package search

import (
	"os"
	"path/filepath"
	"strings"
	"sync/atomic"
	"syscall"
	"testing"
	"time"

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

// hyperguild#157 option 1: search walked and read the brain by path, so a
// symlink anywhere in the Syncthing-shared brain dir (wiki/<w>/<h>/leak.md ->
// /any/file) put the target's contents in brain_query results (reproduced in
// the PR #156 review). Search now walks and reads through an os.Root on the
// brain dir and only reads regular files.

const sentinel157 = "zqsentinelonefiftyseven"

func searchBrain(t *testing.T) (brain, facts, outside string) {
	t.Helper()
	brain = t.TempDir()
	facts = filepath.Join(brain, "wiki", "w", "facts")
	require.NoError(t, os.MkdirAll(facts, 0o755))
	require.NoError(t, os.MkdirAll(filepath.Join(brain, "knowledge"), 0o755))
	outside = filepath.Join(t.TempDir(), "secret.md")
	require.NoError(t, os.WriteFile(outside, []byte("# secret\n\n"+sentinel157), 0o644))
	return brain, facts, outside
}

func leaked(rs []Result) int {
	n := 0
	for _, r := range rs {
		n += strings.Count(r.Excerpt+r.Title, sentinel157)
	}
	return n
}

func TestQueryDoesNotFollowASymlinkInTheWiki(t *testing.T) {
	brain, facts, outside := searchBrain(t)
	require.NoError(t, os.Symlink(outside, filepath.Join(facts, "leak.md")))
	require.NoError(t, os.WriteFile(filepath.Join(facts, "real.md"), []byte("# real\n\nzqrealnote"), 0o644))
	rs, err := Query(brain, QueryOptions{Query: sentinel157, Limit: 10})
	require.NoError(t, err)
	assert.Zero(t, leaked(rs))
	rs, err = Query(brain, QueryOptions{Query: "zqrealnote", Limit: 10})
	require.NoError(t, err)
	assert.Len(t, rs, 1, "regular notes are still found")
}

func TestQueryDoesNotFollowASymlinkedDirectory(t *testing.T) {
	brain, _, outside := searchBrain(t)
	require.NoError(t, os.Symlink(filepath.Dir(outside), filepath.Join(brain, "wiki", "linked")))
	rs, err := Query(brain, QueryOptions{Query: sentinel157, Limit: 10})
	require.NoError(t, err)
	assert.Zero(t, leaked(rs))
}

func swapInto(path, outside string, fifo bool, stop *atomic.Bool) {
	tmp := path + ".swap"
	for i := 0; !stop.Load(); i++ {
		_ = os.Remove(tmp)
		switch {
		case i%2 == 0:
			_ = os.WriteFile(tmp, []byte("# r\n\nzqinside "+"zqracenote"), 0o644)
		case fifo:
			_ = syscall.Mkfifo(tmp, 0o644)
		default:
			_ = os.Symlink(outside, tmp)
		}
		_ = os.Rename(tmp, path)
	}
}

func TestQueryLeaksNothingUnderASymlinkSwapRace(t *testing.T) {
	brain, facts, outside := searchBrain(t)
	var stop atomic.Bool
	go swapInto(filepath.Join(facts, "r.md"), outside, false, &stop)
	defer stop.Store(true)
	leaks, iters := 0, 0
	for deadline := time.Now().Add(1500 * time.Millisecond); time.Now().Before(deadline); iters++ {
		rs, _ := Query(brain, QueryOptions{Query: sentinel157, Limit: 10})
		leaks += leaked(rs)
	}
	if leaks > 0 {
		t.Fatalf("outside file leaked %d times in %d iterations", leaks, iters)
	}
}

func TestQueryDoesNotHangUnderAFIFOSwapRace(t *testing.T) {
	brain, facts, outside := searchBrain(t)
	var stop atomic.Bool
	go swapInto(filepath.Join(facts, "r.md"), outside, true, &stop)
	done := make(chan struct{})
	go func() {
		for deadline := time.Now().Add(1500 * time.Millisecond); time.Now().Before(deadline); {
			_, _ = Query(brain, QueryOptions{Query: "zqracenote", Limit: 10})
		}
		close(done)
	}()
	select {
	case <-done:
		stop.Store(true)
	case <-time.After(6 * time.Second):
		stop.Store(true)
		if f, err := os.OpenFile(filepath.Join(facts, "r.md"), os.O_WRONLY|syscall.O_NONBLOCK, 0); err == nil {
			_ = f.Close()
		}
		t.Fatal("search hung on a swapped-in FIFO")
	}
}

// hydrate (vector-only hits) reads by relative path; it must refuse a symlink.
func TestHydrateRefusesASymlink(t *testing.T) {
	brain, facts, outside := searchBrain(t)
	require.NoError(t, os.Symlink(outside, filepath.Join(facts, "leak.md")))
	r, err := hydrate(brain, "wiki/w/facts/leak.md")
	assert.Error(t, err)
	assert.NotContains(t, r.Excerpt, sentinel157)
}