package installer

import (
	"archive/tar"
	"bytes"
	"context"
	"os"
	"path/filepath"
	"testing"

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

func TestTarPreflightRejectsOversizedHeaderBeforeReadingPayload(t *testing.T) {
	var archive bytes.Buffer
	writer := tar.NewWriter(&archive)
	require.NoError(t, writer.WriteHeader(&tar.Header{Name: "huge", Typeflag: tar.TypeReg, Mode: 0600, Size: int64(maxSevenZipExpandedSize + 1)}))
	// No payload follows the advertised huge file. Reading/skipping it would
	// return unexpected EOF; preflight must reject its budget first.
	_, err := preflightTar(context.Background(), tar.NewReader(bytes.NewReader(archive.Bytes())))
	require.ErrorContains(t, err, "expands beyond")
}

type cancelAfterFirstRead struct {
	reader *bytes.Reader
	cancel context.CancelFunc
}

func (r *cancelAfterFirstRead) Read(p []byte) (int, error) {
	n, err := r.reader.Read(p)
	r.cancel()
	return n, err
}

func TestTarPreflightObservesCancellationWhileSkippingBody(t *testing.T) {
	data := makeTarBytes(t, map[string][]byte{"payload": bytes.Repeat([]byte("x"), 128<<10)})
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()
	reader := contextReader{ctx: ctx, reader: &cancelAfterFirstRead{reader: bytes.NewReader(data), cancel: cancel}}
	_, err := preflightTar(ctx, tar.NewReader(reader))
	require.ErrorIs(t, err, context.Canceled)
}

func TestCancelledTarExtractionAndHashLeaveDestinationUntouched(t *testing.T) {
	root := t.TempDir()
	source := filepath.Join(root, "broken.tar.gz")
	destination := filepath.Join(root, "live")
	require.NoError(t, os.WriteFile(source, []byte("malformed gzip"), 0600))
	require.NoError(t, os.Mkdir(destination, 0700))
	sentinel := filepath.Join(destination, "original")
	require.NoError(t, os.WriteFile(sentinel, []byte("keep"), 0600))
	ctx, cancel := context.WithCancel(context.Background())
	cancel()
	inst := NewInstaller(ReleaseInfo{}, "")
	require.ErrorIs(t, inst.extractArchive(ctx, source, destination, nil), context.Canceled)
	require.ErrorIs(t, verifyBLAKE3File(ctx, source, blake3HashOf([]byte("malformed gzip"))), context.Canceled)
	assertTransactionFile(t, sentinel, "keep")
	entries, err := os.ReadDir(root)
	require.NoError(t, err)
	require.Len(t, entries, 2)
}