package httpclient

import (
	"context"
	"errors"
	"fmt"
	"net/http"
	"strings"
	"testing"
	"time"

	"evobgp/internal/observability"
	"github.com/prometheus/client_golang/prometheus"
)

func TestBreakerCanonicalHostAndActiveRetention(t *testing.T) {
	c := breakerCache{entries: make(map[string]*breakerEntry), maximum: 1, idle: time.Minute}
	now := time.Now()
	first, key, release, err := c.acquire("Cache-Test.Example.", now)
	if err != nil || key != "cache-test.example" {
		t.Fatalf("canonical key=%s err=%v", key, err)
	}
	second, _, release2, err := c.acquire("cache-test.example", now)
	if err != nil || first != second || len(c.entries) != 1 {
		t.Fatal("alias bypassed shared breaker")
	}
	observability.SetUpstreamBreakerOpen(key, true)
	first.openUntil = now.Add(3 * time.Minute)
	if _, _, _, err := c.acquire("other.example", now.Add(2*time.Minute)); !errors.Is(err, ErrBreakerCapacity) {
		t.Fatalf("active entry evicted: %v", err)
	}
	release()
	release()
	release2()
	if _, _, _, err := c.acquire("other.example", now.Add(2*time.Minute+2*time.Second)); !errors.Is(err, ErrBreakerCapacity) {
		t.Fatalf("open breaker evicted: %v", err)
	}
	_, _, done, err := c.acquire("other.example", now.Add(4*time.Minute))
	if err != nil {
		t.Fatal(err)
	}
	defer done()
	if len(c.entries) != 1 || c.entries[key] != nil {
		t.Fatal("idle closed entry retained")
	}
	families, err := prometheus.DefaultGatherer.Gather()
	if err != nil {
		t.Fatal(err)
	}
	for _, family := range families {
		if strings.HasSuffix(family.GetName(), "upstream_breaker_open") {
			for _, metric := range family.Metric {
				for _, label := range metric.Label {
					if label.GetName() == "host" && label.GetValue() == key {
						t.Fatal("evicted host metric retained")
					}
				}
			}
		}
	}
}

type breakerTransport func(*http.Request) (*http.Response, error)

func (f breakerTransport) RoundTrip(r *http.Request) (*http.Response, error) { return f(r) }

func TestBreakerCapacityRejectsBeforeDial(t *testing.T) {
	ResetHostBreakers()
	var releases []func()
	defer func() {
		for _, release := range releases {
			release()
		}
		ResetHostBreakers()
	}()
	for i := 0; i < hostBreakers.maximum; i++ {
		_, _, release, err := hostBreakers.acquire(fmt.Sprintf("capacity-%d.example", i), time.Now())
		if err != nil {
			t.Fatal(err)
		}
		releases = append(releases, release)
	}
	called := false
	hc := &http.Client{Transport: breakerTransport(func(*http.Request) (*http.Response, error) { called = true; return nil, errors.New("unexpected dial") })}
	req, _ := http.NewRequest(http.MethodGet, "https://overflow.example/", nil)
	_, err := DoWithBreaker(context.Background(), hc, req, 1)
	if !errors.Is(err, ErrBreakerCapacity) || called {
		t.Fatalf("capacity err=%v dial=%t", err, called)
	}
	if len(SnapshotBreakers()) != hostBreakers.maximum {
		t.Fatal("cache capacity changed")
	}
	ResetHostBreakers()
	if len(SnapshotBreakers()) != hostBreakers.maximum {
		t.Fatal("reset discarded in-flight references")
	}
}

func TestBreakerRejectsOversizedIdentity(t *testing.T) {
	c := breakerCache{entries: make(map[string]*breakerEntry), maximum: 1, idle: time.Minute}
	if _, _, _, err := c.acquire(strings.Repeat("x", 254), time.Now()); err == nil || len(c.entries) != 0 {
		t.Fatal("oversized identity retained")
	}
	name := strings.Repeat("a", 253)
	first, key, release, err := c.acquire(name, time.Now())
	if err != nil {
		t.Fatal(err)
	}
	defer release()
	second, alias, release2, err := c.acquire(strings.ToUpper(name)+".", time.Now())
	if err != nil {
		t.Fatal(err)
	}
	defer release2()
	if first != second || key != alias {
		t.Fatal("maximum length trailing-dot alias differs")
	}
}