package surf

import (
	"context"
	"fmt"
	"net"
	"net/http"
	"net/http/httptest"
	"os"
	"path/filepath"
	"sync/atomic"
	"testing"
	"time"

	"git.golem15.com/golem15/summercms/modules/backpack"
	"git.golem15.com/golem15/summercms/modules/compass"
	"git.golem15.com/golem15/summercms/modules/party"
	"github.com/testcontainers/testcontainers-go"
	"github.com/testcontainers/testcontainers-go/wait"
)

// Smoke tests only; plan 05 of phase 19.3 owns full coverage.

const storeHTTPYAML = `body_limits:
  default_bytes: 1048576
  upload_bytes: 1048576
rate_limit:
  store: redis
`

// redisStoreApp builds an app whose config selects the Redis rate-limit store
// at redisURL.
func redisStoreApp(t *testing.T, redisURL string) *backpack.App {
	t.Helper()
	dir := t.TempDir()
	files := map[string]string{
		"app.yaml":   "name: store-test\n",
		"http.yaml":  storeHTTPYAML,
		"redis.yaml": fmt.Sprintf("url: %q\n", redisURL),
	}
	for name, body := range files {
		if err := os.WriteFile(filepath.Join(dir, name), []byte(body), 0o644); err != nil {
			t.Fatal(err)
		}
	}
	cfg, err := compass.Open(compass.Options{Dir: dir, Environ: []string{"SUMMER_ENV=development"}})
	if err != nil {
		t.Fatal(err)
	}
	return backpack.New(cfg)
}

type countingStore struct{ n atomic.Int64 }

func (s *countingStore) Attempt(_ string, max int, decay time.Duration) (bool, int, time.Duration) {
	n := int(s.n.Add(1))
	return n <= max, n, decay
}

func TestBuildRouterStoreSmoke(t *testing.T) {
	// Redis selected but never installed (route:list's path): BuildRouter
	// must not dial and keeps the in-process store.
	app := redisStoreApp(t, "redis://127.0.0.1:1")
	start := time.Now()
	r, err := BuildRouter(app, nil)
	if err != nil {
		t.Fatal(err)
	}
	if d := time.Since(start); d > time.Second {
		t.Fatalf("BuildRouter took %s; it must not dial Redis", d)
	}
	if _, ok := r.limiter.store.(*MemoryStore); !ok {
		t.Fatalf("limiter store = %T, want *MemoryStore", r.limiter.store)
	}

	// A published Store is what the throttle counts in.
	app = redisStoreApp(t, "redis://127.0.0.1:1")
	fake := &countingStore{}
	if err := app.Publish[Store](fake); err != nil {
		t.Fatal(err)
	}
	p := assemblePlugin{id: "golem15.demo", path: "/ping", use: []string{"throttle:2,1"}}
	h, err := Assemble(app, []party.Plugin{p})
	if err != nil {
		t.Fatal(err)
	}
	rec := httptest.NewRecorder()
	h.ServeHTTP(rec, httptest.NewRequest(http.MethodGet, "/api/ping", nil))
	if rec.Code != http.StatusOK || fake.n.Load() != 1 {
		t.Fatalf("status %d, fake attempts %d; want 200 through the published store", rec.Code, fake.n.Load())
	}
}

func TestRateLimitAcrossInstancesSmoke(t *testing.T) {
	if testing.Short() {
		t.Skip("requires testcontainers redis")
	}
	ctx, cancel := context.WithTimeout(t.Context(), 2*time.Minute)
	defer cancel()
	ctr, err := testcontainers.Run(ctx, "redis:7-alpine",
		testcontainers.WithExposedPorts("6379/tcp"),
		testcontainers.WithWaitStrategy(wait.ForListeningPort("6379/tcp")),
	)
	if err != nil {
		t.Fatalf("redis: testcontainers: %v", err)
	}
	t.Cleanup(func() { _ = testcontainers.TerminateContainer(ctr) })
	host, err := ctr.Host(ctx)
	if err != nil {
		t.Fatal(err)
	}
	port, err := ctr.MappedPort(ctx, "6379/tcp")
	if err != nil {
		t.Fatal(err)
	}
	url := fmt.Sprintf("redis://%s:%s/0", host, port.Port())

	instance := func() http.Handler {
		app := redisStoreApp(t, url)
		hd, err := installCooler(ctx, app)
		if err != nil {
			t.Fatal(err)
		}
		t.Cleanup(func() { _ = hd.Close() })
		p := assemblePlugin{id: "golem15.demo", path: "/ping", use: []string{"throttle:2,1"}}
		h, err := Assemble(app, []party.Plugin{p})
		if err != nil {
			t.Fatal(err)
		}
		return h
	}
	a, b := instance(), instance()
	get := func(h http.Handler) *httptest.ResponseRecorder {
		req := httptest.NewRequest(http.MethodGet, "/api/ping", nil)
		req.RemoteAddr = "192.0.2.10:4000"
		rec := httptest.NewRecorder()
		h.ServeHTTP(rec, req)
		return rec
	}
	for i, tc := range []struct {
		h    http.Handler
		want int
	}{{a, http.StatusOK}, {b, http.StatusOK}, {a, http.StatusTooManyRequests}} {
		rec := get(tc.h)
		if rec.Code != tc.want {
			t.Fatalf("request %d: status %d, want %d", i+1, rec.Code, tc.want)
		}
		if tc.want == http.StatusTooManyRequests && rec.Header().Get("Retry-After") == "" {
			t.Fatal("429 without Retry-After")
		}
	}
}

// Unit tests (plan 05 of phase 19.3) for BuildRouter's rate-limit store
// lookup (D-09).

func TestBuildRouterStoreFallback(t *testing.T) {
	r, err := BuildRouter(nil, nil)
	if err != nil {
		t.Fatal(err)
	}
	if _, ok := r.limiter.store.(*MemoryStore); !ok {
		t.Fatalf("nil app: store = %T", r.limiter.store)
	}
	app := transportApp(t, "development", map[string]string{"http.yaml": transportBodyLimits})
	r, err = BuildRouter(app, nil)
	if err != nil {
		t.Fatal(err)
	}
	mem, ok := r.limiter.store.(*MemoryStore)
	if !ok {
		t.Fatalf("no published store: store = %T", r.limiter.store)
	}
	// The fallback store counts: two attempts, max 1.
	if allowed, _, _ := mem.Attempt("k", 1, time.Minute); !allowed {
		t.Fatal("first attempt refused")
	}
	if allowed, _, _ := mem.Attempt("k", 1, time.Minute); allowed {
		t.Fatal("second attempt admitted")
	}
}

func TestBuildRouterUsesPublishedStore(t *testing.T) {
	app := transportApp(t, "development", map[string]string{"http.yaml": transportBodyLimits})
	fake := &countingStore{}
	if err := app.Publish[Store](fake); err != nil {
		t.Fatal(err)
	}
	r, err := BuildRouter(app, []party.Plugin{assemblePlugin{id: "golem15.demo", path: "/ping", use: []string{"throttle:2,1"}}})
	if err != nil {
		t.Fatal(err)
	}
	if r.limiter.store != Store(fake) {
		t.Fatalf("limiter store = %T, want the published store", r.limiter.store)
	}
	h, err := r.compile()
	if err != nil {
		t.Fatal(err)
	}
	for i, want := range []int{http.StatusOK, http.StatusOK, http.StatusTooManyRequests} {
		rec := httptest.NewRecorder()
		h.ServeHTTP(rec, httptest.NewRequest(http.MethodGet, "/api/ping", nil))
		if rec.Code != want {
			t.Fatalf("request %d: status %d, want %d", i+1, rec.Code, want)
		}
	}
	if fake.n.Load() != 3 {
		t.Fatalf("published store saw %d attempts, want 3", fake.n.Load())
	}
}

func TestBuildRouterNeverDials(t *testing.T) {
	// A listener standing in for Redis counts every connection.
	ln, err := net.Listen("tcp", "127.0.0.1:0")
	if err != nil {
		t.Fatal(err)
	}
	var accepted atomic.Int64
	go func() {
		for {
			c, err := ln.Accept()
			if err != nil {
				return
			}
			accepted.Add(1)
			_ = c.Close()
		}
	}()
	t.Cleanup(func() { _ = ln.Close() })

	app := redisStoreApp(t, "redis://"+ln.Addr().String()+"/0")
	start := time.Now()
	r, err := BuildRouter(app, []party.Plugin{assemblePlugin{id: "golem15.demo", path: "/ping", use: []string{"throttle:5,1"}}})
	if err != nil {
		t.Fatal(err)
	}
	h, err := r.compile()
	if err != nil {
		t.Fatal(err)
	}
	rec := httptest.NewRecorder()
	h.ServeHTTP(rec, httptest.NewRequest(http.MethodGet, "/api/ping", nil))
	if rec.Code != http.StatusOK {
		t.Fatalf("status %d", rec.Code)
	}
	if d := time.Since(start); d > time.Second {
		t.Fatalf("BuildRouter and one request took %s", d)
	}
	if _, ok := r.limiter.store.(*MemoryStore); !ok {
		t.Fatalf("store = %T, want *MemoryStore without install", r.limiter.store)
	}
	time.Sleep(50 * time.Millisecond)
	if n := accepted.Load(); n != 0 {
		t.Fatalf("Redis was dialled %d times without installCooler", n)
	}
}