// mileage-correction writes a confirmed daily terminal odometer correction.
// It is intentionally explicit: callers must provide the VIN, natural day and
// confirmed cumulative mileage; it never derives values from a guess.
package main

import (
	"context"
	"database/sql"
	"flag"
	"fmt"
	"log"
	"os"
	"strings"
	"time"

	_ "github.com/go-sql-driver/mysql"

	"lingniu-vehicle-ingest/go/vehicle-gateway/internal/envelope"
	"lingniu-vehicle-ingest/go/vehicle-gateway/internal/stats"
)

func main() {
	vin := flag.String("vin", "", "VIN")
	date := flag.String("date", "", "natural day, yyyy-MM-dd")
	total := flag.Float64("total-km", 0, "confirmed cumulative mileage, km")
	flag.Parse()
	if strings.TrimSpace(*vin) == "" || strings.TrimSpace(*date) == "" || *total <= 0 {
		log.Fatal("vin, date and positive total-km are required")
	}
	dsn := strings.TrimSpace(os.Getenv("MYSQL_DSN"))
	if dsn == "" {
		log.Fatal("MYSQL_DSN is required")
	}
	loc, err := time.LoadLocation("Asia/Shanghai")
	if err != nil {
		log.Fatal(err)
	}
	eventTime, err := time.ParseInLocation("2006-01-02 15:04:05", strings.TrimSpace(*date)+" 23:59:59", loc)
	if err != nil {
		log.Fatal(err)
	}
	db, err := sql.Open("mysql", dsn)
	if err != nil {
		log.Fatal(err)
	}
	defer db.Close()
	ctx := context.Background()
	if err := db.PingContext(ctx); err != nil {
		log.Fatal(err)
	}
	candidate := stats.SourceMileageSample{
		VIN:             strings.TrimSpace(*vin),
		StatDate:        strings.TrimSpace(*date),
		Protocol:        envelope.ProtocolGB32960,
		SourceKey:       "GB32960:manual-correction@manual",
		SourceIP:        "manual",
		SourceEndpoint:  "manual-correction",
		FirstTotalKM:    *total,
		LatestTotalKM:   *total,
		DailyKM:         0,
		SampleCount:     1,
		FirstEventTime:  eventTime,
		LatestEventTime: eventTime,
		QualityStatus:   stats.QualityOK,
		QualityReason:   "manual_correction_confirmed_total",
	}
	if err := stats.UpsertSourceMileage(ctx, db, candidate); err != nil {
		log.Fatal(err)
	}
	if err := stats.ProjectDailyMileage(ctx, db, candidate.VIN, candidate.StatDate, candidate.Protocol); err != nil {
		log.Fatal(err)
	}
	// Keep both cumulative fields aligned. day_end_total_mileage_km is the API
	// field of record, while latest_total_mileage_km remains useful to internal
	// readers and must not retain the rejected reset value.
	if _, err := db.ExecContext(ctx, `
UPDATE vehicle_daily_mileage
SET latest_total_mileage_km=?, day_end_total_mileage_km=?
WHERE vin=? AND stat_date=? AND protocol=?`,
		*total, *total, candidate.VIN, candidate.StatDate, string(candidate.Protocol)); err != nil {
		log.Fatal(err)
	}
	var daily, latest, dayEnd float64
	if err := db.QueryRowContext(ctx, `SELECT daily_mileage_km,latest_total_mileage_km,day_end_total_mileage_km FROM vehicle_daily_mileage WHERE vin=? AND stat_date=? AND protocol=?`, candidate.VIN, candidate.StatDate, string(candidate.Protocol)).Scan(&daily, &latest, &dayEnd); err != nil {
		log.Fatal(err)
	}
	fmt.Printf("corrected vin=%s date=%s protocol=%s daily_km=%.3f latest_total_km=%.3f day_end_total_km=%.3f\n", candidate.VIN, candidate.StatDate, candidate.Protocol, daily, latest, dayEnd)
}