package services

import (
	"encoding/json"
	"os"
	"path/filepath"
	"sync"
	"time"

	"arma3-web-server/internal/models"
)

func writeFileAtomic(path string, data []byte) error {
	dir := filepath.Dir(path)
	tmp, err := os.CreateTemp(dir, ".tmp-*")
	if err != nil {
		return err
	}
	tmpPath := tmp.Name()
	if _, err := tmp.Write(data); err != nil {
		tmp.Close()
		os.Remove(tmpPath)
		return err
	}
	if err := tmp.Close(); err != nil {
		os.Remove(tmpPath)
		return err
	}
	if err := os.Rename(tmpPath, path); err != nil {
		os.Remove(tmpPath)
		return err
	}
	return nil
}

type SettingsManager struct {
	path string
	mu   sync.Mutex
}

func NewSettingsManager(dataDir string) *SettingsManager {
	return &SettingsManager{
		path: filepath.Join(dataDir, "settings.json"),
	}
}

func (sm *SettingsManager) Load() (*models.ServerSettings, error) {
	sm.mu.Lock()
	defer sm.mu.Unlock()

	data, err := os.ReadFile(sm.path)
	if err != nil {
		if os.IsNotExist(err) {
			return sm.defaults(), nil
		}
		return nil, err
	}

	var s models.ServerSettings
	if err := json.Unmarshal(data, &s); err != nil {
		return nil, err
	}
	return &s, nil
}

func (sm *SettingsManager) Save(s *models.ServerSettings) error {
	sm.mu.Lock()
	defer sm.mu.Unlock()

	s.UpdatedAt = time.Now().UTC()
	data, err := json.MarshalIndent(s, "", "  ")
	if err != nil {
		return err
	}
	return writeFileAtomic(sm.path, data)
}

func (sm *SettingsManager) Update(fn func(*models.ServerSettings)) (*models.ServerSettings, error) {
	sm.mu.Lock()
	defer sm.mu.Unlock()

	data, err := os.ReadFile(sm.path)
	if err != nil {
		if os.IsNotExist(err) {
			s := sm.defaults()
			fn(s)
			s.UpdatedAt = time.Now().UTC()
			out, err := json.MarshalIndent(s, "", "  ")
			if err != nil {
				return nil, err
			}
			if err := writeFileAtomic(sm.path, out); err != nil {
				return nil, err
			}
			return s, nil
		}
		return nil, err
	}

	var s models.ServerSettings
	if err := json.Unmarshal(data, &s); err != nil {
		return nil, err
	}
	fn(&s)
	s.UpdatedAt = time.Now().UTC()
	out, err := json.MarshalIndent(s, "", "  ")
	if err != nil {
		return nil, err
	}
	if err := writeFileAtomic(sm.path, out); err != nil {
		return nil, err
	}
	return &s, nil
}

func (sm *SettingsManager) defaults() *models.ServerSettings {
	return &models.ServerSettings{
		IPPort:                  "0.0.0.0:2302",
		ServerParameters:        "-server -world=empty -loadMissionToMemory -noPause",
		SteamBranch:             "stable",
		SteamUser:               "anonymous",
		Platform:                "linux",
		ActiveConfig:            "",
		ActiveModlist:           "",
		AutoUpdateOnStartup:     false,
		AutoStartOnStartup:      false,
		AutoUpdateModsOnStartup: false,
		WasRunning:              false,
		ScheduledUpdate:         "",
		UpdatedAt:               time.Now().UTC(),
	}
}