package sender

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

	amv2 "github.com/prometheus/alertmanager/api/v2/models"
	"github.com/prometheus/common/model"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

type FakeExternalAlertmanager struct {
	t      *testing.T
	mtx    sync.Mutex
	alerts amv2.PostableAlerts
	Server *httptest.Server
}

func NewFakeExternalAlertmanager(t *testing.T) *FakeExternalAlertmanager {
	t.Helper()

	am := &FakeExternalAlertmanager{
		t:      t,
		alerts: amv2.PostableAlerts{},
	}
	am.Server = httptest.NewServer(http.HandlerFunc(am.Handler()))

	return am
}

func (am *FakeExternalAlertmanager) URL() string {
	return am.Server.URL
}

func (am *FakeExternalAlertmanager) AlertNamesCompare(expected []string) bool {
	n := []string{}
	alerts := am.Alerts()

	if len(expected) != len(alerts) {
		return false
	}

	for _, a := range am.Alerts() {
		for k, v := range a.Alert.Labels {
			if k == model.AlertNameLabel {
				n = append(n, v)
			}
		}
	}

	return assert.ObjectsAreEqual(expected, n)
}

func (am *FakeExternalAlertmanager) AlertsCount() int {
	am.mtx.Lock()
	defer am.mtx.Unlock()

	return len(am.alerts)
}

func (am *FakeExternalAlertmanager) Alerts() amv2.PostableAlerts {
	am.mtx.Lock()
	defer am.mtx.Unlock()
	return am.alerts
}

func (am *FakeExternalAlertmanager) Handler() func(w http.ResponseWriter, r *http.Request) {
	return func(w http.ResponseWriter, r *http.Request) {
		b, err := io.ReadAll(r.Body)
		require.NoError(am.t, err)

		a := amv2.PostableAlerts{}
		require.NoError(am.t, json.Unmarshal(b, &a))

		am.mtx.Lock()
		am.alerts = append(am.alerts, a...)
		am.mtx.Unlock()
	}
}

func (am *FakeExternalAlertmanager) Close() {
	am.Server.Close()
}