package common

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

func TestGameClockSharedStateAndReset(t *testing.T) {
	raw, err := os.ReadFile(filepath.Join("..", "..", "server.json"))
	if err != nil {
		t.Fatal(err)
	}
	var cfg RuntimeConfig
	if err := json.Unmarshal(raw, &cfg); err != nil {
		t.Fatal(err)
	}
	dir := t.TempDir()
	cfg.GameClock.StateFile = filepath.Join(dir, "clock.json")
	configPath := filepath.Join(dir, "server.json")
	raw, _ = json.Marshal(cfg)
	if err := os.WriteFile(configPath, raw, 0600); err != nil {
		t.Fatal(err)
	}
	t.Setenv("GAC_CONFIG", configPath)
	t.Setenv("GAC_GAME_CLOCK_STATE_FILE", cfg.GameClock.StateFile)
	target := time.Date(2025, 1, 2, 3, 4, 5, 0, time.UTC)
	if _, err := SetGameTime(&target); err != nil {
		t.Fatal(err)
	}
	now, err := GameTime()
	if err != nil || now.Sub(target) < 0 || now.Sub(target) > time.Second {
		t.Fatalf("target not preserved: %v %v", now, err)
	}
	before, _ := os.ReadFile(cfg.GameClock.StateFile)
	if _, err := ReadGameClock(); err != nil {
		t.Fatal(err)
	}
	after, _ := os.ReadFile(cfg.GameClock.StateFile)
	if string(before) != string(after) {
		t.Fatal("read rewrote state")
	}
	begin := time.Date(2025, 1, 1, 0, 0, 0, 0, time.UTC)
	end := begin.Add(24 * time.Hour)
	if _, err := SetGameTimeWindow(begin, end); err != nil {
		t.Fatal(err)
	}
	window, err := ReadGameClock()
	if err != nil || window.WindowBeginMS != begin.UnixMilli() || window.WindowEndMS != end.UnixMilli() {
		t.Fatalf("window not saved: %+v %v", window, err)
	}
	// Simulate the clock having advanced beyond the end without waiting a day.
	window.OffsetMS = end.Add(time.Hour).UnixMilli() - time.Now().UnixMilli()
	raw, _ = json.Marshal(window)
	if err := os.WriteFile(cfg.GameClock.StateFile, raw, 0600); err != nil {
		t.Fatal(err)
	}
	now, err = GameTime()
	if err != nil || now.Sub(begin.Add(time.Hour)) < 0 || now.Sub(begin.Add(time.Hour)) > time.Second {
		t.Fatalf("window did not wrap: %v %v", now, err)
	}
	before, _ = os.ReadFile(cfg.GameClock.StateFile)
	if _, err := GameTime(); err != nil {
		t.Fatal(err)
	}
	after, _ = os.ReadFile(cfg.GameClock.StateFile)
	if string(before) != string(after) {
		t.Fatal("window read rewrote state")
	}
	if _, err := SetGameTimeWindow(end, begin); err == nil {
		t.Fatal("invalid window accepted")
	}
	if _, err := SetGameTime(nil); err != nil {
		t.Fatal(err)
	}
	now, err = GameTime()
	if err != nil || time.Since(now).Abs() > time.Second {
		t.Fatalf("real time not restored: %v %v", now, err)
	}
	window, err = ReadGameClock()
	if err != nil || window.WindowBeginMS != 0 || window.WindowEndMS != 0 {
		t.Fatalf("reset retained window: %+v %v", window, err)
	}
	if err := os.WriteFile(cfg.GameClock.StateFile, []byte(`{"offset_ms":9223372036854775807}`), 0600); err != nil {
		t.Fatal(err)
	}
	if _, err := GameTime(); err == nil {
		t.Fatal("overflowing offset accepted")
	}
}