package main

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

	_ "github.com/go-sql-driver/mysql"
	_ "github.com/taosdata/driver-go/v3/taosWS"

	"lingniu/vehicle-data-platform/apps/api/internal/config"
	"lingniu/vehicle-data-platform/apps/api/internal/openplatform"
)

func main() {
	date := flag.String("date", "", "last date to calculate in yyyy-MM-dd; defaults to yesterday in Asia/Shanghai")
	lookback := flag.Int("lookback-days", envInt("OPEN_STAT_LOOKBACK_DAYS", 2), "number of dates ending at -date")
	noise := flag.Float64("hydrogen-noise-kg", envFloat("OPEN_STAT_HYDROGEN_NOISE_KG", 0.05), "ignored mass jitter")
	maxDrop := flag.Float64("hydrogen-max-drop-kg", envFloat("OPEN_STAT_HYDROGEN_MAX_DROP_KG", 20), "maximum accepted drop between samples")
	flag.Parse()

	cfg := config.Load()
	if cfg.MySQLDSN == "" || cfg.TDengineDSN == "" {
		log.Fatal("MYSQL_DSN and TDENGINE_DSN are required")
	}
	mysqlDB, err := sql.Open("mysql", cfg.MySQLDSN)
	if err != nil {
		log.Fatal(err)
	}
	defer mysqlDB.Close()
	tdengineDB, err := sql.Open(cfg.TDengineDriver, cfg.TDengineDSN)
	if err != nil {
		log.Fatal(err)
	}
	defer tdengineDB.Close()

	location := time.FixedZone("Asia/Shanghai", 8*60*60)
	endDate := time.Now().In(location).AddDate(0, 0, -1)
	if *date != "" {
		endDate, err = time.ParseInLocation("2006-01-02", *date, location)
		if err != nil {
			log.Fatal("-date must use yyyy-MM-dd")
		}
	}
	if *lookback < 1 || *lookback > 31 {
		log.Fatal("-lookback-days must be between 1 and 31")
	}
	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Minute)
	defer cancel()
	capacities, err := openplatform.LoadHydrogenCapacities(ctx, mysqlDB)
	if err != nil {
		log.Fatalf("load hydrogen tank capacities: %v", err)
	}
	for offset := *lookback - 1; offset >= 0; offset-- {
		start := time.Date(endDate.Year(), endDate.Month(), endDate.Day(), 0, 0, 0, 0, location).AddDate(0, 0, -offset)
		observations, err := openplatform.LoadHydrogenObservations(ctx, tdengineDB, cfg.TDengineDatabase, start, start.AddDate(0, 0, 1), capacities)
		if err != nil {
			log.Fatalf("load hydrogen observations for %s: %v", start.Format("2006-01-02"), err)
		}
		stats := openplatform.BuildHydrogenDailyStats(observations, start.Format("2006-01-02"), *noise, *maxDrop)
		if err := openplatform.ReplaceHydrogenDailyStats(ctx, mysqlDB, start.Format("2006-01-02"), stats); err != nil {
			log.Fatalf("persist hydrogen statistics for %s: %v", start.Format("2006-01-02"), err)
		}
		fmt.Printf("date=%s observations=%d vehicles=%d\n", start.Format("2006-01-02"), len(observations), len(stats))
	}
}

func envInt(name string, fallback int) int {
	value, err := strconv.Atoi(os.Getenv(name))
	if err != nil {
		return fallback
	}
	return value
}

func envFloat(name string, fallback float64) float64 {
	value, err := strconv.ParseFloat(os.Getenv(name), 64)
	if err != nil {
		return fallback
	}
	return value
}