package magic

import (
	"errors"
	"strings"
	"testing"

	"sneak.berlin/go/pixa/internal/imagerequest"
)

// TestDetectFormat_SVG checks that DetectFormat names SVG text with what may
// come before the root element, and does not name as SVG text that does not
// start with "<" or has no "<svg" within its first MaxMagicBytes bytes.
func TestDetectFormat_SVG(t *testing.T) {
	t.Parallel()

	const root = `<svg xmlns="http://www.w3.org/2000/svg" width="4" height="4"/>`

	tests := []struct {
		name    string
		data    string
		wantErr error
	}{
		{name: "root element only", data: root},
		{name: "XML declaration", data: `<?xml version="1.0"?>` + "\n" + root},
		{name: "byte order mark and white space", data: "\xEF\xBB\xBF \n\t" + root},
		{name: "comment", data: "<!-- a drawing -->" + root},
		{
			name: "DOCTYPE",
			data: `<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" ` +
				`"http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">` + root,
		},
		{
			name:    "root element after the first bytes",
			data:    "<!--" + strings.Repeat(" ", MaxMagicBytes) + "-->" + root,
			wantErr: ErrUnknownFormat,
		},
		{name: "text naming <svg", data: "draw it with " + root, wantErr: ErrUnknownFormat},
		{name: "HTML", data: "<!DOCTYPE html><html></html>", wantErr: ErrUnknownFormat},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			t.Parallel()

			got, err := DetectFormat([]byte(tt.data))
			t.Logf("DetectFormat() = %q, %v", got, err)

			if tt.wantErr != nil {
				if !errors.Is(err, tt.wantErr) {
					t.Errorf("DetectFormat() error = %v, want %v", err, tt.wantErr)
				}

				return
			}

			if err != nil || got != imagerequest.FormatSVG {
				t.Errorf("DetectFormat() = %q, %v; want %q", got, err,
					imagerequest.FormatSVG)
			}
		})
	}
}

// TestValidateMagicBytes_SVG checks that SVG data is SVG for the
// Content-Type image/svg+xml, with a charset too, and a mismatch for another.
func TestValidateMagicBytes_SVG(t *testing.T) {
	t.Parallel()

	data := []byte(`<svg xmlns="http://www.w3.org/2000/svg" width="4" height="4"/>`)

	for _, declared := range []string{"image/svg+xml", "image/svg+xml; charset=utf-8"} {
		got, err := ValidateMagicBytes(data, declared)
		if err != nil || got != imagerequest.FormatSVG {
			t.Errorf("ValidateMagicBytes(%q) = %q, %v; want %q", declared, got,
				err, imagerequest.FormatSVG)
		}
	}

	_, err := ValidateMagicBytes(data, "image/png")
	if !errors.Is(err, ErrMagicByteMismatch) {
		t.Errorf("ValidateMagicBytes(image/png) error = %v, want %v", err,
			ErrMagicByteMismatch)
	}
}