package uploads

import (
	"bytes"
	"image"
	"image/color"
	"image/jpeg"
	"image/png"
	"strings"
	"testing"
)

// makePNG and makeJPEG produce a tiny valid image for the round-trip tests.
func makePNG(t *testing.T) []byte {
	t.Helper()
	img := image.NewRGBA(image.Rect(0, 0, 4, 4))
	img.Set(0, 0, color.RGBA{34, 197, 94, 255})
	var b bytes.Buffer
	if err := png.Encode(&b, img); err != nil {
		t.Fatalf("encode png: %v", err)
	}
	return b.Bytes()
}

func makeJPEG(t *testing.T) []byte {
	t.Helper()
	img := image.NewRGBA(image.Rect(0, 0, 4, 4))
	img.Set(0, 0, color.RGBA{34, 197, 94, 255})
	var b bytes.Buffer
	if err := jpeg.Encode(&b, img, &jpeg.Options{Quality: 80}); err != nil {
		t.Fatalf("encode jpeg: %v", err)
	}
	return b.Bytes()
}

func TestDecodeAndReencode_PNG(t *testing.T) {
	out, format, err := DecodeAndReencode(makePNG(t))
	if err != nil {
		t.Fatalf("decode png: %v", err)
	}
	if format != FormatPNG {
		t.Errorf("format: got %q want png", format)
	}
	// Output must be valid PNG (round-trip decode).
	if _, _, err := image.Decode(bytes.NewReader(out)); err != nil {
		t.Errorf("re-encoded png is not valid: %v", err)
	}
}

func TestDecodeAndReencode_JPEG(t *testing.T) {
	out, format, err := DecodeAndReencode(makeJPEG(t))
	if err != nil {
		t.Fatalf("decode jpeg: %v", err)
	}
	if format != FormatJPEG {
		t.Errorf("format: got %q want jpeg", format)
	}
	if _, _, err := image.Decode(bytes.NewReader(out)); err != nil {
		t.Errorf("re-encoded jpeg is not valid: %v", err)
	}
}

func TestDecodeAndReencode_RejectsNonImage(t *testing.T) {
	_, _, err := DecodeAndReencode([]byte("hello, world"))
	if err == nil {
		t.Fatal("expected an error decoding a non-image payload")
	}
	if !strings.Contains(err.Error(), "not a recognised image") {
		t.Errorf("error: got %q want 'not a recognised image'", err)
	}
}

func TestDecodeAndReencode_RejectsTooLarge(t *testing.T) {
	big := make([]byte, MaxUploadBytes+1)
	_, _, err := DecodeAndReencode(big)
	if err == nil || !strings.Contains(err.Error(), "exceeds") {
		t.Errorf("expected size-limit error, got %v", err)
	}
}

func TestLocalFSStore_FilePath_RejectsTraversal(t *testing.T) {
	s := &LocalFSStore{Dir: "/tmp/x", PublicBase: "http://localhost/up"}
	cases := []string{"../etc/passwd", "a/b.png", "..", ".env"}
	for _, in := range cases {
		if _, err := s.FilePath(in); err == nil {
			t.Errorf("FilePath(%q) should have refused", in)
		}
	}
	// A bare random filename should be accepted.
	if _, err := s.FilePath("ok.png"); err != nil {
		t.Errorf("FilePath(ok.png) should have accepted: %v", err)
	}
}