package configgen

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

func TestAtomicWrite_CreatesAndChmods(t *testing.T) {
	dir := t.TempDir()
	target := filepath.Join(dir, "sub", "out.conf")
	data := []byte("hello config\n")
	if err := AtomicWrite(target, data, 0o644); err != nil {
		t.Fatalf("AtomicWrite: %v", err)
	}
	got, err := os.ReadFile(target)
	if err != nil {
		t.Fatalf("read back: %v", err)
	}
	if string(got) != string(data) {
		t.Errorf("content mismatch: %q", got)
	}
	st, err := os.Stat(target)
	if err != nil {
		t.Fatalf("stat: %v", err)
	}
	if st.Mode().Perm() != 0o644 {
		t.Errorf("mode: %v", st.Mode().Perm())
	}
}

func TestAtomicWrite_OverwritesExisting(t *testing.T) {
	dir := t.TempDir()
	target := filepath.Join(dir, "out.conf")
	if err := os.WriteFile(target, []byte("old\n"), 0o600); err != nil {
		t.Fatalf("seed: %v", err)
	}
	if err := AtomicWrite(target, []byte("new\n"), 0o640); err != nil {
		t.Fatalf("AtomicWrite: %v", err)
	}
	got, _ := os.ReadFile(target)
	if string(got) != "new\n" {
		t.Errorf("expected 'new\\n', got %q", got)
	}
	st, _ := os.Stat(target)
	if st.Mode().Perm() != 0o640 {
		t.Errorf("mode: %v", st.Mode().Perm())
	}
}

func TestAtomicWrite_NoTempLeak(t *testing.T) {
	dir := t.TempDir()
	target := filepath.Join(dir, "out.conf")
	if err := AtomicWrite(target, []byte("x"), 0o644); err != nil {
		t.Fatalf("AtomicWrite: %v", err)
	}
	entries, _ := os.ReadDir(dir)
	for _, e := range entries {
		if e.Name() != "out.conf" {
			t.Errorf("unexpected leftover: %s", e.Name())
		}
	}
}