package store

import (
	"context"
	"sync"
	"sync/atomic"
	"testing"
)

func TestReaderPoolCapAndQueryOnly(t *testing.T) {
	t.Parallel()
	dir := t.TempDir()
	db, err := Open(dir, "FULL")
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(func() { _ = db.Close() })

	ctx := context.Background()
	if _, err := db.Read.ExecContext(ctx, `INSERT INTO settings(key,value,updated_at) VALUES('x','y',1)`); err == nil {
		t.Fatal("query_only reader accepted write")
	}

	var maxOpen atomic.Int32
	var wg sync.WaitGroup
	for i := 0; i < 200; i++ {
		wg.Add(1)
		go func() {
			defer wg.Done()
			var one int
			if qErr := db.Read.QueryRowContext(ctx, `SELECT 1`).Scan(&one); qErr != nil {
				t.Errorf("read: %v", qErr)
				return
			}
			n := int32(db.Read.Stats().OpenConnections)
			for {
				cur := maxOpen.Load()
				if n <= cur || maxOpen.CompareAndSwap(cur, n) {
					break
				}
			}
		}()
	}
	wg.Wait()
	if maxOpen.Load() > 64 {
		t.Fatalf("open connections %d exceed 64", maxOpen.Load())
	}
}