//go:build darwin || linux

package safeio

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

func TestReadCanonicalRegularRejectsReplacementDuringRead(t *testing.T) {
	root := canonicalSafeioTempDir(t)
	path := filepath.Join(root, "schema.sql")
	replacement := filepath.Join(root, "replacement.sql")
	parked := filepath.Join(root, "parked.sql")
	contents := make([]byte, 64<<20)
	if err := os.WriteFile(path, contents, 0o600); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(replacement, contents, 0o600); err != nil {
		t.Fatal(err)
	}

	entered := make(chan struct{})
	proceed := make(chan struct{})
	result := make(chan error, 1)
	go func() {
		_, err := readCanonicalRegularWithHook(path, int64(len(contents)), func() {
			close(entered)
			<-proceed
		})
		result <- err
	}()
	<-entered
	if err := os.Rename(path, parked); err != nil {
		t.Fatal(err)
	}
	if err := os.Rename(replacement, path); err != nil {
		t.Fatal(err)
	}
	close(proceed)
	err := <-result
	if !errors.Is(err, ErrUnsafeFile) {
		t.Fatalf("replacement during read error = %v, want ErrUnsafeFile", err)
	}
}

func canonicalSafeioTempDir(t *testing.T) string {
	t.Helper()
	root, err := filepath.EvalSymlinks(os.TempDir())
	if err != nil {
		t.Fatal(err)
	}
	directory, err := os.MkdirTemp(root, "thothctl-safeio-test-")
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(func() { _ = os.RemoveAll(directory) })
	return directory
}