package integration

import (
	"net"
	"testing"
	"time"

	"hash-of-wisdom/internal/protocol"
	"hash-of-wisdom/internal/server"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

func TestTCPServer_TimeoutProtection_SlowReader(t *testing.T) {
	// Setup server with very short read timeout for testing
	serverConfig := &server.Config{
		Address:  ":0",
		Timeouts: server.TimeoutConfig{
			Read:       500 * time.Millisecond,
			Write:      5 * time.Second,
			Connection: 15 * time.Second,
		},
	}
	srv := setupTestServerWithConfig(t, serverConfig)
	defer srv.Stop()

	// Connect to server
	conn, err := net.Dial("tcp", srv.Address())
	require.NoError(t, err)
	defer conn.Close()

	// Send partial message header (just type byte)
	_, err = conn.Write([]byte{0x01}) // Challenge request type
	require.NoError(t, err)

	// Wait longer than read timeout before sending length
	time.Sleep(700 * time.Millisecond)

	// Try to send more data - connection should be timed out
	_, err = conn.Write([]byte{0x00, 0x00, 0x00, 0x00}) // Payload length

	// Verify connection is closed by reading
	buffer := make([]byte, 1024)
	conn.SetReadDeadline(time.Now().Add(1 * time.Second))
	_, err = conn.Read(buffer)
	assert.Error(t, err, "Connection should be closed due to slow reading")
}

func TestTCPServer_TimeoutProtection_ConnectionTimeout(t *testing.T) {
	// Setup server with very short connection timeout
	serverConfig := &server.Config{
		Address:  ":0",
		Timeouts: server.TimeoutConfig{
			Read:       5 * time.Second,
			Write:      5 * time.Second,
			Connection: 1 * time.Second,
		},
	}
	srv := setupTestServerWithConfig(t, serverConfig)
	defer srv.Stop()

	// Connect to server
	conn, err := net.Dial("tcp", srv.Address())
	require.NoError(t, err)
	defer conn.Close()

	// Wait longer than connection timeout
	time.Sleep(1500 * time.Millisecond)

	// Try to read from connection - should get EOF or connection reset
	buffer := make([]byte, 1024)
	conn.SetReadDeadline(time.Now().Add(500 * time.Millisecond))
	_, err = conn.Read(buffer)
	assert.Error(t, err, "Connection should be closed due to timeout")
}

func TestTCPServer_NormalOperation_WithinTimeouts(t *testing.T) {
	srv := setupTestServer(t)
	defer srv.Stop()

	// Connect and complete normal flow quickly
	conn, err := net.Dial("tcp", srv.Address())
	require.NoError(t, err)
	defer conn.Close()

	// Request challenge using new protocol API
	challengeReq := &protocol.ChallengeRequest{}
	err = challengeReq.Encode(conn)
	require.NoError(t, err)

	// Should receive challenge response without timeout
	decoder := protocol.NewMessageDecoder()
	msg, err := decoder.Decode(conn)
	require.NoError(t, err)
	assert.Equal(t, protocol.ChallengeResponseType, msg.Type)
	assert.Greater(t, msg.PayloadLength, uint32(0), "Challenge payload should not be empty")
}

func TestTCPServer_MultipleConnections_IndependentTimeouts(t *testing.T) {
	serverConfig := &server.Config{
		Address:  ":0",
		Timeouts: server.TimeoutConfig{
			Read:       1 * time.Second,
			Write:      5 * time.Second,
			Connection: 3 * time.Second,
		},
	}
	srv := setupTestServerWithConfig(t, serverConfig)
	defer srv.Stop()

	// Start two connections
	conn1, err := net.Dial("tcp", srv.Address())
	require.NoError(t, err)
	defer conn1.Close()

	conn2, err := net.Dial("tcp", srv.Address())
	require.NoError(t, err)
	defer conn2.Close()

	// Conn1: Send complete request quickly
	go func() {
		req := &protocol.ChallengeRequest{}
		req.Encode(conn1)
	}()

	// Conn2: Send partial request and stall
	conn2.Write([]byte{0x01}) // Just message type

	// Wait for read timeout
	time.Sleep(1500 * time.Millisecond)

	// Conn1 should still work, Conn2 should be closed
	buffer := make([]byte, 1024)

	// Conn1 should receive response
	conn1.SetReadDeadline(time.Now().Add(1 * time.Second))
	n, err := conn1.Read(buffer)
	assert.NoError(t, err)
	assert.Greater(t, n, 0, "Conn1 should receive response")

	// Conn2 should be closed
	conn2.SetReadDeadline(time.Now().Add(500 * time.Millisecond))
	_, err = conn2.Read(buffer)
	assert.Error(t, err, "Conn2 should be closed due to timeout")
}

// Helper function to create test server with default config
func setupTestServer(t *testing.T) *server.TCPServer {
	serverConfig := &server.Config{
		Address:  ":0",
		Timeouts: server.TimeoutConfig{
			Read:       5 * time.Second,
			Write:      5 * time.Second,
			Connection: 15 * time.Second,
		},
	}
	return setupTestServerWithConfig(t, serverConfig)
}

// Helper function to create test server with custom config