#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
SQLite 資料庫優化腳本
建議在低流量時段執行（晚上 8 點後）

功能：
1. 添加缺失的索引（提升查詢效能）
2. 執行 VACUUM 清理（回收空間、優化儲存）
3. 分析資料庫統計（更新查詢規劃器統計資訊）
"""

import sqlite3
import os
import sys
import time
from datetime import datetime

# 資料庫路徑
DB_PATH = '/home/ogt/momo_pro_system/data/momo_database.db'

# 日誌函數
def log(message, level="INFO"):
    timestamp = datetime.now().strftime('%Y-%m-%d %H:%M:%S')
    print(f"[{timestamp}] [{level}] {message}")

# 檢查資料庫大小
def get_db_size():
    size_bytes = os.path.getsize(DB_PATH)
    size_mb = size_bytes / (1024 * 1024)
    return size_bytes, size_mb

# 檢查索引是否存在
def index_exists(cursor, index_name):
    cursor.execute(
        "SELECT name FROM sqlite_master WHERE type='index' AND name=?",
        (index_name,)
    )
    return cursor.fetchone() is not None

# 添加索引
def add_indexes(conn):
    log("開始添加索引...")
    cursor = conn.cursor()

    indexes = [
        # products 表索引
        ("idx_products_category", "CREATE INDEX IF NOT EXISTS idx_products_category ON products (category)"),
        ("idx_products_status", "CREATE INDEX IF NOT EXISTS idx_products_status ON products (status)"),
        ("idx_products_updated_at", "CREATE INDEX IF NOT EXISTS idx_products_updated_at ON products (updated_at DESC)"),

        # price_records 表索引
        ("idx_price_records_product_id", "CREATE INDEX IF NOT EXISTS idx_price_records_product_id ON price_records (product_id)"),
        ("idx_price_records_product_time", "CREATE INDEX IF NOT EXISTS idx_price_records_product_time ON price_records (product_id, timestamp DESC)"),

        # promo_products 表索引
        ("idx_promo_crawled_at", "CREATE INDEX IF NOT EXISTS idx_promo_crawled_at ON promo_products (crawled_at DESC)"),
        ("idx_promo_batch_id", "CREATE INDEX IF NOT EXISTS idx_promo_batch_id ON promo_products (batch_id)"),
        ("idx_promo_status_change", "CREATE INDEX IF NOT EXISTS idx_promo_status_change ON promo_products (status_change)"),
    ]

    added_count = 0
    skipped_count = 0

    for index_name, create_sql in indexes:
        try:
            if index_exists(cursor, index_name):
                log(f"  索引已存在，跳過: {index_name}", "INFO")
                skipped_count += 1
                continue

            log(f"  創建索引: {index_name}...", "INFO")
            start_time = time.time()
            cursor.execute(create_sql)
            conn.commit()
            elapsed = time.time() - start_time
            log(f"  ✓ 索引創建成功: {index_name} (耗時 {elapsed:.2f} 秒)", "SUCCESS")
            added_count += 1

        except Exception as e:
            log(f"  ✗ 索引創建失敗: {index_name} - {e}", "ERROR")
            conn.rollback()

    log(f"索引添加完成：新增 {added_count} 個，跳過 {skipped_count} 個", "INFO")
    return added_count

# 執行 VACUUM
def run_vacuum(conn):
    log("開始執行 VACUUM 清理...", "INFO")
    log("⚠️  注意：此操作會鎖定整個資料庫，期間無法讀寫", "WARNING")

    try:
        start_time = time.time()
        conn.execute("VACUUM")
        elapsed = time.time() - start_time
        log(f"✓ VACUUM 執行成功 (耗時 {elapsed:.2f} 秒)", "SUCCESS")
        return True
    except Exception as e:
        log(f"✗ VACUUM 執行失敗: {e}", "ERROR")
        return False

# 分析資料庫統計
def analyze_database(conn):
    log("開始分析資料庫統計...", "INFO")
    try:
        start_time = time.time()
        conn.execute("ANALYZE")
        elapsed = time.time() - start_time
        log(f"✓ 資料庫分析完成 (耗時 {elapsed:.2f} 秒)", "SUCCESS")
        return True
    except Exception as e:
        log(f"✗ 資料庫分析失敗: {e}", "ERROR")
        return False

# 顯示優化前後對比
def show_statistics(before_size, after_size):
    log("=" * 60)
    log("資料庫優化統計報告", "INFO")
    log("=" * 60)
    log(f"優化前大小: {before_size:.2f} MB", "INFO")
    log(f"優化後大小: {after_size:.2f} MB", "INFO")

    if before_size > after_size:
        saved = before_size - after_size
        saved_pct = (saved / before_size) * 100
        log(f"節省空間: {saved:.2f} MB ({saved_pct:.1f}%)", "SUCCESS")
    else:
        log("空間無變化（資料庫已經很緊湊）", "INFO")

    log("=" * 60)

def main():
    log("=" * 60)
    log("SQLite 資料庫優化腳本啟動", "INFO")
    log("=" * 60)

    # 檢查資料庫是否存在
    if not os.path.exists(DB_PATH):
        log(f"錯誤：資料庫不存在 - {DB_PATH}", "ERROR")
        sys.exit(1)

    # 記錄開始時間和大小
    before_bytes, before_mb = get_db_size()
    log(f"當前資料庫大小: {before_mb:.2f} MB", "INFO")

    try:
        # 連接資料庫
        log("連接到資料庫...", "INFO")
        conn = sqlite3.connect(DB_PATH, timeout=30.0)

        # 步驟 1: 添加索引
        log("\n" + "=" * 60)
        log("步驟 1/3: 添加索引", "INFO")
        log("=" * 60)
        added_count = add_indexes(conn)

        # 步驟 2: 執行 VACUUM
        log("\n" + "=" * 60)
        log("步驟 2/3: 執行 VACUUM 清理", "INFO")
        log("=" * 60)
        vacuum_success = run_vacuum(conn)

        # 步驟 3: 分析資料庫
        log("\n" + "=" * 60)
        log("步驟 3/3: 分析資料庫統計", "INFO")
        log("=" * 60)
        analyze_success = analyze_database(conn)

        # 關閉連接
        conn.close()
        log("資料庫連接已關閉", "INFO")

        # 顯示統計
        after_bytes, after_mb = get_db_size()
        log("")
        show_statistics(before_mb, after_mb)

        # 最終結果
        log("")
        log("=" * 60)
        if added_count > 0 or vacuum_success:
            log("✓ 資料庫優化完成！", "SUCCESS")
        else:
            log("資料庫優化執行完畢（無顯著變化）", "INFO")
        log("=" * 60)

    except sqlite3.OperationalError as e:
        log(f"資料庫操作錯誤: {e}", "ERROR")
        log("可能原因：資料庫正在被其他程序使用", "ERROR")
        sys.exit(1)
    except Exception as e:
        log(f"未預期的錯誤: {e}", "ERROR")
        import traceback
        traceback.print_exc()
        sys.exit(1)

if __name__ == "__main__":
    main()