package parser

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

func TestDiscoverSlideFiles_SortsByPrefixAndIgnoresNonMarkdown(t *testing.T) {
	dir := t.TempDir()
	writeFiles(t, dir, map[string]string{
		"020-second.md":  "body",
		"010-first.md":   "body",
		"030-third.md":   "body",
		"README.txt":     "not a slide",
		"assets/img.png": "binary",
	})

	got, err := discoverSlideFiles(dir)
	if err != nil {
		t.Fatalf("discoverSlideFiles() error = %v", err)
	}

	want := []string{"010-first.md", "020-second.md", "030-third.md"}
	if !equalStrings(got, want) {
		t.Errorf("discoverSlideFiles() = %v, want %v", got, want)
	}
}

func TestDiscoverSlideFiles_SortsNumericallyAcrossDigitCounts(t *testing.T) {
	dir := t.TempDir()
	writeFiles(t, dir, map[string]string{
		"10-b.md":   "body",
		"9-a.md":    "body",
		"1000-d.md": "body",
		"999-c.md":  "body",
	})

	got, err := discoverSlideFiles(dir)
	if err != nil {
		t.Fatalf("discoverSlideFiles() error = %v", err)
	}

	want := []string{"9-a.md", "10-b.md", "999-c.md", "1000-d.md"}
	if !equalStrings(got, want) {
		t.Errorf("discoverSlideFiles() = %v, want %v", got, want)
	}
}

func TestParseDir_RespectsSkip(t *testing.T) {
	dir := t.TempDir()
	writeFiles(t, dir, map[string]string{
		"010-intro.md":  "---\ntitle: Intro\n---\n# Intro\n",
		"020-hidden.md": "---\ntitle: Hidden\nskip: true\n---\n# Hidden\n",
		"030-outro.md":  "---\ntitle: Outro\n---\n# Outro\n",
	})

	slides, err := ParseDir(dir)
	if err != nil {
		t.Fatalf("ParseDir() error = %v", err)
	}

	if len(slides) != 2 {
		t.Fatalf("len(slides) = %d, want 2", len(slides))
	}
	if slides[0].Title != "Intro" || slides[1].Title != "Outro" {
		t.Errorf("slides = %+v, want Intro then Outro (Hidden skipped)", slides)
	}
}

func TestParseDir_OrderAndFields(t *testing.T) {
	dir := t.TempDir()
	writeFiles(t, dir, map[string]string{
		"020-second.md": "---\ntitle: Second\nclass: center\nnotes: speak here\n---\n# Second\n",
		"010-first.md":  "---\ntitle: First\n---\n# First\n",
	})

	slides, err := ParseDir(dir)
	if err != nil {
		t.Fatalf("ParseDir() error = %v", err)
	}

	if len(slides) != 2 {
		t.Fatalf("len(slides) = %d, want 2", len(slides))
	}
	if slides[0].Filename != "010-first.md" || slides[1].Filename != "020-second.md" {
		t.Fatalf("slides in wrong order: %+v", slides)
	}
	if slides[1].Class != "center" || slides[1].Notes != "speak here" {
		t.Errorf("slides[1] = %+v, want Class=center Notes=\"speak here\"", slides[1])
	}
}

func TestParseDir_Incremental(t *testing.T) {
	dir := t.TempDir()
	writeFiles(t, dir, map[string]string{
		"010-a.md": "---\nincremental: true\n---\n# A\n",
		"020-b.md": "# B\n",
	})

	slides, err := ParseDir(dir)
	if err != nil {
		t.Fatalf("ParseDir() error = %v", err)
	}

	if !slides[0].Incremental {
		t.Errorf("slides[0].Incremental = false, want true")
	}
	if slides[1].Incremental {
		t.Errorf("slides[1].Incremental = true, want false")
	}
}

func TestParseDir_NewSlideMarkerSplitsOneFileIntoMultipleSlides(t *testing.T) {
	dir := t.TempDir()
	writeFiles(t, dir, map[string]string{
		"010-combo.md": "---\ntitle: Combo\nclass: center\n---\n# One\n\n<!-- new slide -->\n\n# Two\n",
		"020-after.md": "# Three\n",
	})

	slides, err := ParseDir(dir)
	if err != nil {
		t.Fatalf("ParseDir() error = %v", err)
	}

	if len(slides) != 3 {
		t.Fatalf("len(slides) = %d, want 3: %+v", len(slides), slides)
	}
	if !bytes.Contains([]byte(slides[0].HTML), []byte("One")) {
		t.Errorf("slides[0].HTML = %q, want it to contain %q", slides[0].HTML, "One")
	}
	if !bytes.Contains([]byte(slides[1].HTML), []byte("Two")) {
		t.Errorf("slides[1].HTML = %q, want it to contain %q", slides[1].HTML, "Two")
	}
	if !bytes.Contains([]byte(slides[2].HTML), []byte("Three")) {
		t.Errorf("slides[2].HTML = %q, want it to contain %q", slides[2].HTML, "Three")
	}
	// Both parts of the split file share its frontmatter.
	if slides[0].Title != "Combo" || slides[1].Title != "Combo" {
		t.Errorf("slides[0..1].Title = %q, %q, want both %q", slides[0].Title, slides[1].Title, "Combo")
	}
	if slides[0].Class != "center" || slides[1].Class != "center" {
		t.Errorf("slides[0..1].Class = %q, %q, want both %q", slides[0].Class, slides[1].Class, "center")
	}
}

func TestParseDir_NewSlideMarkerIgnoredInsideFencedCodeBlock(t *testing.T) {
	dir := t.TempDir()
	writeFiles(t, dir, map[string]string{
		"010-doc.md": "# Doc\n\n```\n<!-- new slide -->\n```\n",
	})

	slides, err := ParseDir(dir)
	if err != nil {
		t.Fatalf("ParseDir() error = %v", err)
	}

	if len(slides) != 1 {
		t.Fatalf("len(slides) = %d, want 1 (marker inside fence must not split): %+v", len(slides), slides)
	}
}

func writeFiles(t *testing.T, dir string, files map[string]string) {
	t.Helper()
	for name, content := range files {
		path := filepath.Join(dir, name)
		if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
			t.Fatalf("MkdirAll(%s) error = %v", filepath.Dir(path), err)
		}
		if err := os.WriteFile(path, []byte(content), 0o644); err != nil {
			t.Fatalf("WriteFile(%s) error = %v", path, err)
		}
	}
}

func equalStrings(a, b []string) bool {
	if len(a) != len(b) {
		return false
	}
	for i := range a {
		if a[i] != b[i] {
			return false
		}
	}
	return true
}