package main

import (
	"fmt"
	"io/ioutil"
	"os"
	"path/filepath"
	"testing"
)

func TestLink(t *testing.T) {
	for _, isTmpDir := range []bool{true, false} {
		t.Run(fmt.Sprintf("tempDir=%t", isTmpDir), func(t *testing.T) {
			from, to := "smlinktestfrom", "symlinktestto"
			if isTmpDir {
				tmpDir, err := ioutil.TempDir("", "logtest")
				if err != nil {
					t.Fatalf("could not create temporary directory: %s", err)
				}
				defer func() {
					if err := os.RemoveAll(tmpDir); err != nil {
						t.Fatalf("failed to clean up temp directory: %s", err)
					}
				}()

				from, to = filepath.Join(tmpDir, from), filepath.Join(tmpDir, to)
			}

			os.Remove(from) // Just in case.
			file, err := os.Create(to)
			if err != nil {
				t.Fatalf("open %q failed: %v", to, err)
			}
			defer os.Remove(to)
			if err = file.Close(); err != nil {
				t.Errorf("close %q failed: %v", to, err)
			}
			err = os.Symlink(filepath.Base(to), from)
			if err != nil {
				t.Fatalf("symlink %q, %q failed: %v", to, from, err)
			}
			defer os.Remove(from)
			tostat, err := os.Lstat(to)
			if err != nil {
				t.Fatalf("stat %q failed: %v", to, err)
			}
			if tostat.Mode()&os.ModeSymlink != 0 {
				t.Fatalf("stat %q claims to have found a symlink", to)
			}
			fromstat, err := os.Stat(from)
			if err != nil {
				t.Fatalf("stat %q failed: %v", from, err)
			}
			if !os.SameFile(tostat, fromstat) {
				t.Errorf("symlink %q, %q did not create symlink", to, from)
			}
			fromstat, err = os.Lstat(from)
			if err != nil {
				t.Fatalf("lstat %q failed: %v", from, err)
			}
			if fromstat.Mode()&os.ModeSymlink == 0 {
				t.Fatalf("symlink %q, %q did not create symlink", to, from)
			}
			fromstat, err = os.Stat(from)
			if err != nil {
				t.Fatalf("stat %q failed: %v", from, err)
			}
			if fromstat.Mode()&os.ModeSymlink != 0 {
				t.Fatalf("stat %q did not follow symlink", from)
			}
			s, err := os.Readlink(from)
			if err != nil {
				t.Fatalf("readlink %q failed: %v", from, err)
			}
			if s != filepath.Base(to) {
				t.Fatalf("after symlink %q != %q", s, filepath.Base(to))
			}
			file, err = os.Open(from)
			if err != nil {
				t.Fatalf("open %q failed: %v", from, err)
			}
			file.Close()
		})
	}
}