/**
 * Client-side notification preference management
 * Stores user's per-review notification opt-in choices in localStorage
 */

interface NotificationPreferences {
  [reviewUri: string]: {
    stage2?: boolean
    stage3?: boolean
  }
}

const STORAGE_KEY = 'drydown:notification-prefs'

export class NotificationService {
  /**
   * Get notification preferences for a specific review
   */
  static getPreferences(reviewUri: string): { stage2: boolean; stage3: boolean } {
    const prefs = this.getAllPreferences()
    const reviewPrefs = prefs[reviewUri] || {}
    return {
      stage2: reviewPrefs.stage2 || false,
      stage3: reviewPrefs.stage3 || false
    }
  }

  /**
   * Set notification preference for a specific review stage
   */
  static setPreference(reviewUri: string, stage: 'stage2' | 'stage3', enabled: boolean): void {
    const prefs = this.getAllPreferences()

    if (!prefs[reviewUri]) {
      prefs[reviewUri] = {}
    }

    prefs[reviewUri][stage] = enabled

    localStorage.setItem(STORAGE_KEY, JSON.stringify(prefs))
  }

  /**
   * Check if user should be notified for a specific review + stage
   */
  static shouldNotify(reviewUri: string, stage: 'stage2' | 'stage3'): boolean {
    const prefs = this.getPreferences(reviewUri)
    return prefs[stage] || false
  }

  /**
   * Request browser notification permission if needed
   * Returns true if permission is granted or was already granted
   */
  static async requestPermission(): Promise<boolean> {
    if (!('Notification' in window)) {
      return false
    }

    if (Notification.permission === 'granted') {
      return true
    }

    if (Notification.permission === 'default') {
      const result = await Notification.requestPermission()
      return result === 'granted'
    }

    return false
  }

  /**
   * Get all stored notification preferences
   */
  private static getAllPreferences(): NotificationPreferences {
    try {
      const stored = localStorage.getItem(STORAGE_KEY)
      return stored ? JSON.parse(stored) : {}
    } catch (e) {
      console.error('Failed to parse notification preferences', e)
      return {}
    }
  }

  /**
   * Clear all notification preferences (for testing/debugging)
   */
  static clearAll(): void {
    localStorage.removeItem(STORAGE_KEY)
  }
}