package com.kaidi.oa.web;

import com.kaidi.oa.common.ApiException;
import com.kaidi.oa.common.ApiResp;
import com.kaidi.oa.common.Money;
import com.kaidi.oa.common.NotFoundException;
import com.kaidi.oa.domain.SewageEnergyLog;
import com.kaidi.oa.repository.SewageEnergyLogRepository;
import org.springframework.web.bind.annotation.DeleteMapping;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PatchMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import java.math.BigDecimal;
import java.math.RoundingMode;
import java.time.Instant;
import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

/**
 * 城镇污水运营·药剂与能耗管理。药耗/电耗日台账 CRUD，单耗与成本由后端自动计算（非前端传）：
 *   吨水电耗(kWh/m³)、吨水药耗(g/m³)、当日电费/药剂费(BigDecimal)、吨水成本(元/m³)。
 * 另提供按月成本归集汇总（电费/药费/合计、加权吨水成本）与单耗异常预警（与历史均值偏离）。
 *
 * 金额一律 BigDecimal（电价、药剂单价、各项费用）；水量/电耗/药量为数量用 double。
 * 写口默认受 default-deny(ADMIN/APPROVER) 保护，已登记 sewage-energy-logs 进财务/敏感读前缀。
 */
@RestController
@RequestMapping("/api/oa/sewage-energy-logs")
public class SewageEnergyLogController {

    private final SewageEnergyLogRepository logRepo;

    public SewageEnergyLogController(SewageEnergyLogRepository logRepo) {
        this.logRepo = logRepo;
    }

    @GetMapping
    public ApiResp<List<SewageEnergyLog>> list(@RequestParam(required = false) String plant) {
        if (plant != null && !plant.isBlank()) {
            return ApiResp.ok(logRepo.findByPlant(plant));
        }
        return ApiResp.ok(logRepo.findAll());
    }

    @GetMapping("/{id}")
    public ApiResp<SewageEnergyLog> get(@PathVariable Long id) {
        return ApiResp.ok(logRepo.findById(id)
                .orElseThrow(() -> new NotFoundException("energy log not found: " + id)));
    }

    public record EnergyRequest(
            String code, String logDate, String plant, Double treatedWater, Double powerKwh,
            Double powerPrice, String reagentName, Double reagentKg, Double reagentPrice,
            String owner) {
    }

    @PostMapping
    public ApiResp<SewageEnergyLog> create(@RequestBody EnergyRequest req) {
        if (req.logDate() == null || req.logDate().isBlank()) {
            throw new ApiException(400, "统计日期(logDate) 不能为空");
        }
        SewageEnergyLog e = new SewageEnergyLog();
        e.setCode(req.code() == null || req.code().isBlank()
                ? "NHD-" + (logRepo.count() + 1) : req.code());
        e.setLogDate(req.logDate());
        e.setPlant(req.plant());
        e.setReagentName(req.reagentName());
        e.setOwner(req.owner());
        e.setCreatedAt(Instant.now());
        applyMeasures(e, req.treatedWater(), req.powerKwh(), req.powerPrice(),
                req.reagentKg(), req.reagentPrice());
        return ApiResp.ok(logRepo.save(e));
    }

    @PatchMapping("/{id}")
    public ApiResp<SewageEnergyLog> update(@PathVariable Long id, @RequestBody EnergyRequest req) {
        SewageEnergyLog e = logRepo.findById(id)
                .orElseThrow(() -> new NotFoundException("energy log not found: " + id));
        if (req.logDate() != null && !req.logDate().isBlank()) e.setLogDate(req.logDate());
        if (req.plant() != null) e.setPlant(req.plant());
        if (req.reagentName() != null) e.setReagentName(req.reagentName());
        if (req.owner() != null) e.setOwner(req.owner());
        // 任一计量字段变更则按合并后的值重算（null 视为沿用旧值）。
        Double water = req.treatedWater() != null ? req.treatedWater() : e.getTreatedWater();
        Double power = req.powerKwh() != null ? req.powerKwh() : e.getPowerKwh();
        Double pPrice = req.powerPrice() != null ? req.powerPrice() : e.getPowerPrice().doubleValue();
        Double rKg = req.reagentKg() != null ? req.reagentKg() : e.getReagentKg();
        Double rPrice = req.reagentPrice() != null ? req.reagentPrice() : e.getReagentPrice().doubleValue();
        applyMeasures(e, water, power, pPrice, rKg, rPrice);
        return ApiResp.ok(logRepo.save(e));
    }

    @DeleteMapping("/{id}")
    public ApiResp<Void> delete(@PathVariable Long id) {
        if (!logRepo.existsById(id)) {
            throw new NotFoundException("energy log not found: " + id);
        }
        logRepo.deleteById(id);
        return ApiResp.ok(null);
    }

    /**
     * 计量字段落库并自动派生单耗与成本：
     *   吨水电耗 = powerKwh / water；吨水药耗(g/m³) = reagentKg*1000 / water；
     *   电费 = powerKwh × powerPrice；药剂费 = reagentKg × reagentPrice（BigDecimal.multiply）；
     *   吨水成本 = (电费 + 药剂费) / water。
     */
    private void applyMeasures(SewageEnergyLog e, Double water, Double power, Double powerPrice,
                               Double reagentKg, Double reagentPrice) {
        double w = nz(water);
        double pw = nz(power);
        double rk = nz(reagentKg);
        BigDecimal pPrice = Money.of(powerPrice);
        BigDecimal rPrice = Money.of(reagentPrice);
        e.setTreatedWater(w);
        e.setPowerKwh(pw);
        e.setPowerPrice(pPrice);
        e.setReagentKg(rk);
        e.setReagentPrice(rPrice);

        e.setUnitPower(w <= 0 ? 0 : round3(pw / w));
        e.setUnitReagent(w <= 0 ? 0 : round3(rk * 1000.0 / w));

        BigDecimal powerCost = Money.of(BigDecimal.valueOf(pw).multiply(pPrice));
        BigDecimal reagentCost = Money.of(BigDecimal.valueOf(rk).multiply(rPrice));
        e.setPowerCost(powerCost);
        e.setReagentCost(reagentCost);

        BigDecimal totalCost = Money.add(powerCost, reagentCost);
        BigDecimal unitCost = w <= 0 ? BigDecimal.ZERO
                : totalCost.divide(BigDecimal.valueOf(w), Money.SCALE + 2, RoundingMode.HALF_UP);
        e.setUnitCost(Money.of(unitCost));
    }

    // ---------- 成本归集（按月） ----------

    public record CostRow(String month, double treatedWater, double powerKwh, double reagentKg,
                          double powerCost, double reagentCost, double totalCost,
                          double unitPower, double unitReagent, double unitCost) {
    }

    public record CostSummary(List<CostRow> rows, double totalWater, double totalCost,
                              double weightedUnitCost) {
    }

    /**
     * 成本归集：按月(logDate 前 7 位 yyyy-MM)汇总处理水量、电耗、药量、电费、药费、合计，
     * 并算月吨水电耗/药耗/成本与全期加权吨水成本。供绩效成本看板与预算对比取数。
     */
    @GetMapping("/cost/summary")
    public ApiResp<CostSummary> costSummary() {
        Map<String, double[]> agg = new LinkedHashMap<>();
        // [water, powerKwh, reagentKg, powerCost, reagentCost]
        for (SewageEnergyLog e : logRepo.findAll()) {
            String month = monthOf(e.getLogDate());
            double[] a = agg.computeIfAbsent(month, k -> new double[5]);
            a[0] += nz(e.getTreatedWater());
            a[1] += nz(e.getPowerKwh());
            a[2] += nz(e.getReagentKg());
            a[3] += e.getPowerCost() == null ? 0 : e.getPowerCost().doubleValue();
            a[4] += e.getReagentCost() == null ? 0 : e.getReagentCost().doubleValue();
        }
        List<CostRow> rows = new ArrayList<>();
        double totalWater = 0;
        double totalCost = 0;
        for (Map.Entry<String, double[]> en : agg.entrySet()) {
            double[] a = en.getValue();
            double tc = a[3] + a[4];
            rows.add(new CostRow(en.getKey(), round1(a[0]), round1(a[1]), round1(a[2]),
                    round2(a[3]), round2(a[4]), round2(tc),
                    a[0] <= 0 ? 0 : round3(a[1] / a[0]),
                    a[0] <= 0 ? 0 : round3(a[2] * 1000.0 / a[0]),
                    a[0] <= 0 ? 0 : round3(tc / a[0])));
            totalWater += a[0];
            totalCost += tc;
        }
        rows.sort((x, y) -> x.month().compareTo(y.month()));
        double weighted = totalWater <= 0 ? 0 : round3(totalCost / totalWater);
        return ApiResp.ok(new CostSummary(rows, round1(totalWater), round2(totalCost), weighted));
    }

    // ---------- 单耗异常预警 ----------

    public record AnomalyRow(Long id, String logDate, String plant, double unitPower,
                             double avgUnitPower, double deviationPct, String level) {
    }

    /**
     * 单耗异常预警：以全期吨水电耗均值为基线，单条偏离 > thresholdPct%（默认 15）记预警，
     * > 30% 记异常。与需求"异常时预警/与历史值对比"一致。
     */
    @GetMapping("/alerts/energy")
    public ApiResp<List<AnomalyRow>> energyAlerts(@RequestParam(required = false, defaultValue = "15") double thresholdPct) {
        List<SewageEnergyLog> all = logRepo.findAll();
        double sum = 0;
        int cnt = 0;
        for (SewageEnergyLog e : all) {
            if (nz(e.getUnitPower()) > 0) {
                sum += e.getUnitPower();
                cnt++;
            }
        }
        double avg = cnt == 0 ? 0 : sum / cnt;
        List<AnomalyRow> out = new ArrayList<>();
        if (avg <= 0) {
            return ApiResp.ok(out);
        }
        for (SewageEnergyLog e : all) {
            double up = nz(e.getUnitPower());
            if (up <= 0) {
                continue;
            }
            double dev = (up - avg) / avg * 100.0;
            if (Math.abs(dev) < thresholdPct) {
                continue;
            }
            String level = Math.abs(dev) >= 30 ? "异常" : "预警";
            out.add(new AnomalyRow(e.getId(), e.getLogDate(), e.getPlant(), round3(up),
                    round3(avg), round1(dev), level));
        }
        out.sort((a, b) -> Double.compare(Math.abs(b.deviationPct()), Math.abs(a.deviationPct())));
        return ApiResp.ok(out);
    }

    // ---------- helpers ----------

    private static double nz(Double v) {
        return v == null ? 0.0 : v;
    }

    private static String monthOf(String date) {
        if (date == null || date.length() < 7) {
            return "未知";
        }
        return date.substring(0, 7);
    }

    private static double round1(double v) {
        return BigDecimal.valueOf(v).setScale(1, RoundingMode.HALF_UP).doubleValue();
    }

    private static double round2(double v) {
        return BigDecimal.valueOf(v).setScale(2, RoundingMode.HALF_UP).doubleValue();
    }

    private static double round3(double v) {
        return BigDecimal.valueOf(v).setScale(3, RoundingMode.HALF_UP).doubleValue();
    }
}