//go:build load

package api

import (
	"bytes"
	"context"
	"fmt"
	"net/http"
	"net/http/httptest"
	"os"
	"sort"
	"strconv"
	"sync"
	"testing"
	"time"

	"github.com/cosmic-clash/cosmic-clash/server/domain"
)

// TestQueueCreateHTTPLoad is the bounded, repeatable API portion of §8.51.
// It deliberately uses the real HTTP handler and in-process queue boundary;
// database/replica capacity and matcher throughput remain separate gates.
func TestQueueCreateHTTPLoad(t *testing.T) {
	clients := loadInt(t, "COSMIC_CLASH_LOAD_CLIENTS", 10000)
	concurrency := loadInt(t, "COSMIC_CLASH_LOAD_CONCURRENCY", 256)
	p95Limit := time.Duration(loadInt(t, "COSMIC_CLASH_LOAD_P95_MS", 250)) * time.Millisecond
	if clients < 1 || clients > 100000 || concurrency < 1 || concurrency > clients || p95Limit <= 0 || p95Limit > 10*time.Second {
		t.Fatalf("invalid load configuration clients=%d concurrency=%d p95=%s", clients, concurrency, p95Limit)
	}
	now := time.Unix(1_000_000, 0).UTC()
	sessions := domain.NewSessionStore()
	queue := domain.NewQueue()
	service := &Service{
		Sessions: sessions,
		Queue:    queue,
		Now:      func() time.Time { return now },
		CandidateV2: func(playerID, ticketID string, spec domain.QueueSpec) (domain.Candidate, error) {
			return domain.Candidate{
				PlayerID: playerID, TicketID: ticketID, Playlist: spec.Playlist,
				ClientBuild: spec.ClientBuild, ProtocolVersion: spec.ProtocolVersion,
				EnqueuedAt: now, PredictedRTT: map[string]float64{"EU": 20},
			}, nil
		},
	}
	httpServer := httptest.NewServer(service.Handler())
	defer httpServer.Close()

	tokens := make([]string, clients)
	for i := range tokens {
		session, token, err := sessions.Issue(fmt.Sprintf("load-player-%d", i), time.Hour, now)
		if err != nil {
			t.Fatalf("issue session %d: %v", i, err)
		}
		tokens[i] = session.SessionID + ":" + token
	}
	client := &http.Client{Transport: &http.Transport{MaxIdleConns: clients, MaxIdleConnsPerHost: clients}}
	start := make(chan struct{})
	jobs := make(chan int)
	durations := make([]time.Duration, clients)
	statuses := make([]int, clients)
	var wg sync.WaitGroup
	for worker := 0; worker < concurrency; worker++ {
		wg.Add(1)
		go func() {
			defer wg.Done()
			<-start
			for index := range jobs {
				started := time.Now()
				body := fmt.Sprintf(`{"ticket_id":"load-ticket-%08d","playlist":"casual","client_build":"build-1","protocol_version":1}`, index)
				request, err := http.NewRequestWithContext(context.Background(), http.MethodPost, httpServer.URL+"/v1/queue", bytes.NewBufferString(body))
				if err != nil {
					continue
				}
				request.Header.Set("Authorization", "Bearer "+tokens[index])
				request.Header.Set("Idempotency-Key", fmt.Sprintf("load-create-key-%08d", index))
				request.Header.Set("Content-Type", "application/json")
				response, err := client.Do(request)
				if err == nil {
					statuses[index] = response.StatusCode
					response.Body.Close()
				}
				durations[index] = time.Since(started)
			}
		}()
	}
	close(start)
	for i := 0; i < clients; i++ {
		jobs <- i
	}
	close(jobs)
	wg.Wait()

	ordered := append([]time.Duration(nil), durations...)
	sort.Slice(ordered, func(i, j int) bool { return ordered[i] < ordered[j] })
	p95 := ordered[(len(ordered)*95+99)/100-1]
	for i, status := range statuses {
		if status != http.StatusCreated {
			t.Fatalf("client %d returned HTTP %d; the load request must create a queue ticket", i, status)
		}
	}
	if p95 > p95Limit {
		t.Fatalf("queue-create HTTP p95=%s exceeds %s for %d clients at %d in-flight", p95, p95Limit, clients, concurrency)
	}
	t.Logf("queue-create load: clients=%d concurrency=%d p95=%s p99=%s", clients, concurrency, p95, ordered[(len(ordered)*99+99)/100-1])
}

func loadInt(t *testing.T, name string, fallback int) int {
	t.Helper()
	value := fallback
	if raw := os.Getenv(name); raw != "" {
		parsed, err := strconv.Atoi(raw)
		if err != nil {
			t.Fatalf("%s=%q is not an integer", name, raw)
		}
		value = parsed
	}
	return value
}