// Most recent timestamp wins
const resolution = resolveLastWriteWins(entity)

// Server version always wins
const resolution = {
  resolvedData: entity.remoteData,
}

// Local version always wins
const resolution = {
  resolvedData: entity.localData,
}

// Intelligent merge of both versions
const resolution = mergeObjects(local, remote)

function mergeObjects(local: object, remote: object): object {
  const merged = {}

  for (const key in { ...local, ...remote }) {
    const localValue = local[key]
    const remoteValue = remote[key]

    // Only one side has value
    if (localValue === undefined) {
      merged[key] = remoteValue
    } else if (remoteValue === undefined) {
      merged[key] = localValue
    }

    // Both have same value
    else if (deepEqual(localValue, remoteValue)) {
      merged[key] = localValue
    }

    // Nested objects - recurse
    else if (isObject(localValue) && isObject(remoteValue)) {
      merged[key] = mergeObjects(localValue, remoteValue)
    }

    // Arrays - union
    else if (isArray(localValue) && isArray(remoteValue)) {
      merged[key] = [...new Set([...localValue, ...remoteValue])]
    }

    // Primitives - remote wins
    else {
      merged[key] = remoteValue
    }
  }

  return merged
}

// User must choose resolution
const resolution = {
  resolvedData: remoteData, // Default
  requiresUserAction: true,
}

interface UserSettings {
  theme: ThemeSettings // CLIENT_WINS
  notifications: NotificationSettings // MERGE
  privacy: PrivacySettings // SERVER_WINS
  accessibility: AccessibilitySettings // CLIENT_WINS
  locale: LocaleSettings // CLIENT_WINS
  keyboardShortcuts: KeyboardShortcutSettings // CLIENT_WINS
}

merged.privacy = remote.privacy

merged.notifications = {
  ...remote.notifications,
  ...local.notifications,
  quietHoursEnabled: local.quietHoursEnabled || remote.quietHoursEnabled,
}

merged.theme = local.theme

merged.locale = local.locale

function detectSettingsConflict(
  local: UserSettings,
  remote: UserSettings,
  localVersion: number,
  remoteVersion: number
): ConflictDetectionResult {
  // Version mismatch
  if (localVersion !== remoteVersion) {
    const severity = calculateSeverity(local, remote)
    return {
      hasConflict: true,
      severity,
      suggestedStrategy: severity === 'critical' ? 'manual' : 'merge',
    }
  }

  // Content mismatch
  if (JSON.stringify(local) !== JSON.stringify(remote)) {
    return {
      hasConflict: true,
      severity: 'low',
      suggestedStrategy: 'merge',
    }
  }

  // No conflict
  return { hasConflict: false, severity: 'low' }
}

function hasCriticalSettingsConflict(local: UserSettings, remote: UserSettings): boolean {
  const criticalFields = [
    'privacy.onlineStatusVisible',
    'privacy.profileVisible',
    'privacy.lastSeenVisible',
  ]

  for (const field of criticalFields) {
    const [category, key] = field.split('.')
    if (local[category][key] !== remote[category][key]) {
      return true
    }
  }

  return false
}

function validateSettings(settings: unknown): UserSettings {
  const validated = { ...DEFAULT_USER_SETTINGS }

  for (const category in settings) {
    if (isValidCategory(category)) {
      try {
        validated[category] = validateCategory(category, settings[category])
      } catch (error) {
        console.error(`Invalid ${category} settings:`, error)
        // Keep default for invalid category
      }
    }
  }

  return validated
}

interface SettingsMetadata {
  schemaVersion: number
  lastSyncedAt: string
  lastSyncedDevice: string
}

function migrateSettings(
  settings: UserSettings,
  fromVersion: number,
  toVersion: number
): UserSettings {
  let migrated = { ...settings }

  for (let v = fromVersion; v < toVersion; v++) {
    migrated = migrations[v](migrated)
  }

  return migrated
}

async function syncWithRetry(settings: UserSettings, maxRetries = 3): Promise<void> {
  for (let i = 0; i < maxRetries; i++) {
    try {
      await syncSettings(settings)
      return
    } catch (error) {
      if (isVersionConflict(error)) {
        // Fetch latest, merge, retry
        const latest = await fetchLatestSettings()
        settings = mergeSettings(settings, latest)
        await delay(Math.pow(2, i) * 1000) // Exponential backoff
      } else {
        throw error
      }
    }
  }

  throw new Error('Max retries exceeded')
}

class ConflictResolutionService {
  initialize(): void
  destroy(): void

  // Detection
  detectConflict(entity: ConflictEntity): ConflictDetectionResult

  // Resolution
  resolveConflict(
    detection: ConflictDetectionResult,
    strategy?: ResolutionStrategy,
    userChoice?: unknown
  ): ConflictResolutionResult

  autoResolve(detection: ConflictDetectionResult): ConflictResolutionResult | null

  // History
  getHistory(filter?: { type?: ConflictType; limit?: number }): ConflictHistoryEntry[]

  clearHistory(): void

  // Events
  subscribe(listener: ConflictEventListener): () => void

  // Stats
  getStats(): ConflictStats
}

class SettingsSyncService {
  initialize(): Promise<void>
  destroy(): void

  // Sync
  sync(): Promise<SettingsSyncResult>

  // Settings
  getSettings(): UserSettings
  getCategory<K extends keyof UserSettings>(category: K): UserSettings[K]
  updateSettings(updates: Partial<UserSettings>, category?: keyof UserSettings): Promise<void>
  resetSettings(): Promise<void>

  // Status
  getSyncStatus(): SettingsSyncStatus
  getLastSyncTimestamp(): number
  getVersion(): number

  // Events
  subscribe(listener: SettingsSyncEventListener): () => void
}

describe('Conflict Resolution', () => {
  it('should detect message edit conflict')
  it('should resolve with last-write-wins')
  it('should merge settings intelligently')
  it('should require manual resolution for critical conflicts')
  it('should handle concurrent edits')
  it('should recover from network interruption')
  it('should validate settings before sync')
  it('should migrate old settings schema')
})