#!/bin/bash

# Usage: curl -sSL https://git.ivanch.me/ivanch/server-scripts/raw/branch/main/scripts-download.sh | bash

set -euo pipefail

#==============================================================================
# CONFIGURATION
#==============================================================================

# Color definitions for output formatting
readonly RED='\033[1;31m'
readonly GREEN='\033[1;32m'
readonly NC='\033[0m'
readonly LIGHT_BLUE='\033[1;34m'
readonly LIGHT_RED='\033[1;31m'
readonly LIGHT_GREEN='\033[1;32m'
readonly GREY='\033[1;30m'
readonly YELLOW='\033[1;33m'

# Configuration
readonly FILES_URL="https://git.ivanch.me/ivanch/server-scripts/raw/branch/main"
readonly REQUIRED_PACKAGES=("zip" "unzip" "sha256sum" "curl" "crontab")
readonly AVAILABLE_SCRIPTS=("clean.sh" "backup.sh" "docker-updater.sh")

# Format: [script_name]="cron_schedule"
declare -A CRONTAB_SCHEDULES=(
    ["clean.sh"]="0 23 * * *"              # Daily at 11 PM
    ["backup.sh"]="30 23 * * 1,5"          # Monday and Friday at 11:30 PM
    ["docker-updater.sh"]="0 3 */4 * *"    # Every 4 days at 3 AM
)

#==============================================================================
# UTILITY FUNCTIONS
#==============================================================================

# Print formatted log messages
log_info() { echo -e "${GREY}[i] $1${NC}"; }
log_success() { echo -e "${GREEN}[✓] $1${NC}"; }
log_warning() { echo -e "${YELLOW}[!] $1${NC}"; }
log_error() { echo -e "${RED}[x] $1${NC}" >&2; }
log_step() { echo -e "${LIGHT_BLUE}[i] $1${NC}"; }

# Exit with error message
die() {
    log_error "$1"
    exit 1
}

# Check if a command exists
command_exists() {
    command -v "$1" >/dev/null 2>&1
}

# Check if a process is running
process_running() {
    pgrep "$1" >/dev/null 2>&1
}

#==============================================================================
# MAIN FUNCTIONS
#==============================================================================

# Detect the operating system
detect_operating_system() {
    log_info "Detecting operating system..."
    
    if command_exists apk; then
        echo "Alpine"
    elif command_exists apt; then
        echo "Debian"
    else
        die "Unsupported operating system. This script supports Alpine and Debian-based systems only."
    fi
}

# Check for missing packages
get_missing_packages() {
    local missing=()
    
    for package in "${REQUIRED_PACKAGES[@]}"; do
        if ! command_exists "$package"; then
            missing+=("$package")
        fi
    done
    
    printf '%s\n' "${missing[@]}"
}

# Install packages based on the detected OS
install_packages() {
    local os="$1"
    shift
    local packages=("$@")
    
    if [[ ${#packages[@]} -eq 0 ]]; then
        return 0
    fi
    
    log_info "Installing required packages: ${packages[*]}"
    
    case "$os" in
        "Alpine")
            log_info "Updating APK package index..."
            apk update >/dev/null || die "Failed to update APK package index"
            
            log_info "Installing packages via APK..."
            apk add --no-cache "${packages[@]}" >/dev/null || die "Failed to install packages via APK"
            ;;
        "Debian")
            log_info "Updating APT package index..."
            apt-get update -y >/dev/null || die "Failed to update APT package index"
            
            log_info "Installing packages via APT..."
            apt-get install -y "${packages[@]}" >/dev/null || die "Failed to install packages via APT"
            ;;
        *)
            log_error "Debug info - OS variable content: '$os'"
            log_error "Debug info - OS variable length: ${#os}"
            die "Unknown operating system: '$os'"
            ;;
    esac
}

# Verify all required packages are available
verify_packages() {
    log_info "Verifying package installation..."
    
    local missing_packages
    readarray -t missing_packages < <(get_missing_packages)
    
    if [[ ${#missing_packages[@]} -gt 0 ]]; then
        die "Failed to install required packages: ${missing_packages[*]}"
    fi
    
    log_success "All required packages are available"
}

# Check if crontab service is running
check_crontab_service() {
    log_info "Checking crontab service status..."
    
    if ! process_running "cron"; then
        die "Crontab service is not running. Please start the cron service first."
    fi
    
    log_success "Crontab service is running"
}

# Prompt user to select scripts for installation
select_scripts() {
    local selected=()
    
    log_info "Available scripts for download and installation:"
    echo
    
    for script in "${AVAILABLE_SCRIPTS[@]}"; do
        local schedule="${CRONTAB_SCHEDULES[$script]:-"0 0 * * *"}"
        echo -e "  ${LIGHT_BLUE}$script${NC} - Schedule: ${GREY}$schedule${NC}"
    done
    
    echo
    log_info "Select scripts to download and install:"
    
    for script in "${AVAILABLE_SCRIPTS[@]}"; do
        read -p "Install $script? [Y/n]: " choice </dev/tty
        if [[ "$choice" =~ ^[Yy]?$ ]]; then
            selected+=("$script")
        fi
    done
    
    if [[ ${#selected[@]} -eq 0 ]]; then
        die "No scripts selected. Exiting..."
    fi
    
    printf '%s\n' "${selected[@]}"
}

# Verify server connectivity for selected scripts
verify_server_connectivity() {
    local scripts=("$@")
    
    log_info "Verifying server connectivity..."
    
    for script in "${scripts[@]}"; do
        local url="$FILES_URL/$script"
        if ! curl -s --head "$url" | head -n 1 | grep -E "HTTP/[12] [23].." >/dev/null; then
            die "Script '$script' not found on server: $url"
        fi
    done
    
    log_success "Server connectivity verified"
}

# Download selected scripts
download_scripts() {
    local scripts=("$@")
    
    log_info "Downloading ${#scripts[@]} script(s)..."
    
    for script in "${scripts[@]}"; do
        local url="$FILES_URL/$script"
        log_step "Downloading $script..."
        
        if ! curl -s -o "./$script" "$url"; then
            die "Failed to download $script from $url"
        fi
        
        # Set executable permissions
        chmod +x "./$script" || die "Failed to set executable permissions for $script"
    done
    
    log_success "All scripts downloaded and configured"
}

# Setup crontab entries for selected scripts
setup_crontab() {
    local scripts=("$@")
    local current_workdir
    current_workdir=$(pwd)
    
    log_info "Setting up crontab entries..."
    
    for script in "${scripts[@]}"; do
        local schedule="${CRONTAB_SCHEDULES[$script]:-"0 0 * * *"}"
        local log_file="/tmp/${script%.*}.log"
        local cron_entry="$schedule $current_workdir/$script > $log_file 2>&1"
        
        log_step "Configuring crontab for $script (Schedule: $schedule)..."
        
        # Remove existing crontab entry for this script
        if crontab -l 2>/dev/null | grep -q "$script"; then
            log_step "Removing existing crontab entry for $script..."
            crontab -l 2>/dev/null | grep -v "$script" | crontab - || die "Failed to remove existing crontab entry"
        fi
        
        # Add new crontab entry
        (crontab -l 2>/dev/null; echo "$cron_entry") | crontab - || die "Failed to add crontab entry for $script"
        
        # Verify the entry was added
        if ! crontab -l 2>/dev/null | grep -q "$script"; then
            die "Failed to verify crontab entry for $script"
        fi
        
        log_success "Crontab configured for $script"
    done
    
    log_success "All crontab entries configured successfully"
}

#==============================================================================
# MAIN EXECUTION
#==============================================================================

main() {
    log_step "Starting Server Scripts Downloader"
    echo
    
    # System detection and validation
    local detected_os
    detected_os=$(detect_operating_system)
    detected_os=$(echo "$detected_os" | tr -d '\n\r' | xargs)  # Clean any whitespace/newlines
    log_success "Detected $detected_os Linux"
    
    # Package management
    local missing_packages
    readarray -t missing_packages < <(get_missing_packages)
    
    if [[ ${#missing_packages[@]} -gt 0 ]]; then
        log_warning "Missing packages detected: ${missing_packages[*]}"
        install_packages "$detected_os" "${missing_packages[@]}"
    fi
    
    verify_packages
    check_crontab_service
    
    # Script selection and installation
    local selected_scripts
    readarray -t selected_scripts < <(select_scripts)
    
    log_info "Selected scripts: ${selected_scripts[*]}"
    
    verify_server_connectivity "${selected_scripts[@]}"
    download_scripts "${selected_scripts[@]}"
    setup_crontab "${selected_scripts[@]}"
    
    echo
    log_success "Installation completed successfully!"
    log_info "Scripts have been downloaded to: $(pwd)"
    log_info "Crontab entries have been configured. Use 'crontab -l' to view them."
    log_info "Log files will be created in /tmp/ directory."
}

# Execute main function
main "$@"