package brain_test

import (
	"os"
	"path/filepath"
	"strings"
	"testing"

	"github.com/mathiasbq/hyperguild/ingestion/internal/brain"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

// seedNote writes a minimal markdown note at brainDir/relPath with the given body.
func seedNote(t *testing.T, brainDir, relPath, body string) {
	t.Helper()
	full := filepath.Join(brainDir, relPath)
	require.NoError(t, os.MkdirAll(filepath.Dir(full), 0o755))
	require.NoError(t, os.WriteFile(full, []byte(body), 0o644))
}

func TestWriteTunnel_AppendsBidirectionalLinks(t *testing.T) {
	dir := t.TempDir()
	seedNote(t, dir, "wiki/jepa-fx/decisions/val-vol.md",
		"---\nwing: jepa-fx\nhall: decisions\n---\n# Val Vol R2\n\nbody.\n")
	seedNote(t, dir, "wiki/hyperguild/decisions/routing.md",
		"---\nwing: hyperguild\nhall: decisions\n---\n# Routing\n\nbody.\n")

	err := brain.WriteTunnel(dir,
		"wiki/jepa-fx/decisions/val-vol.md",
		"wiki/hyperguild/decisions/routing.md",
	)
	require.NoError(t, err)

	src, err := os.ReadFile(filepath.Join(dir, "wiki/jepa-fx/decisions/val-vol.md"))
	require.NoError(t, err)
	assert.Contains(t, string(src), "## See also")
	assert.Contains(t, string(src), "[[hyperguild/decisions/routing]]")

	tgt, err := os.ReadFile(filepath.Join(dir, "wiki/hyperguild/decisions/routing.md"))
	require.NoError(t, err)
	assert.Contains(t, string(tgt), "## See also")
	assert.Contains(t, string(tgt), "[[jepa-fx/decisions/val-vol]]")
}

func TestWriteTunnel_Idempotent(t *testing.T) {
	dir := t.TempDir()
	seedNote(t, dir, "wiki/a/facts/x.md", "# X\n\nbody.\n")
	seedNote(t, dir, "wiki/b/facts/y.md", "# Y\n\nbody.\n")

	for i := 0; i < 3; i++ {
		require.NoError(t, brain.WriteTunnel(dir,
			"wiki/a/facts/x.md", "wiki/b/facts/y.md"))
	}

	src, err := os.ReadFile(filepath.Join(dir, "wiki/a/facts/x.md"))
	require.NoError(t, err)
	assert.Equal(t, 1, strings.Count(string(src), "[[b/facts/y]]"),
		"link should appear exactly once after 3 calls")
	assert.Equal(t, 1, strings.Count(string(src), "## See also"))

	tgt, err := os.ReadFile(filepath.Join(dir, "wiki/b/facts/y.md"))
	require.NoError(t, err)
	assert.Equal(t, 1, strings.Count(string(tgt), "[[a/facts/x]]"))
	assert.Equal(t, 1, strings.Count(string(tgt), "## See also"))
}

func TestWriteTunnel_RejectsSameWing(t *testing.T) {
	dir := t.TempDir()
	seedNote(t, dir, "wiki/jepa-fx/facts/x.md", "x")
	seedNote(t, dir, "wiki/jepa-fx/facts/y.md", "y")
	err := brain.WriteTunnel(dir,
		"wiki/jepa-fx/facts/x.md", "wiki/jepa-fx/facts/y.md")
	require.Error(t, err)
	assert.Contains(t, err.Error(), "cross wings")
}

func TestWriteTunnel_RejectsMissingNote(t *testing.T) {
	dir := t.TempDir()
	seedNote(t, dir, "wiki/a/facts/x.md", "x")
	err := brain.WriteTunnel(dir,
		"wiki/a/facts/x.md", "wiki/b/facts/ghost.md")
	require.Error(t, err)
}

func TestDetectTunnels_ExactTitleMatch(t *testing.T) {
	dir := t.TempDir()
	seedNote(t, dir, "wiki/jepa-fx/decisions/val-vol.md",
		"---\nwing: jepa-fx\nhall: decisions\ntitle: Val Vol R2\n---\nbody.\n")
	seedNote(t, dir, "wiki/jepa-fx/facts/lejpa.md",
		"---\nwing: jepa-fx\nhall: facts\ntitle: LeJPA Architecture\n---\nbody.\n")

	candidates, err := brain.DetectTunnels(dir,
		"We need to revisit Val Vol R2 in light of new tier data.")
	require.NoError(t, err)

	require.Len(t, candidates, 1)
	assert.Equal(t, "wiki/jepa-fx/decisions/val-vol.md", candidates[0].TargetPath)
	assert.Equal(t, "Val Vol R2", candidates[0].MatchedTerm)
	assert.True(t, candidates[0].Exact)
}

func TestDetectTunnels_FuzzyMatch(t *testing.T) {
	dir := t.TempDir()
	seedNote(t, dir, "wiki/x/facts/routing.md",
		"---\ntitle: Routing\n---\nbody.\n")

	// Substring of title appears in content, but not as a whole word.
	candidates, err := brain.DetectTunnels(dir, "rerouting handles failover")
	require.NoError(t, err)
	require.Len(t, candidates, 1)
	assert.False(t, candidates[0].Exact, "substring-only match should be fuzzy")
}

func TestDetectTunnels_NoFrontmatterFallsBackToSlug(t *testing.T) {
	dir := t.TempDir()
	seedNote(t, dir, "wiki/x/facts/widget-flags.md", "# widget flags\n\nbody.\n")

	candidates, err := brain.DetectTunnels(dir,
		"Documented Widget Flags after the deploy issue.")
	require.NoError(t, err)
	require.Len(t, candidates, 1)
	assert.True(t, candidates[0].Exact)
	assert.Equal(t, "widget flags", candidates[0].MatchedTerm)
}

func TestAutoTunnel_FuzzyGoesToCandidatesFile(t *testing.T) {
	dir := t.TempDir()
	// Existing note in a different wing whose title is "Routing".
	seedNote(t, dir, "wiki/other/facts/routing.md",
		"---\nwing: other\nhall: facts\ntitle: Routing\n---\nbody.\n")
	// Source note in another wing whose body mentions "rerouting" (substring match only).
	seedNote(t, dir, "wiki/jepa-fx/facts/new.md",
		"---\nwing: jepa-fx\nhall: facts\n---\nrerouting traffic\n")

	require.NoError(t, brain.AutoTunnel(dir,
		"wiki/jepa-fx/facts/new.md", "rerouting traffic"))

	// Source must not get auto-linked (fuzzy).
	got, err := os.ReadFile(filepath.Join(dir, "wiki/jepa-fx/facts/new.md"))
	require.NoError(t, err)
	assert.NotContains(t, string(got), "[[other/facts/routing]]")

	// Candidates file must list the pair.
	matches, err := filepath.Glob(filepath.Join(dir, "raw", "tunnel-candidates-*.md"))
	require.NoError(t, err)
	require.Len(t, matches, 1)
	body, err := os.ReadFile(matches[0])
	require.NoError(t, err)
	assert.Contains(t, string(body), "wiki/jepa-fx/facts/new.md")
	assert.Contains(t, string(body), "wiki/other/facts/routing.md")
	assert.Contains(t, string(body), "Routing")
}

func TestDetectTunnels_EmptyWiki(t *testing.T) {
	dir := t.TempDir()
	cs, err := brain.DetectTunnels(dir, "anything")
	require.NoError(t, err)
	assert.Empty(t, cs)
}

func TestWriteTunnel_AppendsToExistingSeeAlso(t *testing.T) {
	dir := t.TempDir()
	seedNote(t, dir, "wiki/a/facts/x.md",
		"# X\n\nbody.\n\n## See also\n\n- [[a/facts/old]]\n")
	seedNote(t, dir, "wiki/b/facts/y.md", "# Y\n\nbody.\n")

	require.NoError(t, brain.WriteTunnel(dir,
		"wiki/a/facts/x.md", "wiki/b/facts/y.md"))

	src, err := os.ReadFile(filepath.Join(dir, "wiki/a/facts/x.md"))
	require.NoError(t, err)
	s := string(src)
	assert.Equal(t, 1, strings.Count(s, "## See also"), "should reuse existing section")
	assert.Contains(t, s, "[[a/facts/old]]")
	assert.Contains(t, s, "[[b/facts/y]]")
}