package web

import (
	"log"
	"net/http"
	"net/http/httptest"
	"net/url"
	"strings"
	"sync"
	"testing"
	"time"
)

func postCreate(s *Server, id string) *httptest.ResponseRecorder {
	form := url.Values{"customer_id": {id}, "customer_name": {"Tester"}, "email": {"t@felhom.example"}}
	req := httptest.NewRequest(http.MethodPost, "/configs/new", strings.NewReader(form.Encode()))
	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	rr := httptest.NewRecorder()
	s.handleConfigCreate(rr, req)
	return rr
}

// R-728: a second submit for the same customer ID while the first is still between its duplicate check
// and its save must NOT create (and mint) a second time. The first create is held at the save by the
// test seam while the second runs to completion.
func TestConfigCreate_ConcurrentSubmitCreatesOnce(t *testing.T) {
	s, _ := newTestServer(t)
	var logBuf syncBuf
	s.logger = log.New(&logBuf, "", 0)

	started, release := make(chan struct{}), make(chan struct{})
	var once sync.Once
	s.beforeCreateSave = func(string) {
		first := false
		once.Do(func() { first = true })
		if first {
			close(started)
			<-release
		}
	}

	done := make(chan *httptest.ResponseRecorder)
	go func() { done <- postCreate(s, "tester-2") }()
	select {
	case <-started:
	case <-time.After(5 * time.Second):
		t.Fatal("the first create never reached the save")
	}
	second := postCreate(s, "tester-2")
	close(release)
	first := <-done

	if first.Code != http.StatusSeeOther {
		t.Fatalf("first create = %d, want 303", first.Code)
	}
	if n := strings.Count(logBuf.String(), "Customer config created: tester-2"); n != 1 {
		t.Fatalf("customer created %d times for one press, want exactly 1:\n%s", n, logBuf.String())
	}
	if !strings.Contains(second.Body.String(), "already being created") {
		t.Errorf("the second submit must be told a create is in progress; got %d", second.Code)
	}

	// The guard is released: a later create of the SAME id is refused by the ordinary duplicate check,
	// not stuck behind the in-flight guard.
	s.beforeCreateSave = nil
	if body := postCreate(s, "tester-2").Body.String(); !strings.Contains(body, "already exists") {
		t.Error("after the first create returned, a re-submit must meet the ordinary 'already exists' check")
	}
}

// syncBuf is a goroutine-safe log sink.
type syncBuf struct {
	mu sync.Mutex
	b  strings.Builder
}

func (w *syncBuf) Write(p []byte) (int, error) { w.mu.Lock(); defer w.mu.Unlock(); return w.b.Write(p) }
func (w *syncBuf) String() string              { w.mu.Lock(); defer w.mu.Unlock(); return w.b.String() }