package scrape

import (
	"context"
	"net/http"
	"net/http/httptest"
	"sync/atomic"
	"testing"
	"time"

	"github.com/rs/zerolog"
)

func newHygieneForTest(t *testing.T) *Hygiene {
	t.Helper()
	return New(nil, Options{
		MinRequestSpacing: 10 * time.Millisecond,
		MaxBackoff:        100 * time.Millisecond,
	}, zerolog.Nop())
}

func TestDoSucceedsAndResetsFailureCount(t *testing.T) {
	h := newHygieneForTest(t)
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		w.WriteHeader(200)
		_, _ = w.Write([]byte("ok"))
	}))
	defer srv.Close()

	for i := 0; i < 3; i++ {
		req, _ := http.NewRequestWithContext(context.Background(), "GET", srv.URL, nil)
		resp, err := h.Do(context.Background(), req, "t1")
		if err != nil {
			t.Fatalf("Do[%d]: %v", i, err)
		}
		body, err := h.ReadBody(resp)
		if err != nil {
			t.Fatalf("ReadBody: %v", err)
		}
		if string(body) != "ok" {
			t.Errorf("body[%d] = %q, want ok", i, string(body))
		}
	}
	h.mu.Lock()
	if h.failCount["t1"] != 0 {
		t.Errorf("expected failCount reset, got %d", h.failCount["t1"])
	}
	h.mu.Unlock()
}

func TestRespectsMinRequestSpacing(t *testing.T) {
	h := New(nil, Options{MinRequestSpacing: 50 * time.Millisecond}, zerolog.Nop())
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		w.WriteHeader(200)
	}))
	defer srv.Close()

	start := time.Now()
	for i := 0; i < 3; i++ {
		req, _ := http.NewRequest("GET", srv.URL, nil)
		resp, err := h.Do(context.Background(), req, "t1")
		if err != nil {
			t.Fatalf("Do[%d]: %v", i, err)
		}
		_ = resp.Body.Close()
	}
	elapsed := time.Since(start)
	// 3 requests at 50ms spacing → at least 100ms (no spacing before first).
	if elapsed < 90*time.Millisecond {
		t.Errorf("expected ~100ms total, got %v", elapsed)
	}
}

func TestRetryAfterHeaderHonored(t *testing.T) {
	h := New(nil, Options{MinRequestSpacing: time.Millisecond}, zerolog.Nop())
	var calls atomic.Int32
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		if calls.Add(1) == 1 {
			w.Header().Set("Retry-After", "1") // 1 second
			w.WriteHeader(429)
			return
		}
		w.WriteHeader(200)
	}))
	defer srv.Close()

	req1, _ := http.NewRequest("GET", srv.URL, nil)
	resp, err := h.Do(context.Background(), req1, "t1")
	if err != nil {
		t.Fatalf("first Do: %v", err)
	}
	_ = resp.Body.Close()
	if resp.StatusCode != 429 {
		t.Fatalf("first status: %d", resp.StatusCode)
	}

	start := time.Now()
	req2, _ := http.NewRequest("GET", srv.URL, nil)
	resp, err = h.Do(context.Background(), req2, "t1")
	if err != nil {
		t.Fatalf("second Do: %v", err)
	}
	_ = resp.Body.Close()
	elapsed := time.Since(start)
	if elapsed < 900*time.Millisecond {
		t.Errorf("second request fired in %v; expected ≥ 1s wait from Retry-After", elapsed)
	}
}

func TestExponentialBackoffOnConsecutiveFailures(t *testing.T) {
	h := New(nil, Options{
		MinRequestSpacing: time.Millisecond,
		MaxBackoff:        50 * time.Millisecond,
	}, zerolog.Nop())
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		w.WriteHeader(500)
	}))
	defer srv.Close()

	for i := 0; i < 3; i++ {
		req, _ := http.NewRequest("GET", srv.URL, nil)
		resp, err := h.Do(context.Background(), req, "t1")
		if err != nil {
			t.Fatalf("Do[%d]: %v", i, err)
		}
		_ = resp.Body.Close()
	}
	h.mu.Lock()
	defer h.mu.Unlock()
	if h.failCount["t1"] != 3 {
		t.Errorf("failCount[t1] = %d, want 3", h.failCount["t1"])
	}
	if _, ok := h.retryAfter["t1"]; !ok {
		t.Errorf("expected retryAfter hint to be set after 500s")
	}
}

func TestContextCancelDuringWait(t *testing.T) {
	h := New(nil, Options{MinRequestSpacing: 5 * time.Second}, zerolog.Nop())
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) { w.WriteHeader(200) }))
	defer srv.Close()

	// Prime: one request to set lastReq.
	req1, _ := http.NewRequest("GET", srv.URL, nil)
	resp, err := h.Do(context.Background(), req1, "t1")
	if err != nil {
		t.Fatalf("prime: %v", err)
	}
	_ = resp.Body.Close()

	// Now a follow-up should block on MinRequestSpacing. Cancel quickly.
	ctx, cancel := context.WithTimeout(context.Background(), 50*time.Millisecond)
	defer cancel()
	req2, _ := http.NewRequestWithContext(ctx, "GET", srv.URL, nil)
	_, err = h.Do(ctx, req2, "t1")
	if err == nil {
		t.Fatal("expected context cancel error, got nil")
	}
}

func TestParseRetryAfterSeconds(t *testing.T) {
	d, ok := parseRetryAfter("5")
	if !ok || d != 5*time.Second {
		t.Errorf("parseRetryAfter(5) = %v, %v", d, ok)
	}
}

func TestParseRetryAfterHTTPDate(t *testing.T) {
	future := time.Now().Add(10 * time.Second).UTC().Format(http.TimeFormat)
	d, ok := parseRetryAfter(future)
	if !ok {
		t.Fatalf("parseRetryAfter(date) returned ok=false")
	}
	if d < 8*time.Second || d > 11*time.Second {
		t.Errorf("parseRetryAfter(date) = %v, want ~10s", d)
	}
}

func TestParseRetryAfterEmpty(t *testing.T) {
	if _, ok := parseRetryAfter(""); ok {
		t.Error("parseRetryAfter('') returned ok=true")
	}
}