package brain_test

import (
	"os"
	"path/filepath"
	"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"
)

func readIndex(t *testing.T, brainDir, wing string) string {
	t.Helper()
	b, _ := os.ReadFile(filepath.Join(brainDir, "wiki", wing, "_index.md"))
	return string(b)
}

// hyperguild#157 slice 5: BuildWingIndex listed wiki/<wing>/<hall>/ with
// os.ReadDir and opened each note by path, so a symlinked note put the
// target's title into _index.md, and a FIFO hung the index build.
func TestBuildWingIndexRefusesSymlinkedNotesAndSurvivesSwapRaces(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\n---\n"), 0o644))
	require.NoError(t, os.Symlink(brainfstest.Outside(t), filepath.Join(facts, "leak.md")))
	inBrain := brainfstest.WriteSentinelAt(t, filepath.Join(b, "raw", "s.md"))
	require.NoError(t, os.Symlink(filepath.Join("..", "..", "..", "raw", "s.md"), filepath.Join(facts, "inlink.md")))

	require.NoError(t, brain.BuildWingIndex(b, "w"))
	idx := readIndex(t, b, "w")
	assert.Contains(t, idx, "zqinside", "positive control")
	assert.NotContains(t, idx, brainfstest.Sentinel)
	assert.NotContains(t, idx, "leak")
	assert.NotContains(t, idx, "inlink")

	p := filepath.Join(facts, "r.md")
	read := func() string {
		_ = brain.BuildWingIndex(b, "w")
		return readIndex(t, b, "w")
	}
	brainfstest.AssertNoLeak(t, p, "---\ntitle: zqinside\n---\n", 1500*time.Millisecond, read)
	brainfstest.AssertNoLeakFrom(t, p, "---\ntitle: zqinside\n---\n", inBrain, 1500*time.Millisecond, read)
	brainfstest.AssertNoHang(t, p, "---\ntitle: zqinside\n---\n", 1500*time.Millisecond, 6*time.Second, func() { _ = read() })
}

// A symlinked hall is skipped while a real hall next to it is indexed; a
// symlinked wing is refused and nothing is written into its target.
func TestBuildWingIndexSkipsASymlinkedHallAndRefusesASymlinkedWing(t *testing.T) {
	b := t.TempDir()
	require.NoError(t, os.MkdirAll(filepath.Join(b, "raw", "facts"), 0o755))
	require.NoError(t, os.WriteFile(filepath.Join(b, "raw", "facts", "r.md"), []byte("---\ntitle: zqrawonly\n---\n"), 0o644))
	require.NoError(t, os.MkdirAll(filepath.Join(b, "wiki", "w", "decisions"), 0o755))
	require.NoError(t, os.WriteFile(filepath.Join(b, "wiki", "w", "decisions", "d.md"), []byte("---\ntitle: zqrealhall\n---\n"), 0o644))
	require.NoError(t, os.Symlink(filepath.Join("..", "..", "raw", "facts"), filepath.Join(b, "wiki", "w", "facts")))
	require.NoError(t, os.Symlink(filepath.Join("..", "raw"), filepath.Join(b, "wiki", "alias")))

	require.NoError(t, brain.BuildWingIndex(b, "w"))
	idx, err := os.ReadFile(filepath.Join(b, "wiki", "w", "_index.md"))
	require.NoError(t, err, "the wing index is written")
	assert.Contains(t, string(idx), "zqrealhall", "the real hall is indexed")
	assert.NotContains(t, string(idx), "zqrawonly", "the symlinked hall is not")

	assert.Error(t, brain.BuildWingIndex(b, "alias"))
	_, err = os.Stat(filepath.Join(b, "raw", "_index.md"))
	assert.True(t, os.IsNotExist(err), "an index was written into the symlinked wing's target")
}

// BuildAllWingIndexes indexes the real wings and skips a symlinked one.
func TestBuildAllWingIndexesSkipsASymlinkedWing(t *testing.T) {
	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", "n.md"), []byte("---\ntitle: zqrealwing\n---\n"), 0o644))
	require.NoError(t, os.MkdirAll(filepath.Join(b, "raw", "facts"), 0o755))
	require.NoError(t, os.Symlink(filepath.Join("..", "raw"), filepath.Join(b, "wiki", "alias")))

	require.NoError(t, brain.BuildAllWingIndexes(b))
	idx, err := os.ReadFile(filepath.Join(b, "wiki", "w", "_index.md"))
	require.NoError(t, err)
	assert.Contains(t, string(idx), "zqrealwing")
	_, err = os.Stat(filepath.Join(b, "raw", "_index.md"))
	assert.True(t, os.IsNotExist(err))
}

// A link to a symlinked note does not resolve: only regular files count as
// entries, so StripUnresolvedLinks unwraps it.
func TestStripUnresolvedLinksDoesNotCountASymlinkedNoteAsAnEntry(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, "real.md"), []byte("x"), 0o644))
	brainfstest.WriteSentinelAt(t, filepath.Join(b, "raw", "s.md"))
	require.NoError(t, os.Symlink(filepath.Join("..", "..", "..", "raw", "s.md"), filepath.Join(facts, "ghost.md")))
	out, unlinked, err := brain.StripUnresolvedLinks(b, "see [[real]] and [[ghost]]")
	require.NoError(t, err)
	assert.Contains(t, out, "[[real]]", "positive control")
	assert.NotContains(t, out, "[[ghost]]")
	assert.Contains(t, unlinked, "ghost")
}

// A linked tree (knowledge/ or wiki/) that is not a real directory is
// skipped, not an error: StripUnresolvedLinks runs before every brain_write,
// and an error there loses the learning.
func TestStripUnresolvedLinksSkipsALinkedTreeThatIsNotARealDirectory(t *testing.T) {
	for name, mk := range map[string]func(t *testing.T, b string){
		"symlink to an in-brain dir": func(t *testing.T, b string) {
			require.NoError(t, os.MkdirAll(filepath.Join(b, "raw", "k"), 0o755))
			require.NoError(t, os.Symlink(filepath.Join("raw", "k"), filepath.Join(b, "knowledge")))
		},
		"dangling symlink": func(t *testing.T, b string) {
			require.NoError(t, os.Symlink("nowhere", filepath.Join(b, "knowledge")))
		},
		"regular file": func(t *testing.T, b string) {
			require.NoError(t, os.WriteFile(filepath.Join(b, "knowledge"), []byte("x"), 0o644))
		},
	} {
		t.Run(name, func(t *testing.T) {
			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", "real.md"), []byte("x"), 0o644))
			mk(t, b)
			out, _, err := brain.StripUnresolvedLinks(b, "learning [[real]] and [[gone]]")
			require.NoError(t, err)
			assert.Contains(t, out, "[[real]]", "links into wiki/ still resolve")
			assert.NotContains(t, out, "[[gone]]")
		})
	}
}