package rootpath

import (
	"os"
	"path/filepath"
	"strings"
	"testing"
)

func TestResolve(t *testing.T) {
	rootfs := t.TempDir()
	if err := os.MkdirAll(filepath.Join(rootfs, "usr", "bin"), 0o755); err != nil {
		t.Fatal(err)
	}
	for link, target := range map[string]string{"bin": "usr/bin", "abs": "/usr", "loop": "loop", "out": "../.."} {
		if err := os.Symlink(target, filepath.Join(rootfs, link)); err != nil {
			t.Fatal(err)
		}
	}
	tests := []struct{ in, want, wantErr string }{
		{"/bin/sh", "usr/bin/sh", ""},
		{"/abs/bin/x", "usr/bin/x", ""},
		{"/new/dir/file", "new/dir/file", ""},
		{"/../x", "x", ""},
		{"/usr/../etc", "etc", ""},
		{"/", "", ""},
		{"/loop/x", "", "too many levels"},
		{"/out/x", "x", ""}, // .. above the root stays at the root
	}
	for _, tt := range tests {
		got, err := Resolve(rootfs, tt.in)
		if tt.wantErr != "" {
			if err == nil || !strings.Contains(err.Error(), tt.wantErr) {
				t.Errorf("%s: got %q, %v; want error %q", tt.in, got, err, tt.wantErr)
			}
			continue
		}
		if err != nil || got != filepath.Join(rootfs, tt.want) {
			t.Errorf("%s: got %q, %v; want %q", tt.in, got, err, filepath.Join(rootfs, tt.want))
		}
	}
}