package handlers_test

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

	"go.uber.org/fx/fxtest"

	"sneak.berlin/go/dnswatcher/internal/config"
	"sneak.berlin/go/dnswatcher/internal/globals"
	"sneak.berlin/go/dnswatcher/internal/handlers"
	"sneak.berlin/go/dnswatcher/internal/logger"
	"sneak.berlin/go/dnswatcher/internal/notify"
	"sneak.berlin/go/dnswatcher/internal/state"
)

// The state the handler tests serve: www.example.com has one nameserver
// that answered and one whose query failed, and its certificate check
// failed.
const (
	testHostname     = "www.example.com"
	answeringNS      = "ns1.example.com."
	failedNS         = "ns2.example.com."
	nsFailureReason  = "server returned a referral"
	certKey          = "192.0.2.1:443:www.example.com"
	certFailedReason = "x509: certificate has expired or is not yet valid"
)

// newHandlersWithFailures builds real Handlers whose state holds the
// entries described above.
func newHandlersWithFailures(t *testing.T) *handlers.Handlers {
	t.Helper()

	glob, err := globals.New(nil)
	if err != nil {
		t.Fatalf("globals.New: %v", err)
	}

	log, err := logger.New(nil, logger.Params{Globals: glob})
	if err != nil {
		t.Fatalf("logger.New: %v", err)
	}

	notifier, err := notify.New(fxtest.NewLifecycle(t), notify.Params{
		Logger: log,
		Config: &config.Config{},
	})
	if err != nil {
		t.Fatalf("notify.New: %v", err)
	}

	st, err := state.New(fxtest.NewLifecycle(t), state.Params{
		Logger: log,
		Config: &config.Config{DataDir: t.TempDir()},
	})
	if err != nil {
		t.Fatalf("state.New: %v", err)
	}

	now := time.Now()

	st.SetHostnameState(testHostname, &state.HostnameState{
		RecordsByNameserver: map[string]*state.NameserverRecordState{
			answeringNS: {
				Records:     map[string][]string{"A": {"192.0.2.1"}},
				Status:      "ok",
				LastChecked: now,
			},
			failedNS: {
				Records:     map[string][]string{},
				Status:      "error",
				Error:       nsFailureReason,
				LastChecked: now,
			},
		},
		LastChecked: now,
	})

	st.SetCertificateState(certKey, &state.CertificateState{
		Status:      "error",
		Error:       certFailedReason,
		LastChecked: now,
	})

	hnd, err := handlers.New(nil, handlers.Params{
		Logger:  log,
		Globals: glob,
		State:   st,
		Notify:  notifier,
	})
	if err != nil {
		t.Fatalf("handlers.New: %v", err)
	}

	return hnd
}

// get serves one GET request to handler and returns the response body.
func get(t *testing.T, handler http.HandlerFunc) string {
	t.Helper()

	rec := httptest.NewRecorder()
	req := httptest.NewRequestWithContext(
		t.Context(), http.MethodGet, "/", nil,
	)

	handler(rec, req)

	if rec.Code != http.StatusOK {
		t.Fatalf("status = %d, want 200", rec.Code)
	}

	return rec.Body.String()
}

// TestStatusGivesFailureReasons checks that /api/v1/status gives the
// reason for a failed nameserver entry and a failed certificate entry,
// and no error for a nameserver that answered.
func TestStatusGivesFailureReasons(t *testing.T) {
	t.Parallel()

	body := get(t, newHandlersWithFailures(t).HandleStatus())

	var resp struct {
		Hostnames map[string]struct {
			Nameservers map[string]map[string]any `json:"nameservers"`
		} `json:"hostnames"`
		Certificates map[string]map[string]any `json:"certificates"`
	}

	err := json.Unmarshal([]byte(body), &resp)
	if err != nil {
		t.Fatalf("decoding response: %v", err)
	}

	nameservers := resp.Hostnames[testHostname].Nameservers

	got := nameservers[failedNS]["error"]
	if got != nsFailureReason {
		t.Errorf("failed nameserver error = %v, want %q",
			got, nsFailureReason)
	}

	_, has := nameservers[answeringNS]["error"]
	if has {
		t.Errorf("answering nameserver has an error field: %v",
			nameservers[answeringNS])
	}

	got = resp.Certificates[certKey]["error"]
	if got != certFailedReason {
		t.Errorf("failed certificate error = %v, want %q",
			got, certFailedReason)
	}
}