package mysql

import (
	"context"
	"database/sql"
	"os"
	"sync"
	"sync/atomic"
	"testing"
	"time"
)

func TestIntegrationWithTxRetriesPreCommitDeadlock(t *testing.T) {
	dsn := os.Getenv("ORBIT_TEST_MYSQL_DSN")
	if dsn == "" {
		t.Skip("requires disposable MySQL")
	}
	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer cancel()
	db, err := Open(ctx, dsn, 8, 4)
	if err != nil {
		t.Fatal(err)
	}
	defer db.Close()
	if _, err := db.ExecContext(ctx, `CREATE TABLE orbit_test_tx_retry (
        id INT NOT NULL COMMENT '测试锁顺序行标识',
        value INT NOT NULL COMMENT '测试事务累加值',
        PRIMARY KEY (id)
    ) ENGINE=InnoDB COMMENT='测试提交前死锁重试表'`); err != nil {
		t.Fatal(err)
	}
	defer db.ExecContext(context.Background(), "DROP TABLE orbit_test_tx_retry")
	if _, err := db.ExecContext(ctx, "INSERT INTO orbit_test_tx_retry(id,value) VALUES (1,0),(2,0)"); err != nil {
		t.Fatal(err)
	}

	var barrier sync.WaitGroup
	barrier.Add(2)
	var callbackCalls atomic.Int32
	run := func(first, second int) error {
		attempt := 0
		return WithTx(ctx, db, func(tx *sql.Tx) error {
			attempt++
			callbackCalls.Add(1)
			order := []int{first, second}
			if attempt > 1 {
				order = []int{1, 2}
			}
			for index, id := range order {
				if _, err := tx.ExecContext(ctx, "SELECT id FROM orbit_test_tx_retry WHERE id=? FOR UPDATE", id); err != nil {
					return err
				}
				if attempt == 1 && index == 0 {
					barrier.Done()
					barrier.Wait()
				}
			}
			_, err := tx.ExecContext(ctx, "UPDATE orbit_test_tx_retry SET value=value+1 WHERE id IN (1,2)")
			return err
		})
	}

	results := make(chan error, 2)
	go func() { results <- run(1, 2) }()
	go func() { results <- run(2, 1) }()
	for i := 0; i < 2; i++ {
		if err := <-results; err != nil {
			t.Fatal(err)
		}
	}
	if callbackCalls.Load() < 3 {
		t.Fatalf("deadlock did not cause a bounded pre-commit retry; callback calls=%d", callbackCalls.Load())
	}
	var value int
	if err := db.QueryRowContext(ctx, "SELECT COALESCE(MIN(value),0) FROM orbit_test_tx_retry").Scan(&value); err != nil {
		t.Fatal(err)
	}
	if value != 2 {
		t.Fatalf("committed value=%d want 2", value)
	}
	t.Logf("pre-commit deadlock recovered with %d callback attempts and two committed transactions", callbackCalls.Load())
}