package api

import (
	"encoding/json"
	"fmt"
	"net/http"
	"net/http/httptest"
	"strings"
	"sync"
	"testing"
)

// TestBurnAfterReadConcurrentRace is the #58 regression test: N concurrent
// readers of a burn-after-read paste must receive exactly one success with
// content; every other reader must get 404 and never any content.
func TestBurnAfterReadConcurrentRace(t *testing.T) {
	s := testServer(t)
	h := s.routes()
	id := createBurnReads(t, h, 1)

	const readers = 24
	var wg sync.WaitGroup
	var mu sync.Mutex
	wins, losses := 0, 0
	for i := 0; i < readers; i++ {
		wg.Add(1)
		go func(i int) {
			defer wg.Done()
			req := httptest.NewRequest("GET", "/api/pastes/"+id, nil)
			req.AddCookie(&http.Cookie{Name: "vwr", Value: fmt.Sprintf("racer-%d", i)})
			rec := httptest.NewRecorder()
			h.ServeHTTP(rec, req)
			mu.Lock()
			defer mu.Unlock()
			if rec.Code == 200 {
				wins++
				var got struct {
					Content string `json:"content"`
				}
				if err := json.Unmarshal(rec.Body.Bytes(), &got); err != nil || got.Content != "limited" {
					t.Errorf("winning read returned wrong content: %v %q", err, got.Content)
				}
			} else if rec.Code == 404 {
				losses++
				if strings.Contains(rec.Body.String(), "limited") {
					t.Errorf("losing read leaked content: %s", rec.Body.String())
				}
			} else {
				t.Errorf("unexpected status %d: %s", rec.Code, rec.Body.String())
			}
		}(i)
	}
	wg.Wait()

	if wins != 1 {
		t.Fatalf("expected exactly 1 winning read of burn paste, got %d (losses=%d)", wins, losses)
	}
	if losses != readers-1 {
		t.Fatalf("expected %d losing reads, got %d", readers-1, losses)
	}
}

// TestBurnAfterNReadsConcurrentBudget hammers a burn-after-N paste with many
// more concurrent distinct readers than the budget: total admissions must
// equal exactly N, and no losing read may see content.
func TestBurnAfterNReadsConcurrentBudget(t *testing.T) {
	s := testServer(t)
	h := s.routes()
	const budget = 3
	id := createBurnReads(t, h, budget)

	const readers = 30
	var wg sync.WaitGroup
	var mu sync.Mutex
	wins := 0
	for i := 0; i < readers; i++ {
		wg.Add(1)
		go func(i int) {
			defer wg.Done()
			req := httptest.NewRequest("GET", "/api/pastes/"+id, nil)
			req.AddCookie(&http.Cookie{Name: "vwr", Value: fmt.Sprintf("racer-%d", i)})
			rec := httptest.NewRecorder()
			h.ServeHTTP(rec, req)
			mu.Lock()
			defer mu.Unlock()
			if rec.Code == 200 {
				wins++
			} else if rec.Code != 404 {
				t.Errorf("unexpected status %d: %s", rec.Code, rec.Body.String())
			}
		}(i)
	}
	wg.Wait()

	if wins != budget {
		t.Fatalf("expected exactly %d admitted reads, got %d", budget, wins)
	}

	// After the race, the paste is burned for everyone.
	if rec := getWithCookie(t, h, id, "after-the-fact"); rec.Code != 404 {
		t.Fatalf("paste should be burned after budget exhausted, got %d", rec.Code)
	}
}