#!/bin/bash

set -euo pipefail

RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
BLUE='\033[0;34m'
NC='\033[0m'

VERSION=${VERSION:-"v0.1.0"}
DOWNLOAD_URL="https://git.littlediary.cn/CN-JS-HuiBai/PromdataPanel/archive/${VERSION}.zip"
MIN_NODE_VERSION=18
SERVICE_NAME="promdatapanel"
SERVICE_FILE="/etc/systemd/system/${SERVICE_NAME}.service"

OS_ID=""
OS_VER=""
PROJECT_DIR=""
REAL_USER=""

echo -e "${BLUE}================================================${NC}"
echo -e "${BLUE}          PromdataPanel Auto-Installer          ${NC}"
echo -e "${BLUE}             Version: ${VERSION}                ${NC}"
echo -e "${BLUE}================================================${NC}"

detect_os() {
    if [ -f /etc/os-release ]; then
        # shellcheck disable=SC1091
        . /etc/os-release
        OS_ID="${ID:-}"
        OS_VER="${VERSION_ID:-}"
    else
        echo -e "${RED}Error: Cannot detect operating system type (/etc/os-release missing).${NC}"
        exit 1
    fi

    if [ -z "$OS_ID" ]; then
        echo -e "${RED}Error: Unable to determine operating system ID.${NC}"
        exit 1
    fi

    echo -e "Detected OS: ${GREEN}${OS_ID} ${OS_VER}${NC}"
}

require_cmd() {
    local cmd="$1"
    local hint="${2:-}"
    if ! command -v "$cmd" >/dev/null 2>&1; then
        echo -e "${RED}Missing required command: ${cmd}.${NC}"
        if [ -n "$hint" ]; then
            echo -e "${YELLOW}${hint}${NC}"
        fi
        exit 1
    fi
}

install_packages() {
    case "$OS_ID" in
        ubuntu|debian|raspbian)
            sudo apt-get update
            sudo apt-get install -y "$@"
            ;;
        centos|rhel|almalinux|rocky)
            sudo yum install -y "$@"
            ;;
        fedora)
            sudo dnf install -y "$@"
            ;;
        *)
            echo -e "${RED}Unsupported OS for automatic package installation: ${OS_ID}${NC}"
            echo -e "${YELLOW}Please install the following packages manually: $*${NC}"
            exit 1
            ;;
    esac
}

ensure_tooling() {
    if ! command -v curl >/dev/null 2>&1; then
        echo -e "${BLUE}Installing curl...${NC}"
        install_packages curl
    fi

    if ! command -v unzip >/dev/null 2>&1; then
        echo -e "${BLUE}Installing unzip...${NC}"
        install_packages unzip
    fi
}

configure_nodesource_apt_repo() {
    sudo install -d -m 0755 /etc/apt/keyrings
    curl -fsSL https://deb.nodesource.com/gpgkey/nodesource-repo.gpg.key | sudo gpg --dearmor -o /etc/apt/keyrings/nodesource.gpg
    echo "deb [signed-by=/etc/apt/keyrings/nodesource.gpg] https://deb.nodesource.com/node_20.x nodistro main" | sudo tee /etc/apt/sources.list.d/nodesource.list >/dev/null
}

install_node() {
    echo -e "${BLUE}Verifying Node.js environment...${NC}"

    local node_installed=false
    if command -v node >/dev/null 2>&1; then
        local current_node_ver
        current_node_ver=$(node -v | cut -d'v' -f2 | cut -d'.' -f1)
        if [ "$current_node_ver" -ge "$MIN_NODE_VERSION" ]; then
            echo -e "${GREEN}Node.js $(node -v) is already installed.${NC}"
            node_installed=true
        else
            echo -e "${YELLOW}Existing Node.js $(node -v) is too old (requires >= ${MIN_NODE_VERSION}).${NC}"
        fi
    fi

    if [ "$node_installed" = true ]; then
        return
    fi

    echo -e "${BLUE}Installing Node.js 20.x...${NC}"
    case "$OS_ID" in
        ubuntu|debian|raspbian)
            install_packages ca-certificates curl gnupg
            configure_nodesource_apt_repo
            sudo apt-get update
            sudo apt-get install -y nodejs
            ;;
        centos|rhel|almalinux|rocky)
            install_packages nodejs
            ;;
        fedora)
            install_packages nodejs
            ;;
        *)
            echo -e "${RED}Unsupported OS for automatic Node.js installation: ${OS_ID}${NC}"
            echo -e "${YELLOW}Please install Node.js >= ${MIN_NODE_VERSION} manually.${NC}"
            exit 1
            ;;
    esac

    require_cmd node "Please install Node.js >= ${MIN_NODE_VERSION} manually and rerun the installer."
    local installed_major
    installed_major=$(node -v | cut -d'v' -f2 | cut -d'.' -f1)
    if [ "$installed_major" -lt "$MIN_NODE_VERSION" ]; then
        echo -e "${RED}Installed Node.js $(node -v) is still below the required version.${NC}"
        echo -e "${YELLOW}Please upgrade Node.js manually to >= ${MIN_NODE_VERSION}.${NC}"
        exit 1
    fi
}

download_project_if_needed() {
    if [ -f "server/index.js" ]; then
        return
    fi

    echo -e "${YELLOW}Project files not found. Starting download...${NC}"
    ensure_tooling

    local temp_dir
    temp_dir=$(mktemp -d "${TMPDIR:-/tmp}/promdatapanel-install-XXXXXX")
    local temp_zip="${temp_dir}/promdatapanel_${VERSION}.zip"

    echo -e "${BLUE}Downloading ${DOWNLOAD_URL}...${NC}"
    curl -fL "$DOWNLOAD_URL" -o "$temp_zip"

    echo -e "${BLUE}Extracting files...${NC}"
    unzip -q "$temp_zip" -d "$temp_dir"

    local extracted_dir
    extracted_dir=$(find "$temp_dir" -mindepth 1 -maxdepth 1 -type d | head -n 1)
    if [ -z "$extracted_dir" ] || [ ! -f "$extracted_dir/server/index.js" ]; then
        echo -e "${RED}Download succeeded, but archive structure is invalid.${NC}"
        exit 1
    fi

    cd "$extracted_dir"
}

detect_runtime_user() {
    if [ "$EUID" -eq 0 ]; then
        REAL_USER="${SUDO_USER:-${USER:-root}}"
    else
        REAL_USER="${USER}"
    fi
}

write_service_file() {
    local node_path
    node_path=$(command -v node)
    if [ -z "$node_path" ]; then
        echo -e "${RED}Unable to locate node executable after installation.${NC}"
        exit 1
    fi

    local tmp_service
    tmp_service=$(mktemp "${TMPDIR:-/tmp}/${SERVICE_NAME}.service.XXXXXX")

    cat > "$tmp_service" <<EOF
[Unit]
Description=PromdataPanel Monitoring Dashboard
After=network.target mysql.service redis-server.service valkey-server.service
Wants=mysql.service

[Service]
Type=simple
User=${REAL_USER}
WorkingDirectory=${PROJECT_DIR}
ExecStart=${node_path} server/index.js
Restart=always
RestartSec=10
StandardOutput=journal
StandardError=journal
SyslogIdentifier=${SERVICE_NAME}
EnvironmentFile=-${PROJECT_DIR}/.env
Environment=NODE_ENV=production

[Install]
WantedBy=multi-user.target
EOF

    echo -e "${BLUE}Creating systemd service at ${SERVICE_FILE}...${NC}"
    sudo install -m 0644 "$tmp_service" "$SERVICE_FILE"
    rm -f "$tmp_service"
}

detect_os
download_project_if_needed
detect_runtime_user
install_node

PROJECT_DIR=$(pwd)
echo -e "Project Directory: ${GREEN}${PROJECT_DIR}${NC}"
echo -e "Running User:      ${GREEN}${REAL_USER}${NC}"

if [ ! -f ".env" ] && [ -f ".env.example" ]; then
    echo -e "${BLUE}Creating .env from .env.example...${NC}"
    cp .env.example .env
fi

echo -e "${BLUE}Installing NPM dependencies...${NC}"
npm install --production

write_service_file

echo -e "${BLUE}Reloading systemd and restarting service...${NC}"
sudo systemctl daemon-reload
sudo systemctl enable "$SERVICE_NAME"
sudo systemctl restart "$SERVICE_NAME"

echo -e "${BLUE}Checking service status...${NC}"
sleep 2
if sudo systemctl is-active --quiet "$SERVICE_NAME"; then
    echo -e "${GREEN}SUCCESS: PromdataPanel is now running.${NC}"
    PORT=$(grep "^PORT=" .env 2>/dev/null | cut -d'=' -f2 || true)
    PORT=${PORT:-3000}
    IP_ADDR=$(hostname -I 2>/dev/null | awk '{print $1}')
    if [ -n "${IP_ADDR:-}" ]; then
        echo -e "Dashboard URL: ${YELLOW}http://${IP_ADDR}:${PORT}${NC}"
    fi
else
    echo -e "${RED}FAILED: Service failed to start.${NC}"
    echo -e "Check logs with: ${BLUE}journalctl -u ${SERVICE_NAME} -xe${NC}"
fi

echo -e "${BLUE}================================================${NC}"
echo -e "${GREEN}Installation completed!${NC}"
echo -e "${BLUE}================================================${NC}"