package openplatform

import (
	"context"
	"database/sql"
	"encoding/json"
	"fmt"
	"math"
	"sort"
	"strconv"
	"strings"
	"time"
)

var hydrogenMassFields = []string{
	"gb32960.gd_fc_vehicle_info.hydrogen_mass_kg",
	"gb32960.gd_fc_vehicle.hydrogen_mass_kg",
	"gb32960.gd_fc_vehicle_info.gd_fc_vehicle_hydrogen_mass_kg",
	"gd_fc_vehicle_hydrogen_mass_kg",
}

func BuildHydrogenDailyStats(observations []HydrogenObservation, date string, noiseKg, maxDropKg float64) []HydrogenDailyStat {
	if noiseKg <= 0 {
		noiseKg = 0.05
	}
	if maxDropKg <= noiseKg {
		maxDropKg = 20
	}
	grouped := map[string]map[string][]HydrogenObservation{}
	for _, observation := range observations {
		observation.VIN = strings.ToUpper(strings.TrimSpace(observation.VIN))
		observation.Source = strings.TrimSpace(observation.Source)
		if len(observation.VIN) != 17 || math.IsNaN(observation.MassKg) || math.IsInf(observation.MassKg, 0) || observation.MassKg < 0 || observation.MassKg > 200 {
			continue
		}
		if grouped[observation.VIN] == nil {
			grouped[observation.VIN] = map[string][]HydrogenObservation{}
		}
		grouped[observation.VIN][observation.Source] = append(grouped[observation.VIN][observation.Source], observation)
	}
	vins := make([]string, 0, len(grouped))
	for vin := range grouped {
		vins = append(vins, vin)
	}
	sort.Strings(vins)
	stats := make([]HydrogenDailyStat, 0, len(vins))
	for _, vin := range vins {
		var selected *HydrogenDailyStat
		for source, values := range grouped[vin] {
			candidate := buildHydrogenDailyStat(vin, source, date, values, noiseKg, maxDropKg)
			if selected == nil || betterHydrogenStat(candidate, *selected) {
				copy := candidate
				selected = &copy
			}
		}
		if selected != nil {
			stats = append(stats, *selected)
		}
	}
	return stats
}

func buildHydrogenDailyStat(vin, source, date string, values []HydrogenObservation, noiseKg, maxDropKg float64) HydrogenDailyStat {
	sort.SliceStable(values, func(i, j int) bool { return values[i].ObservedAt.Before(values[j].ObservedAt) })
	stat := HydrogenDailyStat{
		VIN: vin, Source: source, Date: date,
		FirstMassKg: values[0].MassKg, LastMassKg: values[len(values)-1].MassKg,
		SampleCount: len(values), QualityStatus: "OK",
	}
	abnormalDrops := 0
	cycleMinimum := values[0].MassKg
	for index := 1; index < len(values); index++ {
		value := values[index]
		sampleNoise := noiseKg
		if value.NoiseKg > sampleNoise {
			sampleNoise = value.NoiseKg
		}
		refuelThreshold := math.Max(1, cycleMinimum*0.05)
		if value.RefuelThresholdKg > 0 {
			refuelThreshold = value.RefuelThresholdKg
		}
		delta := cycleMinimum - value.MassKg
		switch {
		case value.MassKg-cycleMinimum > refuelThreshold:
			stat.RefuelCount++
			cycleMinimum = value.MassKg
		case delta > sampleNoise && delta <= maxDropKg:
			stat.ConsumptionKg += delta
			cycleMinimum = value.MassKg
		case delta > maxDropKg:
			abnormalDrops++
		}
	}
	stat.ConsumptionKg = round3(stat.ConsumptionKg)
	if stat.SampleCount < 2 {
		stat.QualityStatus = "NO_DATA"
		stat.QualityReason = "有效车载氢量样本不足2条"
	} else if abnormalDrops > 0 {
		stat.QualityStatus = "SUSPECT"
		stat.QualityReason = fmt.Sprintf("过滤%d次超过%.3fkg的异常下降", abnormalDrops, maxDropKg)
	}
	return stat
}

func betterHydrogenStat(candidate, current HydrogenDailyStat) bool {
	rank := func(status string) int {
		switch status {
		case "OK":
			return 0
		case "SUSPECT":
			return 1
		default:
			return 2
		}
	}
	if rank(candidate.QualityStatus) != rank(current.QualityStatus) {
		return rank(candidate.QualityStatus) < rank(current.QualityStatus)
	}
	if candidate.SampleCount != current.SampleCount {
		return candidate.SampleCount > current.SampleCount
	}
	return candidate.Source < current.Source
}

func ExtractHydrogenMass(parsedJSON string) (float64, bool) {
	var fields map[string]any
	if err := json.Unmarshal([]byte(parsedJSON), &fields); err != nil {
		return 0, false
	}
	for _, key := range hydrogenMassFields {
		if value, ok := numericValue(fields[key]); ok && value >= 0 && value <= 200 {
			return value, true
		}
	}
	return 0, false
}

func ExtractHydrogenRateAndMileage(parsedJSON string) (float64, float64, bool) {
	var fields map[string]any
	if err := json.Unmarshal([]byte(parsedJSON), &fields); err != nil {
		return 0, 0, false
	}
	rate, rateOK := numericValue(fields["gb32960.fuel_cell.hydrogen_consumption_kg_per_100km"])
	mileage, mileageOK := numericValue(fields["gb32960.vehicle.total_mileage_km"])
	return rate, mileage, rateOK && mileageOK && rate >= 0 && rate <= 50 && mileage > 0
}

func BuildHydrogenRateDailyStats(observations []HydrogenRateObservation, date string, maxDeltaKm float64) []HydrogenRateDailyStat {
	if maxDeltaKm <= 0 {
		maxDeltaKm = 10
	}
	grouped := map[string]map[string][]HydrogenRateObservation{}
	for _, value := range observations {
		value.VIN = strings.ToUpper(strings.TrimSpace(value.VIN))
		if len(value.VIN) != 17 || value.Rate < 0 || value.Rate > 50 || value.MileageKm <= 0 {
			continue
		}
		if grouped[value.VIN] == nil {
			grouped[value.VIN] = map[string][]HydrogenRateObservation{}
		}
		grouped[value.VIN][strings.TrimSpace(value.Source)] = append(grouped[value.VIN][strings.TrimSpace(value.Source)], value)
	}
	result := make([]HydrogenRateDailyStat, 0, len(grouped))
	for vin, sources := range grouped {
		var best *HydrogenRateDailyStat
		for source, values := range sources {
			sort.SliceStable(values, func(i, j int) bool { return values[i].ObservedAt.Before(values[j].ObservedAt) })
			stat := HydrogenRateDailyStat{VIN: vin, Source: source, Date: date, SampleCount: len(values), QualityStatus: "NO_DATA", QualityReason: "尚无有效行驶里程区间"}
			movement, abnormal := 0, 0
			for i := 1; i < len(values); i++ {
				delta := values[i].MileageKm - values[i-1].MileageKm
				if delta > 0 && delta <= maxDeltaKm {
					stat.ConsumptionKg += delta * (values[i-1].Rate + values[i].Rate) / 200
					movement++
				} else if delta < 0 || delta > maxDeltaKm {
					abnormal++
				}
			}
			stat.ConsumptionKg = round3(stat.ConsumptionKg)
			if abnormal > 0 {
				stat.QualityStatus, stat.QualityReason = "SUSPECT", "存在异常里程跳变"
			} else if movement > 0 {
				stat.QualityStatus, stat.QualityReason = "OK", "按里程区间积分百公里氢耗"
			}
			if best == nil || (stat.QualityStatus == "OK" && best.QualityStatus != "OK") || (stat.QualityStatus == best.QualityStatus && stat.SampleCount > best.SampleCount) {
				copy := stat
				best = &copy
			}
		}
		if best != nil {
			result = append(result, *best)
		}
	}
	sort.Slice(result, func(i, j int) bool { return result[i].VIN < result[j].VIN })
	return result
}

func LoadHydrogenCapacities(ctx context.Context, db *sql.DB) (map[string]float64, error) {
	rows, err := db.QueryContext(ctx, `SELECT UPPER(TRIM(vin)),tank_capacity_l FROM vehicle_hydrogen_tank_capacity WHERE active=1 AND tank_capacity_l>0`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	capacities := map[string]float64{}
	for rows.Next() {
		var vin string
		var capacity float64
		if err := rows.Scan(&vin, &capacity); err != nil {
			return nil, err
		}
		if len(vin) == 17 && capacity > 0 && capacity <= 10000 {
			capacities[vin] = capacity
		}
	}
	return capacities, rows.Err()
}

func LoadHydrogenObservations(ctx context.Context, tdengine *sql.DB, database string, start, end time.Time, capacities map[string]float64) ([]HydrogenObservation, error) {
	database = strings.TrimSpace(database)
	if database == "" {
		database = "lingniu_vehicle_ts"
	}
	query := `SELECT vin,source_endpoint,CAST(ts AS BIGINT),parsed_json
FROM ` + database + `.raw_frames
WHERE protocol='GB32960'
  AND ts>='` + quoteTDTime(start) + `'
  AND ts<'` + quoteTDTime(end) + `'
  AND parse_status='OK'
ORDER BY vin,source_endpoint,ts`
	rows, err := tdengine.QueryContext(ctx, query)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	observations := make([]HydrogenObservation, 0)
	for rows.Next() {
		var vin, parsed string
		var source sql.NullString
		var unixMS int64
		if err := rows.Scan(&vin, &source, &unixMS, &parsed); err != nil {
			return nil, err
		}
		vin = strings.ToUpper(strings.TrimSpace(vin))
		capacity, capacityOK := capacities[vin]
		pressure, temperature, ok := ExtractHydrogenPressureTemperature(parsed)
		if !capacityOK || !ok {
			continue
		}
		mass, ok := PressureHydrogenMassKg(pressure, temperature, capacity)
		if !ok {
			continue
		}
		stepMass, _ := PressureHydrogenMassKg(math.Max(0, pressure-0.2), temperature, capacity)
		noise := math.Min(1, math.Max(0.05, mass-stepMass))
		observations = append(observations, HydrogenObservation{
			VIN: vin, Source: source.String, ObservedAt: time.UnixMilli(unixMS), MassKg: mass,
			TankCapacityLiter: capacity, PressureMPa: pressure, TemperatureC: temperature,
			NoiseKg: noise, RefuelThresholdKg: math.Max(1, mass*0.05),
		})
	}
	return observations, rows.Err()
}

func ExtractHydrogenPressureTemperature(parsedJSON string) (float64, float64, bool) {
	var fields map[string]any
	if err := json.Unmarshal([]byte(parsedJSON), &fields); err != nil {
		return 0, 0, false
	}
	pressure, pressureOK := numericValue(fields["gb32960.fuel_cell.max_hydrogen_pressure_mpa"])
	temperature, temperatureOK := numericValue(fields["gb32960.fuel_cell.max_hydrogen_temperature_c"])
	return pressure, temperature, pressureOK && temperatureOK
}

func PressureHydrogenMassKg(pressureMPa, temperatureC, capacityLiter float64) (float64, bool) {
	temperatureK := temperatureC + 273.15
	if pressureMPa < 0 || pressureMPa > 70 || temperatureK < 220 || temperatureK > 1000 || capacityLiter <= 0 || capacityLiter > 10000 {
		return 0, false
	}
	a := [...]float64{0.05888460, -0.06136111, -0.002650473, 0.002731125, 0.001802374, -0.001150707, 0.00009588528, -0.0000001109040, 0.0000000001264403}
	b := [...]float64{1.325, 1.87, 2.5, 2.8, 2.938, 3.14, 3.37, 3.75, 4.0}
	c := [...]float64{1, 1, 2, 2, 2.42, 2.63, 3, 4, 5}
	z := 1.0
	for index := range a {
		z += a[index] * math.Pow(100/temperatureK, b[index]) * math.Pow(pressureMPa, c[index])
	}
	if z <= 0 {
		return 0, false
	}
	density := pressureMPa * 1000 / (8.314472 * temperatureK * z) * 0.00201588 * 1000
	mass := density * capacityLiter / 1000
	return mass, !math.IsNaN(mass) && !math.IsInf(mass, 0) && mass >= 0 && mass <= 500
}

func ReplaceHydrogenDailyStats(ctx context.Context, db *sql.DB, date string, stats []HydrogenDailyStat) error {
	tx, err := db.BeginTx(ctx, nil)
	if err != nil {
		return err
	}
	defer tx.Rollback()
	// A pressure-based rebuild is authoritative for the whole day. Delete every
	// previous hydrogen row first so legacy rate/direct-mass results cannot remain
	// for vehicles without valid pressure observations in this run.
	if _, err := tx.ExecContext(ctx, `DELETE FROM vehicle_open_daily_energy WHERE stat_date=? AND energy_type='HYDROGEN'`, date); err != nil {
		return err
	}
	for _, stat := range stats {
		if _, err := tx.ExecContext(ctx, `
INSERT INTO vehicle_open_daily_energy(
  vin,stat_date,energy_type,source_endpoint,consumption_kg,unit,first_mass_kg,last_mass_kg,
  sample_count,refuel_count,quality_status,quality_reason,calculated_at
) VALUES(?,?,'HYDROGEN',?,?,'kg',?,?,?,?,?,?,NOW(3))`,
			stat.VIN, stat.Date, stat.Source, stat.ConsumptionKg, stat.FirstMassKg, stat.LastMassKg,
			stat.SampleCount, stat.RefuelCount, stat.QualityStatus, stat.QualityReason,
		); err != nil {
			return err
		}
	}
	return tx.Commit()
}

func numericValue(value any) (float64, bool) {
	switch typed := value.(type) {
	case float64:
		return typed, true
	case json.Number:
		parsed, err := typed.Float64()
		return parsed, err == nil
	case string:
		parsed, err := strconv.ParseFloat(strings.TrimSpace(typed), 64)
		return parsed, err == nil
	default:
		return 0, false
	}
}

func quoteTDTime(value time.Time) string {
	return strings.ReplaceAll(value.Format(time.RFC3339Nano), "'", "''")
}