package main

// preferences_test.go — M8-4 Preferences 持久化單元測試

import (
	"encoding/json"
	"os"
	"path/filepath"
	"runtime"
	"testing"
)

func TestDefaultPreferences_PlatformSpecific(t *testing.T) {
	p := DefaultPreferences()
	wantOpen := runtime.GOOS != "linux"
	if p.AutoOpenBrowser != wantOpen {
		t.Fatalf("DefaultPreferences.AutoOpenBrowser=%v on %s, want %v", p.AutoOpenBrowser, runtime.GOOS, wantOpen)
	}
	if p.Locale != "" {
		t.Fatalf("default Locale=%q, want empty", p.Locale)
	}
	if p.LogRingSize != 0 {
		t.Fatalf("default LogRingSize=%d, want 0", p.LogRingSize)
	}
}

func TestLoadPreferences_MissingFile(t *testing.T) {
	dir := t.TempDir()
	p := LoadPreferences(dir)
	want := DefaultPreferences()
	if p != want {
		t.Fatalf("LoadPreferences on empty dir=%+v, want default %+v", p, want)
	}
}

func TestLoadPreferences_CorruptJSON(t *testing.T) {
	dir := t.TempDir()
	path := preferencesPath(dir)
	if err := os.WriteFile(path, []byte("{not json"), 0o644); err != nil {
		t.Fatalf("prep: %v", err)
	}
	p := LoadPreferences(dir)
	want := DefaultPreferences()
	if p != want {
		t.Fatalf("LoadPreferences on corrupt json=%+v, want default %+v", p, want)
	}
}

func TestSaveAndLoadPreferences_Roundtrip(t *testing.T) {
	dir := t.TempDir()

	orig := Preferences{
		AutoOpenBrowser: false,
		Locale:          "zh-TW",
		LogRingSize:     1000,
	}
	if err := SavePreferences(dir, orig); err != nil {
		t.Fatalf("Save: %v", err)
	}

	// 確認 .tmp 不存在（rename 已完成）
	if _, err := os.Stat(preferencesPath(dir) + ".tmp"); !os.IsNotExist(err) {
		t.Fatalf("tmp file should not exist after rename, got err=%v", err)
	}

	// 檢查檔案內容是合法 JSON
	raw, err := os.ReadFile(preferencesPath(dir))
	if err != nil {
		t.Fatalf("read file: %v", err)
	}
	var check Preferences
	if err := json.Unmarshal(raw, &check); err != nil {
		t.Fatalf("unmarshal: %v", err)
	}
	if check != orig {
		t.Fatalf("on-disk=%+v, want %+v", check, orig)
	}

	// Load 回來應該一致
	loaded := LoadPreferences(dir)
	if loaded != orig {
		t.Fatalf("loaded=%+v, want %+v", loaded, orig)
	}
}

func TestSavePreferences_AtomicRename(t *testing.T) {
	dir := t.TempDir()
	// 預先寫一個舊 preferences.json
	oldData := `{"autoOpenBrowser":true,"locale":"en-US"}`
	if err := os.WriteFile(preferencesPath(dir), []byte(oldData), 0o644); err != nil {
		t.Fatalf("prep: %v", err)
	}

	// 寫新的
	newPref := Preferences{AutoOpenBrowser: false, Locale: "zh-TW"}
	if err := SavePreferences(dir, newPref); err != nil {
		t.Fatalf("Save: %v", err)
	}

	loaded := LoadPreferences(dir)
	if loaded != newPref {
		t.Fatalf("loaded=%+v, want %+v", loaded, newPref)
	}

	// tmp cleanup 後 data dir 只該有 preferences.json
	entries, _ := os.ReadDir(dir)
	for _, e := range entries {
		if filepath.Ext(e.Name()) == ".tmp" {
			t.Fatalf("leftover tmp file: %s", e.Name())
		}
	}
}