package cli //nolint:testpackage // shares the prune fixtures and capture helpers

import (
	"bytes"
	"io"
	"os"
	"testing"

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

// staleRecordLogMessage is the local-cleanup audit line CleanupLocalSnapshots
// logs for each stale record. It is exactly the signal issue #112 says a
// machine consumer lost under --json: gated off stdout, and pinned below
// the log level on stderr because --json used to force Quiet.
const staleRecordLogMessage = "Removing stale local snapshot record"

// TestEntryPruneJSONStderrHonoursVerbosity is the end-to-end regression
// guard for issue #112. Under --json the log level must still follow
// --verbose/--debug rather than being pinned to WARN, so the
// local-cleanup records reach stderr under --verbose while stdout stays
// exactly one JSON document; without --verbose they stay below the
// level, as they do without --json.
//
// Both halves are asserted together on the same run, because the fix has
// to keep the document clean (issue #108) while freeing stderr.
//
// Not parallel: it replaces os.Args, os.Stdout, os.Stderr and the xdg
// globals.
//
//nolint:paralleltest // replaces os.Args, os.Stdout, os.Stderr and the xdg globals
func TestEntryPruneJSONStderrHonoursVerbosity(t *testing.T) {
	for _, testCase := range []struct {
		name         string
		verbose      bool
		wantOnStderr bool
	}{
		{
			name:         "verbose json surfaces the cleanup record on stderr",
			verbose:      true,
			wantOnStderr: true,
		},
		{
			name:         "json alone keeps the cleanup record below the level",
			verbose:      false,
			wantOnStderr: false,
		},
	} {
		t.Run(testCase.name, func(t *testing.T) {
			configPath := writeHermeticPruneConfig(t, true)

			previousArgs := os.Args

			t.Cleanup(func() {
				os.Args = previousArgs
				rootFlags = RootFlags{}
			})

			args := []string{
				programName, flagConfig, configPath, cmdPrune, flagJSON,
			}
			if testCase.verbose {
				args = append(args, "--verbose")
			}

			os.Args = args

			stdout, stderr := captureProcessStdoutAndStderr(t, Entry)

			// The document stays clean in both cases: freeing stderr must
			// not regress issue #108.
			requireExactlyOneJSONDocument(t, stdout)

			if testCase.wantOnStderr {
				assert.Contains(t, stderr, staleRecordLogMessage,
					"--verbose --json must emit the cleanup record on stderr")
				assert.Contains(t, stderr, stalePruneSnapshotID,
					"the record must name the snapshot it removed")
			} else {
				assert.NotContains(t, stderr, staleRecordLogMessage,
					"without --verbose the record stays below the log level")
			}
		})
	}
}

// captureProcessStdoutAndStderr redirects both of the process's own
// standard streams to pipes for the duration of fn and returns what was
// written to each. The redirection is at the file-descriptor level
// because the logger binds os.Stderr when it initializes inside fn, and
// the JSON document reaches os.Stdout independently; the point is to see
// where each actually lands.
//
// Not parallel-safe: os.Stdout and os.Stderr are process-global.
func captureProcessStdoutAndStderr(t *testing.T, fn func()) (string, string) {
	t.Helper()

	outReader, outWriter, err := os.Pipe()
	require.NoError(t, err)

	errReader, errWriter, err := os.Pipe()
	require.NoError(t, err)

	previousOut, previousErr := os.Stdout, os.Stderr
	os.Stdout, os.Stderr = outWriter, errWriter

	capturedOut := drain(outReader)
	capturedErr := drain(errReader)

	fn()

	os.Stdout, os.Stderr = previousOut, previousErr

	require.NoError(t, outWriter.Close())
	require.NoError(t, errWriter.Close())

	out, errOut := <-capturedOut, <-capturedErr

	require.NoError(t, outReader.Close())
	require.NoError(t, errReader.Close())

	return out, errOut
}

// drain copies a reader to a string on a goroutine and delivers the
// result once the writer end is closed.
func drain(reader io.Reader) <-chan string {
	captured := make(chan string, 1)

	go func() {
		var buf bytes.Buffer

		_, _ = io.Copy(&buf, reader)
		captured <- buf.String()
	}()

	return captured
}