package main

import (
	"database/sql"
	"fmt"
	"os"
	"sync"
	"testing"
	"time"
)

func TestConcurrentLedger(t *testing.T) {
	dsn := os.Getenv("LAB_MYSQL_TEST_DSN")
	if dsn == "" {
		t.Skip("requires empty test schema initialized from schema.sql")
	}
	db, e := sql.Open("mysql", dsn)
	if e != nil {
		t.Fatal(e)
	}
	defer db.Close()
	for i := range 20 {
		if e := submit(db, fmt.Sprintf("job-%d", i), "team-a", 1, i); e != nil {
			t.Fatal(e)
		}
	}
	var wg sync.WaitGroup
	for range 8 {
		wg.Add(1)
		go func() {
			defer wg.Done()
			for range 4 {
				if e := admit(db); e != nil {
					time.Sleep(20 * time.Millisecond)
				}
			}
		}()
	}
	wg.Wait()
	var used, rows, msgs int
	db.QueryRow("SELECT used FROM tenant_quota WHERE tenant='team-a'").Scan(&used)
	db.QueryRow("SELECT count(*) FROM reservation WHERE state='reserved'").Scan(&rows)
	db.QueryRow("SELECT count(*) FROM outbox").Scan(&msgs)
	if used != 2 || rows != used || msgs != used {
		t.Fatalf("used=%d reserved=%d outbox=%d", used, rows, msgs)
	}
	if e := submit(db, "job-0", "team-a", 2, 0); e == nil {
		t.Fatal("changed payload accepted")
	}

	// Inject a collision at the LAST insert, after both counters were updated.
	if err := submit(db, "rollback-probe", "team-b", 1, 100); err != nil {
		t.Fatal(err)
	}
	if _, err := db.Exec("INSERT INTO outbox(id) VALUES('rollback-probe')"); err != nil {
		t.Fatal(err)
	}
	if err := admit(db); err == nil {
		t.Fatal("expected duplicate outbox error")
	}
	var state string
	var tenantUsed, poolUsed int
	if err := db.QueryRow("SELECT state FROM reservation WHERE id='rollback-probe'").Scan(&state); err != nil {
		t.Fatal(err)
	}
	if err := db.QueryRow("SELECT used FROM tenant_quota WHERE tenant='team-b'").Scan(&tenantUsed); err != nil {
		t.Fatal(err)
	}
	if err := db.QueryRow("SELECT SUM(used) FROM gpu_pool").Scan(&poolUsed); err != nil {
		t.Fatal(err)
	}
	if state != "waiting" || tenantUsed != 0 || poolUsed != used {
		t.Fatalf("partial commit: state=%s tenant=%d pool=%d", state, tenantUsed, poolUsed)
	}
	if _, err := db.Exec("DELETE FROM outbox WHERE id='rollback-probe'"); err != nil {
		t.Fatal(err)
	}
	if err := admit(db); err != nil {
		t.Fatal(err)
	}
	if err := db.QueryRow("SELECT state FROM reservation WHERE id='rollback-probe'").Scan(&state); err != nil || state != "reserved" {
		t.Fatalf("retry: %s %v", state, err)
	}
}