package metrics_test

import (
	"encoding/json"
	"errors"
	"net/http/httptest"
	"testing"

	apierrors "git.yuntuo.hk/k2safe/go-omni/errors"
	"git.yuntuo.hk/k2safe/go-omni/httpx"
	"git.yuntuo.hk/k2safe/go-omni/metrics"
)

func TestMiddlewareCollectsStatusesAndErrors(t *testing.T) {
	collector := metrics.New()
	request := httptest.NewRequest("GET", "/health", nil)
	first := httptest.NewRecorder()
	ctx := httpx.NewContext(request, first, nil)
	if err := collector.Middleware()(func(c *httpx.Context) error { return c.OK("ok") })(ctx); err != nil {
		t.Fatal(err)
	}

	second := httptest.NewRecorder()
	ctx = httpx.NewContext(request, second, nil)
	handled := collector.Middleware()(func(*httpx.Context) error {
		return apierrors.NotFound("MISSING", "missing")
	})
	if err := handled(ctx); err == nil {
		t.Fatal("expected handler error")
	}

	snapshot := collector.Snapshot()
	if snapshot.Requests != 2 || snapshot.Errors != 1 || snapshot.InFlight != 0 || snapshot.StatusCounts["200"] != 1 || snapshot.StatusCounts["404"] != 1 {
		t.Fatalf("unexpected snapshot: %+v", snapshot)
	}
}

func TestHandlerReturnsJSONSnapshot(t *testing.T) {
	collector := metrics.New()
	request := httptest.NewRequest("GET", "/metrics", nil)
	recorder := httptest.NewRecorder()
	ctx := httpx.NewContext(request, recorder, nil)
	if err := collector.Handler()(ctx); err != nil {
		t.Fatal(err)
	}
	var envelope struct {
		Code string           `json:"code"`
		Data metrics.Snapshot `json:"data"`
	}
	if err := json.Unmarshal(recorder.Body.Bytes(), &envelope); err != nil {
		t.Fatal(err)
	}
	if envelope.Code != "OK" || envelope.Data.StatusCounts == nil {
		t.Fatalf("unexpected metrics response: %s", recorder.Body)
	}
}

func TestMiddlewarePreservesApplicationErrors(t *testing.T) {
	collector := metrics.New()
	request := httptest.NewRequest("GET", "/", nil)
	ctx := httpx.NewContext(request, httptest.NewRecorder(), nil)
	want := errors.New("database unavailable")
	got := collector.Middleware()(func(*httpx.Context) error { return want })(ctx)
	if !errors.Is(got, want) {
		t.Fatalf("middleware replaced error: %v", got)
	}
}