// SPDX-License-Identifier: MIT

package state

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

func TestRoundTrip(t *testing.T) {
	path := filepath.Join(t.TempDir(), "run", "prx", "state.json")
	s := &State{
		Enabled:      true,
		WANInterface: "wlan0",
		Gateway4:     "192.168.1.1",
		Mark:         0x100,
		TableV4:      100,
		TableV6:      101,
		PriorityV4:   100,
		PriorityV6:   100,
	}
	if err := Save(path, s); err != nil {
		t.Fatalf("Save: %v", err)
	}
	got, err := Load(path)
	if err != nil {
		t.Fatalf("Load: %v", err)
	}
	if !got.Enabled || got.WANInterface != "wlan0" || got.Mark != 0x100 {
		t.Fatalf("round trip mismatch: %+v", got)
	}
	if err := Remove(path); err != nil {
		t.Fatalf("Remove: %v", err)
	}
	empty, err := Load(path)
	if err != nil {
		t.Fatalf("Load after remove: %v", err)
	}
	if empty.Enabled {
		t.Fatal("expected disabled state after removal")
	}
	if err := Remove(path); err != nil {
		t.Fatalf("second Remove should be a no-op: %v", err)
	}
}

// TestLoadCorruptNeverReturnsNil guards against the nil-pointer panic that a
// caller ignoring the error would otherwise hit on a corrupt state file.
func TestLoadCorruptNeverReturnsNil(t *testing.T) {
	path := filepath.Join(t.TempDir(), "state.json")
	if err := os.WriteFile(path, []byte("{ not json"), 0o644); err != nil {
		t.Fatal(err)
	}
	st, err := Load(path)
	if err == nil {
		t.Fatal("expected a parse error for a corrupt state file")
	}
	if st == nil {
		t.Fatal("Load must never return a nil state alongside an error")
	}
	if st.Enabled {
		t.Fatal("expected a zero-value state")
	}
}