package com.dashboard.aws.lambda.service;

import com.dashboard.aws.lambda.entity.AggregationLevel;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.time.LocalDateTime;

public class AccumulateIncrementService {

    private static final Logger logger = LoggerFactory.getLogger(AccumulateIncrementService.class);

    private static final String MYSQL_URL = System.getenv("DB_URL");
    private static final String DB_USER = System.getenv("DB_USER");
    private static final String DB_PASSWORD = System.getenv("DB_PASSWORD");

    private Connection getConnection() throws SQLException {
        return DriverManager.getConnection(MYSQL_URL, DB_USER, DB_PASSWORD);
    }

    public void aggregate(Long companyId, AggregationLevel level, LocalDateTime now) {
        String sourceTable;
        String targetTable;
        String sourceColumn;
        String timeWhereColumn;

        switch (level) {
            case MIN_30 -> {
                sourceTable = "dashboard_record_accumulate";
                targetTable = "dashboard_aggregate_accumulate_30min";
                sourceColumn = "increment_minute";
                timeWhereColumn = "upload_at";
            }
            case HOUR -> {
                sourceTable = "dashboard_aggregate_accumulate_30min";
                targetTable = "dashboard_aggregate_accumulate_hour";
                sourceColumn = "aggregate_value";
                timeWhereColumn = "time_start";
            }
            case DAY -> {
                sourceTable = "dashboard_aggregate_accumulate_hour";
                targetTable = "dashboard_aggregate_accumulate_day";
                sourceColumn = "aggregate_value";
                timeWhereColumn = "time_start";
            }
            case MONTH -> {
                sourceTable = "dashboard_aggregate_accumulate_day";
                targetTable = "dashboard_aggregate_accumulate_month";
                sourceColumn = "aggregate_value";
                timeWhereColumn = "time_start";
            }
            case YEAR -> {
                sourceTable = "dashboard_aggregate_accumulate_month";
                targetTable = "dashboard_aggregate_accumulate_year";
                sourceColumn = "aggregate_value";
                timeWhereColumn = "time_start";
            }
            default -> {
                logger.warn("Unsupported aggregation level: {}", level);
                return;
            }
        }

        // --- 1) 计算 start/end（东京时区），并计算要写入的 date 字段 ---
        java.time.ZoneId zone = java.time.ZoneId.of("Asia/Tokyo");

        java.time.LocalDateTime end;   // 区间右开端点（不包含）
        java.time.LocalDateTime start; // 区间起点（包含）

        switch (level) {
            case MIN_30:
                // 触发时应该是在 minute == 0 或 30。以当前时间向下取整到 0 或 30。
                int minute = now.getMinute();
                int roundedMinute = (minute >= 30) ? 30 : 0;
                end = now.withMinute(roundedMinute).withSecond(0).withNano(0);
                // 如果 now 正好在 0/30 分（触发时），end==now; 否则我们仍以向下取整后的 end 为区间结束
                start = end.minusMinutes(30);
                break;
            case HOUR:
                end = now.withMinute(0).withSecond(0).withNano(0);
                start = end.minusHours(1);
                break;
            case DAY:
                end = now.withHour(0).withMinute(0).withSecond(0).withNano(0);
                start = end.minusDays(1);
                break;
            case MONTH:
                end = now.withDayOfMonth(1).withHour(0).withMinute(0).withSecond(0).withNano(0);
                start = end.minusMonths(1);
                break;
            case YEAR:
                end = now.withMonth(1).withDayOfMonth(1).withHour(0).withMinute(0).withSecond(0).withNano(0);
                start = end.minusYears(1);
                break;
            default:
                logger.warn("Unsupported level for time calc: {}", level);
                return;
        }

        long startMillis = start.atZone(zone).toInstant().toEpochMilli();
        long endMillis = end.atZone(zone).toInstant().toEpochMilli();

        // 计算写入的 date 字段（基于 end 的“窗口标识时间”）
        int y = end.getYear();
        int m = end.getMonthValue();
        int d = end.getDayOfMonth();
        int h = end.getHour();
        int mm = (level == AggregationLevel.MIN_30) ? (end.getMinute() == 0 ? 0 : 30) : end.getMinute();

        // 根据级别决定要写入哪些 date 列和参数顺序
        String dateCols;
        java.util.List<Object> dateValues = new java.util.ArrayList<>();
        switch (level) {
            case MIN_30 -> {
                dateCols = "date_year, date_month, date_day, date_hour, date_minute";
                dateValues.add(y); dateValues.add(m); dateValues.add(d); dateValues.add(h); dateValues.add(mm);
            }
            case HOUR -> {
                dateCols = "date_year, date_month, date_day, date_hour";
                dateValues.add(y); dateValues.add(m); dateValues.add(d); dateValues.add(h);
            }
            case DAY -> {
                dateCols = "date_year, date_month, date_day";
                dateValues.add(y); dateValues.add(m); dateValues.add(d);
            }
            case MONTH -> {
                dateCols = "date_year, date_month";
                dateValues.add(y); dateValues.add(m);
            }
            case YEAR -> {
                dateCols = "date_year";
                dateValues.add(y);
            }
            default -> {
                logger.warn("unexpected level");
                return;
            }
        }

        String schema = "data_center_dongjian_" + companyId;

        // --- 2) SQL：用占位符传入 date 字段 + start/end 时间戳（毫秒） ---
        String sql = String.format(
                "INSERT INTO %s.%s (device_id, aggregate_value, %s, time_start, time_end, aggregated_at) " +
                        "SELECT device_id, SUM(CAST(%s AS DECIMAL(20,6))) AS aggregate_value, %s, ?, ?, ? " +
                        "FROM %s.%s " +
                        "WHERE %s >= ? AND %s < ? " +
                        "GROUP BY device_id",
                schema, targetTable, dateCols,
                sourceColumn,
                // 下面占位符用于 date 列，会被 PreparedStatement 替换（数量与 dateValues.size() 一致）
                String.join(", ", java.util.Collections.nCopies(dateValues.size(), "?")),
                schema, sourceTable, timeWhereColumn, timeWhereColumn
        );

        try (Connection conn = getConnection();
             PreparedStatement ps = conn.prepareStatement(sql)) {

            int idx = 1;
            for (Object v : dateValues) {
                if (v instanceof Integer) ps.setInt(idx++, (Integer) v);
                else if (v instanceof Long) ps.setLong(idx++, (Long) v);
                else ps.setObject(idx++, v);
            }
            ps.setObject(idx++, startMillis);
            ps.setObject(idx++, endMillis);
            // aggregated_at
            ps.setObject(idx++, now);
            ps.setLong(idx++, startMillis);
            ps.setLong(idx, endMillis);

            int inserted = ps.executeUpdate();
            logger.info("[company:{}][{}] aggregated {} -> rows inserted: {}, start={}, end={}", companyId, level, targetTable, inserted, startMillis, endMillis);
        } catch (SQLException e) {
            logger.error("[company:{}][{}] aggregation failed, start={}, end={}", companyId, level, startMillis, endMillis, e);
        }
    }
}