#!/bin/bash

##############################################################################
# SCP Wiki Downloader
# Downloads SCP articles from the wiki and converts them to PDF/EPUB
##############################################################################

set -euo pipefail

# Configuration
OUTPUT_DIR="${OUTPUT_DIR:-./scp_downloads}"
FORMAT="${FORMAT:-pdf}"  # pdf, epub, or both
CONCURRENT_DOWNLOADS=3
RETRY_ATTEMPTS=3
RETRY_DELAY=2

# Colors for output
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
BLUE='\033[0;34m'
NC='\033[0m' # No Color

##############################################################################
# Functions
##############################################################################

print_usage() {
    cat << EOF
Usage: $0 <start> <end> [options]

Arguments:
  start           Starting SCP number (e.g., 2)
  end             Ending SCP number (e.g., 99)

Options:
  -f, --format    Output format: pdf, epub, or both (default: pdf)
  -o, --output    Output directory (default: ./scp_downloads)
  -c, --concurrent Number of concurrent downloads (default: 3)
  -h, --help      Show this help message

Examples:
  $0 2 99
  $0 100 199 --format both
  $0 1 50 --output ~/scp_collection --concurrent 5

EOF
}

log_info() {
    echo -e "${BLUE}[INFO]${NC} $1"
}

log_success() {
    echo -e "${GREEN}[✓]${NC} $1"
}

log_warning() {
    echo -e "${YELLOW}[WARN]${NC} $1"
}

log_error() {
    echo -e "${RED}[✗]${NC} $1"
}

check_dependencies() {
    local missing=0
    
    for cmd in curl pandoc; do
        if ! command -v "$cmd" &> /dev/null; then
            log_error "Missing dependency: $cmd"
            missing=1
        fi
    done
    
    if [ $missing -eq 1 ]; then
        log_error "Please install missing dependencies:"
        echo "  Ubuntu/Debian: sudo apt-get install curl pandoc"
        echo "  macOS: brew install curl pandoc"
        echo "  Fedora: sudo dnf install curl pandoc"
        exit 1
    fi
}

get_scp_url() {
    local num=$1
    echo "https://scp-wiki.wikidot.com/scp-$(printf "%03d" "$num")"
}

sanitize_filename() {
    echo "$1" | sed 's/[^a-zA-Z0-9._-]/_/g'
}

download_scp_html() {
    local num=$1
    local url=$(get_scp_url "$num")
    local html_file="$OUTPUT_DIR/html/scp-$(printf "%03d" "$num").html"
    
    mkdir -p "$OUTPUT_DIR/html"
    
    for attempt in $(seq 1 $RETRY_ATTEMPTS); do
        if curl -s -L -A "Mozilla/5.0" "$url" -o "$html_file" 2>/dev/null; then
            # Check if we got a valid page (not 404)
            if grep -q "SCP-$(printf "%03d" "$num")" "$html_file" 2>/dev/null; then
                return 0
            else
                rm -f "$html_file"
                return 1
            fi
        fi
        
        if [ $attempt -lt $RETRY_ATTEMPTS ]; then
            log_warning "Download attempt $attempt failed for SCP-$(printf "%03d" "$num"), retrying..."
            sleep $RETRY_DELAY
        fi
    done
    
    return 1
}

extract_scp_content() {
    local html_file=$1
    local scp_num=$(basename "$html_file" .html | sed 's/scp-//')
    
    # Extract title and content using pandoc
    # This is a basic extraction; you might need to adjust selectors
    
    local title=$(grep -oP '(?<=<title>)[^<]*' "$html_file" | head -1 | sed 's/ - SCP Foundation.*//')
    
    if [ -z "$title" ]; then
        title="SCP-$scp_num"
    fi
    
    # Create a markdown file from HTML
    pandoc -f html -t markdown "$html_file" -o "${html_file%.html}.md" 2>/dev/null || {
        log_warning "Could not convert SCP-$scp_num to markdown"
        return 1
    }
    
    echo "$title"
}

convert_to_pdf() {
    local md_file=$1
    local scp_num=$(basename "$md_file" .md | sed 's/scp-//')
    local title=$(extract_scp_content "$OUTPUT_DIR/html/scp-$scp_num.html" 2>/dev/null || echo "SCP-$scp_num")
    local pdf_file="$OUTPUT_DIR/pdf/SCP-$(printf "%03d" "$scp_num") - ${title}.pdf"
    
    mkdir -p "$OUTPUT_DIR/pdf"
    
    if pandoc "$md_file" -o "$pdf_file" \
        -V colorlinks=true \
        -V linkcolor=blue \
        -V geometry=margin=1in \
        2>/dev/null; then
        log_success "Converted SCP-$(printf "%03d" "$scp_num") to PDF"
        return 0
    else
        log_error "Failed to convert SCP-$(printf "%03d" "$scp_num") to PDF"
        return 1
    fi
}

convert_to_epub() {
    local md_file=$1
    local scp_num=$(basename "$md_file" .md | sed 's/scp-//')
    local title=$(extract_scp_content "$OUTPUT_DIR/html/scp-$scp_num.html" 2>/dev/null || echo "SCP-$scp_num")
    local epub_file="$OUTPUT_DIR/epub/SCP-$(printf "%03d" "$scp_num") - ${title}.epub"
    
    mkdir -p "$OUTPUT_DIR/epub"
    
    if pandoc "$md_file" -o "$epub_file" \
        --metadata author="SCP Foundation" \
        2>/dev/null; then
        log_success "Converted SCP-$(printf "%03d" "$scp_num") to EPUB"
        return 0
    else
        log_error "Failed to convert SCP-$(printf "%03d" "$scp_num") to EPUB"
        return 1
    fi
}

download_and_convert() {
    local num=$1
    local scp_num=$(printf "%03d" "$num")
    
    log_info "Processing SCP-$scp_num..."
    
    if ! download_scp_html "$num"; then
        log_error "Failed to download SCP-$scp_num"
        return 1
    fi
    
    local md_file="$OUTPUT_DIR/html/scp-$scp_num.md"
    
    if [ "$FORMAT" = "pdf" ] || [ "$FORMAT" = "both" ]; then
        convert_to_pdf "$md_file" &
    fi
    
    if [ "$FORMAT" = "epub" ] || [ "$FORMAT" = "both" ]; then
        convert_to_epub "$md_file" &
    fi
    
    wait
}

##############################################################################
# Main
##############################################################################

main() {
    local start=$1
    local end=$2
    
    # Validate arguments
    if [ -z "$start" ] || [ -z "$end" ]; then
        print_usage
        exit 1
    fi
    
    if ! [[ "$start" =~ ^[0-9]+$ ]] || ! [[ "$end" =~ ^[0-9]+$ ]]; then
        log_error "Start and end must be valid numbers"
        exit 1
    fi
    
    if [ "$start" -gt "$end" ]; then
        log_error "Start must be less than or equal to end"
        exit 1
    fi
    
    check_dependencies
    mkdir -p "$OUTPUT_DIR"
    
    log_info "Downloading SCPs from $start to $end"
    log_info "Format: $FORMAT"
    log_info "Output directory: $OUTPUT_DIR"
    
    local count=0
    for num in $(seq "$start" "$end"); do
        download_and_convert "$num" &
        
        # Limit concurrent downloads
        ((count++))
        if [ $((count % CONCURRENT_DOWNLOADS)) -eq 0 ]; then
            wait
        fi
    done
    
    # Wait for remaining processes
    wait
    
    log_success "Download and conversion complete!"
    log_info "Files saved to: $OUTPUT_DIR"
}

# Parse command line arguments
START=""
END=""

while [[ $# -gt 0 ]]; do
    case $1 in
        -h|--help)
            print_usage
            exit 0
            ;;
        -f|--format)
            FORMAT="$2"
            shift 2
            ;;
        -o|--output)
            OUTPUT_DIR="$2"
            shift 2
            ;;
        -c|--concurrent)
            CONCURRENT_DOWNLOADS="$2"
            shift 2
            ;;
        -*)
            log_error "Unknown option: $1"
            print_usage
            exit 1
            ;;
        *)
            if [ -z "$START" ]; then
                START="$1"
            elif [ -z "$END" ]; then
                END="$1"
            else
                log_error "Too many positional arguments"
                print_usage
                exit 1
            fi
            shift
            ;;
    esac
done

main "$START" "$END"