package telemetry

import (
	"context"
	"encoding/json"
	"io"
	"net/http"
	"net/http/httptest"
	"sync/atomic"
	"testing"
)

func TestFlushAndRetry(t *testing.T) {
	var fail atomic.Bool
	var got []batch
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.URL.Path != "/back/telemetry" || r.Header.Get("X-SECRET-KEY") != "k" {
			w.WriteHeader(http.StatusForbidden)
			return
		}
		if fail.Load() {
			w.WriteHeader(http.StatusServiceUnavailable)
			return
		}
		body, _ := io.ReadAll(r.Body)
		var b batch
		if err := json.Unmarshal(body, &b); err != nil {
			t.Error(err)
		}
		got = append(got, b)
		w.Write([]byte(`{"accepted":1}`))
	}))
	defer srv.Close()

	c := New(Config{BaseURL: srv.URL + "/", SecretKey: "k", Service: "indexer", Instance: "i1"})
	c.Counter("jobs_total", "result", "ok").Add(2)
	c.Gauge("queue").Set(7)
	c.Summary("took_seconds").Observe(1)
	c.Summary("took_seconds").Observe(3)
	c.Event(Warn, "hello", nil)

	fail.Store(true)
	if err := c.Flush(context.Background()); err == nil {
		t.Fatal("expected an error while the server fails")
	}
	c.Counter("jobs_total", "result", "ok").Add(1)

	fail.Store(false)
	if err := c.Flush(context.Background()); err != nil {
		t.Fatal(err)
	}
	if len(got) != 2 {
		t.Fatalf("got %d batches, want the retried one plus the new one", len(got))
	}
	first := got[0]
	if first.Service != "indexer" || first.Instance != "i1" || len(first.Events) != 1 {
		t.Fatalf("unexpected first batch %+v", first)
	}
	var sum float64
	for _, b := range got {
		for _, m := range b.Metrics {
			if m.Name == "jobs_total" {
				sum += m.Value
			}
			if m.Name == "took_seconds" && (m.Count != 2 || m.Min != 1 || m.Max != 3) {
				t.Fatalf("bad summary %+v", m)
			}
		}
	}
	if sum != 3 {
		t.Fatalf("counter total = %v, want 3", sum)
	}
}