'use server'

/**
 * AI Server Actions Stub File
 *
 * This file provides a centralized location for all AI-related server action interfaces
 * and serves as documentation for the AI server action architecture.
 *
 * IMPLEMENTATION STATUS:
 * - Title Suggestions: ✅ Implemented (see app/actions/title-suggestions.ts)
 * - Semantic Search: ✅ Implemented (see app/actions/semantic-search.ts)
 * - Paragraph Reformulation: ✅ Implemented (see app/actions/paragraph-refactor.ts)
 * - Memory Echo: ⏳ STUB - To be implemented in Epic 5 (Story 5-1)
 * - Language Detection: ✅ Implemented (see app/actions/detect-language.ts)
 * - AI Settings: ✅ Implemented (see app/actions/ai-settings.ts)
 *
 * NOTE: This file defines TypeScript interfaces and placeholder functions.
 * Actual implementations are in separate action files (see references above).
 */

import { auth } from '@/auth'
import { prisma } from '@/lib/prisma'
import { revalidatePath } from 'next/cache'

// ============================================================================
// TYPESCRIPT INTERFACES
// ============================================================================

/**
 * Title Suggestions Interfaces
 * @see app/actions/title-suggestions.ts for implementation
 */
export interface GenerateTitlesRequest {
  noteId: string
}

export interface GenerateTitlesResponse {
  suggestions: Array<{
    title: string
    confidence: number
    reasoning?: string
  }>
  noteId: string
}

/**
 * Semantic Search Interfaces
 * @see app/actions/semantic-search.ts for implementation
 */
export interface SearchResult {
  noteId: string
  title: string | null
  content: string
  similarity: number
  matchType: 'exact' | 'related'
}

export interface SemanticSearchRequest {
  query: string
  options?: {
    limit?: number
    threshold?: number
    notebookId?: string
  }
}

export interface SemanticSearchResponse {
  results: SearchResult[]
  query: string
  totalResults: number
}

/**
 * Paragraph Reformulation Interfaces
 * @see app/actions/paragraph-refactor.ts for implementation
 */
export type RefactorMode = 'clarify' | 'shorten' | 'improve'

export interface RefactorParagraphRequest {
  noteId: string
  selectedText: string
  option: RefactorMode
}

export interface RefactorParagraphResponse {
  originalText: string
  refactoredText: string
}

/**
 * Memory Echo Interfaces
 * STUB - To be implemented in Epic 5 (Story 5-1)
 *
 * This feature will analyze all user notes with embeddings to find
 * connections with cosine similarity > 0.75 and provide proactive insights.
 */
export interface GenerateMemoryEchoRequest {
  // No params - uses current user session
}

export interface MemoryEchoInsight {
  note1Id: string
  note2Id: string
  similarityScore: number
}

export interface GenerateMemoryEchoResponse {
  success: boolean
  insight: MemoryEchoInsight | null
}

/**
 * Language Detection Interfaces
 * @see app/actions/detect-language.ts for implementation
 */
export interface DetectLanguageRequest {
  content: string
}

export interface DetectLanguageResponse {
  language: string
  confidence: number
  method: 'tinyld' | 'ai'
}

/**
 * AI Settings Interfaces
 * @see app/actions/ai-settings.ts for implementation
 */
export interface AISettingsConfig {
  titleSuggestions?: boolean
  semanticSearch?: boolean
  paragraphRefactor?: boolean
  memoryEcho?: boolean
  memoryEchoFrequency?: 'daily' | 'weekly' | 'custom'
  aiProvider?: 'auto' | 'openai' | 'ollama'
  preferredLanguage?: 'auto' | 'en' | 'fr' | 'es' | 'de' | 'fa' | 'it' | 'pt' | 'ru' | 'zh' | 'ja' | 'ko' | 'ar' | 'hi' | 'nl' | 'pl'
  demoMode?: boolean
}

export interface UpdateAISettingsRequest {
  settings: Partial<AISettingsConfig>
}

export interface UpdateAISettingsResponse {
  success: boolean
}

// ============================================================================
// PLACEHOLDER FUNCTIONS
// ============================================================================

/**
 * Generate Title Suggestions
 *
 * ALREADY IMPLEMENTED: See app/actions/title-suggestions.ts
 *
 * This function generates 3 AI-powered title suggestions for a note when it
 * reaches 50+ words without a title.
 *
 * @see generateTitleSuggestions in app/actions/title-suggestions.ts
 */
export async function generateTitles(
  request: GenerateTitlesRequest
): Promise<GenerateTitlesResponse> {
  // TODO: Import and use implementation from title-suggestions.ts
  // import { generateTitleSuggestions } from './title-suggestions'
  // return generateTitleSuggestions(request.noteId)

  throw new Error('Not implemented in stub: Use app/actions/title-suggestions.ts')
}

/**
 * Semantic Search
 *
 * ALREADY IMPLEMENTED: See app/actions/semantic-search.ts
 *
 * This function performs hybrid semantic + keyword search across user notes.
 *
 * @see semanticSearch in app/actions/semantic-search.ts
 */
export async function semanticSearch(
  request: SemanticSearchRequest
): Promise<SemanticSearchResponse> {
  // TODO: Import and use implementation from semantic-search.ts
  // import { semanticSearch } from './semantic-search'
  // return semanticSearch(request.query, request.options)

  throw new Error('Not implemented in stub: Use app/actions/semantic-search.ts')
}

/**
 * Refactor Paragraph
 *
 * ALREADY IMPLEMENTED: See app/actions/paragraph-refactor.ts
 *
 * This function refactors a paragraph using AI with specific mode (clarify/shorten/improve).
 *
 * @see refactorParagraph in app/actions/paragraph-refactor.ts
 */
export async function refactorParagraph(
  request: RefactorParagraphRequest
): Promise<RefactorParagraphResponse> {
  // TODO: Import and use implementation from paragraph-refactor.ts
  // import { refactorParagraph } from './paragraph-refactor'
  // return refactorParagraph(request.selectedText, request.option)

  throw new Error('Not implemented in stub: Use app/actions/paragraph-refactor.ts')
}

/**
 * Generate Memory Echo Insights
 *
 * STUB: To be implemented in Epic 5 (Story 5-1)
 *
 * This will analyze all user notes with embeddings to find
 * connections with cosine similarity > 0.75.
 *
 * Implementation Plan:
 * - Fetch all user notes with embeddings
 * - Calculate pairwise cosine similarities
 * - Find top connection with similarity > 0.75
 * - Store in MemoryEchoInsight table
 * - Return insight or null if none found
 *
 * @see Epic 5 Story 5-1 in planning/epics.md
 */
export async function generateMemoryEcho(): Promise<GenerateMemoryEchoResponse> {
  const session = await auth()
  if (!session?.user?.id) {
    throw new Error('Unauthorized')
  }

  // TODO: Implement Memory Echo background processing
  // - Fetch all user notes with embeddings from prisma.note
  // - Calculate pairwise cosine similarities using embedding vectors
  // - Filter for similarity > 0.75
  // - Select top insight
  // - Store in prisma.memoryEchoInsight table (if it exists)
  // - Return { success: true, insight: {...} }

  throw new Error('Not implemented: See Epic 5 Story 5-1')
}

/**
 * Detect Language
 *
 * ALREADY IMPLEMENTED: See app/actions/detect-language.ts
 *
 * This function detects the language of user content.
 *
 * @see getInitialLanguage in app/actions/detect-language.ts
 */
export async function detectLanguage(
  request: DetectLanguageRequest
): Promise<DetectLanguageResponse> {
  // TODO: Import and use implementation from detect-language.ts
  // import { detectUserLanguage } from '@/lib/i18n/detect-user-language'
  // const language = await detectUserLanguage()
  // return { language, confidence: 0.95, method: 'tinyld' }

  throw new Error('Not implemented in stub: Use app/actions/detect-language.ts')
}

/**
 * Update AI Settings
 *
 * ALREADY IMPLEMENTED: See app/actions/ai-settings.ts
 *
 * This function updates user AI preferences.
 *
 * @see updateAISettings in app/actions/ai-settings.ts
 */
export async function updateAISettings(
  request: UpdateAISettingsRequest
): Promise<UpdateAISettingsResponse> {
  const session = await auth()
  if (!session?.user?.id) {
    throw new Error('Unauthorized')
  }

  // TODO: Import and use implementation from ai-settings.ts
  // import { updateAISettings } from './ai-settings'
  // return updateAISettings(request.settings)

  throw new Error('Not implemented in stub: Use app/actions/ai-settings.ts')
}

/**
 * Get AI Settings
 *
 * ALREADY IMPLEMENTED: See app/actions/ai-settings.ts
 *
 * This function retrieves user AI preferences.
 *
 * @see getAISettings in app/actions/ai-settings.ts
 */
export async function getAISettings(): Promise<AISettingsConfig> {
  const session = await auth()
  if (!session?.user?.id) {
    throw new Error('Unauthorized')
  }

  // TODO: Import and use implementation from ai-settings.ts
  // import { getAISettings } from './ai-settings'
  // return getAISettings()

  throw new Error('Not implemented in stub: Use app/actions/ai-settings.ts')
}

// ============================================================================
// UTILITY FUNCTIONS
// ============================================================================

/**
 * Check if a specific AI feature is enabled for the user
 *
 * UTILITY: Helper function to check feature flags
 *
 * @param feature - The AI feature to check
 * @returns Promise<boolean> - Whether the feature is enabled
 */
export async function isAIFeatureEnabled(
  feature: keyof AISettingsConfig
): Promise<boolean> {
  const session = await auth()
  if (!session?.user?.id) {
    return false
  }

  try {
    const settings = await prisma.userAISettings.findUnique({
      where: { userId: session.user.id }
    })

    if (!settings) {
      // Default to enabled for new users
      return true
    }

    switch (feature) {
      case 'titleSuggestions':
        return settings.titleSuggestions ?? true
      case 'semanticSearch':
        return settings.semanticSearch ?? true
      case 'paragraphRefactor':
        return settings.paragraphRefactor ?? true
      case 'memoryEcho':
        return settings.memoryEcho ?? true
      default:
        return true
    }
  } catch (error) {
    console.error('Error checking AI feature enabled:', error)
    return true
  }
}

/**
 * Get user's preferred AI provider
 *
 * UTILITY: Helper function to get provider preference
 *
 * @returns Promise<'auto' | 'openai' | 'ollama'> - The AI provider
 */
export async function getUserAIPreference(): Promise<'auto' | 'openai' | 'ollama'> {
  const session = await auth()
  if (!session?.user?.id) {
    return 'auto'
  }

  try {
    const settings = await prisma.userAISettings.findUnique({
      where: { userId: session.user.id }
    })

    return (settings?.aiProvider || 'auto') as 'auto' | 'openai' | 'ollama'
  } catch (error) {
    console.error('Error getting user AI preference:', error)
    return 'auto'
  }
}