#!/usr/bin/env bash

# Read the tool input from stdin
INPUT=$(cat)
TOOL_NAME=$(echo "$INPUT" | jq -r '.tool_name')
FILE_PATH=$(echo "$INPUT" | jq -r '.tool_input.file_path // .tool_input.path // ""')

if [ -z "$FILE_PATH" ]; then
  exit 0
fi

# Check if this is a markdown file
if [[ "$FILE_PATH" == *.md ]] || [[ "$FILE_PATH" == *.mdx ]] || [[ "$FILE_PATH" == *.markdown ]]; then
  echo "🔗 Markdown Link Validation for: $(basename "$FILE_PATH")" >&2
  
  # Initialize validation counters
  ERRORS=0
  WARNINGS=0
  VALIDATIONS_PASSED=0
  TOTAL_LINKS=0
  EXTERNAL_LINKS=0
  INTERNAL_LINKS=0
  
  # Function to report validation results
  report_validation() {
    local level="$1"
    local message="$2"
    
    case "$level" in
      "ERROR")
        echo "❌ ERROR: $message" >&2
        ERRORS=$((ERRORS + 1))
        ;;
      "WARNING")
        echo "⚠️ WARNING: $message" >&2
        WARNINGS=$((WARNINGS + 1))
        ;;
      "PASS")
        echo "✅ PASS: $message" >&2
        VALIDATIONS_PASSED=$((VALIDATIONS_PASSED + 1))
        ;;
      "INFO")
        echo "ℹ️ INFO: $message" >&2
        ;;
    esac
  }
  
  # Check if file exists and is readable
  if [ ! -f "$FILE_PATH" ]; then
    report_validation "ERROR" "Markdown file not found: $FILE_PATH"
    exit 1
  fi
  
  if [ ! -r "$FILE_PATH" ]; then
    report_validation "ERROR" "Markdown file is not readable: $FILE_PATH"
    exit 1
  fi
  
  # Get file information
  FILE_NAME="$(basename "$FILE_PATH")"
  FILE_DIR="$(dirname "$FILE_PATH")"
  FILE_SIZE=$(wc -c < "$FILE_PATH" 2>/dev/null || echo "0")
  LINE_COUNT=$(wc -l < "$FILE_PATH" 2>/dev/null || echo "0")
  
  echo "📊 Markdown file: $FILE_NAME ($(( FILE_SIZE / 1024 ))KB, $LINE_COUNT lines)" >&2
  
  # 1. Extract All Links from Markdown
  echo "🔍 Extracting links from markdown..." >&2
  
  # Create temporary files for link analysis
  TEMP_LINKS="/tmp/markdown_links_$$"
  TEMP_IMAGES="/tmp/markdown_images_$$"
  TEMP_ANCHORS="/tmp/markdown_anchors_$$"
  
  # Extract markdown links [text](url)
  grep -oE '\[([^\]]+)\]\(([^)]+)\)' "$FILE_PATH" | sed 's/\[.*\](\(.*\))/\1/' > "$TEMP_LINKS" 2>/dev/null || true
  
  # Extract image links ![alt](url)
  grep -oE '!\[([^\]]*)\]\(([^)]+)\)' "$FILE_PATH" | sed 's/!\[.*\](\(.*\))/\1/' > "$TEMP_IMAGES" 2>/dev/null || true
  
  # Extract reference-style links
  grep -oE '\[([^\]]+)\]\[([^\]]+)\]' "$FILE_PATH" | sed 's/\[.*\]\[\(.*\)\]/\1/' >> "$TEMP_LINKS" 2>/dev/null || true
  
  # Count total links
  TOTAL_LINKS=$(cat "$TEMP_LINKS" "$TEMP_IMAGES" 2>/dev/null | wc -l || echo "0")
  
  if [ "$TOTAL_LINKS" -eq 0 ]; then
    echo "   📋 No links found in markdown file" >&2
    report_validation "INFO" "No links to validate"
  else
    echo "   📊 Found $TOTAL_LINKS total links/images" >&2
  fi
  
  # 2. Validate External Links
  echo "🌐 Validating external links..." >&2
  
  # Try using markdown-link-check if available
  if command -v npx &> /dev/null; then
    echo "   🔍 Using markdown-link-check for comprehensive validation..." >&2
    
    # Create a temporary config if none exists
    CONFIG_FILE=".markdown-link-check.json"
    TEMP_CONFIG=false
    
    if [ ! -f "$CONFIG_FILE" ]; then
      TEMP_CONFIG=true
      CONFIG_FILE="/tmp/markdown_link_config_$$"
      cat > "$CONFIG_FILE" << 'EOF'
{
  "timeout": "30s",
  "retryOn429": true,
  "retryCount": 3,
  "fallbackProtocols": ["http", "https"],
  "ignorePatterns": [
    { "pattern": "^http://localhost" },
    { "pattern": "^https://localhost" },
    { "pattern": "^http://127.0.0.1" },
    { "pattern": "^#" }
  ]
}
EOF
    fi
    
    MLC_OUTPUT_FILE="/tmp/mlc_output_$$"
    if timeout 60s npx markdown-link-check "$FILE_PATH" --config "$CONFIG_FILE" > "$MLC_OUTPUT_FILE" 2>&1; then
      # Parse results
      DEAD_LINKS=$(grep -c '✖' "$MLC_OUTPUT_FILE" 2>/dev/null || echo "0")
      ALIVE_LINKS=$(grep -c '✓' "$MLC_OUTPUT_FILE" 2>/dev/null || echo "0")
      
      if [ "$DEAD_LINKS" -eq 0 ]; then
        report_validation "PASS" "All external links are valid ($ALIVE_LINKS checked)"
      else
        report_validation "ERROR" "Found $DEAD_LINKS dead external links"
        echo "   📝 Dead links details:" >&2
        grep '✖' "$MLC_OUTPUT_FILE" | head -5 | while read line; do
          echo "     $line" >&2
        done
      fi
    else
      # Fallback to basic URL validation
      echo "   ⚠️ markdown-link-check failed, using basic validation..." >&2
      
      # Extract HTTP/HTTPS URLs
      EXTERNAL_URLS=$(grep -oE 'https?://[^)]+' "$TEMP_LINKS" 2>/dev/null || true)
      
      if [ -n "$EXTERNAL_URLS" ]; then
        EXTERNAL_COUNT=$(echo "$EXTERNAL_URLS" | wc -l)
        echo "   🌐 Found $EXTERNAL_COUNT external URLs to validate" >&2
        
        # Basic URL validation using curl
        if command -v curl &> /dev/null; then
          EXTERNAL_ERRORS=0
          echo "$EXTERNAL_URLS" | head -10 | while read -r url; do
            if [ -n "$url" ]; then
              if curl -s --head --max-time 10 "$url" >/dev/null 2>&1; then
                echo "     ✅ Valid: $url" >&2
              else
                echo "     ❌ Invalid: $url" >&2
                EXTERNAL_ERRORS=$((EXTERNAL_ERRORS + 1))
              fi
            fi
          done
        else
          echo "   ⚠️ curl not available for URL validation" >&2
        fi
      else
        echo "   📋 No external URLs found" >&2
      fi
    fi
    
    # Clean up temporary config if created
    [ "$TEMP_CONFIG" = true ] && rm -f "$CONFIG_FILE"
    rm -f "$MLC_OUTPUT_FILE"
    
  else
    echo "   ⚠️ npx not available, using basic link validation" >&2
  fi
  
  # 3. Validate Internal Links
  echo "📁 Validating internal links and references..." >&2
  
  # Extract internal links (relative paths)
  INTERNAL_URLS=$(cat "$TEMP_LINKS" "$TEMP_IMAGES" 2>/dev/null | grep -E '^\./|^\.\./' || true)
  ABSOLUTE_PATHS=$(cat "$TEMP_LINKS" "$TEMP_IMAGES" 2>/dev/null | grep -E '^/' || true)
  
  INTERNAL_ERRORS=0
  
  # Check relative path links
  if [ -n "$INTERNAL_URLS" ]; then
    echo "   📂 Checking relative path links..." >&2
    
    echo "$INTERNAL_URLS" | while read -r link; do
      if [ -n "$link" ]; then
        # Remove anchor if present
        FILE_PART=$(echo "$link" | cut -d'#' -f1)
        ANCHOR_PART=$(echo "$link" | cut -d'#' -f2)
        
        if [ -n "$FILE_PART" ]; then
          # Resolve relative path
          RESOLVED_PATH="$(cd "$FILE_DIR" && realpath "$FILE_PART" 2>/dev/null || echo "$FILE_PART")"
          
          if [ -f "$RESOLVED_PATH" ] || [ -d "$RESOLVED_PATH" ]; then
            echo "     ✅ Valid: $link" >&2
          else
            echo "     ❌ Broken: $link (resolved to: $RESOLVED_PATH)" >&2
            INTERNAL_ERRORS=$((INTERNAL_ERRORS + 1))
          fi
        fi
        
        # Check anchor if present (simplified check)
        if [ "$link" != "$FILE_PART" ] && [ -n "$ANCHOR_PART" ]; then
          echo "     ℹ️ Anchor found: #$ANCHOR_PART" >&2
        fi
      fi
    done
  fi
  
  # Check absolute path links
  if [ -n "$ABSOLUTE_PATHS" ]; then
    echo "   📁 Checking absolute path links..." >&2
    
    echo "$ABSOLUTE_PATHS" | while read -r link; do
      if [ -n "$link" ]; then
        FILE_PART=$(echo "$link" | cut -d'#' -f1)
        
        if [ -f "$FILE_PART" ] || [ -d "$FILE_PART" ]; then
          echo "     ✅ Valid: $link" >&2
        else
          echo "     ❌ Broken: $link" >&2
          INTERNAL_ERRORS=$((INTERNAL_ERRORS + 1))
        fi
      fi
    done
  fi
  
  if [ "$INTERNAL_ERRORS" -eq 0 ]; then
    report_validation "PASS" "All internal links are valid"
  else
    report_validation "ERROR" "Found $INTERNAL_ERRORS broken internal links"
  fi
  
  # 4. Validate Image Links
  echo "🖼️ Validating image links..." >&2
  
  IMAGE_COUNT=$(cat "$TEMP_IMAGES" 2>/dev/null | wc -l || echo "0")
  
  if [ "$IMAGE_COUNT" -gt 0 ]; then
    echo "   📊 Found $IMAGE_COUNT image links" >&2
    
    IMAGE_ERRORS=0
    
    cat "$TEMP_IMAGES" | while read -r img_link; do
      if [ -n "$img_link" ]; then
        if [[ "$img_link" == http* ]]; then
          echo "     🌐 External image: $img_link" >&2
        else
          # Local image file
          if [[ "$img_link" == /* ]]; then
            IMG_PATH="$img_link"
          else
            IMG_PATH="$FILE_DIR/$img_link"
          fi
          
          if [ -f "$IMG_PATH" ]; then
            echo "     ✅ Valid image: $img_link" >&2
          else
            echo "     ❌ Missing image: $img_link" >&2
            IMAGE_ERRORS=$((IMAGE_ERRORS + 1))
          fi
        fi
      fi
    done
    
    if [ "$IMAGE_ERRORS" -eq 0 ]; then
      report_validation "PASS" "All local images found"
    else
      report_validation "ERROR" "$IMAGE_ERRORS local images missing"
    fi
  else
    echo "   📋 No image links found" >&2
  fi
  
  # 5. Validate Internal Anchors
  echo "⚓ Validating document anchors..." >&2
  
  # Extract anchor-only links (starting with #)
  ANCHOR_LINKS=$(cat "$TEMP_LINKS" | grep '^#' 2>/dev/null || true)
  
  if [ -n "$ANCHOR_LINKS" ]; then
    echo "   🔗 Found anchor links to validate" >&2
    
    # Extract headers from markdown to validate anchors
    HEADERS_FILE="/tmp/markdown_headers_$$"
    grep -E '^#{1,6} ' "$FILE_PATH" | sed 's/^#* *//' | tr '[:upper:]' '[:lower:]' | sed 's/[^a-z0-9 -]//g' | sed 's/ /-/g' > "$HEADERS_FILE" 2>/dev/null || true
    
    ANCHOR_ERRORS=0
    
    echo "$ANCHOR_LINKS" | while read -r anchor; do
      if [ -n "$anchor" ]; then
        CLEAN_ANCHOR=$(echo "$anchor" | sed 's/^#//' | tr '[:upper:]' '[:lower:]')
        
        if grep -q "^$CLEAN_ANCHOR$" "$HEADERS_FILE" 2>/dev/null; then
          echo "     ✅ Valid anchor: $anchor" >&2
        else
          echo "     ❌ Invalid anchor: $anchor" >&2
          ANCHOR_ERRORS=$((ANCHOR_ERRORS + 1))
        fi
      fi
    done
    
    rm -f "$HEADERS_FILE"
    
    if [ "$ANCHOR_ERRORS" -eq 0 ]; then
      report_validation "PASS" "All document anchors valid"
    else
      report_validation "ERROR" "$ANCHOR_ERRORS invalid document anchors"
    fi
  else
    echo "   📋 No document anchors found" >&2
  fi
  
  # 6. Markdown Quality Checks
  echo "📝 Markdown quality and accessibility checks..." >&2
  
  # Check for alt text in images
  IMAGES_WITHOUT_ALT=$(grep -c '!\[\](' "$FILE_PATH" 2>/dev/null || echo "0")
  
  if [ "$IMAGES_WITHOUT_ALT" -gt 0 ]; then
    report_validation "WARNING" "$IMAGES_WITHOUT_ALT images missing alt text for accessibility"
  else
    if [ "$IMAGE_COUNT" -gt 0 ]; then
      report_validation "PASS" "All images have alt text"
    fi
  fi
  
  # Check for bare URLs (not wrapped in markdown links)
  BARE_URLS=$(grep -oE 'https?://[^\s\)\]]+' "$FILE_PATH" | grep -v '](http' | head -5 | wc -l || echo "0")
  
  if [ "$BARE_URLS" -gt 0 ]; then
    report_validation "WARNING" "Found $BARE_URLS bare URLs - consider wrapping in markdown links"
  fi
  
  # 7. Generate Validation Summary
  echo "" >&2
  echo "📋 Markdown Link Validation Summary:" >&2
  echo "===================================" >&2
  echo "   📄 File: $FILE_NAME" >&2
  echo "   📏 Size: $(( FILE_SIZE / 1024 ))KB, $LINE_COUNT lines" >&2
  echo "   🔗 Total links: $TOTAL_LINKS" >&2
  echo "   🖼️ Images: $IMAGE_COUNT" >&2
  echo "   ✅ Validations passed: $VALIDATIONS_PASSED" >&2
  echo "   ⚠️ Warnings: $WARNINGS" >&2
  echo "   ❌ Errors: $ERRORS" >&2
  
  if [ "$ERRORS" -eq 0 ]; then
    if [ "$WARNINGS" -eq 0 ]; then
      echo "   🎉 Status: EXCELLENT - All links are valid and accessible" >&2
    else
      echo "   ✅ Status: GOOD - Links are valid with minor accessibility recommendations" >&2
    fi
  else
    echo "   ❌ Status: ERRORS - Found broken links that must be fixed" >&2
  fi
  
  echo "" >&2
  echo "💡 Markdown Link Best Practices:" >&2
  echo "   • Use descriptive link text instead of 'click here'" >&2
  echo "   • Add alt text to all images for accessibility" >&2
  echo "   • Use relative paths for internal documentation" >&2
  echo "   • Validate external links regularly" >&2
  echo "   • Keep anchor links synchronized with headers" >&2
  echo "   • Consider using reference-style links for readability" >&2
  
  # Clean up temporary files
  rm -f "$TEMP_LINKS" "$TEMP_IMAGES" "$TEMP_ANCHORS"
  
  # Exit with error if there are critical link issues
  if [ "$ERRORS" -gt 0 ]; then
    echo "⚠️ Markdown link validation completed with errors" >&2
    exit 1
  fi
  
else
  # Not a markdown file
  exit 0
fi

exit 0