package migrate_test

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

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

	"github.com/mathiasbq/hyperguild/ingestion/internal/migrate"
	"github.com/mathiasbq/hyperguild/ingestion/internal/wing"
)

// keywordClassifier picks a wing by a marker word in the text, and the scorer
// agrees by the same marker, so a page "belongs" to the wing whose marker it holds.
type keywordClassifier struct{}

func (keywordClassifier) Classify(_ context.Context, text string, _ []string) (wing.Suggestion, error) {
	for _, w := range []string{"alpha", "beta"} {
		if strings.Contains(text, strings.ToUpper(w)) {
			return wing.Suggestion{Wing: w, Confidence: 0.95, Reason: "marker"}, nil
		}
	}
	return wing.Suggestion{}, nil
}

type keywordScorer struct{}

func (keywordScorer) Score(text string) map[string]float64 {
	out := map[string]float64{}
	for _, w := range []string{"alpha", "beta"} {
		if strings.Contains(text, strings.ToUpper(w)) {
			out[w] = 1
		}
	}
	return out
}

func resolverFor(string) *wing.Resolver {
	return &wing.Resolver{
		Known:      []string{"alpha", "beta", "client"},
		Eligible:   func(w string) bool { return w != "client" },
		Classifier: keywordClassifier{},
		Scorer:     keywordScorer{},
		Threshold:  0.8,
	}
}

func page(t *testing.T, dir, rel, body string) {
	t.Helper()
	full := filepath.Join(dir, rel)
	require.NoError(t, os.MkdirAll(filepath.Dir(full), 0o755))
	require.NoError(t, os.WriteFile(full, []byte(body), 0o644))
}

func src(title, marker string) string {
	return "---\ntitle: " + title + "\ntype: video\n---\n\n## Summary\n\n" + marker + " content.\n"
}

func entity(title string, sources ...string) string {
	var b strings.Builder
	b.WriteString("---\ntitle: " + title + "\ntype: tool\n---\n\n## Definition\n\nA thing.\n\n## Sources\n\n")
	for _, s := range sources {
		b.WriteString("- [[" + s + "|" + s + "]]\n")
	}
	return b.String()
}

func byFrom(items []migrate.Item) map[string]migrate.Item {
	m := map[string]migrate.Item{}
	for _, it := range items {
		m[it.From] = it
	}
	return m
}

func TestPlan_AResolvedSourceGoesToItsWingsSourcesHall(t *testing.T) {
	dir := t.TempDir()
	page(t, dir, "wiki/sources/talk-a.md", src("Talk A", "ALPHA"))

	items, err := migrate.BuildPlan(context.Background(), dir, resolverFor)
	require.NoError(t, err)
	it := byFrom(items)["wiki/sources/talk-a.md"]
	assert.Equal(t, migrate.Auto, it.Status)
	assert.Equal(t, "wiki/alpha/sources/talk-a.md", it.To)
}

func TestPlan_AutoTunnelLogsAreJunkNotSources(t *testing.T) {
	dir := t.TempDir()
	page(t, dir, "wiki/sources/tunnel-candidates-2026-06-14.md", src("t", "ALPHA"))

	items, err := migrate.BuildPlan(context.Background(), dir, resolverFor)
	require.NoError(t, err)
	it := byFrom(items)["wiki/sources/tunnel-candidates-2026-06-14.md"]
	assert.Equal(t, migrate.Exception, it.Status, "never auto-moved, whatever the classifier says")
	assert.Equal(t, "junk", it.Method)
}

func TestPlan_AnEntityFollowsTheMajorityWingOfItsSources(t *testing.T) {
	dir := t.TempDir()
	page(t, dir, "wiki/sources/a1.md", src("A1", "ALPHA"))
	page(t, dir, "wiki/sources/a2.md", src("A2", "ALPHA"))
	page(t, dir, "wiki/sources/b1.md", src("B1", "BETA"))
	page(t, dir, "wiki/entities/jev.md", entity("Jev", "a1", "a2", "b1"))
	page(t, dir, "wiki/concepts/factory.md", "---\ntitle: Factory\n---\n\n## Definition\n\nx\n\n## Sources\n\n- [[a1|A1]]\n")

	items, err := migrate.BuildPlan(context.Background(), dir, resolverFor)
	require.NoError(t, err)
	m := byFrom(items)
	assert.Equal(t, "wiki/alpha/facts/jev.md", m["wiki/entities/jev.md"].To)
	assert.Equal(t, "entity", m["wiki/entities/jev.md"].Kind)
	assert.Equal(t, "wiki/alpha/facts/factory.md", m["wiki/concepts/factory.md"].To)
	assert.Equal(t, "concept", m["wiki/concepts/factory.md"].Kind)
}

func TestPlan_ATieBetweenWingsIsAnException(t *testing.T) {
	dir := t.TempDir()
	page(t, dir, "wiki/sources/a1.md", src("A1", "ALPHA"))
	page(t, dir, "wiki/sources/b1.md", src("B1", "BETA"))
	page(t, dir, "wiki/entities/jev.md", entity("Jev", "a1", "b1"))

	items, err := migrate.BuildPlan(context.Background(), dir, resolverFor)
	require.NoError(t, err)
	it := byFrom(items)["wiki/entities/jev.md"]
	assert.Equal(t, migrate.Exception, it.Status)
	assert.Contains(t, it.Reason, "disagree")
}

func TestPlan_AnEntityWhoseSourcesWereNotPlacedIsAnException(t *testing.T) {
	dir := t.TempDir()
	page(t, dir, "wiki/sources/mystery.md", src("Mystery", "nothing recognisable"))
	page(t, dir, "wiki/entities/orphan.md", entity("Orphan", "mystery"))
	page(t, dir, "wiki/entities/nosources.md", "---\ntitle: No Sources\n---\n\n## Definition\n\nx\n")

	items, err := migrate.BuildPlan(context.Background(), dir, resolverFor)
	require.NoError(t, err)
	m := byFrom(items)
	assert.Equal(t, migrate.Exception, m["wiki/entities/orphan.md"].Status)
	assert.Equal(t, migrate.Exception, m["wiki/entities/nosources.md"].Status)
}

func TestPlan_ADestinationThatAlreadyExistsIsAnException(t *testing.T) {
	dir := t.TempDir()
	page(t, dir, "wiki/sources/talk-a.md", src("Talk A", "ALPHA"))
	page(t, dir, "wiki/alpha/sources/talk-a.md", "someone else's page")

	items, err := migrate.BuildPlan(context.Background(), dir, resolverFor)
	require.NoError(t, err)
	it := byFrom(items)["wiki/sources/talk-a.md"]
	assert.Equal(t, migrate.Exception, it.Status)
	assert.Contains(t, it.Reason, "already exists", "the occupied destination is named as the reason, not a generic slug clash")
}

func TestPlan_ASlugAlreadyUsedInAnotherWingIsAnException(t *testing.T) {
	// Graph identity is the slug alone; two pages with one slug would merge.
	dir := t.TempDir()
	page(t, dir, "wiki/sources/talk-a.md", src("Talk A", "ALPHA"))
	page(t, dir, "wiki/beta/facts/talk-a.md", "a beta page with the same slug")

	items, err := migrate.BuildPlan(context.Background(), dir, resolverFor)
	require.NoError(t, err)
	it := byFrom(items)["wiki/sources/talk-a.md"]
	assert.Equal(t, migrate.Exception, it.Status)
	assert.Contains(t, it.Reason, "slug")
}

func TestApply_MovesOnlyAutoItemsAndStampsFrontmatterWithoutTouchingTheBody(t *testing.T) {
	dir := t.TempDir()
	body := src("Talk A", "ALPHA") + "\nSee [[jev|Jev]] and [[unknown-slug]].\n"
	page(t, dir, "wiki/sources/talk-a.md", body)
	page(t, dir, "wiki/sources/tunnel-candidates-2026-06-14.md", src("t", "ALPHA"))
	page(t, dir, "wiki/entities/jev.md", entity("Jev", "talk-a"))

	items, err := migrate.BuildPlan(context.Background(), dir, resolverFor)
	require.NoError(t, err)
	n, err := migrate.Apply(dir, items)
	require.NoError(t, err)
	assert.Equal(t, 2, n)

	moved, err := os.ReadFile(filepath.Join(dir, "wiki/alpha/sources/talk-a.md"))
	require.NoError(t, err)
	assert.Contains(t, string(moved), "wing: alpha")
	assert.Contains(t, string(moved), "hall: sources")
	assert.Contains(t, string(moved), "See [[jev|Jev]] and [[unknown-slug]].", "links and body are byte-preserved")

	ent, err := os.ReadFile(filepath.Join(dir, "wiki/alpha/facts/jev.md"))
	require.NoError(t, err)
	assert.Contains(t, string(ent), "kind: entity")

	_, err = os.Stat(filepath.Join(dir, "wiki/sources/talk-a.md"))
	assert.ErrorIs(t, err, os.ErrNotExist, "the original is removed after the copy is written")
	_, err = os.Stat(filepath.Join(dir, "wiki/sources/tunnel-candidates-2026-06-14.md"))
	assert.NoError(t, err, "an exception is left exactly where it is")
}

func TestApply_NeverOverwritesAndKeepsTheSourceWhenTheDestinationAppearsLate(t *testing.T) {
	dir := t.TempDir()
	page(t, dir, "wiki/sources/talk-a.md", src("Talk A", "ALPHA"))
	items, err := migrate.BuildPlan(context.Background(), dir, resolverFor)
	require.NoError(t, err)
	page(t, dir, "wiki/alpha/sources/talk-a.md", "appeared after the plan")

	n, err := migrate.Apply(dir, items)
	require.Error(t, err)
	assert.Zero(t, n)
	got, _ := os.ReadFile(filepath.Join(dir, "wiki/alpha/sources/talk-a.md"))
	assert.Equal(t, "appeared after the plan", string(got))
	_, statErr := os.Stat(filepath.Join(dir, "wiki/sources/talk-a.md"))
	assert.NoError(t, statErr, "the source survives a failed write")
}

func TestPlan_IsEmptyOnceEverythingIsMigrated(t *testing.T) {
	dir := t.TempDir()
	page(t, dir, "wiki/sources/talk-a.md", src("Talk A", "ALPHA"))
	items, err := migrate.BuildPlan(context.Background(), dir, resolverFor)
	require.NoError(t, err)
	_, err = migrate.Apply(dir, items)
	require.NoError(t, err)

	again, err := migrate.BuildPlan(context.Background(), dir, resolverFor)
	require.NoError(t, err)
	assert.Empty(t, again)
}

// An exception that blocked on a collision still carries a destination; Apply
// must treat Status, not the presence of a path, as the decision.
func TestApply_LeavesACollisionExceptionAloneEvenThoughItHasADestination(t *testing.T) {
	dir := t.TempDir()
	page(t, dir, "wiki/sources/talk-a.md", src("Talk A", "ALPHA"))
	page(t, dir, "wiki/alpha/sources/talk-a.md", "occupied")
	items, err := migrate.BuildPlan(context.Background(), dir, resolverFor)
	require.NoError(t, err)
	require.Equal(t, migrate.Exception, byFrom(items)["wiki/sources/talk-a.md"].Status)

	n, err := migrate.Apply(dir, items)
	require.NoError(t, err)
	assert.Zero(t, n)
	_, statErr := os.Stat(filepath.Join(dir, "wiki/sources/talk-a.md"))
	assert.NoError(t, statErr)
}