package transport

import (
	"context"
	"errors"
	"net"
	"strconv"
	"strings"
	"testing"
	"time"

	toki "git.toki-labs.com/toki/proto-socket/go"
	"go.uber.org/zap"
	"google.golang.org/protobuf/proto"

	iop "iop/proto/gen/iop"
)

type recordingConn struct {
	writeDeadlines []time.Time
}

func (c *recordingConn) Read(_ []byte) (int, error)        { return 0, nil }
func (c *recordingConn) Write(b []byte) (int, error)       { return len(b), nil }
func (c *recordingConn) Close() error                      { return nil }
func (c *recordingConn) LocalAddr() net.Addr               { return noopAddr("local") }
func (c *recordingConn) RemoteAddr() net.Addr              { return noopAddr("remote") }
func (c *recordingConn) SetDeadline(_ time.Time) error     { return nil }
func (c *recordingConn) SetReadDeadline(_ time.Time) error { return nil }
func (c *recordingConn) SetWriteDeadline(t time.Time) error {
	c.writeDeadlines = append(c.writeDeadlines, t)
	return nil
}

type noopAddr string

func (a noopAddr) Network() string { return string(a) }
func (a noopAddr) String() string  { return string(a) }

// closedLocalAddr returns a loopback address that has no listener, so a dial to
// it is refused deterministically.
func closedLocalAddr(t *testing.T) string {
	t.Helper()
	l, err := net.Listen("tcp", "127.0.0.1:0")
	if err != nil {
		t.Fatalf("listen: %v", err)
	}
	addr := l.Addr().String()
	_ = l.Close()
	return addr
}

func rejectingEdgeParserMap() toki.ParserMap {
	return toki.ParserMap{
		toki.TypeNameOf(&iop.RegisterRequest{}): func(b []byte) (proto.Message, error) {
			m := &iop.RegisterRequest{}
			return m, proto.Unmarshal(b, m)
		},
	}
}

// startRejectingEdge starts a mock edge that answers RegisterRequest with
// Accepted=false and the given reason.
func startRejectingEdge(t *testing.T, ctx context.Context, reason string) string {
	t.Helper()
	l, err := net.Listen("tcp", "127.0.0.1:0")
	if err != nil {
		t.Fatalf("listen: %v", err)
	}
	addr := l.Addr().String()
	host, portStr, _ := net.SplitHostPort(addr)
	port, _ := strconv.Atoi(portStr)
	_ = l.Close()

	server := toki.NewTcpServer(host, port, func(conn net.Conn) *toki.TcpClient {
		client := toki.NewTcpClient(conn, 30, 10, rejectingEdgeParserMap())
		toki.AddRequestListenerTyped[*iop.RegisterRequest, *iop.RegisterResponse](
			&client.Communicator,
			func(_ *iop.RegisterRequest) (*iop.RegisterResponse, error) {
				return &iop.RegisterResponse{Accepted: false, Reason: reason}, nil
			},
		)
		return client
	})
	if err := server.Start(ctx); err != nil {
		t.Fatalf("start rejecting edge: %v", err)
	}
	t.Cleanup(func() { server.Stop() })
	return addr
}

// TestDialEdgeClassifiesConnectFailures verifies that DialEdge classifies its
// failures into fatal (invalid address, authoritative registration rejection)
// and retryable (Edge unavailable) while preserving the underlying cause. REFACTOR-2.
func TestDialEdgeClassifiesConnectFailures(t *testing.T) {
	logger := zap.NewNop()

	t.Run("invalid address is fatal", func(t *testing.T) {
		ctx, cancel := context.WithTimeout(context.Background(), time.Second)
		defer cancel()
		_, err := DialEdge(ctx, "missing-port", "tok", logger)
		if err == nil {
			t.Fatal("expected error for invalid address")
		}
		if !IsFatalConnectError(err) {
			t.Fatalf("invalid address must be fatal, got retryable: %v", err)
		}
		var ce *ConnectError
		if !errors.As(err, &ce) || ce.Retryable() {
			t.Fatalf("expected non-retryable ConnectError, got %v", err)
		}
	})

	t.Run("non-numeric port is fatal", func(t *testing.T) {
		ctx, cancel := context.WithTimeout(context.Background(), time.Second)
		defer cancel()
		_, err := DialEdge(ctx, "127.0.0.1:not-a-port", "tok", logger)
		if err == nil {
			t.Fatal("expected error for invalid port")
		}
		if !IsFatalConnectError(err) {
			t.Fatalf("invalid port must be fatal, got retryable: %v", err)
		}
		var numErr *strconv.NumError
		if !errors.As(err, &numErr) || !errors.Is(err, strconv.ErrSyntax) {
			t.Fatalf("expected preserved strconv syntax cause, got %v", err)
		}
	})

	for _, port := range []string{"0", "-1", "65536"} {
		port := port
		t.Run("out-of-range port "+port+" is fatal", func(t *testing.T) {
			ctx, cancel := context.WithTimeout(context.Background(), time.Second)
			defer cancel()
			_, err := DialEdge(ctx, net.JoinHostPort("127.0.0.1", port), "tok", logger)
			if err == nil {
				t.Fatalf("expected error for out-of-range port %s", port)
			}
			if !IsFatalConnectError(err) {
				t.Fatalf("out-of-range port %s must be fatal, got retryable: %v", port, err)
			}
			var ce *ConnectError
			if !errors.As(err, &ce) || ce.Retryable() {
				t.Fatalf("expected non-retryable ConnectError, got %v", err)
			}
			var numErr *strconv.NumError
			if !errors.As(err, &numErr) || !errors.Is(err, strconv.ErrRange) {
				t.Fatalf("expected preserved strconv range cause, got %v", err)
			}
			if numErr.Num != port {
				t.Fatalf("range cause port = %q, want %q", numErr.Num, port)
			}
		})
	}

	t.Run("connection refused is retryable and preserves cause", func(t *testing.T) {
		ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
		defer cancel()
		_, err := DialEdge(ctx, closedLocalAddr(t), "tok", logger)
		if err == nil {
			t.Fatal("expected error for refused connection")
		}
		if IsFatalConnectError(err) {
			t.Fatalf("refused connection must be retryable, got fatal: %v", err)
		}
		var ce *ConnectError
		if !errors.As(err, &ce) || !ce.Retryable() {
			t.Fatalf("expected retryable ConnectError, got %v", err)
		}
		// The underlying network error must remain reachable through the wrap.
		var opErr *net.OpError
		if !errors.As(err, &opErr) {
			t.Fatalf("expected wrapped *net.OpError cause, got %v", err)
		}
	})

	t.Run("registration rejected is fatal and preserves reason", func(t *testing.T) {
		ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
		defer cancel()
		addr := startRejectingEdge(t, ctx, "bad-token")
		_, err := DialEdge(ctx, addr, "tok", logger)
		if err == nil {
			t.Fatal("expected error for rejected registration")
		}
		if !IsFatalConnectError(err) {
			t.Fatalf("rejected registration must be fatal, got retryable: %v", err)
		}
		if !strings.Contains(err.Error(), "bad-token") {
			t.Fatalf("expected rejection reason preserved in error, got %v", err)
		}
	})

	t.Run("unclassified error defaults to retryable", func(t *testing.T) {
		if IsFatalConnectError(errors.New("plain")) {
			t.Fatal("unclassified error must not be fatal")
		}
	})
}

func TestWriteDeadlineConnSetsAndClearsDeadline(t *testing.T) {
	base := &recordingConn{}
	conn := &writeDeadlineConn{Conn: base, timeout: 25 * time.Millisecond}

	n, err := conn.Write([]byte("ping"))
	if err != nil {
		t.Fatalf("Write: %v", err)
	}
	if n != 4 {
		t.Fatalf("Write bytes: got %d want 4", n)
	}
	if len(base.writeDeadlines) != 2 {
		t.Fatalf("write deadline calls: got %d want 2", len(base.writeDeadlines))
	}
	if base.writeDeadlines[0].IsZero() {
		t.Fatal("first write deadline must be non-zero")
	}
	if !base.writeDeadlines[1].IsZero() {
		t.Fatalf("second write deadline must clear the deadline, got %v", base.writeDeadlines[1])
	}
}