#!/usr/bin/env bash

set -e

# Color codes for output
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
NC='\033[0m' # No Color

# Function to check if a URL is reachable
check_url() {
    local url="$1"
    local file="$2"
    local line_num="$3"

    # Skip relative URLs and internal anchors
    if [[ "$url" =~ ^(#|/[^/]|\./) ]]; then
        return 0
    fi

    # Skip mailto and other non-http protocols
    if [[ "$url" =~ ^(mailto:|ftp:|file:|javascript:) ]]; then
        return 0
    fi

    # For URLs without protocol, assume https
    if [[ ! "$url" =~ ^https?:// ]]; then
        url="https://$url"
    fi

    # Use curl to check the URL with a reasonable timeout
    # Follow redirects, but limit to 5 redirects to prevent infinite loops
    local http_code
    http_code=$(curl -s -o /dev/null -w "%{http_code}" \
        --max-time 10 \
        --max-redirs 5 \
        --retry 1 \
        --user-agent "Mozilla/5.0 (compatible; FossCat Link Checker)" \
        "$url" 2>/dev/null || echo "000")

    # Consider 2xx and 3xx status codes as success
    if [[ "$http_code" =~ ^[23][0-9][0-9]$ ]]; then
        return 0
    else
        echo -e "${RED}❌ Dead link in $file:$line_num${NC}"
        echo -e "   URL: $url"
        echo -e "   Status: $http_code"
        return 1
    fi
}

# Function to extract and check links from a markdown file
check_markdown_links() {
    local file="$1"
    local failed=0

    echo "Checking links in $file..."

    # Use a simpler approach that works with basic grep
    # Extract URLs from markdown links [text](url) and images ![alt](url)
    local urls=$(grep -o '\]([^)]*)' "$file" | sed 's/](\([^)]*\)).*/\1/' | grep -v '^$')

    if [ -n "$urls" ]; then
        while IFS= read -r url; do
            if [ -n "$url" ]; then
                # Get line number where this URL appears
                local line_num=$(grep -n "$url" "$file" | head -1 | cut -d: -f1)
                if ! check_url "$url" "$file" "$line_num"; then
                    failed=1
                fi
            fi
        done <<< "$urls"
    fi

    # Also check for reference-style links [ref]: url
    local ref_urls=$(grep -o '^\[.*\]: *[^ ]*' "$file" | sed 's/^\[.*\]: *//' | grep -v '^$')

    if [ -n "$ref_urls" ]; then
        while IFS= read -r url; do
            if [ -n "$url" ]; then
                local line_num=$(grep -n "$url" "$file" | head -1 | cut -d: -f1)
                if ! check_url "$url" "$file" "$line_num"; then
                    failed=1
                fi
            fi
        done <<< "$ref_urls"
    fi

    return $failed
}

# Main function
main() {
    local files_to_check=()
    local failed_files=0
    local total_files=0

    # If arguments provided, check those files, otherwise check all markdown files
    if [ $# -gt 0 ]; then
        files_to_check=("$@")
    else
        while IFS= read -r -d '' file; do
            files_to_check+=("$file")
        done < <(find content -name "*.md" -type f -print0)
    fi

    if [ ${#files_to_check[@]} -eq 0 ]; then
        echo -e "${YELLOW}No markdown files to check.${NC}"
        exit 0
    fi

    echo -e "${GREEN}🔗 Checking links in ${#files_to_check[@]} markdown file(s)...${NC}"
    echo

    for file in "${files_to_check[@]}"; do
        if [ -f "$file" ]; then
            total_files=$((total_files + 1))
            if ! check_markdown_links "$file"; then
                failed_files=$((failed_files + 1))
            fi
        else
            echo -e "${YELLOW}⚠️  File not found: $file${NC}"
        fi
    done

    echo
    if [ $failed_files -eq 0 ]; then
        echo -e "${GREEN}✅ All links are working! Checked $total_files file(s).${NC}"
        exit 0
    else
        echo -e "${RED}❌ Found broken links in $failed_files file(s) out of $total_files checked.${NC}"
        exit 1
    fi
}

# Check if curl is available
if ! command -v curl &> /dev/null; then
    echo -e "${RED}❌ curl is required but not installed.${NC}"
    echo "Please install curl to use the link checker."
    exit 1
fi

# Check if basic grep and sed are available
if ! command -v sed &> /dev/null; then
    echo -e "${RED}❌ sed is required but not installed.${NC}"
    exit 1
fi

main "$@"