// 2026-03-21 — go-pg-race: параллельные INSERT из нескольких горутин внутри одной функции.
// Тестирует: race condition устойчивость Go + PG при concurrent writes из одного пода.
// Использует pgx/v5 (pre-cached в base image).
package handler

import (
	"context"
	"fmt"
	"os"
	"sync"
	"sync/atomic"
	"time"

	"github.com/jackc/pgx/v5/pgxpool"
)

// Handle запускает workers горутин, каждая делает n_per_worker INSERTs.
func Handle(event map[string]interface{}) interface{} {
	workers := intParam(event, "workers", 5)
	if workers > 20 {
		workers = 20
	}
	nPerWorker := intParam(event, "n_per_worker", 10)
	if nPerWorker > 50 {
		nPerWorker = 50
	}

	dsn := fmt.Sprintf(
		"host=%s port=%s dbname=%s user=%s password=%s sslmode=%s",
		os.Getenv("PGHOST"), getenv("PGPORT", "5432"),
		os.Getenv("PGDATABASE"), os.Getenv("PGUSER"),
		os.Getenv("PGPASSWORD"), getenv("PGSSLMODE", "require"),
	)
	pool, err := pgxpool.New(context.Background(), dsn)
	if err != nil {
		return map[string]interface{}{"error": err.Error()}
	}
	defer pool.Close()

	var (
		wg       sync.WaitGroup
		ok       int64
		errCount int64
	)
	t0 := time.Now()
	for w := 0; w < workers; w++ {
		wg.Add(1)
		go func(wid int) {
			defer wg.Done()
			for i := 0; i < nPerWorker; i++ {
				title := fmt.Sprintf("go-race-w%d-%d-%d", wid, time.Now().UnixMilli(), i)
				_, err := pool.Exec(context.Background(),
					"INSERT INTO terraform_demo_table (title) VALUES ($1)", title)
				if err != nil {
					atomic.AddInt64(&errCount, 1)
				} else {
					atomic.AddInt64(&ok, 1)
				}
			}
		}(w)
	}
	wg.Wait()
	elapsed := time.Since(t0).Seconds()

	return map[string]interface{}{
		"workers":      workers,
		"n_per_worker": nPerWorker,
		"inserted":     ok,
		"errors":       errCount,
		"elapsed_sec":  elapsed,
		"ops_per_sec":  float64(ok) / elapsed,
	}
}

func intParam(event map[string]interface{}, key string, def int) int {
	v, ok := event[key]
	if !ok {
		return def
	}
	switch val := v.(type) {
	case float64:
		return int(val)
	case int:
		return val
	}
	return def
}

func getenv(key, def string) string {
	if v := os.Getenv(key); v != "" {
		return v
	}
	return def
}