSession = func(client *ssh.Client) (*ssh.Session, error) {
		return &ssh.Session{}, nil
	}
	newSSHAgentForwarder = func(timeout time.Duration) (sshagent.Agent, io.Closer, error) {
		return sshagent.NewKeyring(), &testCloser{}, nil
	}
	routeSSHAgentForwarding = func(client *ssh.Client, keyring sshagent.Agent) error { return nil }
	requestSSHAgentForwarding = func(session *ssh.Session) error {
		return errors.New("forwarding request denied")
	}

	if _, err := star.NewExecSession(); err != nil {
		t.Fatalf("new exec session should ignore denied agent forwarding: %v", err)
	}
}

func TestNewExecSessionIgnoresAgentForwardingUnavailable(t *testing.T) {
	oldNewSSHSession := newSSHSession
	oldNewSSHAgentForwarder := newSSHAgentForwarder
	t.Cleanup(func() {
		newSSHSession = oldNewSSHSession
		newSSHAgentForwarder = oldNewSSHAgentForwarder
	})

	star := &StarSSH{
		LoginInfo: LoginInput{
			ForwardSSHAgent: true,
		},
	}
	star.setTransport(&ssh.Client{}, nil)

	newSSHSession = func(client *ssh.Client) (*ssh.Session, error) {
		return &ssh.Session{}, nil
	}
	newSSHAgentForwarder = func(timeout time.Duration) (sshagent.Agent, io.Closer, error) {
		return nil, nil, errors.New("ssh-agent forwarding unavailable: ssh-agent unavailable")
	}

	if _, err := star.NewExecSession(); err != nil {
		t.Fatalf("new exec session should ignore unavailable agent forwarding: %v", err)
	}
}

func TestNewExecSessionIgnoresAgentForwardingSetupError(t *testing.T) {
	oldNewSSHSession := newSSHSession
	oldNewSSHAgentForwarder := newSSHAgentForwarder
	t.Cleanup(func() {
		newSSHSession = oldNewSSHSession
		newSSHAgentForwarder = oldNewSSHAgentForwarder
	})

	star := &StarSSH{
		LoginInfo: LoginInput{
			ForwardSSHAgent: true,
		},
	}
	star.setTransport(&ssh.Client{}, nil)

	newSSHSession = func(client *ssh.Client) (*ssh.Session, error) {
		return &ssh.Session{}, nil
	}
	newSSHAgentForwarder = func(timeout time.Duration) (sshagent.Agent, io.Closer, error) {
		return nil, nil, errors.New("dial unix /tmp/ssh-broken.sock: connect: connection refused")
	}

	if _, err := star.NewExecSession(); err != nil {
		t.Fatalf("new exec session should ignore agent setup error: %v", err)
	}
}

func TestEnsureAgentForwardingClosesNewForwarderWhenCloseStarts(t *testing.T) {
	oldNewSSHAgentForwarder := newSSHAgentForwarder
	oldRouteSSHAgentForwarding := routeSSHAgentForwarding
	oldCloseSSHClient := closeSSHClient
	t.Cleanup(func() {
		newSSHAgentForwarder = oldNewSSHAgentForwarder
		routeSSHAgentForwarding = oldRouteSSHAgentForwarding
		closeSSHClient = oldCloseSSHClient
	})

	star := &StarSSH{
		LoginInfo: LoginInput{
			ForwardSSHAgent: true,
		},
	}
	star.setTransport(&ssh.Client{}, nil)

	started := make(chan struct{})
	release := make(chan struct{})
	closer := &testCloser{}
	newSSHAgentForwarder = func(timeout time.Duration) (sshagent.Agent, io.Closer, error) {
		close(started)
		<-release
		return sshagent.NewKeyring(), closer, nil
	}
	routeSSHAgentForwarding = func(client *ssh.Client, keyring sshagent.Agent) error {
		return nil
	}
	closeSSHClient = func(client sshClientRequester) error { return nil }

	errCh := make(chan error, 1)
	go func() {
		errCh <- star.ensureAgentForwarding()
	}()

	<-started
	closeDone := make(chan struct{})
	go func() {
		_ = star.Close()
		close(closeDone)
	}()

	deadline := time.Now().Add(time.Second)
	for !star.closing.Load() {
		if time.Now().After(deadline) {
			t.Fatal("close did not enter closing state in time")
		}
		time.Sleep(time.Millisecond)
	}

	close(release)

	err := <-errCh
	if !errors.Is(err, errSSHClientClosing) {
		t.Fatalf("expected closing error, got %v", err)
	}
	<-closeDone

	if closer.closed.Load() != 1 {
		t.Fatalf("expected new forwarder closer to be closed once, got %d", closer.closed.Load())
	}
	if got := star.takeAgentForwarder(); got != nil {
		t.Fatal("expected no leaked agent forwarder after close race")
	}
}