package brain_test

import (
	"fmt"
	"os"
	"path/filepath"
	"syscall"
	"testing"
	"time"

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

	"github.com/mathiasbq/hyperguild/ingestion/internal/brain"
	"github.com/mathiasbq/hyperguild/ingestion/internal/brainfs/brainfstest"
)

// hyperguild#174 / #157 slice 5b: DetectTunnels walked wiki/ and opened
// every note with a blocking os.Open, so a FIFO named *.md anywhere under
// wiki/ hung every brain_write and brain_update (wikiUpkeep -> AutoTunnel),
// and a symlinked note's title became a tunnel candidate.
func TestDetectTunnelsReturnsPromptlyWithAFIFOUnderWikiWithAndWithoutAWriter(t *testing.T) {
	for _, withWriter := range []bool{false, true} {
		t.Run(fmt.Sprintf("writer=%v", withWriter), func(t *testing.T) {
			b := t.TempDir()
			facts := filepath.Join(b, "wiki", "w", "facts")
			require.NoError(t, os.MkdirAll(facts, 0o755))
			require.NoError(t, os.WriteFile(filepath.Join(facts, "ok.md"), []byte("---\ntitle: Zqinside Phrase\n---\n"), 0o644))
			fifo := filepath.Join(facts, "f.md")
			require.NoError(t, syscall.Mkfifo(fifo, 0o644))
			if withWriter {
				// A writer held open: a reader that opens the FIFO gets no
				// EOF and parks, unless the FIFO is never opened.
				w, err := os.OpenFile(fifo, os.O_RDWR, 0)
				require.NoError(t, err)
				t.Cleanup(func() { _ = w.Close() })
			}
			done := make(chan []brain.TunnelCandidate, 1)
			go func() {
				cs, _ := brain.DetectTunnels(b, "text mentioning zqinside phrase here")
				done <- cs
			}()
			select {
			case cs := <-done:
				assert.Contains(t, fmt.Sprintf("%+v", cs), "Zqinside Phrase", "positive control")
			case <-time.After(3 * time.Second):
				if r, err := os.OpenFile(fifo, os.O_WRONLY|syscall.O_NONBLOCK, 0); err == nil {
					_ = r.Close()
				}
				t.Fatal("DetectTunnels blocked on a FIFO")
			}
		})
	}
}

func TestDetectTunnelsRefusesSymlinkedNotesAndSurvivesSwapRaces(t *testing.T) {
	b := t.TempDir()
	facts := filepath.Join(b, "wiki", "w", "facts")
	require.NoError(t, os.MkdirAll(facts, 0o755))
	// The static note's title differs from the raced note's, so the
	// harness's "inside was read" floor can only be met by reading r.md.
	require.NoError(t, os.WriteFile(filepath.Join(facts, "ok.md"), []byte("---\ntitle: Zqstatic Words\n---\n"), 0o644))
	require.NoError(t, os.Symlink(brainfstest.Outside(t), filepath.Join(facts, "out.md")))
	inBrain := brainfstest.WriteSentinelAt(t, filepath.Join(b, "raw", "s.md"))
	require.NoError(t, os.Symlink(filepath.Join("..", "..", "..", "raw", "s.md"), filepath.Join(facts, "in.md")))
	content := "zqstatic words, zqinside phrase and " + brainfstest.Sentinel

	cs, err := brain.DetectTunnels(b, content)
	require.NoError(t, err)
	got := fmt.Sprintf("%+v", cs)
	assert.Contains(t, got, "Zqstatic Words", "positive control")
	assert.NotContains(t, got, brainfstest.Sentinel)

	p := filepath.Join(facts, "r.md")
	read := func() string {
		cs, _ := brain.DetectTunnels(b, content)
		return fmt.Sprintf("%+v", cs)
	}
	brainfstest.AssertNoLeak(t, p, "---\ntitle: Zqinside Phrase\n---\n", 1500*time.Millisecond, read)
	brainfstest.AssertNoLeakFrom(t, p, "---\ntitle: Zqinside Phrase\n---\n", inBrain, 1500*time.Millisecond, read)
}

// A wiki/ that is not a real directory yields no candidates and no error:
// AutoTunnel runs inside brain_write.
func TestDetectTunnelsSkipsAWikiThatIsNotARealDirectory(t *testing.T) {
	b := t.TempDir()
	require.NoError(t, os.MkdirAll(filepath.Join(b, "raw", "w", "facts"), 0o755))
	require.NoError(t, os.WriteFile(filepath.Join(b, "raw", "w", "facts", "r.md"), []byte("---\ntitle: Zqrawonly Phrase\n---\n"), 0o644))
	require.NoError(t, os.Symlink("raw", filepath.Join(b, "wiki")))
	cs, err := brain.DetectTunnels(b, "zqrawonly phrase")
	require.NoError(t, err)
	assert.Empty(t, cs)
}

// An unreadable directory under wiki/ is a walk error and DetectTunnels
// reports it, as filepath.WalkDir did; it is not silently dropped.
func TestDetectTunnelsReportsAnUnreadableDirectoryUnderWiki(t *testing.T) {
	if os.Geteuid() == 0 {
		t.Skip("root ignores directory permissions")
	}
	b := t.TempDir()
	require.NoError(t, os.MkdirAll(filepath.Join(b, "wiki", "w", "facts"), 0o755))
	require.NoError(t, os.WriteFile(filepath.Join(b, "wiki", "w", "facts", "ok.md"), []byte("---\ntitle: Zqinside Phrase\n---\n"), 0o644))
	locked := filepath.Join(b, "wiki", "other", "locked")
	require.NoError(t, os.MkdirAll(locked, 0o755))
	require.NoError(t, os.Chmod(locked, 0o000))
	t.Cleanup(func() { _ = os.Chmod(locked, 0o755) })
	_, err := brain.DetectTunnels(b, "zqinside phrase")
	assert.ErrorIs(t, err, os.ErrPermission)
}

// _index.md files are generated, not notes: their title never becomes a
// candidate.
func TestDetectTunnelsSkipsIndexFiles(t *testing.T) {
	b := t.TempDir()
	w := filepath.Join(b, "wiki", "w")
	require.NoError(t, os.MkdirAll(filepath.Join(w, "facts"), 0o755))
	require.NoError(t, os.WriteFile(filepath.Join(w, "_index.md"), []byte("---\ntitle: Zqindex Words\n---\n"), 0o644))
	require.NoError(t, os.WriteFile(filepath.Join(w, "facts", "ok.md"), []byte("---\ntitle: Zqinside Phrase\n---\n"), 0o644))
	cs, err := brain.DetectTunnels(b, "zqindex words and zqinside phrase")
	require.NoError(t, err)
	got := fmt.Sprintf("%+v", cs)
	assert.Contains(t, got, "Zqinside Phrase", "positive control")
	assert.NotContains(t, got, "Zqindex")
}