package sha1x_test

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

	"code.yun.ink/pkg/encryptx/sha1x"
)

// 测试向量来源：FIPS 180-1 / RFC 3174 附录 A，并经 Python 3 hashlib 独立复算确认。
var vectors = []struct {
	name  string
	input string
	want  string
}{
	{"空串", "", "da39a3ee5e6b4b0d3255bfef95601890afd80709"},
	{"abc", "abc", "a9993e364706816aba3e25717850c26c9cd0d89d"},
	{"message digest", "message digest", "c12252ceda8be8994d5fa0290a47231c1d16aae3"},
	{"The quick brown fox jumps over the lazy dog", "The quick brown fox jumps over the lazy dog", "2fd4e1c67a2d28fced849ee1bb76e7391b93eb12"},
}

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 sha1x.Size != 20 {
		t.Fatalf("Size = %d, 期望 20", sha1x.Size)
	}
	if sha1x.BlockSize != 64 {
		t.Fatalf("BlockSize = %d, 期望 64", sha1x.BlockSize)
	}
}

func TestVectors(t *testing.T) {
	for _, v := range vectors {
		t.Run(v.name, func(t *testing.T) {
			data := []byte(v.input)
			sum := sha1x.Sum(data)
			if len(sum) != sha1x.Size {
				t.Fatalf("Sum 长度 = %d, 期望 %d", len(sum), sha1x.Size)
			}
			if got := hex.EncodeToString(sum); got != v.want {
				t.Errorf("Sum = %s, 期望 %s", got, v.want)
			}
			if got := sha1x.Hex(data); got != v.want {
				t.Errorf("Hex = %s, 期望 %s", got, v.want)
			}
			if want := base64.StdEncoding.EncodeToString(sum); sha1x.Base64(data) != want {
				t.Errorf("Base64 = %s, 期望 %s", sha1x.Base64(data), want)
			}
			h := sha1x.New()
			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("New+Write = %s, 期望 %s", got, v.want)
			}
		})
	}
}

func TestStreamingMatchesSum(t *testing.T) {
	data := []byte(strings.Repeat("encryptx-sha1-", 100))
	h := sha1x.New()
	for i := 0; i < len(data); i += 13 {
		end := i + 13
		if end > len(data) {
			end = len(data)
		}
		if _, err := h.Write(data[i:end]); err != nil {
			t.Fatalf("Write 失败: %v", err)
		}
	}
	if got, want := h.Sum(nil), sha1x.Sum(data); !bytes.Equal(got, want) {
		t.Errorf("分块写入 = %x, 期望 %x", got, want)
	}
}

func TestReaderConsistency(t *testing.T) {
	const s = "encryptx 一致性检查"
	sum, err := sha1x.SumReader(strings.NewReader(s))
	if err != nil {
		t.Fatalf("SumReader 失败: %v", err)
	}
	if want := sha1x.Sum([]byte(s)); !bytes.Equal(sum, want) {
		t.Errorf("SumReader = %x, 期望 %x", sum, want)
	}
	hexStr, err := sha1x.HexReader(strings.NewReader(s))
	if err != nil {
		t.Fatalf("HexReader 失败: %v", err)
	}
	if want := sha1x.Hex([]byte(s)); hexStr != want {
		t.Errorf("HexReader = %s, 期望 %s", hexStr, want)
	}
}

func TestReaderErrors(t *testing.T) {
	if _, err := sha1x.SumReader(nil); err == nil {
		t.Fatal("nil 读取器应返回 error")
	}
	if _, err := sha1x.HexReader(nil); err == nil {
		t.Fatal("nil 读取器应返回 error")
	}
	if _, err := sha1x.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 := sha1x.HexFile(path)
	if err != nil {
		t.Fatalf("HexFile 失败: %v", err)
	}
	if want := sha1x.Hex(content); got != want {
		t.Errorf("HexFile = %s, 期望 %s", got, want)
	}
}

func TestHexFileErrors(t *testing.T) {
	if _, err := sha1x.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 := sha1x.HexFile(""); err == nil {
		t.Fatal("空路径应返回 error")
	}
	if _, err := sha1x.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 := sha1x.Hex(data)
	if got := sha1x.Hex(data); got != want {
		t.Errorf("重复计算结果不一致: %s vs %s", got, want)
	}

	got, err := sha1x.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 := sha1x.New()
	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
}