// src/main/db/index.ts
// 사용자별 SQLite 격리 (SaaS 데스크톱 클라이언트 Phase 1)
//
// - 로그인 전: DB 미오픈. getDatabase() 호출 시 throw.
// - 로그인 후: userData/d3ro-voice/users/${userId}/d3ro.db 로 분리.
// - 로그아웃: DB close.
// - CloudSyncService가 lifecycle 단일 진입점(_onAuthenticated / signOut)에서 호출.

import Database from 'better-sqlite3'
import { drizzle, type BetterSQLite3Database } from 'drizzle-orm/better-sqlite3'
import { app } from 'electron'
import fs from 'fs'
import path from 'path'
import * as schema from './schema'
import { getLogger } from '../services/LoggerService'
import { D3ROError, ErrorCode } from '@d3ro/core/errors'

const logger = getLogger('database')

// ─────────────────────────────────────────────────────────────
// 모듈 상태
// ─────────────────────────────────────────────────────────────

/**
 * 로컬(익명) 모드 user id. OAuth 로그인 없이 동작하는 무료 로컬 모드의
 * 데이터 디렉토리 식별자. `userData/users/_local/d3ro.db`에 저장된다.
 *
 * 비즈니스 모델 관점:
 * - `_local`: 무료 익명 사용자 entry point (킬러 피처 — 회원가입 0, 로컬 STT/LLM)
 * - 실제 uuid: OAuth 로그인 후 클라우드 sync + premium 기능 (유료 SaaS 수익화)
 */
export const LOCAL_USER_ID = '_local'

let currentUserId: string | null = null
let sqlite: Database.Database | null = null
let db: BetterSQLite3Database<typeof schema> | null = null

// ─────────────────────────────────────────────────────────────
// 경로 헬퍼
// ─────────────────────────────────────────────────────────────

/** 사용자별 DB 파일 경로. */
function getUserDbPath(userId: string): string {
  // 안전 가드: userId에 path separator 들어가지 않도록
  if (!userId || userId.includes('/') || userId.includes('\\') || userId.includes('..')) {
    throw new D3ROError(ErrorCode.DBOpenFailed, `Invalid userId for DB path: "${userId}"`)
  }
  return path.join(app.getPath('userData'), 'users', userId, 'd3ro.db')
}

/** 현재 모드가 익명 로컬 모드인지. */
export function isLocalMode(): boolean {
  return currentUserId === LOCAL_USER_ID
}

/** 레거시(V1) 단일 DB 파일 경로. 한 번도 정식 서비스되지 않았으므로 발견 시 silent archive. */
function getLegacyDbPath(): string {
  return path.join(app.getPath('userData'), 'd3ro-voice.db')
}

function archiveLegacyDbIfExists(): void {
  const legacyPath = getLegacyDbPath()
  if (!fs.existsSync(legacyPath)) return

  try {
    const ts = new Date()
      .toISOString()
      .replace(/[:.]/g, '-')
      .replace('T', '_')
      .replace('Z', '')
    const archivePath = path.join(
      app.getPath('userData'),
      `d3ro-voice.legacy-${ts}.db`
    )
    fs.renameSync(legacyPath, archivePath)
    logger.info(`Legacy DB archived: ${legacyPath} -> ${archivePath}`)
  } catch (err) {
    logger.warn(
      `Legacy DB archive failed (leaving in place): ${err instanceof Error ? err.message : String(err)}`
    )
  }
}

// ─────────────────────────────────────────────────────────────
// 스키마 적용 (테이블 생성 + 인라인 ALTER 마이그레이션)
// ─────────────────────────────────────────────────────────────

function applySchema(s: Database.Database): void {
  s.pragma('journal_mode = WAL')
  s.pragma('foreign_keys = ON')
  s.pragma('busy_timeout = 5000')

  s.exec(`
    CREATE TABLE IF NOT EXISTS history (
      id                      TEXT PRIMARY KEY,
      original_text           TEXT NOT NULL,
      polished_text           TEXT,
      focused_app             TEXT,
      focused_app_name        TEXT,
      focused_app_window_title TEXT,
      mode                    TEXT NOT NULL DEFAULT 'dictation',
      status                  TEXT NOT NULL DEFAULT 'completed',
      error_code              TEXT,
      audio_local_path        TEXT,
      duration                REAL NOT NULL,
      detected_language       TEXT,
      mic_device              TEXT,
      word_count              INTEGER NOT NULL DEFAULT 0,
      stt_model               TEXT,
      llm_model               TEXT,
      stt_latency_ms          INTEGER,
      llm_latency_ms          INTEGER,
      created_at              INTEGER NOT NULL,
      updated_at              INTEGER NOT NULL,
      app_version             TEXT NOT NULL DEFAULT '1.0.0'
    );

    CREATE INDEX IF NOT EXISTS idx_history_created_at ON history(created_at DESC);
    CREATE INDEX IF NOT EXISTS idx_history_status ON history(status);
    CREATE INDEX IF NOT EXISTS idx_history_detected_language ON history(detected_language);
    CREATE INDEX IF NOT EXISTS idx_history_focused_app_name ON history(focused_app_name);
    CREATE INDEX IF NOT EXISTS idx_history_mode ON history(mode);

    CREATE TABLE IF NOT EXISTS dictionary (
      id            TEXT PRIMARY KEY,
      word          TEXT NOT NULL,
      pronunciation TEXT,
      category      TEXT NOT NULL DEFAULT 'user',
      usage_count   INTEGER NOT NULL DEFAULT 0,
      last_used_at  INTEGER,
      created_at    INTEGER NOT NULL,
      updated_at    INTEGER NOT NULL
    );

    CREATE UNIQUE INDEX IF NOT EXISTS idx_dictionary_word_category ON dictionary(word, category);
    CREATE INDEX IF NOT EXISTS idx_dictionary_created_at ON dictionary(created_at);
    CREATE INDEX IF NOT EXISTS idx_dictionary_usage_count ON dictionary(usage_count DESC);

    CREATE TABLE IF NOT EXISTS stats (
      id              INTEGER PRIMARY KEY CHECK (id = 1),
      total_duration  REAL NOT NULL DEFAULT 0,
      total_words     INTEGER NOT NULL DEFAULT 0,
      session_count   INTEGER NOT NULL DEFAULT 0,
      streak_days     INTEGER NOT NULL DEFAULT 0,
      last_session_at INTEGER,
      last_updated    INTEGER NOT NULL
    );

    INSERT OR IGNORE INTO stats (id, total_duration, total_words, session_count, streak_days, last_updated)
    VALUES (1, 0, 0, 0, 0, ${Date.now()});

    CREATE TABLE IF NOT EXISTS memo_tags (
      id          TEXT PRIMARY KEY,
      history_id  TEXT NOT NULL,
      tag         TEXT NOT NULL,
      created_at  INTEGER NOT NULL
    );

    CREATE UNIQUE INDEX IF NOT EXISTS idx_memo_tags_unique ON memo_tags(history_id, tag);
    CREATE INDEX IF NOT EXISTS idx_memo_tags_history_id ON memo_tags(history_id);
    CREATE INDEX IF NOT EXISTS idx_memo_tags_tag ON memo_tags(tag);

    CREATE TABLE IF NOT EXISTS daily_usage (
      id      INTEGER PRIMARY KEY AUTOINCREMENT,
      date    TEXT NOT NULL,
      feature TEXT NOT NULL,
      count   INTEGER NOT NULL DEFAULT 0
    );

    CREATE UNIQUE INDEX IF NOT EXISTS idx_daily_usage_date_feature ON daily_usage(date, feature);
    CREATE INDEX IF NOT EXISTS idx_daily_usage_date ON daily_usage(date);
  `)

  // Phase 13.2: RAG 테이블
  s.exec(`
    CREATE TABLE IF NOT EXISTS rag_documents (
      id          TEXT PRIMARY KEY,
      file_name   TEXT NOT NULL,
      file_path   TEXT NOT NULL,
      file_type   TEXT NOT NULL,
      chunk_count INTEGER NOT NULL DEFAULT 0,
      indexed     INTEGER NOT NULL DEFAULT 0,
      indexed_at  INTEGER,
      added_at    INTEGER NOT NULL
    );
    CREATE INDEX IF NOT EXISTS idx_rag_documents_added_at ON rag_documents(added_at);

    CREATE TABLE IF NOT EXISTS rag_chunks (
      id           TEXT PRIMARY KEY,
      document_id  TEXT NOT NULL,
      content      TEXT NOT NULL,
      embedding    TEXT NOT NULL,
      chunk_index  INTEGER NOT NULL
    );
    CREATE INDEX IF NOT EXISTS idx_rag_chunks_document_id ON rag_chunks(document_id);
  `)

  // Phase 14: Meeting Mode 테이블
  s.exec(`
    CREATE TABLE IF NOT EXISTS meeting_sessions (
      id               TEXT PRIMARY KEY,
      title            TEXT,
      status           TEXT NOT NULL DEFAULT 'recording',
      started_at       INTEGER NOT NULL,
      ended_at         INTEGER,
      duration_ms      INTEGER,
      raw_transcript   TEXT,
      minutes_markdown TEXT,
      minutes_json     TEXT,
      stt_model        TEXT,
      llm_model        TEXT,
      stt_latency_ms   INTEGER,
      llm_latency_ms   INTEGER,
      error_message    TEXT,
      created_at       INTEGER NOT NULL,
      updated_at       INTEGER NOT NULL
    );
    CREATE INDEX IF NOT EXISTS idx_meeting_sessions_created_at ON meeting_sessions(created_at DESC);
    CREATE INDEX IF NOT EXISTS idx_meeting_sessions_status ON meeting_sessions(status);

    CREATE TABLE IF NOT EXISTS meeting_memos (
      id            TEXT PRIMARY KEY,
      session_id    TEXT NOT NULL,
      content       TEXT NOT NULL,
      timestamp_ms  INTEGER NOT NULL,
      created_at    INTEGER NOT NULL
    );
    CREATE INDEX IF NOT EXISTS idx_meeting_memos_session_id ON meeting_memos(session_id);
    CREATE INDEX IF NOT EXISTS idx_meeting_memos_timestamp ON meeting_memos(timestamp_ms);
  `)

  // Phase 14.5: meeting_documents 테이블
  s.exec(`
    CREATE TABLE IF NOT EXISTS meeting_documents (
      id               TEXT PRIMARY KEY,
      session_id       TEXT NOT NULL,
      template_type    TEXT NOT NULL,
      title            TEXT NOT NULL,
      content          TEXT NOT NULL DEFAULT '',
      prompt_used      TEXT,
      llm_model        TEXT,
      llm_latency_ms   INTEGER,
      created_at       INTEGER NOT NULL,
      updated_at       INTEGER NOT NULL
    );
    CREATE INDEX IF NOT EXISTS idx_meeting_documents_session_id ON meeting_documents(session_id);
  `)

  // Phase 14.5: meeting_sessions에 edited_transcript 컬럼
  try {
    const msCols = s.pragma('table_info(meeting_sessions)') as Array<{ name: string }>
    if (!msCols.some((c) => c.name === 'edited_transcript')) {
      s.exec('ALTER TABLE meeting_sessions ADD COLUMN edited_transcript TEXT')
      logger.info('Migrated: added edited_transcript column to meeting_sessions')
    }
  } catch (err) {
    logger.warn(
      `edited_transcript migration check failed: ${err instanceof Error ? err.message : String(err)}`
    )
  }

  // Phase 15: history 테이블에 title 컬럼
  try {
    const histCols = s.pragma('table_info(history)') as Array<{ name: string }>
    if (!histCols.some((c) => c.name === 'title')) {
      s.exec('ALTER TABLE history ADD COLUMN title TEXT')
      logger.info('Migrated: added title column to history')
    }
  } catch (err) {
    logger.warn(
      `title migration check failed: ${err instanceof Error ? err.message : String(err)}`
    )
  }

  // Phase 12.2: history 테이블에 summary_text 컬럼
  try {
    const columns = s.pragma('table_info(history)') as Array<{ name: string }>
    const hasSummaryText = columns.some((c) => c.name === 'summary_text')
    if (!hasSummaryText) {
      s.exec('ALTER TABLE history ADD COLUMN summary_text TEXT')
      logger.info('Migrated: added summary_text column to history')
    }
  } catch (err) {
    logger.warn(
      `summary_text migration check failed: ${err instanceof Error ? err.message : String(err)}`
    )
  }
}

// ─────────────────────────────────────────────────────────────
// Public API
// ─────────────────────────────────────────────────────────────

export interface OpenForUserResult {
  created: boolean
  dbPath: string
}

/**
 * 사용자별 DB 열기 — userData/users/${userId}/d3ro.db
 * 이미 다른 사용자 DB가 열려있으면 먼저 close 후 오픈.
 * 동일 사용자면 no-op.
 */
export function openForUser(userId: string): OpenForUserResult {
  if (!userId) {
    throw new D3ROError(ErrorCode.DBOpenFailed, 'openForUser requires a userId')
  }

  if (currentUserId === userId && sqlite && db) {
    logger.info(`Database already open for user: ${userId}`)
    return { created: false, dbPath: getUserDbPath(userId) }
  }

  // 다른 사용자가 열려있으면 먼저 닫기
  if (sqlite) {
    closeCurrent()
  }

  // 레거시 DB는 첫 오픈 직전 silent archive
  archiveLegacyDbIfExists()

  const dbPath = getUserDbPath(userId)
  const dirPath = path.dirname(dbPath)
  const existed = fs.existsSync(dbPath)

  if (!fs.existsSync(dirPath)) {
    fs.mkdirSync(dirPath, { recursive: true })
  }

  logger.info(`Opening database for user ${userId} at: ${dbPath} (existed=${existed})`)

  try {
    sqlite = new Database(dbPath)
    applySchema(sqlite)
    db = drizzle(sqlite, { schema })
    currentUserId = userId
  } catch (err) {
    const message = err instanceof Error ? err.message : String(err)
    logger.error(`Failed to open database for user ${userId}: ${message}`)
    // 부분 상태 초기화
    try {
      sqlite?.close()
    } catch {
      // ignore
    }
    sqlite = null
    db = null
    currentUserId = null
    throw new D3ROError(ErrorCode.DBOpenFailed, `Failed to open user DB: ${message}`)
  }

  logger.info(`Database opened for user: ${userId}`)
  return { created: !existed, dbPath }
}

/**
 * 익명 로컬 모드 DB 열기. 앱 시작 시 기본으로 호출되는 entry point.
 * 로그인 없이 바로 동작해야 하는 킬러 피처의 데이터 저장소.
 *
 * `userData/users/_local/d3ro.db`에 저장. 로그아웃 복귀 시 같은 경로로 재오픈.
 */
export function openLocal(): OpenForUserResult {
  return openForUser(LOCAL_USER_ID)
}

/**
 * 현재 열려있는 DB 닫기. 아무 것도 안 열려 있으면 no-op.
 */
export function closeCurrent(): void {
  if (!sqlite) return

  const prevUserId = currentUserId
  try {
    sqlite.close()
  } catch (err) {
    logger.warn(
      `Database close error: ${err instanceof Error ? err.message : String(err)}`
    )
  }
  sqlite = null
  db = null
  currentUserId = null
  logger.info(`Database closed (user was: ${prevUserId ?? 'none'})`)
}

export function getDatabase(): BetterSQLite3Database<typeof schema> {
  if (!db) {
    throw new D3ROError(
      ErrorCode.DBOpenFailed,
      'Database not initialized. Sign in first (openForUser).'
    )
  }
  return db
}

export function getCurrentUserId(): string | null {
  return currentUserId
}

export function isDatabaseOpen(): boolean {
  return db !== null
}

/**
 * 테스트/개발용 — 현재 오픈된 DB 경로 조회.
 */
export function getCurrentDbPath(): string | null {
  return currentUserId ? getUserDbPath(currentUserId) : null
}