package api

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

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

func writeRaw(t *testing.T, brainDir, name, content string) {
	t.Helper()
	dir := filepath.Join(brainDir, "raw")
	require.NoError(t, os.MkdirAll(dir, 0o755))
	require.NoError(t, os.WriteFile(filepath.Join(dir, name), []byte(content), 0o644))
}

func TestListPendingEmptyWhenAbsent(t *testing.T) {
	got, err := ListPending(t.TempDir())
	require.NoError(t, err, "absent raw/ is not an error")
	assert.Empty(t, got)
}

func TestListPendingReturnsOldestFirstWithExcerpt(t *testing.T) {
	dir := t.TempDir()
	writeRaw(t, dir, "2026-06-02-newer.md", "---\ncreated_at: 2026-06-02T00:00:00Z\n---\nNewer body here.\n")
	writeRaw(t, dir, "2026-06-01-older.md", "---\ncreated_at: 2026-06-01T00:00:00Z\n---\nOlder body content.\n")
	// non-md ignored
	writeRaw(t, dir, "notes.txt", "ignore me")

	got, err := ListPending(dir)
	require.NoError(t, err)
	require.Len(t, got, 2)
	assert.Equal(t, "2026-06-01-older.md", got[0].Filename, "oldest first")
	assert.Equal(t, "2026-06-02-newer.md", got[1].Filename)
	assert.Contains(t, got[0].Excerpt, "Older body content")
	assert.NotContains(t, got[0].Excerpt, "---", "excerpt is body, not frontmatter")
	assert.Positive(t, got[0].SizeBytes)
}

func TestPromoteHappyPath(t *testing.T) {
	dir := t.TempDir()
	writeRaw(t, dir, "2026-06-01-lejpa-decision.md",
		"---\ncreated_at: 2026-06-01T09:00:00Z\ncustom_field: keep-me\n---\n# LeJEPA\n\nbody.\n")

	rel, err := PromoteNote(dir, PromoteOptions{
		Filename: "2026-06-01-lejpa-decision.md", Wing: "jepa-fx", Hall: "decisions",
	})
	require.NoError(t, err)
	assert.Equal(t, "wiki/jepa-fx/decisions/lejpa-decision.md", rel, "slug defaults to filename minus date prefix")

	// Source deleted.
	_, statErr := os.Stat(filepath.Join(dir, "raw", "2026-06-01-lejpa-decision.md"))
	assert.True(t, os.IsNotExist(statErr), "source removed after promote")

	got, err := os.ReadFile(filepath.Join(dir, filepath.FromSlash(rel)))
	require.NoError(t, err)
	s := string(got)
	assert.Contains(t, s, "wing: jepa-fx")
	assert.Contains(t, s, "hall: decisions")
	assert.Contains(t, s, "created_at: 2026-06-01T09:00:00Z", "original created_at preserved")
	assert.Contains(t, s, "promoted_at:")
	assert.Contains(t, s, "custom_field: keep-me", "custom frontmatter preserved")
	assert.Contains(t, s, "# LeJEPA")
}

func TestPromoteExplicitSlug(t *testing.T) {
	dir := t.TempDir()
	writeRaw(t, dir, "2026-06-01-x.md", "body\n")
	rel, err := PromoteNote(dir, PromoteOptions{Filename: "2026-06-01-x.md", Wing: "a", Hall: "facts", Slug: "custom-slug"})
	require.NoError(t, err)
	assert.Equal(t, "wiki/a/facts/custom-slug.md", rel)
}

func TestPromoteInvalidHallErrorsBeforeTouchingFS(t *testing.T) {
	dir := t.TempDir()
	writeRaw(t, dir, "2026-06-01-x.md", "body\n")
	_, err := PromoteNote(dir, PromoteOptions{Filename: "2026-06-01-x.md", Wing: "a", Hall: "garbage"})
	require.Error(t, err)
	// Source untouched.
	_, statErr := os.Stat(filepath.Join(dir, "raw", "2026-06-01-x.md"))
	assert.NoError(t, statErr, "invalid hall must not delete or move the source")
}

func TestPromoteMissingSourceErrors(t *testing.T) {
	_, err := PromoteNote(t.TempDir(), PromoteOptions{Filename: "ghost.md", Wing: "a", Hall: "facts"})
	require.Error(t, err)
}

func TestPromoteSlugCollisionNoOverwrite(t *testing.T) {
	dir := t.TempDir()
	// Pre-existing target.
	dest := filepath.Join(dir, "wiki", "a", "facts", "x.md")
	require.NoError(t, os.MkdirAll(filepath.Dir(dest), 0o755))
	require.NoError(t, os.WriteFile(dest, []byte("EXISTING\n"), 0o644))
	writeRaw(t, dir, "2026-06-01-x.md", "NEW\n")

	_, err := PromoteNote(dir, PromoteOptions{Filename: "2026-06-01-x.md", Wing: "a", Hall: "facts"})
	require.Error(t, err, "collision must error, not overwrite")

	got, _ := os.ReadFile(dest)
	assert.Equal(t, "EXISTING\n", string(got), "target not overwritten")
	_, statErr := os.Stat(filepath.Join(dir, "raw", "2026-06-01-x.md"))
	assert.NoError(t, statErr, "source preserved on collision (atomic: no delete without write)")
}

func TestPromoteRejectsTraversalFilename(t *testing.T) {
	_, err := PromoteNote(t.TempDir(), PromoteOptions{Filename: "../escape.md", Wing: "a", Hall: "facts"})
	require.Error(t, err)
}

func TestPromoteRebuildsWingIndex(t *testing.T) {
	dir := t.TempDir()
	writeRaw(t, dir, "2026-06-01-x.md", "---\ntitle: X Note\n---\nbody\n")
	_, err := PromoteNote(dir, PromoteOptions{Filename: "2026-06-01-x.md", Wing: "a", Hall: "facts"})
	require.NoError(t, err)
	idx, err := os.ReadFile(filepath.Join(dir, "wiki", "a", "_index.md"))
	require.NoError(t, err, "wing _index regenerated")
	assert.Contains(t, string(idx), "x", "promoted note appears in the index")
}