# --- Function to check and install Docker ---
fn_install_docker() {
    echo "Checking for Docker..."
    if command -v docker &> /dev/null; then
        echo "Docker is already installed."
        docker --version
        return 0
    fi

    echo "Docker not found. Attempting to install Docker..."
    if [[ -x "$(command -v apt-get)" ]]; then
        echo "Attempting Docker installation for Debian/Ubuntu..."
        apt-get update -y
        apt-get install -y apt-transport-https ca-certificates curl software-properties-common gnupg lsb-release
        install -m 0755 -d /etc/apt/keyrings # Ensure keyring directory exists
        curl -fsSL https://download.docker.com/linux/$(. /etc/os-release && echo "$ID")/gpg | gpg --dearmor -o /etc/apt/keyrings/docker.gpg
        chmod a+r /etc/apt/keyrings/docker.gpg
        echo \
          "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.gpg] https://download.docker.com/linux/$(. /etc/os-release && echo "$ID") \
          $(lsb_release -cs) stable" | tee /etc/apt/sources.list.d/docker.list > /dev/null
        apt-get update -y
        apt-get install -y docker-ce docker-ce-cli containerd.io docker-compose-plugin || {
            echo -e "${red}Docker installation via apt failed. Trying convenience script...${plain}"
            curl -fsSL https://get.docker.com -o get-docker.sh
            sh get-docker.sh || {
                echo -e "${red}Docker installation failed. Please install Docker manually and re-run this script.${plain}"
                exit 1
            }
            rm get-docker.sh
        }
    elif [[ -x "$(command -v yum)" ]]; then
        echo "Attempting Docker installation for CentOS/RHEL..."
        yum install -y yum-utils
        yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo
        yum install -y docker-ce docker-ce-cli containerd.io docker-compose-plugin || {
            echo -e "${red}Docker installation via yum failed. Trying convenience script...${plain}"
            curl -fsSL https://get.docker.com -o get-docker.sh
            sh get-docker.sh || {
                echo -e "${red}Docker installation failed. Please install Docker manually and re-run this script.${plain}"
                exit 1
            }
            rm get-docker.sh
        }
    elif [[ -x "$(command -v dnf)" ]]; then
        echo "Attempting Docker installation for Fedora..."
        dnf -y install dnf-plugins-core
        dnf config-manager --add-repo https://download.docker.com/linux/fedora/docker-ce.repo
        dnf install -y docker-ce docker-ce-cli containerd.io docker-compose-plugin || {
            echo -e "${red}Docker installation via dnf failed. Please install Docker manually and re-run this script.${plain}"
            exit 1
        }
    else
        echo -e "${red}Unsupported package manager for Docker auto-installation. Trying convenience script...${plain}"
        curl -fsSL https://get.docker.com -o get-docker.sh
        sh get-docker.sh || {
            echo -e "${red}Docker installation failed. Please install Docker manually and re-run this script.${plain}"
            exit 1
        }
        rm get-docker.sh
    fi

    if ! systemctl is-active --quiet docker; then
        systemctl start docker
    fi
    if ! systemctl is-enabled --quiet docker; then
        systemctl enable docker
    fi
    echo "Docker installed and started."
    docker --version
}

# --- Function to check and install Docker Compose ---
fn_install_docker_compose() {
    echo "Checking for Docker Compose..."
    if docker compose version &> /dev/null; then
        echo "Docker Compose (plugin) is already installed."
        docker compose version
        return 0
    fi

    echo "Docker Compose (plugin) not found."
    echo "It's usually included with recent Docker Engine installations (as docker-compose-plugin)."
    echo "If Docker was just installed, it might already be there as part of docker-ce or docker-ce-cli."
    echo "Verifying if 'docker-compose-plugin' can be installed or is part of 'docker-ce-cli' update..."

    # Attempt to install or update packages that might include the compose plugin
    if [[ -x "$(command -v apt-get)" ]]; then
        apt-get install -y docker-compose-plugin docker-ce-cli || echo -e "${yellow}Attempt to install/update docker-compose-plugin via apt failed or already up-to-date.${plain}"
    elif [[ -x "$(command -v yum)" ]]; then
        yum install -y docker-compose-plugin docker-ce-cli || echo -e "${yellow}Attempt to install/update docker-compose-plugin via yum failed or already up-to-date.${plain}"
    elif [[ -x "$(command -v dnf)" ]]; then
        dnf install -y docker-compose-plugin docker-ce-cli || echo -e "${yellow}Attempt to install/update docker-compose-plugin via dnf failed or already up-to-date.${plain}"
    fi

    # Re-check after attempting plugin install
    if docker compose version &> /dev/null; then
        echo "Docker Compose (plugin) is now available."
        docker compose version
        return 0
    fi

    echo -e "${yellow}Docker Compose (plugin) still not found. Checking for legacy docker-compose (standalone)...${plain}"
    if command -v docker-compose &> /dev/null; then
        echo "Legacy docker-compose found."
        docker-compose --version
        echo -e "${yellow}Warning: Legacy docker-compose is deprecated. Consider upgrading your Docker setup to use the Docker Compose plugin (docker compose).${plain}"
        return 0
    fi

    echo "Attempting to install legacy docker-compose as a fallback..."
    LATEST_COMPOSE_VERSION=\$(curl -s https://api.github.com/repos/docker/compose/releases/latest | grep 'tag_name' | cut -d\\\" -f4)
    if [ -z "\$LATEST_COMPOSE_VERSION" ]; then
        echo -e "${red}Failed to fetch latest docker-compose version. Please install Docker Compose manually.${plain}"
        exit 1
    fi
    # Try common locations for Docker CLI plugins or general executables
    INSTALL_PATH1="/usr/local/lib/docker/cli-plugins"
    INSTALL_PATH2="/usr/libexec/docker/cli-plugins" # Original path in some setups
    INSTALL_PATH3="/usr/local/bin" # Common for general executables

    mkdir -p \$INSTALL_PATH1 && \
    curl -SL https://github.com/docker/compose/releases/download/\$LATEST_COMPOSE_VERSION/docker-compose-\$(uname -s)-\$(uname -m) -o \$INSTALL_PATH1/docker-compose && \
    chmod +x \$INSTALL_PATH1/docker-compose || \
    (mkdir -p \$INSTALL_PATH2 && \
     curl -SL https://github.com/docker/compose/releases/download/\$LATEST_COMPOSE_VERSION/docker-compose-\$(uname -s)-\$(uname -m) -o \$INSTALL_PATH2/docker-compose && \
     chmod +x \$INSTALL_PATH2/docker-compose) || \
    (curl -SL https://github.com/docker/compose/releases/download/\$LATEST_COMPOSE_VERSION/docker-compose-\$(uname -s)-\$(uname -m) -o \$INSTALL_PATH3/docker-compose && \
     chmod +x \$INSTALL_PATH3/docker-compose) || \
    {
        echo -e "${red}Failed to download and install legacy docker-compose in standard paths. Please install Docker Compose manually.${plain}"
        exit 1
    }

    # Check if installed version is now callable as `docker-compose` or `docker compose`
    if docker compose version &> /dev/null; then
        echo "Docker Compose (plugin) became available after legacy install attempt (possibly due to PATH or Docker restart)."
    elif command -v docker-compose &> /dev/null; then
        echo "Legacy docker-compose installed successfully."
        docker-compose --version
    else
        echo -e "${red}Failed to make legacy docker-compose command available. Please check your PATH or install manually.${plain}"
        exit 1
    fi
}

# --- Color definitions ---
red=''
green=''
blue=''
yellow=''
plain=''

# --- Main part of the new install script (draft) ---
main_install_logic() {
    echo -e "\${blue}3X-UI New Frontend Docker-based Installer\${plain}"

    # Check root
    [[ \$EUID -ne 0 ]] && echo -e "\${red}Fatal error: \${plain} Please run this script with root privilege" && exit 1

    # Install base dependencies
    echo -e "\${blue}Checking base dependencies (curl, tar, git)...${plain}"
    command -v curl >/dev/null 2>&1 || { echo >&2 -e "\${red}curl is required but it's not installed. Please install it first. Aborting.\${plain}"; exit 1; }
    command -v tar >/dev/null 2>&1 || { echo >&2 -e "\${red}tar is required but it's not installed. Please install it first. Aborting.\${plain}"; exit 1; }
    command -v git >/dev/null 2>&1 || { echo >&2 -e "\${red}git is required but it's not installed. Please install it first. Aborting.\${plain}"; exit 1; }
    echo -e "\${green}Base dependencies checked.\${plain}"

    # Install Docker and Docker Compose
    fn_install_docker
    fn_install_docker_compose

    # Define installation directory
    install_dir="/opt/3x-ui-docker"
    echo -e "\${yellow}3X-UI Docker setup will be located in: \${install_dir}\${plain}"
    mkdir -p "\$install_dir"
    cd "\$install_dir" || { echo -e "\${red}Failed to cd to \${install_dir}\${plain}"; exit 1; }

    # Clone or download the repository
    repo_url="https://github.com/MHSanaei/3x-ui.git" # User should replace with their fork if necessary
    repo_name="3x-ui-source" # Name of the directory for the cloned repo

    if [ -d "\$repo_name" ] && [ -d "\$repo_name/.git" ]; then
      echo -e "\${yellow}Repository directory '\$repo_name' found. Attempting to update...${plain}"
      cd "\$repo_name" || exit 1
      git pull origin \$(git rev-parse --abbrev-ref HEAD) || { # Pull current branch
          echo -e "${red}Failed to pull latest changes. Please check for conflicts or issues.${plain}"
          # Optionally, allow script to continue with existing code or exit
      }
      cd ..
    else
      echo "Cloning repository from \${repo_url} into '\$repo_name'..."
      rm -rf "\$repo_name" # Remove if it exists but isn't a git repo
      git clone --depth 1 "\$repo_url" "\$repo_name" || {
          echo -e "${red}Failed to clone repository. Please check the URL and your internet connection.${plain}"
          exit 1
      }
    fi

    # Navigate into the cloned repository directory where docker-compose.yml is expected
    cd "\$repo_name" || { echo -e "\${red}Failed to cd into repository directory '\$repo_name'.\${plain}"; exit 1; }

    # Ensure Dockerfile.backend and docker-compose.yml are present (they should be in the repo)
    if [ ! -f "Dockerfile.backend" ] || [ ! -f "docker-compose.yml" ]; then
        echo -e "${red}Critical Docker files (Dockerfile.backend or docker-compose.yml) not found in the repository root.${plain}"
        echo -e "${yellow}Please ensure these files are present. If you cloned an old version, try removing the '\$repo_name' directory and re-running the script to get the latest version.${plain}"
        exit 1
    fi
    # Ensure the frontend Dockerfile is present
    if [ ! -f "new-frontend/Dockerfile" ]; then
        echo -e "${red}Frontend Dockerfile (new-frontend/Dockerfile) not found.${plain}"
        echo -e "${yellow}The frontend might not have been prepared correctly in the repository.${plain}"
        exit 1
    fi


    echo "Creating data directories (db, cert) if they don't exist..."
    mkdir -p db
    mkdir -p cert

    echo "Creating/Updating .env file with default settings..."
    cat << EOF_ENV > .env
# .env for 3x-ui docker-compose
PANEL_NAME=3x-ui
FRONTEND_PORT=3000
BACKEND_PANEL_PORT=2053
XRAY_VMESS_AEAD_FORCED=false
XUI_ENABLE_FAIL2BAN=true
NEXT_PUBLIC_API_BASE_URL=http://backend:2053
# To access panel from host via browser using mapped port, use http://localhost:2053 or http://<server_ip>:2053
# If your backend has a base path (e.g. /xui), add it to NEXT_PUBLIC_API_BASE_URL: http://backend:2053/xui
# Ensure XUI_BASE_PATH (if used by Go backend) matches this.

# For Xray-core reality settings, you might need to specify domains/shortids, etc.
# These are not covered by default .env. User should add them if needed.
EOF_ENV
    echo ".env file created/updated."

    echo -e "\${blue}Building and starting services with Docker Compose... (This might take a while)${plain}"
    if docker compose up -d --build --remove-orphans; then
      echo -e "\${green}3X-UI services started successfully!\${plain}"
      echo -e "Frontend should be accessible at: http://<your_server_ip>:\${FRONTEND_PORT:-3000}"
      echo -e "Backend panel (API) is available at port: \${BACKEND_PANEL_PORT:-2053} (primarily for frontend access)"
      echo -e "To manage services, use 'docker compose' commands in '\$(pwd)' directory."
      echo -e "(e.g., \`docker compose logs -f backend\`, \`docker compose stop\`, \`docker compose down\`)"
    else
      echo -e "\${red}Failed to start services with Docker Compose. Please check logs above and Docker Compose logs (\`docker compose logs -f\` for details).${plain}"
      exit 1
    fi

    echo -e "\${green}Installation script finished.\${plain}"
}

# Note: To make this a runnable script, you would save fn_install_docker,
# fn_install_docker_compose, the color vars, and main_install_logic
# into a single install.sh file, then call main_install_logic at the end.
# Example:
# #!/bin/bash
# ... fn_install_docker ...
# ... fn_install_docker_compose ...
# ... color definitions ...
# ... main_install_logic ...
# main_install_logic
# exit 0
# This structure is for the agent to provide the components.
# The final assembly into a single install.sh is implicitly the next step if these blocks are approved.

echo "---------------------------------------------------------------------"
echo "NEW INSTALL.SH SCRIPT DRAFT COMPONENTS CREATED"
echo "(fn_install_docker, fn_install_docker_compose, main_install_logic)"
echo "---------------------------------------------------------------------"

# For the subtask, the output is the text above.
# The actual install.sh file in the repo is not modified by this tool directly yet.
# The agent will take these generated functions and structure to build the final install.sh.
# This is a way to output the bash code as requested by the subtask structure.
# The previous Dockerfile and docker-compose.yml are assumed to be in the repo root for the clone logic.
# The new-frontend/Dockerfile should also be in the repo.
# This script assumes it's run from a location *outside* the cloned repo directory initially,
# then it clones the repo into a subdirectory (e.g., /opt/3x-ui-docker/3x-ui-source) and Cds into it.
# The .env file and data volumes (db, cert) will reside in this cloned directory.