package sha256x_test

import (
	"bytes"
	"encoding/base64"
	"encoding/hex"
	"errors"
	"os"
	"path/filepath"
	"strings"
	"testing"

	"code.yun.ink/pkg/encryptx/sha256x"
)

// 测试向量来源：FIPS 180-4 示例与 NIST 标准测试向量，并经 Python 3 hashlib 独立复算确认。
var vectors224 = []struct {
	name  string
	input string
	want  string
}{
	{"空串", "", "d14a028c2a3a2bc9476102bb288234c415a2b01f828ea62ac5b3e42f"},
	{"abc", "abc", "23097d223405d8228642a477bda255b32aadbce4bda0b3f7e36c9da7"},
}

var vectors256 = []struct {
	name  string
	input string
	want  string
}{
	{"空串", "", "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"},
	{"abc", "abc", "ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad"},
	{"The quick brown fox jumps over the lazy dog", "The quick brown fox jumps over the lazy dog", "d7a8fbb307d7809469ca9abcb0082e4f8d5651e46d3cdb762d02d0bf37c9e592"},
}

type failingReader struct{}

func (failingReader) Read([]byte) (int, error) { return 0, errors.New("模拟读取失败") }

func TestConstants(t *testing.T) {
	if sha256x.Size224 != 28 || sha256x.Size256 != 32 {
		t.Fatalf("Size224 = %d, Size256 = %d, 期望 28 / 32", sha256x.Size224, sha256x.Size256)
	}
	if sha256x.BlockSize != 64 {
		t.Fatalf("BlockSize = %d, 期望 64", sha256x.BlockSize)
	}
}

func TestVectors224(t *testing.T) {
	for _, v := range vectors224 {
		t.Run(v.name, func(t *testing.T) {
			data := []byte(v.input)
			sum := sha256x.Sum224(data)
			if len(sum) != sha256x.Size224 {
				t.Fatalf("Sum224 长度 = %d, 期望 %d", len(sum), sha256x.Size224)
			}
			if got := hex.EncodeToString(sum); got != v.want {
				t.Errorf("Sum224 = %s, 期望 %s", got, v.want)
			}
			if got := sha256x.Hex224(data); got != v.want {
				t.Errorf("Hex224 = %s, 期望 %s", got, v.want)
			}
			if want := base64.StdEncoding.EncodeToString(sum); sha256x.Base64Sum224(data) != want {
				t.Errorf("Base64Sum224 = %s, 期望 %s", sha256x.Base64Sum224(data), want)
			}
			h := sha256x.New224()
			if _, err := h.Write(data); err != nil {
				t.Fatalf("Write 失败: %v", err)
			}
			if got := hex.EncodeToString(h.Sum(nil)); got != v.want {
				t.Errorf("New224+Write = %s, 期望 %s", got, v.want)
			}
		})
	}
}

func TestVectors256(t *testing.T) {
	for _, v := range vectors256 {
		t.Run(v.name, func(t *testing.T) {
			data := []byte(v.input)
			sum := sha256x.Sum256(data)
			if len(sum) != sha256x.Size256 {
				t.Fatalf("Sum256 长度 = %d, 期望 %d", len(sum), sha256x.Size256)
			}
			if got := hex.EncodeToString(sum); got != v.want {
				t.Errorf("Sum256 = %s, 期望 %s", got, v.want)
			}
			if got := sha256x.Hex256(data); got != v.want {
				t.Errorf("Hex256 = %s, 期望 %s", got, v.want)
			}
			if want := base64.StdEncoding.EncodeToString(sum); sha256x.Base64Sum256(data) != want {
				t.Errorf("Base64Sum256 = %s, 期望 %s", sha256x.Base64Sum256(data), want)
			}
			h := sha256x.New256()
			if _, err := h.Write(data); err != nil {
				t.Fatalf("Write 失败: %v", err)
			}
			if got := hex.EncodeToString(h.Sum(nil)); got != v.want {
				t.Errorf("New256+Write = %s, 期望 %s", got, v.want)
			}
		})
	}
}

func TestDefaultAliasesMatch256(t *testing.T) {
	data := []byte("encryptx alias check")
	if !bytes.Equal(sha256x.Sum(data), sha256x.Sum256(data)) {
		t.Error("Sum 应等价于 Sum256")
	}
	if sha256x.Hex(data) != sha256x.Hex256(data) {
		t.Error("Hex 应等价于 Hex256")
	}
	if sha256x.Base64(data) != sha256x.Base64Sum256(data) {
		t.Error("Base64 应等价于 Base64Sum256")
	}
	h := sha256x.New()
	if h.Size() != sha256x.Size256 {
		t.Errorf("New().Size() = %d, 期望 %d", h.Size(), sha256x.Size256)
	}
}

func TestVariantsDiffer(t *testing.T) {
	data := []byte("abc")
	if sha256x.Hex224(data) == sha256x.Hex256(data) {
		t.Error("SHA-224 与 SHA-256 的摘要不应相同")
	}
}

func TestStreamingMatchesSum(t *testing.T) {
	data := []byte(strings.Repeat("encryptx-sha256-", 100))
	for _, tc := range []struct {
		name  string
		h     hashLike
		whole []byte
	}{
		{"SHA-224", sha256x.New224(), sha256x.Sum224(data)},
		{"SHA-256", sha256x.New256(), sha256x.Sum256(data)},
	} {
		t.Run(tc.name, func(t *testing.T) {
			for i := 0; i < len(data); i += 9 {
				end := i + 9
				if end > len(data) {
					end = len(data)
				}
				if _, err := tc.h.Write(data[i:end]); err != nil {
					t.Fatalf("Write 失败: %v", err)
				}
			}
			if sum := tc.h.Sum(nil); !bytes.Equal(sum, tc.whole) {
				t.Errorf("分块写入 = %x, 期望 %x", sum, tc.whole)
			}
		})
	}
}

// hashLike 是测试用的最小哈希接口。
type hashLike interface {
	Write([]byte) (int, error)
	Sum([]byte) []byte
}

func TestReaderConsistency(t *testing.T) {
	const s = "encryptx 一致性检查"
	sum, err := sha256x.SumReader(strings.NewReader(s))
	if err != nil {
		t.Fatalf("SumReader 失败: %v", err)
	}
	if want := sha256x.Sum256([]byte(s)); !bytes.Equal(sum, want) {
		t.Errorf("SumReader = %x, 期望 %x", sum, want)
	}
	hexStr, err := sha256x.HexReader(strings.NewReader(s))
	if err != nil {
		t.Fatalf("HexReader 失败: %v", err)
	}
	if want := sha256x.Hex256([]byte(s)); hexStr != want {
		t.Errorf("HexReader = %s, 期望 %s", hexStr, want)
	}
}

func TestReaderErrors(t *testing.T) {
	if _, err := sha256x.SumReader(nil); err == nil {
		t.Fatal("nil 读取器应返回 error")
	}
	if _, err := sha256x.HexReader(nil); err == nil {
		t.Fatal("nil 读取器应返回 error")
	}
	if _, err := sha256x.SumReader(failingReader{}); err == nil {
		t.Fatal("读取失败时应返回 error")
	}
}

func TestHexFile(t *testing.T) {
	dir := t.TempDir()
	content := []byte("文件内容 file content\n")
	path := filepath.Join(dir, "sample.bin")
	if err := os.WriteFile(path, content, 0o600); err != nil {
		t.Fatalf("写入测试文件失败: %v", err)
	}
	got, err := sha256x.HexFile(path)
	if err != nil {
		t.Fatalf("HexFile 失败: %v", err)
	}
	if want := sha256x.Hex256(content); got != want {
		t.Errorf("HexFile = %s, 期望 %s", got, want)
	}
}

func TestHexFileErrors(t *testing.T) {
	if _, err := sha256x.HexFile(filepath.Join(t.TempDir(), "不存在.bin")); err == nil {
		t.Fatal("不存在的文件应返回 error")
	}
	if _, err := sha256x.HexFile(""); err == nil {
		t.Fatal("空路径应返回 error")
	}
	if _, err := sha256x.HexFile(t.TempDir()); err == nil {
		t.Fatal("目录路径应返回 error")
	}
}

func TestLargeInput(t *testing.T) {
	data := largeData(1 << 20)
	want := sha256x.Hex256(data)
	if got := sha256x.Hex256(data); got != want {
		t.Errorf("重复计算结果不一致: %s vs %s", got, want)
	}

	got, err := sha256x.HexReader(bytes.NewReader(data))
	if err != nil {
		t.Fatalf("HexReader 失败: %v", err)
	}
	if got != want {
		t.Errorf("HexReader = %s, 期望 %s", got, want)
	}

	h := sha256x.New256()
	if _, err := h.Write(data[:1<<19]); err != nil {
		t.Fatalf("Write 失败: %v", err)
	}
	if _, err := h.Write(data[1<<19:]); err != nil {
		t.Fatalf("Write 失败: %v", err)
	}
	if got := hex.EncodeToString(h.Sum(nil)); got != want {
		t.Errorf("1MiB 分块 = %s, 期望 %s", got, want)
	}
}

// largeData 生成确定性的 n 字节数据。
func largeData(n int) []byte {
	b := make([]byte, n)
	for i := range b {
		b[i] = byte(i*31 + i/7)
	}
	return b
}