// Apply a reviewed, backed-up stale-baseline plan and rebuild its projections atomically.
package main

import (
	"context"
	"database/sql"
	"encoding/json"
	"flag"
	"fmt"
	_ "github.com/go-sql-driver/mysql"
	"lingniu-vehicle-ingest/go/vehicle-gateway/internal/envelope"
	"lingniu-vehicle-ingest/go/vehicle-gateway/internal/stats"
	"math"
	"os"
	"sort"
	"strconv"
	"time"
)

type change struct {
	Before struct {
		VIN       string `json:"vin"`
		Protocol  string `json:"protocol"`
		Date      string `json:"stat_date"`
		Source    string `json:"source_key"`
		First     string `json:"first_total_mileage_km"`
		FirstTime string `json:"first_event_time"`
		Total     string `json:"latest_total_mileage_km"`
		LastTime  string `json:"latest_event_time"`
		Daily     string `json:"daily_mileage_km"`
	} `json:"before"`
	Baseline struct {
		Total string `json:"total"`
		Time  string `json:"time"`
	} `json:"baseline"`
	Daily  string `json:"daily"`
	Status string `json:"status"`
	Reason string `json:"reason"`
}

func main() {
	input := flag.String("input", "", "reviewed JSON plan")
	apply := flag.Bool("apply", false, "apply plan and projections in one transaction")
	manifest := flag.String("backup-manifest", "", "verified backup manifest required for apply")
	flag.Parse()
	data, err := os.ReadFile(*input)
	must(err)
	var changes []change
	must(json.Unmarshal(data, &changes))
	if !*apply {
		fmt.Printf("planned=%d dry_run=true\n", len(changes))
		return
	}
	backup, err := os.ReadFile(*manifest)
	must(err)
	if !json.Valid(backup) {
		panic("invalid backup manifest")
	}
	db, err := sql.Open("mysql", os.Getenv("MYSQL_DSN"))
	must(err)
	defer db.Close()
	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Minute)
	defer cancel()
	tx, err := db.BeginTx(ctx, nil)
	must(err)
	defer tx.Rollback()
	affected := map[string]change{}
	for _, c := range changes {
		b := c.Before
		total, stamp, found, err := stats.LookupLatestSourceBaselineBefore(ctx, tx, b.VIN, b.Date, envelope.Protocol(b.Protocol), b.Source)
		must(err)
		expected, err := strconv.ParseFloat(c.Baseline.Total, 64)
		must(err)
		if !found || math.Abs(total-expected) > 0.0001 || stamp.Format("2006-01-02 15:04:05") != c.Baseline.Time {
			panic(fmt.Sprintf("baseline changed: %s %s", b.VIN, b.Date))
		}
		result, err := tx.ExecContext(ctx, `UPDATE vehicle_daily_mileage_source SET first_total_mileage_km=?,first_event_time=?,daily_mileage_km=?,quality_status=?,quality_reason=?
  WHERE vin=? AND stat_date=? AND protocol=? AND source_key=?
  AND first_total_mileage_km <=> ? AND first_event_time <=> ? AND latest_total_mileage_km=?
  AND latest_event_time=? AND daily_mileage_km=? AND quality_status='OK'`, c.Baseline.Total, c.Baseline.Time, c.Daily, c.Status, c.Reason, b.VIN, b.Date, b.Protocol, b.Source, b.First, b.FirstTime, b.Total, b.LastTime, b.Daily)
		must(err)
		n, err := result.RowsAffected()
		must(err)
		if n != 1 {
			panic(fmt.Sprintf("concurrent change: %s %s %s", b.VIN, b.Date, b.Source))
		}
		affected[b.Date+"|"+b.VIN+"|"+b.Protocol] = c
	}
	keys := make([]string, 0, len(affected))
	for key := range affected {
		keys = append(keys, key)
	}
	sort.Strings(keys)
	for _, key := range keys {
		b := affected[key].Before
		must(stats.ProjectDailyMileage(ctx, tx, b.VIN, b.Date, envelope.Protocol(b.Protocol)))
	}
	must(tx.Commit())
	must(json.NewEncoder(os.Stdout).Encode(map[string]any{"updatedSources": len(changes), "reprojectedDays": len(keys), "committed": true}))
}
func must(err error) {
	if err != nil {
		panic(err)
	}
}