package convert

import (
	"bytes"
	"encoding/binary"
	"os"
	"path/filepath"
	"testing"

	"github.com/d4l3k/go-bfloat16"
	"github.com/google/go-cmp/cmp"
	"github.com/x448/float16"
)

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

	root, err := os.OpenRoot(t.TempDir())
	if err != nil {
		t.Fatal(err)
	}
	defer root.Close()

	cases := []struct {
		name,
		dtype string
		offset,
		size int64
		shape []uint64
		setup func(*testing.T, *os.File)
		want  []byte
	}{
		{
			name:  "fp32-fp32",
			dtype: "F32",
			size:  32 * 4, // 32 floats, each 4 bytes
			shape: []uint64{32},
			setup: func(t *testing.T, f *os.File) {
				f32s := make([]float32, 32)
				for i := range f32s {
					f32s[i] = float32(i)
				}

				if err := binary.Write(f, binary.LittleEndian, f32s); err != nil {
					t.Fatal(err)
				}
			},
			want: []byte{
				0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0x3f, 0x00, 0x00, 0x00, 0x40, 0x00, 0x00, 0x40, 0x40,
				0x00, 0x00, 0x80, 0x40, 0x00, 0x00, 0xa0, 0x40, 0x00, 0x00, 0xc0, 0x40, 0x00, 0x00, 0xe0, 0x40,
				0x00, 0x00, 0x00, 0x41, 0x00, 0x00, 0x10, 0x41, 0x00, 0x00, 0x20, 0x41, 0x00, 0x00, 0x30, 0x41,
				0x00, 0x00, 0x40, 0x41, 0x00, 0x00, 0x50, 0x41, 0x00, 0x00, 0x60, 0x41, 0x00, 0x00, 0x70, 0x41,
				0x00, 0x00, 0x80, 0x41, 0x00, 0x00, 0x88, 0x41, 0x00, 0x00, 0x90, 0x41, 0x00, 0x00, 0x98, 0x41,
				0x00, 0x00, 0xa0, 0x41, 0x00, 0x00, 0xa8, 0x41, 0x00, 0x00, 0xb0, 0x41, 0x00, 0x00, 0xb8, 0x41,
				0x00, 0x00, 0xc0, 0x41, 0x00, 0x00, 0xc8, 0x41, 0x00, 0x00, 0xd0, 0x41, 0x00, 0x00, 0xd8, 0x41,
				0x00, 0x00, 0xe0, 0x41, 0x00, 0x00, 0xe8, 0x41, 0x00, 0x00, 0xf0, 0x41, 0x00, 0x00, 0xf8, 0x41,
			},
		},
		{
			name:  "fp32-fp16",
			dtype: "F32",
			size:  32 * 4, // 32 floats, each 4 bytes
			shape: []uint64{16, 2},
			setup: func(t *testing.T, f *os.File) {
				f32s := make([]float32, 32)
				for i := range f32s {
					f32s[i] = float32(i)
				}

				if err := binary.Write(f, binary.LittleEndian, f32s); err != nil {
					t.Fatal(err)
				}
			},
			want: []byte{
				0x00, 0x00, 0x00, 0x3c, 0x00, 0x40, 0x00, 0x42, 0x00, 0x44, 0x00, 0x45, 0x00, 0x46, 0x00, 0x47,
				0x00, 0x48, 0x80, 0x48, 0x00, 0x49, 0x80, 0x49, 0x00, 0x4a, 0x80, 0x4a, 0x00, 0x4b, 0x80, 0x4b,
				0x00, 0x4c, 0x40, 0x4c, 0x80, 0x4c, 0xc0, 0x4c, 0x00, 0x4d, 0x40, 0x4d, 0x80, 0x4d, 0xc0, 0x4d,
				0x00, 0x4e, 0x40, 0x4e, 0x80, 0x4e, 0xc0, 0x4e, 0x00, 0x4f, 0x40, 0x4f, 0x80, 0x4f, 0xc0, 0x4f,
			},
		},
		{
			name:  "fp16-fp16",
			dtype: "F16",
			size:  32 * 2, // 32 floats, each 2 bytes
			shape: []uint64{16, 2},
			setup: func(t *testing.T, f *os.File) {
				u16s := make([]uint16, 32)
				for i := range u16s {
					u16s[i] = float16.Fromfloat32(float32(i)).Bits()
				}

				if err := binary.Write(f, binary.LittleEndian, u16s); err != nil {
					t.Fatal(err)
				}
			},
			want: []byte{
				0x00, 0x00, 0x00, 0x3c, 0x00, 0x40, 0x00, 0x42, 0x00, 0x44, 0x00, 0x45, 0x00, 0x46, 0x00, 0x47,
				0x00, 0x48, 0x80, 0x48, 0x00, 0x49, 0x80, 0x49, 0x00, 0x4a, 0x80, 0x4a, 0x00, 0x4b, 0x80, 0x4b,
				0x00, 0x4c, 0x40, 0x4c, 0x80, 0x4c, 0xc0, 0x4c, 0x00, 0x4d, 0x40, 0x4d, 0x80, 0x4d, 0xc0, 0x4d,
				0x00, 0x4e, 0x40, 0x4e, 0x80, 0x4e, 0xc0, 0x4e, 0x00, 0x4f, 0x40, 0x4f, 0x80, 0x4f, 0xc0, 0x4f,
			},
		},
		{
			name:  "fp16-fp32",
			dtype: "F16",
			size:  32 * 2, // 32 floats, each 2 bytes
			shape: []uint64{32},
			setup: func(t *testing.T, f *os.File) {
				u16s := make([]uint16, 32)
				for i := range u16s {
					u16s[i] = float16.Fromfloat32(float32(i)).Bits()
				}

				if err := binary.Write(f, binary.LittleEndian, u16s); err != nil {
					t.Fatal(err)
				}
			},
			want: []byte{
				0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0x3f, 0x00, 0x00, 0x00, 0x40, 0x00, 0x00, 0x40, 0x40,
				0x00, 0x00, 0x80, 0x40, 0x00, 0x00, 0xa0, 0x40, 0x00, 0x00, 0xc0, 0x40, 0x00, 0x00, 0xe0, 0x40,
				0x00, 0x00, 0x00, 0x41, 0x00, 0x00, 0x10, 0x41, 0x00, 0x00, 0x20, 0x41, 0x00, 0x00, 0x30, 0x41,
				0x00, 0x00, 0x40, 0x41, 0x00, 0x00, 0x50, 0x41, 0x00, 0x00, 0x60, 0x41, 0x00, 0x00, 0x70, 0x41,
				0x00, 0x00, 0x80, 0x41, 0x00, 0x00, 0x88, 0x41, 0x00, 0x00, 0x90, 0x41, 0x00, 0x00, 0x98, 0x41,
				0x00, 0x00, 0xa0, 0x41, 0x00, 0x00, 0xa8, 0x41, 0x00, 0x00, 0xb0, 0x41, 0x00, 0x00, 0xb8, 0x41,
				0x00, 0x00, 0xc0, 0x41, 0x00, 0x00, 0xc8, 0x41, 0x00, 0x00, 0xd0, 0x41, 0x00, 0x00, 0xd8, 0x41,
				0x00, 0x00, 0xe0, 0x41, 0x00, 0x00, 0xe8, 0x41, 0x00, 0x00, 0xf0, 0x41, 0x00, 0x00, 0xf8, 0x41,
			},
		},
		{
			name:  "bf16-bf16",
			dtype: "BF16",
			size:  32 * 2, // 32 brain floats, each 2 bytes
			shape: []uint64{16, 2},
			setup: func(t *testing.T, f *os.File) {
				f32s := make([]float32, 32)
				for i := range f32s {
					f32s[i] = float32(i)
				}

				if err := binary.Write(f, binary.LittleEndian, bfloat16.EncodeFloat32(f32s)); err != nil {
					t.Fatal(err)
				}
			},
			want: []byte{
				0x00, 0x00, 0x80, 0x3f, 0x00, 0x40, 0x40, 0x40, 0x80, 0x40, 0xa0, 0x40, 0xc0, 0x40, 0xe0, 0x40,
				0x00, 0x41, 0x10, 0x41, 0x20, 0x41, 0x30, 0x41, 0x40, 0x41, 0x50, 0x41, 0x60, 0x41, 0x70, 0x41,
				0x80, 0x41, 0x88, 0x41, 0x90, 0x41, 0x98, 0x41, 0xa0, 0x41, 0xa8, 0x41, 0xb0, 0x41, 0xb8, 0x41,
				0xc0, 0x41, 0xc8, 0x41, 0xd0, 0x41, 0xd8, 0x41, 0xe0, 0x41, 0xe8, 0x41, 0xf0, 0x41, 0xf8, 0x41,
			},
		},
		{
			name:  "bf16-fp32",
			dtype: "BF16",
			size:  32 * 2, // 32 brain floats, each 2 bytes
			shape: []uint64{32},
			setup: func(t *testing.T, f *os.File) {
				f32s := make([]float32, 32)
				for i := range f32s {
					f32s[i] = float32(i)
				}

				if err := binary.Write(f, binary.LittleEndian, bfloat16.EncodeFloat32(f32s)); err != nil {
					t.Fatal(err)
				}
			},
			want: []byte{
				0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0x3f, 0x00, 0x00, 0x00, 0x40, 0x00, 0x00, 0x40, 0x40,
				0x00, 0x00, 0x80, 0x40, 0x00, 0x00, 0xa0, 0x40, 0x00, 0x00, 0xc0, 0x40, 0x00, 0x00, 0xe0, 0x40,
				0x00, 0x00, 0x00, 0x41, 0x00, 0x00, 0x10, 0x41, 0x00, 0x00, 0x20, 0x41, 0x00, 0x00, 0x30, 0x41,
				0x00, 0x00, 0x40, 0x41, 0x00, 0x00, 0x50, 0x41, 0x00, 0x00, 0x60, 0x41, 0x00, 0x00, 0x70, 0x41,
				0x00, 0x00, 0x80, 0x41, 0x00, 0x00, 0x88, 0x41, 0x00, 0x00, 0x90, 0x41, 0x00, 0x00, 0x98, 0x41,
				0x00, 0x00, 0xa0, 0x41, 0x00, 0x00, 0xa8, 0x41, 0x00, 0x00, 0xb0, 0x41, 0x00, 0x00, 0xb8, 0x41,
				0x00, 0x00, 0xc0, 0x41, 0x00, 0x00, 0xc8, 0x41, 0x00, 0x00, 0xd0, 0x41, 0x00, 0x00, 0xd8, 0x41,
				0x00, 0x00, 0xe0, 0x41, 0x00, 0x00, 0xe8, 0x41, 0x00, 0x00, 0xf0, 0x41, 0x00, 0x00, 0xf8, 0x41,
			},
		},
		{
			name:  "u8-u8",
			dtype: "U8",
			size:  32, // 32 brain floats, each 1 bytes
			shape: []uint64{32},
			setup: func(t *testing.T, f *os.File) {
				u8s := make([]uint8, 32)
				for i := range u8s {
					u8s[i] = uint8(i)
				}

				if err := binary.Write(f, binary.LittleEndian, u8s); err != nil {
					t.Fatal(err)
				}
			},
			want: []byte{
				0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
				0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
			},
		},
	}

	for _, tt := range cases {
		t.Run(tt.name, func(t *testing.T) {
			path := filepath.Base(t.Name())
			st := safetensor{
				fs:     root.FS(),
				path:   path,
				dtype:  tt.dtype,
				offset: tt.offset,
				size:   tt.size,
				tensorBase: &tensorBase{
					name:  tt.name,
					shape: tt.shape,
				},
			}

			f, err := root.Create(path)
			if err != nil {
				t.Fatal(err)
			}
			defer f.Close()

			tt.setup(t, f)

			var b bytes.Buffer
			if _, err := st.WriteTo(&b); err != nil {
				t.Fatal(err)
			}

			if diff := cmp.Diff(tt.want, b.Bytes()); diff != "" {
				t.Errorf("safetensor.WriteTo() mismatch (-want +got):\n%s", diff)
			}
		})
	}
}