统一归档

package com.archive.plugin;

import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import java.util.List;
import java.util.Map;

@Slf4j
@Service
public class ArchivePlugin {

    @Autowired
    private JdbcTemplate jdbcTemplate;

    @Autowired
    private StringRedisTemplate redisTemplate;

    private static final int PAGE_SIZE = 1000;

    /**
     * 模式1: RENAME 归档
     * @param tableName 原表名
     */
    public void archiveByRename(String tableName) {
        String historyTable = tableName + "_history";
        
        log.info("开始 RENAME 归档: {} -> {}", tableName, historyTable);

        // 1. 重命名表
        jdbcTemplate.execute("RENAME TABLE " + tableName + " TO " + historyTable);
        log.info("表已重命名: {} -> {}", tableName, historyTable);

        // 2. 根据历史表重建新表
        jdbcTemplate.execute("CREATE TABLE " + tableName + " LIKE " + historyTable);
        log.info("新表已创建: {}", tableName);
    }

    /**
     * 模式2: 分页迁移归档
     * @param tableName 原表名
     * @param whereCondition SQL WHERE 条件，如 "created_at < '2024-01-01'"
     */
    public void archiveByPagination(String tableName, String whereCondition) {
        String historyTable = tableName + "_history";
        String cursorKey = "archive:cursor:" + tableName;

        log.info("开始分页归档: {} -> {}, 条件: {}", tableName, historyTable, whereCondition);

        // 确保历史表存在
        ensureHistoryTableExists(tableName, historyTable);

        long lastId = getLastId(cursorKey);
        int totalArchived = 0;

        while (true) {
            // 分页查询
            String sql = String.format(
                "SELECT * FROM %s WHERE id > %d AND (%s) ORDER BY id ASC LIMIT %d",
                tableName, lastId, whereCondition, PAGE_SIZE
            );

            List<Map<String, Object>> rows = jdbcTemplate.queryForList(sql);
            if (rows.isEmpty()) {
                log.info("归档完成，共归档 {} 条记录", totalArchived);
                break;
            }

            // 事务迁移
            int archived = archiveBatch(tableName, historyTable, rows);
            totalArchived += archived;

            // 更新游标
            lastId = (Long) rows.get(rows.size() - 1).get("id");
            saveLastId(cursorKey, lastId);

            log.info("已归档 {} 条，当前游标 lastId: {}", totalArchived, lastId);
        }

        // 清除游标
        redisTemplate.delete(cursorKey);
    }

    /**
     * 批量归档（事务控制）
     */
    @Transactional(rollbackFor = Exception.class)
    public int archiveBatch(String tableName, String historyTable, List<Map<String, Object>> rows) {
        for (Map<String, Object> row : rows) {
            // 插入历史表
            insertIntoHistory(historyTable, row);
            
            // 删除源表
            Long id = (Long) row.get("id");
            jdbcTemplate.update("DELETE FROM " + tableName + " WHERE id = ?", id);
        }
        return rows.size();
    }

    /**
     * 插入历史表
     */
    private void insertIntoHistory(String historyTable, Map<String, Object> row) {
        StringBuilder columns = new StringBuilder();
        StringBuilder values = new StringBuilder();
        Object[] params = new Object[row.size()];
        int i = 0;

        for (Map.Entry<String, Object> entry : row.entrySet()) {
            if (i > 0) {
                columns.append(", ");
                values.append(", ");
            }
            columns.append(entry.getKey());
            values.append("?");
            params[i++] = entry.getValue();
        }

        String sql = String.format("INSERT INTO %s (%s) VALUES (%s)", 
            historyTable, columns, values);
        jdbcTemplate.update(sql, params);
    }

    /**
     * 确保历史表存在
     */
    private void ensureHistoryTableExists(String tableName, String historyTable) {
        String checkSql = "SHOW TABLES LIKE '" + historyTable + "'";
        List<Map<String, Object>> result = jdbcTemplate.queryForList(checkSql);
        
        if (result.isEmpty()) {
            jdbcTemplate.execute("CREATE TABLE " + historyTable + " LIKE " + tableName);
            log.info("历史表已创建: {}", historyTable);
        }
    }

    /**
     * 获取游标
     */
    private long getLastId(String key) {
        String val = redisTemplate.opsForValue().get(key);
        return val == null ? 0L : Long.parseLong(val);
    }

    /**
     * 保存游标
     */
    private void saveLastId(String key, long lastId) {
        redisTemplate.opsForValue().set(key, String.valueOf(lastId));
    }
}