#!/bin/bash

# Script to install Docker on Ubuntu 24.04
# Must be run with root privileges

# Error handling
set -e
trap 'echo "Error on line $LINENO. Exit code: $?"' ERR

# Utility functions
log_message() {
    echo "[$(date '+%Y-%m-%d %H:%M:%S')] $1"
}

is_step_completed() {
    [ -f "/var/log/docker_install/$1" ]
}

save_checkpoint() {
    mkdir -p /var/log/docker_install
    touch "/var/log/docker_install/$1"
}

# Check if script is run as root
if [ "$EUID" -ne 0 ]; then 
    echo "Please run as root"
    exit 1
fi

# Check Ubuntu version
if ! grep -q "Ubuntu 24.04" /etc/os-release; then
    log_message "Warning: This script is designed for Ubuntu 24.04. Your version may differ."
    read -p "Do you want to continue? (y/N) " -n 1 -r
    echo
    if [[ ! $REPLY =~ ^[Yy]$ ]]; then
        exit 1
    fi
fi

# Remove old versions if exist
if ! is_step_completed "old_versions_removed"; then
    log_message "Removing old Docker versions if they exist..."
    for pkg in docker.io docker-doc docker-compose docker-compose-v2 podman-docker containerd runc; do
        apt-get remove -y $pkg >/dev/null 2>&1 || true
    done
    save_checkpoint "old_versions_removed"
fi

# Install prerequisites
if ! is_step_completed "prerequisites_installed"; then
    log_message "Installing prerequisites..."
    apt-get update
    apt-get install -y \
        ca-certificates \
        curl \
        gnupg \
        lsb-release
    save_checkpoint "prerequisites_installed"
fi

# Install Docker
if ! is_step_completed "docker_installed"; then
    log_message "Installing Docker..."
    install -m 0755 -d /etc/apt/keyrings
    curl -fsSL https://download.docker.com/linux/ubuntu/gpg -o /etc/apt/keyrings/docker.asc
    chmod a+r /etc/apt/keyrings/docker.asc

    echo \
      "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.asc] https://download.docker.com/linux/ubuntu \
      $(. /etc/os-release && echo "$VERSION_CODENAME") stable" | \
      tee /etc/apt/sources.list.d/docker.list > /dev/null

    apt-get update
    apt-get install -y docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin

    # Create docker user if not exists
    if ! id "dockeruser" &>/dev/null; then
        useradd -m -s /bin/bash dockeruser
        usermod -aG docker dockeruser
    fi

    save_checkpoint "docker_installed"
fi

# Verify installation
if ! is_step_completed "installation_verified"; then
    log_message "Verifying Docker installation..."
    if ! docker run hello-world > /dev/null; then
        log_message "Error: Docker installation verification failed"
        exit 1
    fi
    save_checkpoint "installation_verified"
fi

# Configure Docker to start on boot
if ! is_step_completed "docker_configured"; then
    log_message "Configuring Docker..."
    systemctl enable docker.service
    systemctl enable containerd.service
    save_checkpoint "docker_configured"
fi

# Set up Docker daemon configuration
if ! is_step_completed "daemon_configured"; then
    log_message "Setting up Docker daemon configuration..."
    mkdir -p /etc/docker
    cat > /etc/docker/daemon.json <<EOF
{
    "log-driver": "json-file",
    "log-opts": {
        "max-size": "100m",
        "max-file": "3"
    },
    "default-address-pools": [
        {
            "base": "172.17.0.0/16",
            "size": 24
        }
    ]
}
EOF
    save_checkpoint "daemon_configured"
fi

# Restart Docker to apply changes
if ! is_step_completed "final_restart"; then
    log_message "Restarting Docker service..."
    systemctl restart docker
    save_checkpoint "final_restart"
fi

log_message "Docker installation completed successfully!"
log_message "Docker version: $(docker --version)"
log_message "Docker Compose version: $(docker compose version)"
log_message "Docker user 'dockeruser' has been created and added to the docker group"
log_message "You may need to log out and back in for group changes to take effect"