package blendfile

import (
	"bytes"
	"compress/gzip"
	"testing"
)

func makeBlendHeader(major, minor int) []byte {
	header := make([]byte, 12)
	copy(header[:7], "BLENDER")
	header[7] = '-'
	header[8] = 'v'
	header[9] = byte('0' + major)
	header[10] = byte('0' + minor/10)
	header[11] = byte('0' + minor%10)
	return header
}

func TestParseVersionFromReader_Uncompressed(t *testing.T) {
	tests := []struct {
		name       string
		major      int
		minor      int
		wantMajor  int
		wantMinor  int
	}{
		{"Blender 4.02", 4, 2, 4, 2},
		{"Blender 3.06", 3, 6, 3, 6},
		{"Blender 2.79", 2, 79, 2, 79},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			header := makeBlendHeader(tt.major, tt.minor)
			r := bytes.NewReader(header)

			major, minor, err := ParseVersionFromReader(r)
			if err != nil {
				t.Fatalf("ParseVersionFromReader: %v", err)
			}
			if major != tt.wantMajor || minor != tt.wantMinor {
				t.Errorf("got %d.%d, want %d.%d", major, minor, tt.wantMajor, tt.wantMinor)
			}
		})
	}
}

func TestParseVersionFromReader_GzipCompressed(t *testing.T) {
	header := makeBlendHeader(4, 2)
	// Pad to ensure gzip has enough data for a full read
	data := make([]byte, 128)
	copy(data, header)

	var buf bytes.Buffer
	gz := gzip.NewWriter(&buf)
	gz.Write(data)
	gz.Close()

	r := bytes.NewReader(buf.Bytes())
	major, minor, err := ParseVersionFromReader(r)
	if err != nil {
		t.Fatalf("ParseVersionFromReader (gzip): %v", err)
	}
	if major != 4 || minor != 2 {
		t.Errorf("got %d.%d, want 4.2", major, minor)
	}
}

func TestParseVersionFromReader_InvalidMagic(t *testing.T) {
	data := []byte("NOT_BLEND_DATA_HERE")
	r := bytes.NewReader(data)

	_, _, err := ParseVersionFromReader(r)
	if err == nil {
		t.Fatal("expected error for invalid magic, got nil")
	}
}

func TestParseVersionFromReader_TooShort(t *testing.T) {
	data := []byte("SHORT")
	r := bytes.NewReader(data)

	_, _, err := ParseVersionFromReader(r)
	if err == nil {
		t.Fatal("expected error for short data, got nil")
	}
}

func TestVersionString(t *testing.T) {
	got := VersionString(4, 2)
	want := "4.2"
	if got != want {
		t.Errorf("VersionString(4, 2) = %q, want %q", got, want)
	}
}