#!/usr/bin/env bash
# Extract klausur-relevant slides from all kapitel
# Usage: ./extract-klausur.sh <course_id>
# Output: slides/<course>/klausur.md

set -e

COURSE="${1:-223015b}"
SLIDES_DIR="slides/$COURSE"
OUTPUT_FILE="$SLIDES_DIR/klausur.md"

# Find the first kapitel file (01-*.md) to copy styles from
FIRST_KAPITEL=$(ls "$SLIDES_DIR"/01-*.md 2>/dev/null | head -1)

if [[ -z "$FIRST_KAPITEL" ]]; then
  echo "Error: No 01-*.md file found in $SLIDES_DIR"
  exit 1
fi

echo "Extracting klausur slides for $COURSE..."

# Extract frontmatter and styles (everything up to first <!-- _class: line after style block)
# This gets the YAML frontmatter + <style> block
awk '
  BEGIN { in_frontmatter = 0; in_style = 0; done = 0 }
  /^---$/ && !in_frontmatter { in_frontmatter = 1; print; next }
  /^---$/ && in_frontmatter && !in_style { in_frontmatter = 0; print; next }
  in_frontmatter { print; next }
  /<style>/ { in_style = 1; print; next }
  /<\/style>/ { in_style = 0; print; print ""; done = 1; next }
  in_style { print; next }
  done { exit }
' "$FIRST_KAPITEL" > "$OUTPUT_FILE"

# Add warning comment
cat >> "$OUTPUT_FILE" << 'EOF'
<!--
  ╔═══════════════════════════════════════════════════════════════════╗
  ║  AUTO-GENERATED FILE - DO NOT EDIT MANUALLY                       ║
  ║                                                                   ║
  ║  This file is generated by: make klausur                          ║
  ║  Source: scripts/extract-klausur.sh                               ║
  ║                                                                   ║
  ║  To update, edit the source slides and re-run make klausur        ║
  ╚═══════════════════════════════════════════════════════════════════╝
-->

EOF

# Extract and copy the cover slide (first slide after frontmatter/styles, up to first ---)
awk '
  BEGIN { past_style = 0; in_cover = 0; printed = 0 }
  /<\/style>/ { past_style = 1; next }
  past_style && !in_cover && /^[^[:space:]]/ { in_cover = 1 }
  in_cover && /^---$/ { print "---\n"; exit }
  in_cover { print }
' "$FIRST_KAPITEL" >> "$OUTPUT_FILE"

# Process each kapitel file in order - extract klausur slides only
for md_file in $(ls "$SLIDES_DIR"/[0-9][0-9]-*.md 2>/dev/null | grep -v klausur | sort); do
  filename=$(basename "$md_file")
  kapitel_num=$(echo "$filename" | grep -oE '^[0-9]+' | sed 's/^0*//')

  # Skip intro (kapitel 0)
  if [[ "$kapitel_num" == "0" ]] || [[ -z "$kapitel_num" ]]; then
    continue
  fi

  # Check if file has any klausur slides
  if ! grep -q '<!-- _class: klausur -->' "$md_file"; then
    continue
  fi

  echo "  Processing Kapitel $kapitel_num..."

  # Extract klausur slides, hide header/footer, convert * to - bullets
  awk '
    /<!-- _class: klausur -->/ {
      in_klausur = 1
      # Add header/footer hiding
      print "<!-- _header: \"\" -->"
      print "<!-- _footer: \"\" -->"
      print ""
      next
    }
    in_klausur && /^---$/ {
      print "\n---\n"
      in_klausur = 0
      next
    }
    in_klausur {
      # Skip marp directives (we add our own)
      if (/<!-- _header:/ || /<!-- _footer:/ || /<!-- _backgroundColor:/) next
      # Convert * bullets to - bullets (avoid fragments)
      gsub(/^\* /, "- ")
      gsub(/^  \* /, "  - ")
      gsub(/^    \* /, "    - ")
      print
    }
  ' "$md_file" >> "$OUTPUT_FILE"

done

# Remove trailing --- and empty lines
perl -i -0777 -pe 's/\n*---\n*$/\n/' "$OUTPUT_FILE"

# Count slides
slide_count=$(grep -c '^---$' "$OUTPUT_FILE" 2>/dev/null || echo "0")

echo ""
echo "Generated: $OUTPUT_FILE"
echo "Total slides: $slide_count"