package cli //nolint:testpackage // shares runEntry and the argument constants

import (
	"fmt"
	"net/http"
	"net/http/httptest"
	"os"
	"os/signal"
	"path/filepath"
	"strings"
	"testing"
	"time"

	"github.com/adrg/xdg"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

// stalledStoreConfig is hermeticConfig with an s3:// destination store
// in place of the file:// one. The server behind it accepts any
// credentials.
const stalledStoreConfig = `age_recipients:
  - age1278m9q7dp3chsh2dcy82qk27v047zywyvtxwnj4cvt0z65jw6a7q5dqhfj
snapshots:
  test:
    paths:
      - %s
storage_url: s3://bucket?endpoint=%s&ssl=false
s3:
  access_key_id: key
  secret_access_key: secret
index_path: %s
hostname: test-host
`

// interruptRepeat is how often interruptOnFirstRequest sends SIGINT.
const interruptRepeat = 50 * time.Millisecond

// TestEntryInterruptedRun sends SIGINT to the test process while a
// command waits on the destination store, and checks that Entry returns
// 130 and prints one line on stderr saying the run was interrupted. The
// store is a local HTTP server that holds every request open, so the
// command is always mid-operation when the signal arrives. The two
// cases cover --cron and --json, which silence other output.
//
// Not parallel: it signals the process and replaces os.Args, os.Stdout,
// os.Stderr and the xdg globals.
//
//nolint:paralleltest // signals the process and replaces process globals
func TestEntryInterruptedRun(t *testing.T) {
	for _, testCase := range []struct {
		name string
		args []string
	}{
		{
			name: "snapshot create --cron",
			args: []string{cmdSnapshot, cmdCreate, "--cron"},
		},
		{
			name: "snapshot verify --json",
			args: []string{cmdSnapshot, cmdVerify, someSnapshotID, flagJSON},
		},
	} {
		t.Run(testCase.name, func(t *testing.T) {
			endpoint, requestArrived := startStalledStore(t)
			configPath := writeStalledStoreConfig(t, endpoint)
			interruptOnFirstRequest(t, requestArrived)

			code, _, stderr := runEntry(t,
				append([]string{flagConfig, configPath}, testCase.args...)...)

			assert.Equal(t, 130, code)
			assert.Equal(t, 1,
				strings.Count(stderr, errInterrupted.Error()), stderr)
		})
	}
}

// interruptOnFirstRequest sends SIGINT to the test process every
// interruptRepeat, from the first request to the destination store until
// the test ends. One signal is not enough: the command can reach the
// store before fx has started catching signals. The test catches SIGINT
// too, so that a signal fx is not catching does not kill the test
// binary.
func interruptOnFirstRequest(t *testing.T, requestArrived <-chan struct{}) {
	t.Helper()

	self, err := os.FindProcess(os.Getpid())
	require.NoError(t, err)

	caught := make(chan os.Signal, 1)
	signal.Notify(caught, os.Interrupt)

	testEnded := make(chan struct{})
	senderDone := make(chan struct{})

	// Stop catching SIGINT only after the sender has returned. The sender
	// waits for each SIGINT it sends to arrive on caught; one still on
	// its way after signal.Stop would kill the test binary.
	t.Cleanup(func() {
		close(testEnded)
		<-senderDone
		signal.Stop(caught)
	})

	go func() {
		defer close(senderDone)

		select {
		case <-requestArrived:
		case <-testEnded:
			return
		}

		ticker := time.NewTicker(interruptRepeat)
		defer ticker.Stop()

		for {
			// Empty caught, so that the receive below waits for this
			// SIGINT rather than an earlier one.
			select {
			case <-caught:
			default:
			}

			sendErr := self.Signal(os.Interrupt)
			if sendErr != nil {
				t.Errorf("sending SIGINT: %v", sendErr)

				return
			}

			<-caught

			select {
			case <-testEnded:
				return
			case <-ticker.C:
			}
		}
	}()
}

// startStalledStore starts an HTTP server that never answers: each
// request is held until the client gives up on it or the test ends.
// It returns the server's host:port and a channel that receives a value
// when the first request arrives.
func startStalledStore(t *testing.T) (string, <-chan struct{}) {
	t.Helper()

	requestArrived := make(chan struct{}, 1)
	release := make(chan struct{})

	server := httptest.NewServer(http.HandlerFunc(
		func(_ http.ResponseWriter, r *http.Request) {
			select {
			case requestArrived <- struct{}{}:
			default:
			}

			select {
			case <-r.Context().Done():
			case <-release:
			}
		}))

	// Cleanups run last-registered first, so release lets any held
	// request return before Close waits for it.
	t.Cleanup(server.Close)
	t.Cleanup(func() { close(release) })

	return server.Listener.Addr().String(), requestArrived
}

// writeStalledStoreConfig writes a config whose destination store is the
// server at endpoint and whose snapshot source holds one small file, so
// that `snapshot create` has a blob to upload. Returns the config path.
func writeStalledStoreConfig(t *testing.T, endpoint string) string {
	t.Helper()

	dir := t.TempDir()
	configPath := filepath.Join(dir, "config.yml")
	sourceDir := filepath.Join(dir, "source")

	require.NoError(t, os.Mkdir(sourceDir, 0o750))
	require.NoError(t, os.WriteFile(filepath.Join(sourceDir, "file.txt"),
		[]byte("contents"), 0o600))

	contents := fmt.Sprintf(stalledStoreConfig,
		sourceDir, endpoint, filepath.Join(dir, "index.sqlite"))

	require.NoError(t,
		os.WriteFile(configPath, []byte(contents), configFileMode))

	// The PID lock lives under xdg.DataHome, which xdg resolves at
	// package init; point it at the temp dir so the test neither
	// touches nor collides with the real one.
	t.Setenv("XDG_DATA_HOME", filepath.Join(dir, "data"))
	xdg.Reload()
	t.Cleanup(xdg.Reload)

	return configPath
}