package settings

import (
	"encoding/json"
	"fmt"
	"log"
	"os"
	"path/filepath"
	"sync"
)

// Settings holds customer-modifiable overrides and cached state.
// Persisted as a single JSON file (settings.json) in the data directory.
type Settings struct {
	mu   sync.RWMutex `json:"-"`
	path string       `json:"-"`
	log  *log.Logger  `json:"-"`

	// Auth
	PasswordHash string `json:"password_hash,omitempty"` // bcrypt hash, overrides controller.yaml

	// Notification preferences (Phase 2 — define struct now, leave empty)
	Notifications *NotificationPrefs `json:"notifications,omitempty"`

	// Cached state
	DBValidations map[string]DBValidationCache `json:"db_validations,omitempty"`

	// Per-app backup preferences
	AppBackup map[string]AppBackupPrefs `json:"app_backup,omitempty"`
}

// AppBackupPrefs holds per-app backup toggle state.
type AppBackupPrefs struct {
	Enabled bool `json:"enabled"`
}

// NotificationPrefs holds customer notification preferences.
type NotificationPrefs struct {
	Email         string   `json:"email,omitempty"`
	EnabledEvents []string `json:"enabled_events,omitempty"`
	CooldownHours int      `json:"cooldown_hours,omitempty"` // default: 6
}

// DefaultEnabledEvents are the events enabled by default for new customers.
var DefaultEnabledEvents = []string{
	"disk_warning",
	"backup_failed",
	"update_available",
}

// DBValidationCache holds cached DB dump validation results.
type DBValidationCache struct {
	ValidatedAt string `json:"validated_at"`     // RFC3339
	TableCount  int    `json:"table_count"`
	HasHeader   bool   `json:"has_header"`
	Error       string `json:"error,omitempty"`
}

// Load reads settings from the given file path.
// Returns empty Settings if the file doesn't exist (not an error).
func Load(path string, logger *log.Logger) (*Settings, error) {
	s := &Settings{
		path: path,
		log:  logger,
	}

	data, err := os.ReadFile(path)
	if err != nil {
		if os.IsNotExist(err) {
			logger.Printf("[INFO] No settings.json found, using defaults")
			return s, nil
		}
		return nil, fmt.Errorf("reading settings file: %w", err)
	}

	if err := json.Unmarshal(data, s); err != nil {
		return nil, fmt.Errorf("parsing settings file: %w", err)
	}

	logger.Printf("[DEBUG] Settings loaded from %s", path)
	return s, nil
}

// Save writes settings to disk atomically (write to .tmp, rename).
// Caller must hold the write lock or call this from a method that does.
func (s *Settings) save() error {
	data, err := json.MarshalIndent(s, "", "  ")
	if err != nil {
		return fmt.Errorf("marshaling settings: %w", err)
	}

	tmpPath := s.path + ".tmp"
	if err := os.MkdirAll(filepath.Dir(s.path), 0755); err != nil {
		return fmt.Errorf("creating settings dir: %w", err)
	}

	if err := os.WriteFile(tmpPath, data, 0644); err != nil {
		return fmt.Errorf("writing tmp settings: %w", err)
	}

	if err := os.Rename(tmpPath, s.path); err != nil {
		os.Remove(tmpPath)
		return fmt.Errorf("renaming settings file: %w", err)
	}

	s.log.Printf("[DEBUG] Settings saved to %s", s.path)
	return nil
}

// GetPasswordHash returns the stored password hash (thread-safe).
func (s *Settings) GetPasswordHash() string {
	s.mu.RLock()
	defer s.mu.RUnlock()
	return s.PasswordHash
}

// SetPasswordHash updates the password hash and saves to disk.
func (s *Settings) SetPasswordHash(hash string) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	s.PasswordHash = hash
	return s.save()
}

// GetDBValidations returns a copy of the cached DB validations.
func (s *Settings) GetDBValidations() map[string]DBValidationCache {
	s.mu.RLock()
	defer s.mu.RUnlock()
	if s.DBValidations == nil {
		return nil
	}
	result := make(map[string]DBValidationCache, len(s.DBValidations))
	for k, v := range s.DBValidations {
		result[k] = v
	}
	return result
}

// SetDBValidation saves a validation result for a dump file and persists to disk.
func (s *Settings) SetDBValidation(filename string, cache DBValidationCache) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	if s.DBValidations == nil {
		s.DBValidations = make(map[string]DBValidationCache)
	}
	s.DBValidations[filename] = cache
	return s.save()
}

// GetNotificationPrefs returns a copy of the notification preferences.
func (s *Settings) GetNotificationPrefs() *NotificationPrefs {
	s.mu.RLock()
	defer s.mu.RUnlock()
	if s.Notifications == nil {
		return &NotificationPrefs{
			EnabledEvents: DefaultEnabledEvents,
			CooldownHours: 6,
		}
	}
	prefs := *s.Notifications
	if prefs.CooldownHours == 0 {
		prefs.CooldownHours = 6
	}
	if prefs.EnabledEvents == nil {
		prefs.EnabledEvents = DefaultEnabledEvents
	}
	// Return a copy of the slice
	events := make([]string, len(prefs.EnabledEvents))
	copy(events, prefs.EnabledEvents)
	prefs.EnabledEvents = events
	return &prefs
}

// SetNotificationPrefs updates notification preferences and saves to disk.
func (s *Settings) SetNotificationPrefs(prefs *NotificationPrefs) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	s.Notifications = prefs
	return s.save()
}

// IsAppBackupEnabled returns whether backup is enabled for the given stack.
func (s *Settings) IsAppBackupEnabled(stackName string) bool {
	s.mu.RLock()
	defer s.mu.RUnlock()
	if s.AppBackup == nil {
		return false
	}
	return s.AppBackup[stackName].Enabled
}

// SetAppBackup enables or disables backup for a stack and saves to disk.
func (s *Settings) SetAppBackup(stackName string, enabled bool) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	if s.AppBackup == nil {
		s.AppBackup = make(map[string]AppBackupPrefs)
	}
	s.AppBackup[stackName] = AppBackupPrefs{Enabled: enabled}
	return s.save()
}

// GetAppBackupMap returns a map of stack_name -> enabled for all app backup prefs.
func (s *Settings) GetAppBackupMap() map[string]bool {
	s.mu.RLock()
	defer s.mu.RUnlock()
	if s.AppBackup == nil {
		return nil
	}
	result := make(map[string]bool, len(s.AppBackup))
	for k, v := range s.AppBackup {
		result[k] = v.Enabled
	}
	return result
}

// SetAppBackupBulk updates backup prefs for all stacks at once and saves to disk.
func (s *Settings) SetAppBackupBulk(prefs map[string]bool) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	s.AppBackup = make(map[string]AppBackupPrefs, len(prefs))
	for name, enabled := range prefs {
		s.AppBackup[name] = AppBackupPrefs{Enabled: enabled}
	}
	return s.save()
}