// +build !js

package websocket

import (
	"bufio"
	"bytes"
	"encoding/binary"
	"math/bits"
	"math/rand"
	"strconv"
	"testing"
	"time"
	_ "unsafe"

	"github.com/gobwas/ws"
	_ "github.com/gorilla/websocket"

	"nhooyr.io/websocket/internal/test/assert"
)

func TestHeader(t *testing.T) {
	t.Parallel()

	t.Run("lengths", func(t *testing.T) {
		t.Parallel()

		lengths := []int{
			124,
			125,
			126,
			127,

			65534,
			65535,
			65536,
			65537,
		}

		for _, n := range lengths {
			n := n
			t.Run(strconv.Itoa(n), func(t *testing.T) {
				t.Parallel()

				testHeader(t, header{
					payloadLength: int64(n),
				})
			})
		}
	})

	t.Run("fuzz", func(t *testing.T) {
		t.Parallel()

		r := rand.New(rand.NewSource(time.Now().UnixNano()))
		randBool := func() bool {
			return r.Intn(1) == 0
		}

		for i := 0; i < 10000; i++ {
			h := header{
				fin:    randBool(),
				rsv1:   randBool(),
				rsv2:   randBool(),
				rsv3:   randBool(),
				opcode: opcode(r.Intn(16)),

				masked:        randBool(),
				maskKey:       r.Uint32(),
				payloadLength: r.Int63(),
			}

			testHeader(t, h)
		}
	})
}

func testHeader(t *testing.T, h header) {
	b := &bytes.Buffer{}
	w := bufio.NewWriter(b)
	r := bufio.NewReader(b)

	err := writeFrameHeader(h, w, make([]byte, 8))
	assert.Success(t, err)

	err = w.Flush()
	assert.Success(t, err)

	h2, err := readFrameHeader(r, make([]byte, 8))
	assert.Success(t, err)

	assert.Equal(t, "read header", h, h2)
}

func Test_mask(t *testing.T) {
	t.Parallel()

	key := []byte{0xa, 0xb, 0xc, 0xff}
	key32 := binary.LittleEndian.Uint32(key)
	p := []byte{0xa, 0xb, 0xc, 0xf2, 0xc}
	gotKey32 := mask(key32, p)

	expP := []byte{0, 0, 0, 0x0d, 0x6}
	assert.Equal(t, "p", expP, p)

	expKey32 := bits.RotateLeft32(key32, -8)
	assert.Equal(t, "key32", expKey32, gotKey32)
}

func basicMask(maskKey [4]byte, pos int, b []byte) int {
	for i := range b {
		b[i] ^= maskKey[pos&3]
		pos++
	}
	return pos & 3
}

//go:linkname gorillaMaskBytes github.com/gorilla/websocket.maskBytes
func gorillaMaskBytes(key [4]byte, pos int, b []byte) int

func Benchmark_mask(b *testing.B) {
	sizes := []int{
		2,
		3,
		4,
		8,
		16,
		32,
		128,
		512,
		4096,
		16384,
	}

	fns := []struct {
		name string
		fn   func(b *testing.B, key [4]byte, p []byte)
	}{
		{
			name: "basic",
			fn: func(b *testing.B, key [4]byte, p []byte) {
				for i := 0; i < b.N; i++ {
					basicMask(key, 0, p)
				}
			},
		},

		{
			name: "nhooyr",
			fn: func(b *testing.B, key [4]byte, p []byte) {
				key32 := binary.LittleEndian.Uint32(key[:])
				b.ResetTimer()

				for i := 0; i < b.N; i++ {
					mask(key32, p)
				}
			},
		},
		{
			name: "gorilla",
			fn: func(b *testing.B, key [4]byte, p []byte) {
				for i := 0; i < b.N; i++ {
					gorillaMaskBytes(key, 0, p)
				}
			},
		},
		{
			name: "gobwas",
			fn: func(b *testing.B, key [4]byte, p []byte) {
				for i := 0; i < b.N; i++ {
					ws.Cipher(p, key, 0)
				}
			},
		},
	}

	key := [4]byte{1, 2, 3, 4}

	for _, size := range sizes {
		p := make([]byte, size)

		b.Run(strconv.Itoa(size), func(b *testing.B) {
			for _, fn := range fns {
				b.Run(fn.name, func(b *testing.B) {
					b.SetBytes(int64(size))

					fn.fn(b, key, p)
				})
			}
		})
	}
}